Plants for the Future Flashcards

Question

What are some examples of Plant derived pharmaceutical products - PDPs

Answer 1

Avidin and Beta-Glucuronidase enzymes in diagnostic kits Trypsin enzyme in pharmaceuticals ZMAPP Ebola vaccine made in tobacco plants

Answer 2

Controversial links to tobacco industry Despite passing trials

Answer 3

Easy to engineer Efficient transformation/generation process Not a food product

Answer 4

Production scale and economy - Keeping cells alive more expensive than plants Product safety - Reduced contamination Ease of storage and distribution - Seeds Opportunity for low cost drugs and vaccines - Edible plants? No need for purification

Answer 5

Consistent quality? - Natural variation and growth/soil/weather condition inconsistencies Differences in post-translational modification - Plant vs animal/microbe antibodies may be finished differently - Eg N-glycosylation - May have consequences for activity of end product Entry into food chain - Especially if food plants used

Answer 6

Currently predominantly from maize (US) and sugarcane (Brazil)

Answer 7

High sugar - accumulation of sucrose in shoots - easy to extract - for conversion to glucose and fructose for yeast based fermentation into ethanol

Answer 8

High starch - breakdown into glucose for same process

Answer 9

Cell walls contain lignin Lignocellulose difficult and expensive to breakdown

Answer 10

Increasing cellulose content - Increase ethanol yield Reduce lignin content/change lignin composition - Improve degrading enzyme access Express cell wall degrading enzymes in plants - Improve cell wall digestion - switched on at harvesting

Answer 11

- Don’t compete with crops for space - Don’t have lignin

Answer 12

- Identify suitable algae strains - Achieve both high oil content and high biomass productivity

Answer 13

Grow algae: Cultivate algae in ponds or photobioreactors Harvest algae: Centrifugation or filtration. Extract oil: Separate the oil from the algae cells using solvents - mechanical pressing Transesterification: React the extracted oil with an alcohol and a catalyst to produce biodiesel and glycerin.

Answer 14

Organism accumulates oil as an energy reserve Breaks down the oil to use it for energy Blocking the breakdown process - can maintain a high oil content

Answer 15

- Reduced expression of gene for lipase enzyme - Reduced lipid breakdown - Increased lipid content - No effect on cell growth - Massive increase in lipid content per cell

Answer 16

Milled - removes nutrient rich embryo and aleourone parts

Answer 17

Expense of nutrient rich pulse/legume farming

Answer 18

Increase plant nutrient content pre-harvest Foods fortified with vitamins and minerals post harvest

Answer 19

Agronomic - using fertiliser Genetic - selective breeding Transgenic - genetic engineering

Answer 20

Beta-carotene - pro-vitamin A Converted to vitamin A in human body Genes to synthesise added to rice - Mitigating vitamin A deficiency

Answer 21

Soil nutrient availability Assimilation efficiency into plants Sequestration into grain or other consumed part Bioavailability during consumption

Answer 22

30% Impairs development and immune system

Answer 23

30% Goiter disease

Answer 24

Can cause low fertility (men) Increased cancer risk

Answer 25

- can lead to osteomalacia or osteoporosis

Answer 26

Genes to - Increase mineral accumulation in roots - Increase transfer to edible tissues - Increase storage - Increase assimilation efficiency

Answer 27

The rhizosphere is the region of soil that surrounds and is influenced by the roots of plants.

Answer 28

Pool of dissolved nutrient ions that are available for root uptake

Answer 29

Soil pH affects nutrient bioavailability, with a low pH typically increasing availability.

Answer 30

area of soil immediately surrounding roots where nutrient availability is reduced due to uptake by the plant.

Answer 31

- by elongating and exploring their root hairs - Actively lowering the surrounding soil pH to increase nutrient availability.

Answer 32

releasing protons or carbon dioxide - Lower the surrounding soil pH - displace positively charged iron ions from negatively charged soil particles

Answer 33

- Increased levels of Fe - Reduced growth and tillers - No significant increase of Fe in rice grain

Answer 34

- Better growth in low Fe conditions - More grains per plant - No significant increase in grain iron content

Answer 35

Higher food demand - increasing population Climate change Decreased biodiveristy

Answer 36

A good thing

Answer 37

Availability - already a problem Access Affortability Quality

Answer 38

No party no problem

Answer 39

More meat consumption More energy and land

Answer 40

Increasing population Changing diets Reduced arable land Climate change

Answer 41

Changes where and when crops can be grown - due to Rising CO2 - temp increase - drying out

Answer 42

Yes, at high latitudes - increased temperature are predicted to give better yields

Answer 43

Orphan (or minor) crops are those crops which are typically not traded internationally but which can play an important role in regional food security - received little attention from crop breeders and researchers

Answer 44

Not tropism Response to non-directional stimulus/in a direction largely independent of stimulus (eg touch)

Answer 45

Not studied or bred so they have potential to provide increase yields

Answer 46

Not studied or bred so they have potential to provide increase yields

Answer 47

Nastic response of a plant to touch or vibration

Answer 48

A nastic movement that is associated with changes in temperature

Answer 49

Don't bother - meat eating plant

Answer 50

- Touch translated into action potentials - 2 required for closure - Moving trapped prey elicits lots of APs - Triggers release of lytic enzymes

Answer 51

Roots growing directionally based on gravity + for roots - for shoots

Answer 52

Thigmotropism Phototropism Hydrotropism Thermotropism Chemotropism

Answer 53

- Controls cell elongation - Controls response to tropism - Mr tropism if you will

Answer 54

Yes, before dawn plants begin to move in anticipation of rising sun

Answer 55

- Release VOCs - Plants express defensive mechanisms when neighbouring plants are attacked - Attract carnivorous insects that prey on the herbivores

Answer 56

- Action potential generated after herbivore feeding - Signals produced near site of attack - Spreads to nearby leaves - Sites receiving signals initiated defence gene expressions

Answer 57

- Structurally similar to receptors involved in rapid excitation of nervous system - Implies emergence before plant animal divergence

Answer 58

An individual possessing four times the chromosomes in a haploid organism

Answer 59

Generally more resistant to drought, disease ect.

Answer 60

- Messier organisation - Harder to use agriculturally

Answer 61

- Hunter gatherers - Subject to seasonal food shortages - Started looking after wild plants for better yield

Answer 62

- 10,000 years ago - Reduced the effects of food shortages - Surplus could be stored over winter - Supported larger populations

Answer 63

Dryer climate - more annual plants

Answer 64

- Early humans gathered nutritious roots and seeds for their food - Such plants actively colonized the bare areas around their dwellings - Were rich with the discarded rubbish.

Answer 65

- Areas where wild relatives occur are likely sites of original domestication - Great amount of natural variation - Linguistic cues Since - Archaeology - DNA/phylogenetics

Answer 66

Similar types of plants in different region - each fill a different nutritional niche Cereals (lysine deficient) Beans/pulse (methionine deficient) Fibres, fruits, tubers

Answer 67

- Between Iraq, Iran and Turkey - Wet climate, mostly grassland

Answer 68

- Non-brittle seed head phenotype in domesticated - Seeds remain attached - Easier to harvest - Must be threshed to release seeds

Answer 69

- 1 mutation - Present but rare in wild populations - Prevents seed dispersal - Selected for by early farmers

Answer 70

- Farmers selected for fast germination - Shorter dormancy

Answer 71

- Loss of seed dispersal - Loss of seed dispersal aids - Increase in seed size - Loss of sensitivity to environmental cues for determination - Synchronous ripening of seeds/fruits - Compact growth habit

Answer 72

Mutation in early domestication Seeds remain attached to mature ear - much easier to harvest

Answer 73

Larger grain surviving deeper burial - confused - allowing farmers to cultivate them in a wider variety of climates and seasons - bred to depend more on human intervention for propagation

Answer 74

- Selected for plants of smaller size and shape using harvesting methods

Answer 75

Farmers knew what they wanted and achieved domestication in a few generations

Answer 76

- Monophyletic origin and fast domestication model - Domestication occurred in a few generations due to low frequency of mutations in the wild - Early farmers knew what they wanted and achieved domestication in a short period of time - Selection was not necessarily purposeful but early farmers placed selection pressure on plants - Crops were disseminated from their area of origin.

