Final exam Flashcards

Question

What are PAMPs/MAMPs?

Answer 1

Pathogens produce PAMPs (pathogen associated molecular patterns) or MAMPs (microbial associated molecular patterns) that place selective pressure on the plants. Plants have a response: PAMPs or MAMPs immunity, that places selective pressure on the pathogens.

Answer 2

PAMP: Pathogen associated molecular patterns. MAMP: Microbial associated molecular patterns. Produced by pathogens/microbial organisms which place selective pressures on plants. 1. PAMP interacts with receptor protein 2. Causes signal transduction 3. Opening of calcium channels 4. Increase in Ca+

Answer 3

Production of reactive oxygen species (hydrogen peroxide) Activation of protein kinases with the interaction of reactive oxygen species and Ca+

Answer 4

Reactive Oxygen Species ROS are toxic to pathogens.

Answer 5

Resistance genes in plants produce receptor molecules which bind to PAMPs/MAMPs Avirulence genes in pathogens produce effector molecules (PAMPs/MAMPs)

Answer 6

In order for a plant to resist specific pathogens, it must have a gene encoding a receptor specific to the pathogen.

Answer 7

The plants that are resistant have a gene which encodes the receptor that provides resistance while the plants that are susceptible don't

Answer 8

Receptor proteins. The R proteins bind directly to the Avr products, which leads to other molecules binding to the receptor to produce a defense response.

Answer 9

Various mutations. In natural plant populations, some individuals will resist some pathogens but be susceptible to others, so polymorphism allows the populations to continue existing as there are individuals with various immunity. The population will likely not be wiped out by a singular pathogen as a result.

Answer 10

Only produced in response to microbial pathogens. Terpenoids, alkaloids, cyanogenic glycosides, glucosinolates, phytoalexins Not all species produce the same compounds.

Answer 11

Cell death. Prevents pathogen invasion into the rest of the plant.

Answer 12

Defense genes are activated across the entire plant and provides broad immunity. Instead of targeting specific pathogens like in animals, SAR resists various kinds of pathogens even if the plant had never encountered them before

Answer 13

Hormone. Phenylalanine -> trans-cinnamic acid -> benzoic acid -> salicylic acid

Answer 14

After introducing a pathogen to a part of a plant, an increase of salicylic acid concentration is observed.

Answer 15

Defense genes

Answer 16

Phloem-mobile signals

Answer 17

Able to be perceived for defense responses

Answer 18

FOR: increase in concentration in response to pathogens AGAINST: a grafting experiment showed that SA is not a transmissible signal - If the rootstock is transformed and expressing nahG and the scion is from a normal plant, there is SAR, and the lesions on the upper leaf are small. This means that even if SA does not accumulate in the bottom leaf, the signal is transmitted to the upper leaf. Therefore, SA is not the transmissible signal. If the rootstock is from a normal plant and the scion is from a transformed plant expressing nahG, there is no SAR and the lesions are large on the upper leaf. Therefore, SA needs to accumulate at the site of the second infection for SAR. SA is necessary for SAR although is not the transmissible signal.

Answer 19

MeSA: Methylsalicylate If the rootstock is from a normal plant and the scion is from an SAPB2-silenced plant there is no SAR. If MeSA cannot be converted into SA at the site of the second infection there is no SAR. If the rootstock is from a SABP2-silenced plant but the scion is from a normal plant, there is SAR. As long as SA can accumulate at the site of second infection there is SAR. SA is essential for SAR but it is not the transmissible signal. It does not need to be transported from the rootstock to the scion. SAMT is SA methyltransferase. If the plant is SAMT1-silenced, there is no production of methyl-SA from SA. If the rootstock is from a normal plant and the scion is from an SAMT1-silenced plant there is SAR. MeSA is not needed at the site of the second infection. If the rootstock is from a SAMT1-silenced plant but the scion is from a normal plant, there is no SAR. MeSA needs to be produced on the bottom leaf. MeSA seems to be the transmissible signal.

Answer 20

Induces the systemic wounding response. Required at the site of infection to promote this response.

