Plant Responses to the Environment

Question 1

Lecture 11 Summary: use light to spy on their neighbor

Answer 1

Challenge: Planting crops at higher density to
increase crop yield.
The shade avoidance syndrome (SAS)
The adaptive value Of the SAS
Molecular basis of neighbour perception uses light
reflected/filtered by leaves.
Red- far red sensing implicates a photoreceptor called phytochrome
Photoreversibility, A Role for PHYB, Molecular mechanism
Example of one GM solution to alleviates density
effects on crop yield.

Question 2

PR vs PFR

Answer 2

Upon activation of Pr by red light, the D ring rotates, causing a conformational change in the phytochrome protein and exposing Nuclear Localisation Sequences, most of the phytochrome (Pfr) moves into the nucleus where it regulates gene expression.

Question 3

Lecture 12 Summary: Using Light to Tell the Seasons

Answer 3

What does flowering mean for a plant
What controls flowering? Day length is one .
parameter.
The ‘florigen’ travels from leaf to apex.
The FT protein is florigen (quest 1936-2007)
How to measure day length: The coincidence model between light and internal clock
Climate change and flowering time.

Question 4

Photoperiod

Answer 4

day length becomes shorter than 12 hours you talk about short for to period And when it’s longer than 12 hours, then you use long photoperiod

Question 5

Cold Acclimation and Vernalisation

Answer 5

So cold acclimation represented on this graph here is activated by a few hours or maximum a day or two or cold here you have period of cold in days and then the response against kind of arbitrary unit. In cold activation , documentation, cold activate gene expression for the plant to tolerate cold, for example, by reducing the cell freezing point

by contrast for when ization. We’re talking about weeks, one week, two weeks, eight weeks. So, in a way, cool, documentation shows that plants are able to sense cold within a day, but vernalization suggest that somehow, the plant is able to compute or many days of cold, other code.

The advantage of having a minimum period of cold required, is that the cold spell
can be interrupted by short period of warm weather during the winter. And this allows the plant to avoid flowering before the cold is over. After a warm spell in Winter returning freeze would destroy the young flowers. On the other hand. The amount of cold required must be compatible with the average length of cold at that plant location. If then has a Vernalisation is not achieved. Then the fitness cost in terms of seed production would be very severe