Answer 77

- Independent multiple domestications model - Agriculture arose independently in different regions of the world - Occurred over a long period of time, as people gradually learned to cultivate and select for desirable traits in plants - Rather than relying on chance mutations or unintended selection pressures - Domesticated crops were adapted to local conditions and environments

Answer 78

- Model 2 suggests that harvesting techniques indirectly selected for the non-brittle character - as crops with brittle stalks would be more difficult to harvest and process

Answer 79

Model 2 suggests that harvesting techniques indirectly selected for the non-brittle character, as crops with brittle stalks would be more difficult to harvest and process.

Answer 80

Model 1 - suggests neolithic farmers may have overlooked the presence of the non-brittle character in their crops, as they may not have been intentionally selecting for it Model 2 - suggests that farmers may have actively selected for the non-brittle character

Answer 81

Presence of large quantities of wild barley at Ohalo 11 (Isreal) - suggests that the stored wild barley was collected in the wild - supports Model 1

Answer 82

- Potential to add new genes in to the current domesticated populations - Important not to release GM crops in these areas spoiling natural diversity by outcompeting wild plants - Future of crop domestication research

Answer 83

- A centre is where a wild ancestor can be found - Crossing into the crop can be valuable for resistance genes - Source of genes for new traits

Answer 84

- non-brittle phenotype - seeds remain attached, must be thrashed to release - easier harvest - Single gene mutation - Found in domesticated plants - Wild-type - seeds detach at maturity, fall on ground

Answer 85

Wildtype - seeds detach at maturity, fall on ground

Answer 86

- Truncation mutation - loss of hydrophobic region Leu-Pro substitution - signal not passed on - New mutation could potentially have implications for plant breeding and crop improvement.

Answer 87

- pauses, took time to adapt to climate to move North 800-1,000 years - Or populations didn’t require agriculture - Or geographical barriers

Answer 88

- Undomesticated barley flowers in response to day length - Increasing day length promotes flowering UK barley - late flowering - harvest late June Doesn’t respond to day length Adaptation to temperate season - Lower temperature and moisture availability for seed production

Answer 89

Ppd-H1 responsive to day length ppd-H1 non-responsive Single mutation between Ppd-H1 and ppd-H1 Wild plants with mutant ppd-H1 occur in modern Israel and Iran

Answer 90

Increased fruit size Loss of husk Increased flower number Optimal flowering time Loss of fruit abscission

Answer 91

Lost genes such as - Wild salt resistance - Resistance to pathogens

Answer 92

- Manipulate existing genes - Introduce novel/foreign genes (from a different organism)

Answer 93

Overexpression of wildtype genes Gene silencing - switch off specific genes

Answer 94

Eg. silencing CaMCMT1 mRNA in coffee plants for low caffeine

Answer 95

- For enhancement of existing characteristics - For completely novel characteristics

Answer 96

Expression of insecticidal toxins encoded by CRY genes from Bacillus thuringiensis (bacteria) into cotton plants

Answer 97

Eg introduction of bacterial gene for tolerance to TNT explosive Tobacco plants expressing nsfl (NR 3-2) can grow on medium containing TNT and detoxify it (into ADNT)

Answer 98

Precision editing tool Various enzymes - molecular scissors Produce Double Strand DNA breaks to introduce site specific mutations CRISPR-Cas - uses RNAs to target nucleates and introduce site specific mutations, insertions or deletions

Answer 99

Agrobacterium-mediated gene transfer Microprojectile bombardment Viral vectors Protoplasts Microinjection Electroporation

Answer 100

- Highly effective - Lower copy numbers - Works better on dicot plants than monocots

Answer 101

- Easy and effective - random integration - high copy numbers - used with a wide range of plants

Answer 102

Not very effective; limited to hosts

Answer 103

Regeneration problems

Answer 104

Tedious and slow

Answer 105

Large foreign DNA; high efficiency; regeneration problems

Answer 106

Genome edited plants becoming exempt from GMO regulations

Answer 107

Gene(s) to be transferred - transgene Host cell/tissue in which gene expressed Mechanism of transfer Method of regulation and selection

Answer 108

Gram -ve rod shaped soil bacteria (rhizosphere) Causal agent of crown gall tumours

Answer 109

- Agrobacterium transfers T-DNA into plant cells using T-complex - T-DNA then integrated into plant genome - T-DNA may contain genes that code for auxin and cytokinins - Causes cell proliferation and the growth of a gall or tumor-like structure on the plant. - Also contain genes that code for the synthesis of opines - Can serve as a food source for Agrobacterium

Answer 110

- Plasmid in Agrobacterium responsible for Auxin and cytokine production

Answer 111

Appropriate promoter - Eg CaMV 35S for overexpression Selectable markers for identification - Eg antibiotic resistance gene Plant needs to recognise gene to translate - Differences in UTR may prevent recognition

Answer 112

- Coat small metal particles (non toxic, heavy eg gold, tungsten) in DNA - Insert into particle gun Some cells killed but number will survive and take up DNA

Answer 113

- Identify suitable explant (e.g. leaf piece) - Co-cultivate with Agrobacterium or DNA bombardment - Kill Agrobacterium with suitable antibiotic which does not harm plant - Select for transformed plant cells (use selectable marker) - Regenerate whole plants

Answer 114

Very slow process

Answer 115

- Dip flowers into solution containing Agrobacterium and a surfactant (a detergent) - Helps the bacteria adhere to the plant tissue - Plants develop and set seed - Select for transgenic plant cells - Using selectable marker (allows the identification of cells that have taken up the foreign DNA)

Answer 116

Low success rate Doesn’t really matter because so many seeds

Answer 117

- Transform developmental genes in along with target transgene - reporter gene above blocks chlorophyll - no green in transformed cells - Produce seedling on plant to be replanted like a cutting

Answer 118

Nuclear and chloroplast genome can be manipulated Mitochondrial genome not manipulable

Answer 119

- Precise insertion - High level of expression - Lots of copies - Coordinated expression of multiple genes - Gene containment

Answer 120

Avoids gene flow to other plants Not transmitted through pollen Maternal inheritance Prevents GM gene escape to non GM plants

Answer 121

Many studies by biotech companies involved in commercialisation of GM - conflict of interest concern

Answer 122

Pathogens Pest damage Wounding (physical damage) ROS (reactive oxygen species) -> oxidative stress - produced by metabolic activity

Answer 123

Heat Chilling Freezing Drought Salinity

Answer 124

Drought Salinity Flooding Heavy metals

Answer 125

Organic carbon compounds released into the soil

Answer 126

- High molecular weight carbon compound - Thick, slimy substance that is produced by certain plants and microorganisms - Composed of long-chain carbohydrates

Answer 127

Help the plant retain moisture Protect against desiccation Aid in seed dispersal

Answer 128

Root cap cells and epidermal cells

Answer 129

Organic acids, phenolics, phytosiderophores

Answer 130

- Ferric chelate reductases (FCRs) in root cells reduce Fe3+ to Fe2+ using NADPH as an electron donor - Fe2+ passes through IRT1 transporters that have a high affinity for Fe2+ - Upregulated under conditions of Fe deficiency.

Answer 131

sequestered in ferritin, a protein that stores Fe2+ ions in a nontoxic form in cells.

Answer 132

Small organic molecules Produced in certain grass species (barley and maize) Response to Fe deficiency Form Fe-PS complexes with Fe3+ Allow uptake by transporters

Answer 133

Root exudates of Fe deficient grass species.

