Thermosensing in Plants

Question 1

Structure

Answer 1

1.
2.
3.

Question 2

Why is thermosensing important in plants?

Answer 2

sessile

Question 3

temperature is a form of

Answer 3

information

Question 4

temperature variations throughout a plant’s life

Answer 4

demand complex perception, for the adaptation of growth and development

Question 5

give some examples of temperature variations throughout a plant’s life

Answer 5

• di/nocturnal
• seasons
• extreme events

Question 6

Future temperature changes

Answer 6

• will impact crop yields
• negatively from 2030 onwards
• will require systemic and transformational adaptations

Question 7

cell-level consequences of temperature changes

Answer 7

1) metabolic consequernces
2) cytoskeletal stability + membrane fluidity
3) ROS production

Question 8

describe the metabolic consequences of temperature changes

Answer 8

• reaction kinetics
• enzyme activity and abundance
• RNA, metabolite and protein stability + interactions

Question 9

decree the cytoskeletal stability and membrane fluidity affects of temperature variations

Answer 9

affects proteins, cargo trafficking and organellar repositioning

Question 10

describe the ROS production affects of temperature variations

Answer 10

• altered electron carrier kinetics
• decreased water availability
• membrane-associated enzymes affected

Question 11

thermomorphogenesis

Answer 11

• 27 degrees
• recapitulates skotomorphogenesis
• avoidance
• hypocotyl extension
• expanded leaves
• deeper roots
• early flowering

Question 12

moderate heat stress

Answer 12

• 37 degrees
• compromised reproductive development
• hindered photosynthesis
• decreased shoot and root growth rates

Question 13

severe heat stress

Answer 13

• decreased cellular integrity
• one hour at 45 degrees: Lethal (can be solved via gradual priming for molecular adaptation)

Question 14

PhyB

Answer 14

• reversion is temperature dependent
• major negative thermomorphogenetic regulator
• some redundancy

Question 15

phyB

Answer 15

• constitutively thermomorphogenic
• long hypocotyl (mm)

Question 16

PIF4, 7

Answer 16

• downstream, positive thermomorphogenic regulators

Question 17

pif4

Answer 17

no change in rosette no.

Question 18

pif4/7

Answer 18

no change in hypocotyl elongation

Question 19

EC

Answer 19

• Evening Complex
• LUX, ELF3/4
• transcriptional repressor
• core component of circadian clock
• assembles in the evening
• represses growth

Question 20

LUX

Answer 20

• LUX ARRHYTHMO
• DNA BP

Question 21

ELF3/4

Answer 21

EARLY FLOWERING

Question 22

EC in the daytime in vivo

Answer 22

• increased temperature
• AtELF3 forms LLPS aggregate speckles via functional IDR domains
• no DNA binding; no PIF4 repression
• photomorphogenesis

Question 23

RNA thermometers

Answer 23

• temperature-dependent RNA folding
• functional pre-AUG hairpin increases translation, despite constant mRNA
• e.g. PIF7

Question 24

What is the major problem with heat stress?

Answer 24

protein unfolding

Question 25

ROS scavengers

Answer 25

- ascorbate peroxidase - catalase

Question 26

How do plants cope with heat stress?

Answer 26

1) HSFs 2) UPR

Question 27

UPR

Answer 27

- Unfolded Protein Response - chaperones prevent unfolding

Question 28

HSFA1

Answer 28

- TF - inactive when bound to HSPs (sumoylated) - high temp: dissociation - preferentiatial homodimerisation - phosphorylation - nuclear localisation - HSP induction - complex

Question 29

hsfa1

Answer 29

severely impaired heat stress response

Question 30

UPR

Answer 30

1) bZIP28 releases BiP chaperone via COPII @ Golgi 2) double endoproteolysis; nuclear localisation 3) HY5 displacement + IRE1 phosphorylation

Question 31

IRE1

Answer 31

- inositol requiring enzyme 1 - induced by MECPP (splices out ER-signal) - splices bZIP60

Question 32

bZIP60

Answer 32

TF

Question 33

cold perception depends on

Answer 33

- sp. - relative change - less well understood

Question 34

mild cold response

Answer 34

- decreased growth rate and leaf expansion - increased anthocyanin - vernalisation

Question 35

severe cold response

Answer 35

- drought stress symptoms - ice crystals: mechanical wounding - death

Question 36

Membrane sensor hypothesis

Answer 36

- decreased fluidity - increased acid desaturases - less dense packing to maintain fluidity

Question 37

Ataciddesaturases

Answer 37

cold intolerant

Question 38

Synechocystis membrane alterations

Answer 38

- induces Hk33 conformational changes and heterodimerisation via reciprocal autophosphorylation - activates downstream cold-response partners

Question 39

Hk33

Answer 39

histidine kinase

Question 40

Cold-response induction: the basics

Answer 40

- stepwise; cascading amplification wave - 15mins -> early genes (CEBFs) - RNA-seq + heatmap/microarray

Question 41

Cold-response induction: the specifics

Answer 41

1) osmoprotectant synthesis 2) lipid modification 3) hormone signalling 4) cell wall modification

Question 42

CBFs

Answer 42

- cold element binding factors - master regulators - KO: impaired growth, organ formation

Question 43

Mechanism of cold response

Answer 43

1) transient ICE1 activation 2) HOS15 degrades HD2C 3) H3 hyperacetylation @ COR domain 4) increased CBF binding

Question 44

HOS15

Answer 44

E3 ligase

Question 45

HD2C

Answer 45

deacetylase

Question 46

ICE1

Answer 46

initiator

Question 47

CBF-dependent growth repression in At

Answer 47

- decreased active GA - DELLA stabilisation (GAI, RGA) - repress growth - dwarf phenotype

Question 48

CBF1oe

Answer 48

- + GA: rescue - - GA: tiny leaf + gai/rga: no effect (DELLAs are downstream)