Answer 21

Jasmonates induce a broad spectrum of defensive responses, production of PIs, the release of volatiles, alkaloid production, etc. MeJA the mutant has a perception issue of jasmonate it results in no resistance. Must be local response to jasmonate when systemin is not perceived by the rootstocks the signals needed cannot be transported when jasmonate is not produced at the rootstock a functioning signal cannot be produced

Answer 22

ISR induced by the release of volatile signals

Answer 23

Rapidly released upon tissue damage and can also act against pathogens. GLV have the ability to alert nearby plants, attract pest controlling insects, etc.

Answer 24

Hormone ISR is triggered by beneficial microbes like bacteria or fungi which causes ethylene to be produced and cause a systemic reaction throughout the plant, enhancing its resistance to a wide range of pathogens For expression of SAR, ethylene perception is required locally in the pathogen-infected leaf ethylene can contribute to resistance against necrotrophic, but not biotrophic pathogens.

Answer 25

- The NahG gene encodes a salicylate hydroxylase that converts salicylic acid into non-SAR-inducing cate-chol. -NahG rootstocks, although unable to accumulate salicylic acid in response to TMV infection, did produce SAR in wild- type scions. -ethylene must be sensed by the plant in order for ISR

Answer 26

overcomes restrictions resulting from the plant’s orthostichy. Plant enemies often move from one leaf to the adjacent one, but directly adjacent leaves usually lack direct vascular connections. volatile signal molecules can reach distal plant parts faster than compounds that are transported through vascular tissues.

Answer 27

Triggers SAR in neighboring plants

Answer 28

Mangroves are essential because, environmentally, they foster marine life where fish and other organisms often live within the mangroves for protection. They also provide storm protection against flooding and erosion.

Answer 29

There are two different kinds of mangroves, where facultative halophytes refer to the species found in less salty/no salt environments. Facultatives can be affected by excess or low salinity environments, but they can survive without. Obligate mangroves require salinity for growth and survival.

Answer 30

Mangroves have adaptations where they have fewer stomata to reduce transportation, smaller and thicker.

Answer 31

The gene revolution refers to the use of gene modification compared to the green revolution for hi yield crop yield through fertilizers and irrigation.

Answer 32

One example is the Hawaiian papaya, where a ring spot virus in 1992 cut papaya production in half. GE-resistant papaya strains were made and produced and then by 2004 the strain accounted for 88% of the crop

Answer 33

One example is transgenic golden rice, which contains beta-carotene using a 2nd-generation daffodil gene, which was intended to provide more nutrients for those in areas of food scarcity. It took two generations to figure out the right gene for the crop as the first-generation crop did not produce a high enough percentage of beta-carotene. The drawback to this crop is the golden color off puts people and discourages them not to consuming the product because it looks "fake"

Answer 34

Reduces the price and chemical use compared to traditional irrigation/fertilizer/pesticide farming practices. GMO plants do not need constant reapplication of treatments in order to be resistant, so it saves farmers the cost of reapplying the treatments. It also reduces chemical use for pesticides and fertilizers and increases biodiversity.

Answer 35

There is a lack of regulation for transgenic crops and a lack of knowledge about what GMOs are and their purpose. Environmentally, there are concerns for unwanted gene flow of GMO crops, giving the genes to wild, potentially invasive species, which could make them even harder to remove from the native environment.

Answer 36

The basis of conventional cross-breeding is crossing two plants with relevant characteristics and selecting the offspring with the desired combinations of genes inherited from the two parents. Disadvantages of this method include it being a time-consuming process with limited control, as well as less genetic variability (can add genes from other plants and animals)

Answer 37

Gene-gun editing: agrobacterium mediated transformation, CRISPR and mutagenesis Mutagenesis: is also called mutation breeding (1920's) involves subjecting plants to radiation or chemical means to induce spontaneous genetic variation to generate new varieties. Cisgenesis: involves introducing a gene from a related plant species Transgenesis (GMO): involves the transfer of foreign DNQ encoding a desired trait into an unrelated plant species. Ex. groundout ready corn is resistant to glyphosate due to genes from agrobacterium CP4

Answer 38

Clustered regularly interspaces short palindrome repeats. CRISPR is a component of immunity in bacteria. DNA from a virus invades the bacteria; the viral DNA is processed into short segments and is made into a new spacer between the repeats. These will serve as genetic segments and become a new spacer between the repeats. These will serve as genetic memories of previous infections. The CRISPR sequence undergoes transcription, including spacers and Cas genes, creating a single-stranded RNA. The resulting single-stranded RNA, called CRISPR RNA, contains copies of invading viral DNA and guides the CRISPR-associated proteins to them. The protein then cleaves and destroys the targeted viral material.