Answer 134

Made from methionine Converted into nicotianamine by NAS (nicotianamine synthase) Converted into phytosiderophores

Answer 135

excretes higher levels of phytosiderophores

Answer 136

- Bottleneck in iron seed partitioning (Iron not reaching grain) - Nicotianamine (NA) regulates iron distribution in the phloem and movement to the seed - Overexpression of NA biosynthesis genes can increase iron content in rice grains

Answer 137

Increase expression of NAS to produce better iron mobilisation into phloem

Answer 138

HvNAAT-A and B

Answer 139

2-3 fold increase

Answer 140

Increased Fe content of grain 4 fold

Answer 141

Fe storage protein Prevents anaemia and iron deficiency

Answer 142

Ferritin expressed in seed endosperm and subaleurone 2-3 fold increase in Fe content

Answer 143

Different chemical forms, binding to different organic or non organic forms - may inhibit transfer across membranes Can be as low as 5% for most plant sources of iron Can vary due to presence of ‘antinutrients’ - compounds that reduce absorption

Answer 144

Negative charge binds positive ions and interferes with assimilation - considered an "antinutrient" - binds minerals - forms insoluble complexes that are not easily absorbed by the body.

Answer 145

Break down metal-phytate complexes - Release positively charged free metals (such as calcium, zinc, iron and mg) - Increasing bioavailability of these minerals

Answer 146

Storage form of phosphorus

Answer 147

Plants with a combination of GM genes which increase iron content in their edible tissues

Answer 148

- risk of increasing accumulation of toxic metals (eg Cd) - Expression worse in certain rice species - More extensive field trials required - test yield - Human feeding trials needed

Answer 149

Expression of nicotianamine synthesis enzymes Expression of Fe-NA (YSL2) transporter Expression of ferritin

Answer 150

Improved long distance transport

Answer 151

Increases transfer into rice grain

Answer 152

Improved Fe storage in grain

Answer 153

Reduces soil water potential Effects large amounts of farmland Reduces yield

Answer 154

Normal conditions - cell surrounded by water containing solutes -> Ice formation begins - Formation of ice decreases water potential outside the cell -> Ice formation continues - Higher solute concentration outside the cell draws water out causing dehydration and cell death

Answer 155

Water potential MPa

Answer 156

Water potential = solute potential + pressure potential

Answer 157

Concentration of solutes dissolved in water

Answer 158

low to high

Answer 159

Physical forces exerted by water on cell membrane and cell wall

Answer 160

When water pressure potential is high (high water status) water enters the cell causing the cell to become turgid

Answer 161

Water leaves cells - turgor is lost - cells become flaccid - Plant wilts

Answer 162

Reversible effects Leaf wilting Declined photosynthetic rates - stomata closed to reduce water loss - reduced CO2 uptake Reduced cellular/metabolic activity - as energy from photosynthesis is required

Answer 163

- Not reversible - Leaf abscission - Cellular toxicity - Ion cytotoxicity - Due to loss of water = < concentration of cellular contents - Severely inhibited photosynthesis and respiration

Answer 164

Seeds Viable seeds can be recovered even after long term water deficit

Answer 165

Altered Na+:K+ ratios Increased NA+ and Cl- Na+ rapidly enters root cell Causing negative membrane potential

Answer 166

Via non-selective channels and K+ transporters - Outcompetes K+ for uptake Na+ cytotoxic - Many enzymes sensitive - denature K+ essential for plant function

Answer 167

Osmoprotectants - Metabolites and molecules involved in protecting cell components from water stress effects - Stress-responsive transcriptional regulation - Osmoregulation via ion/water transporters - Water use efficient carbon fixation

Answer 168

Xerophytes - Thickened cuticles - Reduce water loss - Reduce leaf breakage from wilting - Shiny cuticles - Reflect light and heat - Trichomes (leaf hairs) - Trap damp air above stomata - Reflect light - Sunken stomata - Small/no leaves - Reduces surface area and water loss

Answer 169

- Increased storage ability of water Specialised organs - Enlarged cells - High volume vacuoles Organ can be roots, stems, leaves Low transpiration Thick cuticles

Answer 170

Modified photosynthesis and carbon fixation Such as CAM and the C4 photosynthetic pathways

Answer 171

Improve water use efficiency

Answer 172

Protect against osmotic stress induced by water deficit - abundant in stress-tolerant plants and microbes - non-toxic compounds - do not disrupt hydration shell around the cell

Answer 173

Gives stunted growth Energy intensive production - high metabolic demand

Answer 174

Confers stress tolerance

Answer 175

TPS and TTP enzymes

Answer 176

Using inducible promoters to control expression Rice rbcS promoter - Specific to chloroplasts of leaf mesophyll cells - Allows expression of TPSP (TPS and TPP fused together) - only in chloroplasts of certain cells - limiting energy demand through synthesis of trehalose

Answer 177

ABA-inducible promoter - activated during water deficit stress - ensures energy-intensive production of trehalose is only triggered when the plant is under stress

Answer 178

- Small organic molecules protect cells from osmotic stress (high salt concs) Functions - Molecular chaperones = stabilise and protect conformation of proteins, RNAs and cell membranes

Answer 179

Proteins - Heat shock proteins – HSPs - Cold shock proteins – CSPs

Answer 180

CspB - RNA chaperone from Bacillus subtilis Expression of CspB in various plants has shown increased tolerance to cold treatment, heat treatment and drought treatment

Answer 181

Commercialised CspB transgenic maize in 2010

Answer 182

Hormone abscisic acid (ABA) - Stress hormone - Synthesised in response to environmental stress - Particularly water deficit - Drought, salinity, freezing, cold

Answer 183

Osmoprotectants Molecular chaperones/stabilisers - Heat and cold shock proteins Movement of water and ions - Aquaporins, ion channels Oxidative stress responses

Answer 184

Peroxidase, superoxide dismutase - Reactive oxygen species accumulate and lead to cellular damage - Enzymes that scavenge ROS control indirect stresses

Answer 185

Sugars, proline, glycine betaine

Answer 186

There are 3 response pathways to drought stress, 2 ABA dependant and 1 ABA independent pathways?

Answer 187

- Signal transduction ABA or ABA-independent - in gene promoter regions - Activate gene expression for stress response and tolerance - Increasing transcription factor abundance may increase size of the response - enhancing drought resistance

Answer 188

Drought tolerance increased with no deleterious effects on growth or development in normal conditions

Answer 189

An ABA inducible transcription factor - allows for rapid drought response

Answer 190

Dependant on gradient Increasing abundance does nothing if the gradient isn't present

Answer 191

- Makes it harder for cells to take up water - When it gets into cells, sodium very toxic

Answer 192

Helps reduce salt accumulation in plant cells - can improve plant growth and survival in high-salt conditions

Answer 193

agrobacterium-mediated transfer

Answer 194

Grow well in high-salt conditions without the fruit taking up salt

Answer 195

Xylem connection not there

Answer 196

SOS1 (out of the cell) NHX1 (into the vacuole) - use proton gradients for transport Active transport using ATP or pyrophosphate dependant

Answer 197

Improves both salt and drought tolerance - allows maintenance of salt gradient and water concentration

Answer 198

Allows maintenance of salt gradient and water concentration

Answer 199

Process by which plants fix carbon dioxide while minimizing water loss through stomata.

Answer 200

boptiboop you should really know this by now

Answer 201

ability of guard cells to change their size and shape in order to regulate the opening and closing of stomata.

Answer 202

regulated by both the water status of the plant and the availability of carbon dioxide

Answer 203

Stomata close when the demand for carbon dioxide is low - such as at night.

Answer 204

C4 photosynthesis and CAM (Crassulacean Acid Metabolism) - alternative forms of photosynthesis used by some plants to reduce water loss.

