Plant development

Question 1

Name three stages of plant development in the shoot apical meristem and what they are resonsible for

Answer 1

Juvenile - for stem and juvenile leaves
Adult - stem and adult leaves
Reproductive - stem and flowers

Question 2

Difference between reproductive and vegetative SAM

Answer 2

Reproductive - produces floral meristem in flank

Vegetative - leaves in flank

Question 3

Are state changes reversible?

Answer 3

Normally not (in some cases can switch back to vegetative Calothamnus)

Question 4

Name four signals that can induce flowering in plants

Answer 4

Gibberelins
Photoperiod (daylight)
Vernalisation (cold spell)
Autonomous internal signalling

Question 5

What do maize plants flower in response to?

Answer 5

After having grown 6 leaves (can me modified to increase vegetative (id1 mutation)

Question 6

What is masting and in what plant species is it seen prominantly?

Answer 6

Where all individuals from same stock flower simultaneously regardless of location:0 bamboo

Question 7

What are the three stages of a vegetative meristem to expressing flowers?

Answer 7

Meristem is COMPETENT (Able to recieve signals via induction)
This leads to it being FLORALLY DETERMINED (it will flower regardless of location but then one more signal may be required to begin
EXPRESSION

Question 8

What are the main roles of miR156 and where is derived from?

Answer 8

Leaf derived microRNA (endogeonously produced) in abundance during juvenile phase. Suppresses adult leaf production and competence to flower

Question 9

What does miR156 respond to?

Answer 9

Sugar levels (sucrose accumulation blocks expression so then plant can move to adult phase)

Question 10

What is photoperiodism?

Answer 10

When a plant requires certain length days in order to induce flowering. These can be long or short days and are defined by the longest period of uninterrupted darkness.

Question 11

What hormone is responsible for flowering in plants and where is it formed and move through?

Answer 11

Florigen formed in leaves moves through phloem

Question 12

What did grafting with perilla (mint) leaf show (zeevart)?

Answer 12

That an induced leaf (response to stimuli) producing florigen can transmit this signal to uninduced plants multiple times! Florigen cannot be isolated.

Question 13

What are the roles of FT and FD in the flowering process?

Answer 13

FT is flowering locus T and is a small globular protein expressed in the phloem. It moves through here and into meristematic cells where it binds to FD transcription factor. Together they are both called the florigen activation complex and stimulate expression of APETALA1 gene.

Question 14

Where are fruits derived from?

Answer 14

gynoecium/female flowering parts

Question 15

What are the stages of fruit development?

Answer 15

Iniating - pollen shed
Anthesis - fruit begins to mature and grow
Breaker point- fruit stops growing and begins ripening NOT SENESCENCE

Question 16

What is thought to iniate ripening?

Answer 16

Short burst of CO2 production, called a respiratory climacteric. Fast ripening plants (avos) have bigger climacterics. However this excludes citrus fruits and others like melons.

Question 17

What is the role of ethylene in ripening?

Answer 17

ethylene promotes more ethylene production in climacteric plants and is assocaited with many of the gene expression pathways that produce ripening. This is only relevant to climacteric fruit. Non - climacteric are insensitve.

Question 18

Will addition of ethylene always result in ripening?

Answer 18

NO 1) not all plants are sensitive to it only climacteric fruits (apples pears amngos tomatoes). 2) fruit must be competent first (reached breaker point). If applied befre then it actually delays ripening (system 2 response as opposed to system 1 which is ripening)

Question 19

Why is ethylene production a problem?

Answer 19

Can result in psot harvest losses of up to 100% TOMATOES

Question 20

How is RIN mutation used in tomato production?

Answer 20

Heterozygotes with this mutation have the ACC synthase enzyme affected stopping the biochemical pathway to ethylene. They still stay firm and sweet however but can last 10-14 days longer!