Answer 39

CRISPR is a misnomer when referencing it as a tool for gene editing in fungal, plant, and animal cells because it references repeats in DNA only found in bacteria. The Cas9 protein with an RNA targeting sequence edits fungal, plant, and animal cells without CRISPRs.

Answer 40

CRISPR is much more precise and leaves behind issues like genetic drag found in traditional cross-breeding.

Answer 41

Economic: Gene editing makes produce last long enough to import from overseas growers, diminishing local and national revenue. Toxins/Allergens: Appearing in modified food the genetic modification would have to trigger the production of a specific allergen. This hasn't been documented in GMO food. GMO pollen escape: The movement of GMO pollen can result in transferring genetically modified traits to non-GMO or wild relatives. This unintended genetic mixing may alter non-GMO populations' genetic diversity and characteristics. These traits introduced into wild populations might affect their ecological interactions, competitiveness, or adaptation. Impacts biodiversity.

Answer 42

CRISPR can be utilized without transgenes to create cisgenic species that do not differ from the products of traditional crossbreeding and would evade the current restrictions of GMOs by the USDA. As the law was written in 1992, these plants would be exempt. RJ thinks the law should be rewritten to be more streamlined and with CRISPR in mind.

Answer 43

Gene-Knock out: Gene silencing using CRISPR starts with the use of a single guide RNA to target genes and initiate a double-stranded break using the Ca9 endonuclease; these breaks are then repaired by an innate DNA repair mechanism, the non-homologous end-joining (NHEJ). However, NHEJ is prone to error and can result in genomic deletions or insertions, leading to permanent silencing of the target gene.

Answer 44

Gene Insertions/Knock-ins: The CRISPR-induced double-strand break can also create gene-knock-ins by exploiting the cell's homology-directed repair. The precise insertion of a donor template can alter the coding region of a gene. Previous studies have demonstrated that single-stranded DNA can create exact insertions using the CRISPR-Cas9 system.

Answer 45

Transient Gene silencing: Modifies the Ca9 protein so it cannot cut DNA; it also allows for gene silencing or transcriptional repression can also be done. The modified Cas9, led by a guide RNA, targets the promotor region of a gene and reduces the transcriptional activity and gene expression.

Answer 46

Bacillus thuringiensis is what Bt stands for, it is a group of soil microbes that are used to control certain insect pests.

Answer 47

The first attempts to use Bt for insect control were in 1958 when it was first manufactured commercially and was registered by the US Environmental Protection Agency in 1961. - Bt is toxic because it produces a crystal-shaped protein which is a Cry protein and this is lethal to certain insects

Answer 48

Bt is toxic because it produces a crystal-shaped protein, which is a Cry protein and this is lethal to certain insects What are Cry proteins? - Cry proteins are toxic to insects because they are proteolytically activated by midcut proteases once ingested and bind to specific receptors located in the cell membrane and result in cell disruption which leads to cell death.

Answer 49

- There are 67 subgroups of Cry proteins which equal more than 500 different types of proteins. - The Bt toxin is specific to Lepidoptera, Coleoptera, Hymenoptera, and Diptera. These organisms are different types of worms and caterpillars.

Answer 50

- The alkaline pH in the insects stomach is what activates the Cry protein.

Answer 51

Maize and cotton genes are used ? Advantages: - Increased crop yield - Does not harm beneficial insects - Helps prevent molds from entering the plant - Disadvantages: - Narrow specificity - Cry proteins can be unstable

Answer 52

Maize and cotton The Bt gene has been introduced into plants to make them insect-resistant - Producing transgenic crops expressing the Cry proteins is more beneficial than spraying the plants because it reduces the material and application costs and it kills the insects that are inside the stalk or near the root

Answer 53

The Cry protein being active in the insecticide where as, it is inactive in the soil, this could expand the specificity that it affects and kill insects that are not meant to be killed. - It is not known if the pollen from the genetically modified plant would be able to have gene flow with the same crop or a similar crop.