Answer 205

The C3 pathway is a type of photosynthesis Ribulose 1,5-bisphosphate is carboxylated by Rubisco to give 3-phosphoglycerate.

Answer 206

- Enzyme that catalyzes the first step of the Calvin cycle - It carboxylates Ribulose 1,5-bisphosphate

Answer 207

- series of reactions in the C3 pathway of photosynthesis that converts carbon dioxide into triose phosphates - can be used to synthesize sugars and other organic molecules

Answer 208

- used to synthesize sucrose - transported to other parts of the plant for energy storage

Answer 209

- C3 plants in which Rubisco uses oxygen instead of carbon dioxide - resulting in the production of toxic 2-phosphoglycolate - which must be recycled back into the Calvin cycle at the cost of energy - net loss of one carbon dioxide molecule.

Answer 210

bababadoii

Answer 211

carbon dioxide is first fixed into a four-carbon compound before being converted into triose phosphates in the Calvin cycle.

Answer 212

- Separation of Rubisco - Thick bundle sheath cell walls - No air spaces between their mesophyll and bundle sheath cells

Answer 213

Rubisco never sees oxygen - Continually exposed to saturating CO2 concentrations - Prevent CO2 loss

Answer 214

- CO2 taken up by outer mesophyll cells next to air space - O2 insensitive enzyme PEP carboxylase generates oxaloacetate - 4 carbon molecule - converted to malate Malate is decarboxylated releasing CO2 into a different cell - CO2 assimilated by rubisco in bundle sheets cells

Answer 215

allows C4 plants to efficiently use CO2 - particularly in environments where CO2 levels are low or fluctuating - photorespiration can be a significant energy drain

Answer 216

- transported back to mesophyll cells - converted into PEP (recycled)

Answer 217

More water efficient - All CO2 converted - Stomata need to open less - When stomata closed, all CO2 in air space can be utilised

Answer 218

Arid climates

Answer 219

Difficult because it is a multigenic trait - but has evolved independently multiple times Some plants have use both pathways so very possible

Answer 220

Xerophytes

Answer 221

- Photosynthesis and carbon fixation separated temporally - Stomata open at night when water loss lowest - Convert CO2 to malate as storage form - Stored in vacuoles until day - Closed stomata, photosynthesis using stores during day

Answer 222

Vernalisation is a process whereby plants require a period of cold exposure to switch from vegetative growth to reproductive growth

Answer 223

- helps distinguish between autumn and spring - Tracking photoperiod alone is not enough as the days are equal in length in autumn and spring

Answer 224

Winter wheat is cold-tolerant and can be sown in autumn - whereas spring wheat cannot tolerate cold

Answer 225

- needs to go through the vernalization process first - requires a prolonged period of cold temperatures

Answer 226

Discovered that planting winter wheat in spring did not work unless the seeds were germinated under artificial cold - stupid man rejected mendelian genetics - held Russian science back for years

Answer 227

- mostly in the apical meristem

Answer 228

photoperiod to regulate flowering.

Answer 229

Yes, the longer a winter plant is exposed to cold, the greater the number of flowers it will produce (remain vernalized).

Answer 230

where the species evolved - specific to a plant species environment

Answer 231

- Vernalization is the process of lifting repression to flowering by cold treatment - Cold acclimation is the process of preparing a plant for cold temperatures

Answer 232

neutral for spring/summer annuals that germinate in spring

Answer 233

- flower late without it - without it, will not undergo the molecular changes needed to initiate flowering - the plant remains in a vegetative state and does not switch to reproductive growth.

Answer 234

Including reduced yield Delayed harvest Even plant death in some cases

Answer 235

- required period of cold exposure for some biennial plants (harvested after two years) to ensure successful flowering and seed production - Without it, these plants will not flower at all

Answer 236

- Prolonged cold leads to remodelling of the FLC chromatin and accumulation of histone modifications - leading to the gene being inaccessible to the transcription factor

Answer 237

- Inhibits flowering by preventing dimerisation of FT and FD unless cold exposure is sufficient - Represses expression of floral meristem genes such as AP1

Answer 238

In shoot apex - Also occurs in leaf where inhibition is more direct

Answer 239

- A gene that increases the expression of FLC - thereby delaying flowering until the plant has undergone sufficient vernalization.

Answer 240

- FRI and FLC - leading to adaptive changes in different ecotypes/accessions

Answer 241

Cold independence has evolved twice in Arabidopsis

Answer 242

Vernalization process - which allows plants to flower after a period of cold exposure

Answer 243

They can't afford to flower when it's not spring - so they play it safe by requiring a long period of cold - sometimes means they won't flower at all

Answer 244

Allelic variation in the FRI and FLC genes.

Answer 245

as photoperiod may not be suitable in their current location.

Answer 246

allows the buds to survive cold temperatures and ignore warm winter spells. - If buds opened during a warm spell, a subsequent freeze would kill them.

Answer 247

- Regulates vernalization - Level of expression determines how long a plant needs to be exposed to cold temperatures before it can flower

Answer 248

including - photoperiod - temperature - plant age - soil nutrients - stress

Answer 249

Responses - Elongate stem - Space leaves - Induce early flowering - Angling leaves up - Dependent on species

Answer 250

Stem elongation Petiole elongation Hyponasty Reduced branching

Answer 251

- Increased SLA (Specific Leaf Area) - Ratio of leaf area to leaf mass - Reduced CHl a:b ratio - Increased PSII:PSI ratio - High physical defence

Answer 252

- Plants with a lower Chl a:b ratio tend to be adapted to low-light conditions - Chlorophyll b absorbs light in the green part of the spectrum that is less available under low light

Answer 253

- Adapted to high-light conditions - as PSII is more effective at capturing light energy in bright sunlight.

Answer 254

Alpine ecotype stay small and dispersed - Being tall disadvantageous - exposed Prairie ecotype - lots of competition - SAS

Answer 255

Elongation at expense of harvestable organs

Answer 256

Inhibition of elongation responses to neighbours may enhance harvest index - more carbon allocated to harvestable organs

Answer 257

harvested/total biomass

Answer 258

Chlorophyll does not absorb far red >700nm Far red comes through in neighbour shade Elongation precedes mutual shading - anticipation

Answer 259

Phytochrome

Answer 260

- Absorbs light in the red and far-red regions of the electromagnetic spectrum - Phytochrome exists in two forms: the inactive form (Pr) and the active form (Pfr). - Absorbs red light, phytochrome converted from Pr to Pfr - Conversion triggers a variety of responses in plants. - Pfr is able to detect far-red light, and when it absorbs far-red light, it is converted back to Pr

Answer 261

Phytochrome (in its active Pfr form) can interact with other nuclear proteins to regulate gene expression.

Answer 262

PREs are specific DNA sequences that Pfr can bind to in the nucleus to activate or repress transcription of target genes.

Answer 263

Phosphorylation and dephosphorylation - can affect the stability and interaction of phytochrome with other proteins

Answer 264

If Pfr is not dephosphorylated in the nucleus - recognized by the 26S proteasome and degraded - leading to a decrease in its activity.

Answer 265

There are five members in the phytochrome family

Answer 266

PhyA responds to far-red light.

Answer 267

Red and white light

Answer 268

PhyC, PhyD, and PhyE play roles in regulating responses to red and far-red light.

Answer 269

A mutant with no PhyB shows a reduced shade avoidance response compared to wild-type plants.

Answer 270

PIFs (Phytochrome Interacting Factors) are a family of transcription factors that promote shade response genes.

Answer 271

targets them for degradation by the proteasome, inhibiting shade response.

Answer 272

In the presence of more far-red light than red light, there is less Pfr and more Pr, resulting in less Pfr in the nucleus.

Answer 273

When Pfr is low, PIFs can bind to the promoter region of shade response genes and activate their expression - leading to a shade response, even though some Pfr is still present but not enough to inhibit PIFs

Answer 274

Flowering, seed germination, foliage expansion

Answer 275

- GM increased the total amount of phytochrome - Therefore, increased the amount of Pfr entering in the nucleus in the shade condition - blocking the SAS response In potatoes, alleviates density effects on crop yield

Answer 276

- More susceptible to drought - Increased phytochrome increased density of stomata - More water loss

Answer 277

Shade tolerant Alpine plants

Answer 278

to coincide with the presence of pollinators and to avoid competition with other plants for pollinators - important for successful pollination and seed development.

Answer 279

Climate change can disrupt flowering time by altering temperature and precipitation patterns. - wheat cultivation will move north

Answer 280

- plant stops making leaves and starts making stems and flowers instead - occurs in the meristem, which is the tissue where the plant growth occurs.

Answer 281

The apical vegetative meristem makes leaves indefinitely - but upon flowering induction - it transitions to the floral meristem The floral meristem stops making leaves and starts making flowers, and then eventually stops growing altogether.

Answer 282

Shamabaalalalalalalalalalsalalallad

Answer 283

A plant whose flowering is not affected by the photoperiod.

Answer 284

A plant that only flowers on long days - typically found in Europe Eg. spinach, wheat, Arabidopsis, sugar beets.

Answer 285

A plant that only flowers on short days - typically found in equatorial regions Eg. rice, maize, coffee, cannabis

Answer 286

Photoperiodism is the ability of plants to flower in response to the duration of light exposure - it is a reliable parameter of season at high latitudes but not at low latitudes.

Answer 287

Florigen - travels from the leaf to the apical meristem in plants.

Answer 288

- FT is the gene that produces the FT protein - enters the vascular system of the plant - travels to the apical meristem to initiate flowering

Answer 289

Phytochrome photoreceptor molecule in the leaf that senses light to measure day length and activate the FT gene - response to phytochrome-mediated detection of day length in leaves

Answer 290

Covering one leaf with aluminum foil blocks the leaf from sensing light and activates the FT gene - leading to production of the FT protein and induction of flowering.

Answer 291

The florigen produced in the covered leaf travels through the phloem and induces flowering in the recipient plant's apical meristem.

Answer 292

- Travels through phloem to the apical meristem - associates with the FD transcription factor - forming a dimer that activates the AP1 gene - master switch for flowering.

Answer 293

explains how the FT protein knows when to be expressed - It requires the coincidence of high levels of CO protein and light, hence the name coincidence model.

Answer 294

controls the timing of light-sensitive and light-insensitive phases - internal mechanism that controls rhythms (independent of day/night signals) - allows for the regulation of FT expression at the appropriate time.

Answer 295

CO gene produces mRNA that oscillates over a 24-hour period - with CO protein being destroyed in the dark - CO accumulates more on longer days - when it is present in high amounts along with light, it triggers FT expression

Answer 296

In long day plants, high CO levels and long days coincide to trigger FT expression. In short day plants, CO levels do not reach the required threshold until the appropriate time of year, which results in FT expression at the appropriate time.

Answer 297

Transgenic plants expressing high CO mRNA also express high FT and flower

Answer 298

- CO is an inhibitor of FT expression in short day plants. - During long days, CO accumulates and blocks the expression of FT. - FT is only expressed under low levels of CO in short day plants

Answer 299

Can cause early flowering

Answer 300

determined by flowering time, weather, and water availability.

Answer 301

The drier it is, the earlier plants need to flower.

Answer 302

Will flower when conditions are less viable (changing climate)

Answer 303

spraying the crop with ethanol vapour, which triggers the expression of the FT gene

Answer 304

2-3 harvests per year Disproportionate harvest of rice (55-60% of area, 75% of product)

Answer 305

- No constant water supply/control for irrigation - More subject to flooding and drought - 1 (sometimes 2) harvest per year - More variable yield

Answer 306

- Plant never has fully submerged roots - Fields never flooded - aerobic soil conditions throughout - Low and variable yields

Answer 307

Escape and quiescence

Answer 308

Try to outgrow water level Flood water typically rises slower than rice can grow But flash floods

Answer 309

Hold its breath - Wait it out Limit on time due to lack of oxygen - Severe floods often don’t last anyway

Answer 310

Helps adaptation to oxygen limitation - promotes accumulation enzymes involved in anaerobic respiration - as well as promoting elongation in the escape response

Answer 311

Escape response - Ethylene induces internode elongation - rapid stem elongation - Rice is a grass plant - specific stem architecture - nodes - Close together in small plant - Gibberellin (GA) for cell expansion pushes nodes further apart in response to ethylene

Answer 312

Escape response produces low yields - biomass reallocated to long stem rather than grain

Answer 313

- Submergence response - Ethylene response factors - Promotes gibberellin production and ABA degradation - Promotes elongation growth - Provides submerged tissues with oxygen

Answer 314

Energy maintenance - Minimum elongation - Carbohydrate level in stem - Optimum fermentation - some energy supply - Underwater photosynthesis Protection - Efficient AOS (active oxygen species) scavenging - Low ethylene synthesis or sensitivity - Limiting reoxidation damage

Answer 315

Region of DNA that confers submergence tolerance in rice plants.

Answer 316

The FR13A landrace is unusually tolerant to submergence - dominant trait - can be submerged for 2-3 weeks - low yield

Answer 317

Introduced by micro assisted breeding rather than transgenic technology GM - commercially poor decision (not accepted by many countries)

Answer 318

Submergence increases ethylene Ethylene blocks abscisic acid (ABA) production - ABA blocks GA responses - so block lifted Ethylene blocks SLR1 and SLRL1 - These block GA responses - so block lifted Essentially ethylene blocks GA blockers - GA responses allowed - Elongation growth

Answer 319

Submergence increases ethylene - Ethylene triggers SUB1A - ethylene response factor - SUB1A strongly promotes SLR1 and SLRL1 - DELLA proteins - Blocks on growth pathway (lifted by GA responses) SLR1 and SLRL1 block GA response - Limited elongation growth

Answer 320

- Reduces yield variability - Raises expected yield Social benefits - Disproportionately benefits poorest farmers - Low lying flood prone areas occupied by disadvantaged groups

Answer 321

- Ethylene is a gaseous plant hormone that can diffuse in and out of cells/plants - acts by binding to receptors and activating a signalling pathway that leads to changes in gene expression and various physiological responses

Answer 322

Does not respond to ethylene like other plants. - Triple response observed in Arabidopsis shoots treated with ethylene.

Answer 323

- Does not produce ethylene - therefore does not ripen

Answer 324

- Exaggerated apical hook - Short hypocotyl - Short Root

Answer 325

(Ert1, Ert2, Ers1, Ers2, Ein4) - reside in the endoplasmic reticulum (ER)

Answer 326

Loss of any one receptor has minimal consequences. - Plants with multiple receptor losses exhibit a constitutive ethylene response phenotype. In the absence of ethylene - receptors remain active and suppress the pathway ethylene is present - receptors become inactive, relieving suppression and activating the pathway Mutants that cannot bind ethylene are unable to inactivate the pathway - block on the pathway cannot be removed - inability to express ethylene responses. If the mutant is sufficiently expressed, the plant fails to exhibit an ethylene response.