Answer 54

Possible cause of resistance in insects to Bt toxin: - Mutations in the insect that affect the mode of action in Cry proteins

Answer 55

The “High Dose Refuge Strategy” is used to reduce the appearance of insect resistance to Bt toxin. This is when they plant a large number on non-Bt plants by the Bt producing plants so the insects are attracted to the non-Bt producing plants and then mate with the resistant insects to produce insects that are not resistant. This works due to the resistant allele being recessive.

Answer 56

TI plasmids include: T-DNA or transferred DNA, which includes Repeated sequences at the ends, called the left and right border, which are recognized by the bacterial enzymes encoded by the vir genes. Genes that encode enzymes for the synthesis of auxin and cytokinin, which when moved into the plant cell nucleus results in the plant cell producing these hormones and leading to cell division and formation of a tumor of undifferentiated tissue. Genes that encode the enzymes involved in the synthesis of opines. And virulence genes

Answer 57

No. Repeated sequences at the ends, called the left and right border, which are recognized by the bacterial enzymes encoded by the vir genes. The plasmid will be cut at these sequences, and all the DNA in between will be transferred to the plant cell nucleus

Answer 58

T-DNA or transferred DNA, which includes Repeated sequences at the ends, called the left and right border, which are recognized by the bacterial enzymes encoded by the vir genes.

Answer 59

Starch-Statolith Hypothesis * Says that the primary mechanism for plants to sense gravistimulation is amyloplast sedimentation * This sedimentation activates a receptor, triggering a signal pathway that promotes gravitropic curvature Evidence * Physiological treatments that alter the starch content * Result in decreased amyloplast sedimentation and gravitropic response * Starch-deficient / starchless mutants have poor response to gravistimulation * Scarecrow & shortroot Arabidopsis mutants result in the endodermal layer disappearing in both shoots and roots * Root cap structure is not altered and roots can still respond to gravistimulation This theory does not fully explain gravitropism * Alternative mechanisms possible

Answer 60

Evidence suggesting it is not solely amyloplast sedimentation * Starch sufficient mutants not completely agravitropic Full ablation of Arabidopsis root caps does not fully inhibit gravitropism * Is another mechanism causing this? Possible other mechanism * Cellular device that senses tension between the extracellular matrix

Answer 61

Suspected messengers for communication * Calcium and inositol-1,4,5-trisphosphate Researchers propose involvement of calcium channels in signal transduction * Columella amyloplasts attached to microfilaments that are connected to the ER or plasma membrane, and have high calcium concentration. Not a lot of evidence tho Evidence of IP3 involvement * IP3 levels fluctuate in gravistimulated corn and oat pulvini * Rapid changes of IP3 levels within 10 seconds of gravistimulation * IP3 promotes opening calcium gates

Answer 62

What is it? * Gravistimulation promotes development of auxin gradient across root tip Cellular Elongation * Auxin gradient causes differential rate of cellular elongation * Caused by change in distribution of auxin efflux facilitators * Leads to root curvature

Answer 63

Polar Transport is essential for root gravitropism * Inhibitors of polar auxin transport completely inhibit gravitropism * Mutations that affect auxin transport also affect gravitropism * Arabidopsis AUXI gene appears to function in auxin intake * Mutations in this gene causes root-growth resistance in two auxin types that actively diffuses, but does not cause root-growth resistance in the only auxin type that diffuses freely Arabidopsis AGRI gene essential for root gravitropism * Mutant roots less sensitive t

Answer 64

increases in auxin concentration * Affect roots and shoots differently Roots * Auxin increase inhibits cellular elongation in root * Most likely because root cells are exposed to resting auxin levels normally Shoots * Auxin IAA synthesized in shoot apex * Regulates cell expansion by activating ATPase Asymmetrical distribution in the root * Affects the root elongation zone * Increased auxin levels transported to lower side of the root

Answer 65

Elongation zone

Answer 66

Gravistimulation results in redistribution of PIN proteins to the bottom flanks of cells * Also results in: * fast alkalinization of cytoplasm * Change of cellular polarity