Answer 327

a phenotype observed in plants with mutations in the CTR1 gene - resulting in a plant that always responds as if ethylene were present, even when it is not

Answer 328

Looking for plants that exhibit the constitutive triple response (CTR) phenotype without the presence of ethylene - screening for mutants that act as if ethylene is present - short and shows triple response

Answer 329

CTR1 is a negative regulator of the ethylene signaling pathway in plants - Mutations in CTR1 can result in the constitutive triple response (CTR) phenotype

Answer 330

In the absence of ethylene, CRT1 is active and inhibits the ethylene responses

Answer 331

When ethylene is present, CTR1 kinase is inactive and EIN2 is not phosphorylated - fragment of EIN2 (C-terminus) moves into the nucleus and activates EIN3 and EIL1 TFs - then activate ERF1 TF and ethylene responsive genes

Answer 332

CTR1 kinase phosphorylates the C-terminus of EIN2 constantly - TP1/2 proteins recognise the phosphorylated EIN2 - promote its degradation through ubiquitination for targeting to proteosome

Answer 333

- Ethylene receptor activated - EIN2 C-terminus activates EIN3 and EIL1 in the presence of ethylene - They then activate ERF1 TF and ethylene responsive genes

Answer 334

No response - single constitutively active receptor sufficient to shut off ethylene responses

Answer 335

ACS (enzyme) produces ACC ACC -> ethylene by action of ACC oxidase (ACO)

Answer 336

Tightly regulated - highly unstable enzyme - Constantly synthesised and degraded - proteasome - keep ethylene levels low

Answer 337

Phosphorylation of the C-terminus of ACS - blocks interaction with proteasome

Answer 338

Wounding, pathogen attack and abiotic stress

Answer 339

Petal senescence and wilting, and it ripens fruit - not all fruits are responsive to ethylene

Answer 340

Climacteric fruits

Answer 341

Seeds are prevented from germinating even under optimal environmental conditions - allows seeds to remain viable for extended periods and is an adaptation that allows seeds to survive unfavorable conditions

Answer 342

Seed dormancy - due to desiccation and the presence of specialized proteins that prevent denaturation

Answer 343

maternal tissue in the ovules

Answer 344

The micropile

Answer 345

Becomes the endosperm - which is the nutritional tissue surrounding the embryo

Answer 346

Fusion of male and female gametes - female gametophyte located deep within ovules - male gametophyte (pollen) Pollen attaches to the female gametophyte - releasing 2 sperm cells One sperm cell fertilizes the egg cell - the other fertilizes the central cell

Answer 347

nutritional tissue that surrounds the embryo

Answer 348

First division very asymmetric - Pin head becomes embryo - Length becomes suspensor - like an umbilical cord - connects embryo to maternal material Heart stage Torpedo stage Two lobes at top becomes embryonic leaves Bottom (point of attachment to suspensor) becomes embryonic root - or radical - First to emerge from seed as it germinates

Answer 349

- Cell division & differentiation - Maternal control replaced by filial control - Cell expansion - Accumulation of storage compounds - Preparation for desiccation

Answer 350

Seeds are fully matured but cannot germinate eben under optimal conditions

Answer 351

Typical seeds lose dormancy after a while but remain quiescent - resting state, very low metabolism - suitable environmental conditions required to allow germination

Answer 352

Not tolerant to drying out - do not have long term viability - typically tropical - evolved to fall immediately and germinate

Answer 353

Usually a mutation - germination begins before separation from parent

Answer 354

Mangroves - rooting immediately after falling from tree

Answer 355

Seedling swells via osmosis (rapid water uptake)

Answer 356

Lag - little change in mass Metabolic activity increases ATP production and protein synthesis begin - seeds loaded with RNAs so transcription is not needed initially Minor breakdown of cell walls

Answer 357

Radical emerges - takes up water and nutrients - breaks out of seed coat and endosperm

Answer 358

- High temp. - Drought

Answer 359

- After-ripening - Light - Cold Stratification

Answer 360

Happens in dry seeds - typically involves the breakdown of inhibitory substances in the seed - such as abscisic acid Development of the embryo

Answer 361

Seeds germinate on plant

Answer 362

Induces stomatal closure

Answer 363

VP14 is a gene involved in ABA synthesis regulation, which was discovered through a seed germination mutant - suggested ABA is involved in seed dormancy and germination - VP14 mutant had a phenotype of viviparous (VP) and ineffective stomatal closure, indicating ABA's role in stomatal closure - ABA causes stomatal closure, and adding it to plants can cause water loss - VP14 mutant had a double expected water loss, indicating the significance of ABA in water conservation

Answer 364

ABA produced from carotenoid in plastids

Answer 365

NCED genes are induced by drought stress during maturation - which leads to increased ABA production and subsequent water conservation in plants.

Answer 366

a plant disease caused by gibberellin-producing fungi - Infected plants elongate rapidly and become weak and unable to support themselves

Answer 367

Plant hormones that play a crucial role in regulating plant growth and development - promote cell elongation, stem growth, and seed germination in plants

Answer 368

stops gibberellin synthesis everywhere in the plant - but synthesis can be stopped or enhanced in specific locations within the plant by altering cytoplasmic steps that are location-specific

Answer 369

GA response No GA response in 2nd case

Answer 370

Coupled - NCED (ABA synthesis) activity coupled to GA2ox2 (GA degradation) - GA3ox1 (GA synthesis) activity coupled to ABA hydroxylase (ABA degradation)

Answer 371

Cold and Light

Answer 372

Activates DOG1 gene - reinforces dormancy during cold exposure - Delays germination

Answer 373

- Phytochromes block PIF1 which previously blocked GA - Light blocks the block on germination

Answer 374

GA (gibberellin) is sometimes used to promote the mobilization of starch from the grain during germination - necessary for the production of beer

Answer 375

- Can result in pre-harvest sprouting (PHS) - Which is a common problem in English wet springs and summers.

Answer 376

GA promotes the production of hydrolytic enzymes in the aleurone layer of the barley seed - Maternal tissue surrounding the endosperm - Enzymes break down starch into sugars - diffuse into the endosperm and provide nourishment for the seedling as it grows

Answer 377

higher storage costs (after-ripening)

Answer 378

In the wild, plants want to germinate with variability to ensure not all are affected if there’s a frost etc - In crops, low dormancy and uniform germination desired, so harvest is easier

Answer 379

Pre-harvest sprouting (PHS)

Answer 380

White wheat

Answer 381

Changes wheat behaviour - wheat graded based on this (HFN)

Answer 382

ABA and CO2

Answer 383

Regulates the number of stomata

Answer 384

refers to the brightness of the land surface - measure of the amount of solar radiation that is reflected back from the surface

Answer 385

Limits evaporation not under plant control

Answer 386

Contains lots of water vapor bubbles.

Answer 387

The water would be lost.

Answer 388

CAM, C4 and C3

Answer 389

- Concentration gradient for water about 50x CO2 gradient - CO2 diffuses 1.6x slower through air - Water only needs to go through stomatal pore, CO2 must cross PM, cytoplasm and chloroplast envelope as well

Answer 390

Plants will try to adjust stomatal opening so photosynthetic CO2 gains maximised while water loss minimised

Answer 391

- CO2 promotes carbon fixation by Rubisco, resulting in increased sequestration (carbon fertilisation) - Stomatal conductance decreases with increasing CO2, improving water use efficiency but limiting carbon sequestration

Answer 392

Decreases with increasing CO2

Answer 393

rate at which water vapor diffuses through the stomata, or pores, on the surface of plant leaves

Answer 394

Process by which elevated atmospheric CO2 promotes carbon fixation by Rubisco - results in increased carbon sequestration

Answer 395

Response to elevated CO2 levels depends on the availability of other essential nutrients - Particularly phosphorus Trees exposed to elevated CO2 levels tended to close their stomata - Prevent excessive water loss in conditions of elevated CO2.

Answer 396

Soil drought triggers the production of ABA in roots

Answer 397

Open stomata lead to a cooler leaf due to evaporative cooling

Answer 398

- Study the genes involved in the process of stomatal closure - Mutants that fail to close their stomata in response to drought or ABA are desired for screening

Answer 399

Unable to control water loss - evident from the faster water loss observed in the cut-off leaf of Ost1 mutant compared to the wildtype

Answer 400

Abi1 mutant is a phosphatase protein - involved in the regulation of stomatal closure in response to ABA ABA-insensitive in all responses - including germination and control of stomata - unable to close stomata, essential for regulating water loss in plants

Answer 401

What are the roles of kinase, phosphatase, and receptor in ABA signaling?

Answer 402

SnRK2 (e.g., Ost1) and PP2C (e.g., Abi1) interact ABA absent PP2C inhibits the activity of SnRK2 kinase ABA present ABA binds to its receptor - brings latch and gate of the receptor close together - mimicking the activation loop of SnRK2 - releases kinase. SnRK2 activates downstream targets

Answer 403

- Wildtype plants fail to germinate on ABA containing medium - ABA insensitive mutant germinates - Pyrabactin-insensitive mutants are ABA insensitive - can germinate

Answer 404

mutant does not close its stomata in response to ozone exposure.

Answer 405

SLAC1 is the ion channel involved in stomatal closure in response to ozone.

Answer 406

SLAC1 mutant is deficient in stomatal closure in response to Ozone, CO2, ABA, light/dark transitions, humidity change and more Don't bother - calcium ions, hydrogen peroxide, nitric acid.

Answer 407

In the absence of ABA, SnRK2 protein kinase activity is inhibited by PP2C phosphatases - kinase and phosphatase are bound together - keeping them inactive Stimuli such as light keep proton pump OST2 active - membrane hyperpolarization - keeping stomata open

Answer 408

ABA is detected by ABA receptors (PYR/RCAR) - inhibits the activity of phosphatases PP2Cs - release and activation of SnRK2 kinases These phosphorylate SLAC 1 Activation of calcium channels by superoxide releases Ca2+ into the cytoplasm - Ca2+ activates calcium dependant kinases which phosphorylate SLAC1 as well, and OST2 - allowing stomata to close

Answer 409

Ost1 mutant is mostly unresponsive to CO2 - integrates inputs from both ABA and CO2 Slac1 mutant is insensitive to CO2 and ABA

Answer 410

enzymes that convert CO2 into carbonic acid, which dissociates into bicarbonate - Only bicarbonate can modulate SLAC2 activity - which is required for CO2-induced stomatal closure.

Answer 411

HT1 is a negative regulator of CO2 responses in guard cells - Ht1 mutants are CO2-hypersensitive but respond normally to ABA.

Answer 412

Plants developing in high CO2 have less stomata.

Answer 413

Tightly regulated by spatial control of asymmetric cell divisions

Answer 414

High CO2 -> less stomata Stomatal density regulation -> spatial control of asymmetric cell divisions Pre-industrial age herbarium specimens -> more stomata.

Answer 415

period of rapid technological innovation in agriculture that occurred between the 1940s and 1960s - involved the development and widespread adoption of new high-yielding crop varieties, increased use of chemical fertilizers and pesticides, and irrigation

Answer 416

Conventional crop varieties have a low harvest index (around 30% of biomass is useful) - which results in large amounts of waste biomass. - They are also prone to falling over (lodging)

Answer 417

Increases grain yield - Also promotes leaf and stem growth (not useful for increasing yield as it diverts resources away from the harvestable organs)

Answer 418

- Produces humid environment - Perfect for pathogen to grow and reproduce

Answer 419

introduction of semi-dwarf varieties that increased yield potential - improved resistance to lodging, allowing for planting at higher densities

Answer 420

Selecting for shorter plants - Selecting to plants with affected gibberellins (unwittingly)

Answer 421

Growth without the other characteristics

Answer 422

To get active GAs, GA oxidases are required. - Loss of function of CPS or KS results in severely dwarfed plants

Answer 423

Early enzymes are important as they catalyze the early steps in the synthesis pathway - a single copy of the genes responsible for early enzymes means almost no gibberellins are produced in the plant.

Answer 424

found to be mutated in green revolution rice, which contributed to the semi-dwarfism trait in the rice.

Answer 425

- Act as an off switch for the growth regulator (GA) - Needs to be tightly controlled to avoid unwanted dwarfism

Answer 426

Increased catabolism everywhere decreases seed production Increased GA catabolism only in internodes produces high-yielding dwarf rice plants

Answer 427

- Enzymes in early steps of GA production - Only a single copy of the genes - Almost no gibberellins in the plant

Answer 428

Inactivates DELLA inhibitor enzymes Allowing increased growth of the plant

Answer 429

- Mutant characterized by the loss of the DELLA repressor - Protein that normally inhibits GA signaling. - Constitutive GA signaling - Decreased gibberellin production - Resulting in reduced plant height and a thinner stem

Answer 430

Enhanced DELLA repressor - no response

Answer 431

The receptor domain of GID1 binds to DELLA, and in the absence of GA, DELLA represses growth - When GA binds to GID1, the receptor changes conformation - allowing for the binding of the DELLA protein to form a complex that is recognized by the SLEEPY/GID2 component of the SCF ubiquitin ligase complex - complex targets DELLA for proteolysis, leading to growth-promoting effects of GA.

Answer 432

A type of plant transcription factor that inhibits transcription of growth genes in the absence of gibberellin (GA) and is targeted for destruction in the presence of GA - allowing for growth.

Answer 433

A dark-growth response in plants induced by GA - promotes shoot growth and unopened leaves.

Answer 434

GA is required for the dark-growth response in plants, which induces shoot growth and unopened leaves during etiolation - GA-deficient pea mutants do not show dark growth, but it can be rescued by exogenous GA

Answer 435

inhibition of growth-promoting gene transcription - So GAs allow dark growth response

Answer 436

Compounds for - Defense - Taste - Colour - Scent

Answer 437

- Enzyme responsible for carbon fixation - Confined to bundle sheath cells. - Minimizes photorespiration - Occurs when Rubisco reacts with oxygen instead of carbon dioxide - CO2 is concentrated in the vicinity of the enzyme - Reducing photorespiration

Answer 438

Prevents CO2 diffusion back into the mesophyll cells

Answer 439

- Minimizes the loss of CO2 to the atmosphere - Helps to maintain high CO2 concentrations around Rubisco

Answer 440

- Reduce the likelihood of gene silencing or other adverse effects caused by the overexpression of transgenes - Reduce the potential for genetic instability - Unpredictable effects on the host plant's phenotype

Answer 441

- Photosynthetic photon flux density at the leaf surface - How much sun each cell gets - How much useful light is captured

Answer 442

- Class of plant hormones - Involved in a variety of processes - Including cell elongation, pollen tube growth, seed germination, vascular and root tissue differentiation, and stress tolerance

Answer 443

- Severely dwarfed - can be rescued with exogenous - although Bri1 mutants are BR insensitive

Answer 444

Encodes main BR receptor

Answer 445

Inhibit root growth

Answer 446

- Very small and insensitive to exogenous Brassinosteroids - Exhibiting a phenotype of severely reduced growth

Answer 447

- Plant mutant that partially reverses the dwarf phenotype of the bril-5 mutant when overexpressed

Answer 448

Activation screen - search for plants that partially reverse the dwarf bril-5 phenotype when overexpressed

Answer 449

Biochemical screen - Searching for proteins that physically interact with BRI1

Answer 450

- Functions as a coreceptor with BRI1 - Forming a receptor complex that initiates the BRI1 signaling pathway

Answer 451

BRI1 and BAK1 interact through a double lock mechanism that ensures no signaling occurs in the absence of the ligand - Phosphorylation of BKI1 causes BKI1 to dissociate - Coreceptor BAK1 can then bind to BRI1 - BRI1 signalling activated

Answer 452

Inhibits interaction between BRI1 and BAK1 - preventing signalling

Answer 453

Promotes wider leaf angles

Answer 454

more upright leaves, with narrower leaf angles.

Answer 455

BR Dwarf mutants outperform wildtype - possibly due to reduced shading and competition for light.

Answer 456

- Wild-type roots cannot rescue BR-deficient shoots - indicating that localized BR synthesis is required for stem elongation - opportunity to manipulate BR in different parts of the plant, e.g. stem vs seed

Answer 457

Removal of ligule and auricles results in a very upright leaf angle. Modulation of the size of auricles using brassinosteroid (BR) hormone signaling - can affect leaf angle.

Answer 458

Mutants lacking a midrib have floppy leaves with wide leaf angles.

Answer 459

Maize plants with teosinte UPA2 have a normal plant height and floral branch number - but with only proportionate reduction in auricle size.

Answer 460

- UPA1 is an enzyme catalyzing the last step in brassinosteroid synthesis - UPA2 is involved in UPA1 regulation.

Answer 461

- leads to increased cell cycling of cells on the inside of the plant - leading to worse leaf angle

Answer 462

EncourageS growth in the outside edge of leaves and block the BIN2 pathway - Leads to cyclin expression in the inside edge of leaves - promoting cell division and elongation in the sclerenchyma cells in the m2 region - inhibition of sclerenchyma cell division in the m1 region

Answer 463

BRs act together with gibberellic acid to promote cell expansion

Answer 464

BR mutants also have erect leaves - which can be advantageous for light capture

Answer 465

- control diverse signals - including shoot branching - largely conserved among land plants.

Answer 466

Branching inhibitors also important for nutrient availability response - Inhibit adventurous rooting - promote secondary growth - contribute to leaf senescence.

Answer 467

important for branching in arbuscular mycorrhizal fungi, which are associated with 80% of land plants. - However, plants that do not form this association also produce SLs.

Answer 468

Yes, SLs are highly mobile and can move from root to shoot and vice versa

Answer 469

- Plants produce fewer branches in poor nutrient conditions, such as low phosphorus (P) and low nitrogen (N). - SLs suppress shoot branching in low P - mechanism designed to conserve limited resources and prioritize growth in the main shoot

Answer 470

symbiosis with nitrogen-fixing bacteria instead of producing SLs in response to low N. - but some non-AM host plants do not produce SLs!

Answer 471

- hydrolyses SLs - allowing them to be perceived and triggering the downstream signaling pathway.

Answer 472

- released from inhibition by D53 degradation - play a role in regulating shoot branching by targeting downstream genes such as OsTB1/BRC1

Answer 473

D53 is a negative regulator of SL signaling (inhibits) - its degradation frees up SPL transcription factors - regulate downstream gene expression.

Answer 474

Strigolactones detected by D14 protein - Leading to hydrolysis of the protein and release of D53 D53 usually acts as an inhibitor - Targeted for degradation Frees up SPL transcription factors - Activates downstream targets of strigolactone signaling - One of these is BRC1/TB1 - Regulator of shoot branching

Answer 475

- Strigolactones promote the germination of Striga parasitic weed - preys on plants already under stress - attaches to the roots of host plants and takes nutrients and water from them - can cause significant crop losses

Answer 476

- Before planting, germination stimulants can be applied to promote suicidal germination of Striga without a host - Fertilizers can also be applied to reduce strigolactone production by crop plants - can be expensive. Crops with reduced or impaired strigolactone exudation, such as the LGS1 mutant - Can incur resistance to Striga. Another approach is to rely on different form of strigolactone not utilized by Striga

Answer 477

Nitrogen-fixing legume that enriches soil and produces other allelopathic chemicals that interfere with Striga.

Answer 478

Yes, altering a single strigolactone biosynthesis enzyme can mimic the effect of SLs that are not usable by Striga - can prevent Striga growth without affecting branching.

Answer 479

- Ideal Branching architecture - Lodging resistance - Striga control - Drought resistance - Enhanced mycorrhizal networks - Optimized root architecture

Answer 480

- led to more cells and increased biomass, but also resulted in some abnormalities in cell organization - poplar trees generating about twice as much dry weight as the control - could be used to increase biomass for biofuel production

Answer 481

There is very little going on in Europe in terms of GM crop cultivation - only one GM crop, a Bt-insect-resistant maize, has been approved for commercial cultivation - 0.1% of the global acreage of GM crops is cultivated in the EU

Answer 482

More than 70% of EU animal protein feed requirements are imported as GM crop products, despite the reluctance to grow GM crops in Europe.

Answer 483

Corn borer numbers plummeted even in non-GM maize due to area-wide pest suppression

Answer 484

Corn borers are all killed by GM maize, potentially reducing genetic diversity and causing ecological imbalances.

Answer 485

Wide hybridisations involve hand pollination and culturing embryos in labs to create crosses that defy natural species barriers - This can allow the transfer of one or two genes of interest along with several thousand other genes.

Answer 486

Potato has been crossed with wild relatives, including plants related to deadly nightshade, to create new varieties. - These wild relatives can also contain high levels of toxic alkaloids - can be dangerous.

Answer 487

Mutations can be induced through chemical or radiation treatment. - Point mutations (usually caused by EMS) and chromosome rearrangements (usually caused by radiation) are common.

Answer 488

Includes single nucleotide changes - occurs at a background rate of 7 mutations per billion base pairs of DNA. - Useful traits can be selected for while deleterious mutations are bred out.

Answer 489

can occur through pararetroviral double-stranded DNA viruses or transposable elements. - This can result in the insertion of different pieces of genes, creating novel combinations.

Answer 490

- Transfer of toxins and allergens from one crop to another - Experimental study involving the transfer of Brazil nut proteins to maize showed an allergen - but this was not intended for field use

Answer 491

Transfer of selectable markers to bacteria can result in antibiotic resistance - Although kanamycin resistance is toxic and has limited use in medicine - So resistance is not much of a problem

Answer 492

- use of glyphosate has been controversial - some studies suggesting potential risks to human health and the environment. - important to note that glyphosate use is not synonymous with GM crop use

Answer 493

- high Bt toxin expression in the pollen of one variety of GM crop - causing high mortality in monarch butterfly larvae - studies showed that drought and cold were more likely the responsible party for the decline in monarch butterflies. - Planting milkweed is the best way to save monarch butterflies, as it is their only food source.

Answer 494

- Removal or alteration of antibiotic marker genes - Use of chloroplast genes in GM - Separation of transgenic and non-transgenic crops - Field trials - Following crops after release

Answer 495

- chloroplasts contain their own DNA which is separate from the nuclear DNA. - genes can be inserted into the chloroplast DNA without affecting the nuclear genome of the plant - can be used to produce GM crops that are less likely to crossbreed with wild relatives - chloroplast DNA is usually not transmitted through pollen

Answer 496

No, maize taco shells contaminated with Bt gene that should only have been used in animal feed - resulted in 300 product recalls - company tried to get the GM corn approved for human consumption retrospectively another instance

Answer 497

(0.1-1%) of seeds produced will be transgenic - since large numbers of seeds can be produced overall transformation efficiency is acceptable

Answer 498

Tolerance provided by - Trialose and other compounds that allow survival under drought conditions

Answer 499

- The function of the gene in the donor organism - The effect of the introduced gene in the modified plant - Potential non-target effects of genes within the environment - Changes in the crop plant's ability to persist in the agricultural habitat or its invasiveness in natural habitats - Potential transfer of the introduced gene to other plants or organisms

Answer 500

- USA follows the principle of substantial equivalence - Compared to non-GM product that is already considered safe - evaluated for any significant differences While EU follows the precautionary principle where even potential risks must be anticipated and prevented.

Answer 501

- most stringent system in the world for assessing the safety of GM crops - Applicants must submit risk assessments - risk management options plans for post-market environmental monitoring (PMEM) to look for unforeseen impacts. - This information is scrutinised by experts in the 28 EU member states, Commission's expert advisory committee on GMOs and also includes public consultations

Answer 502

infective stage of T. gondii - that are shed in the feces of infected cats - If ingested by intermediate hosts - transform into tachyzoites

Plants for the Future Flashcards

(549 cards)