the new zealand institute for plant & food research...

The New Zealand Institute for Plant & Food Research Limited

Timing in the plant kingdom

Erika Varkonyi-Gasic


http://www.plantandfood.co.nz/

PFR provides research and innovation to ensure

sustainable growth of plant and marine-based

industries

Plant and Food Research (PFR)

Mt Albert site


PFR science across portfolios

BREEDING & GENOMICS Building knowledge of key traits at the molecular level to inform the

development of new elite cultivars.

BIOPROTECTION Effective control of pest and disease to protect export market access.

SUSTAINABLE PRODUCTION Systems that increase efficiency and retain quality across the supply chain.

FOOD INNOVATION Identifying intrinsic health benefits in natural produce to develop new foods

and beverages.

SEAFOOD TECHNOLOGIES Optimising the value and quality of seafood and aquaculture.


Research sectors

Kiwifruit

Potato

Pipfruit

Cropping

Berryfruit

Vegetable

Summerfruit

Food &

beverage

Wine

Seafood

Environmental

Ornamentals

http://ketenewplymouth.peoplesnetworknz.info/image_files/0000/0002/5239/Actinidia_deliciosa__wild_Kiwifruit_-6.JPG


Fruits of our labor


The importance of timing

» Plants display a sessile life-style.

» They DO move but can’t escape.

» Need to grow in good conditions and survive adverse conditions.

» Coincidence of flowering with optimal conditions is a prerequisite

to successful sexual reproduction and the yield of seeds, grains

and fruit.

» Plants have evolved mechanisms to integrate environmental and

developmental cues to time their development and ensure

survival.


Plant life cycle

Seed

Vegetative

growth Death

Flower

• Plants that flower and fruit

only once and then die are

termed monocarpic or

semelparous.

• Annual plants complete their

life cycle within one year.

• Biennial plants take two years.


Mass flowering bamboos are considered to

be “bad omen“ followed by famine and a

great increase in rat population…

Bamboo flowers once in up to 130 years


Soft bamboo shoots, stems, and leaves are the major

food source of the giant panda of China, the red panda of

Nepal and the bamboo lemurs of Madagascar…


Plant juvenility

» Lack of reproduction under favourable environmental conditions

Amorphophallus titanum 'corpse flower‘ first flowering in7 years


Seed

Dormancy

Vegetative

growth Death

Flower

Perennial plants

• Most perennials are

polycarpic, flowering over

many seasons in their

lifetime.

• Dormant buds = mini

shoots with mini leaves

and flower initials


Ever-growing peach mutant – no dormancy

Bielenberg lab, Clemson, SC


Plants can respond to the environment


Plants can sense and respond to light

Photomorphogenesis

Germination

Shade-avoidance

Phototropism

Stomatal opening

Flavonoid synthesis

Growth and dormancy


Photoperiodic flowering

Tobacco ‘Maryland mammoth’

is a mutant, needs SD to flower


Plant photoreceptors absorb light

phototropins cryptochromes phytochromes


Mutant analysis reveals function of genes

Arabidopsis has 5 PHY and 2 CRY genes

• redundancy

• divergence (new functions)

http://www.yale.edu/dengl

ab/paper/Jigang2011.pdf


Summary of plant responses to light

Light-regulated transcriptional networks in higher plants Yuling Jiao, On Sun Lau & Xing Wang Deng Nature Reviews Genetics 8, 217-230 (March 2007)

http://www.yale.edu/denglab/paper/Jiao2007.pdf

http://www.nature.com/nrg/journal/v8/n3/full/nrg2049.htmlhttp://www.nature.com/nrg/journal/v8/n3/full/nrg2049.htmlhttp://www.nature.com/nrg/journal/v8/n3/full/nrg2049.html


trans

cis Pr

Pfr

Phytochrome forms have differential activity

inactive

active

Far-red

Light

Red

Light

Far-red

Light

Red

Light

Cellular response

Da

rkn

ess

fast

slo

w


Phytochrome activates gene transcription


Photoperiodic flowering in Arabidopsis

CLOCK

CO

LHA

CCA1

TOC1 GI

Photoperiod pathway

Light

External coincidence model

FT

Clock

regulated

CO

Flowering

inducer

FT

CO protein is

stabilized by light!


Florigen moves in the phloem

FT = florigen ATC = antiflorigen?

Similar to FT and

competes for the same

interacting partner


Flowering pathways in Arabidopsis

GA1, GAI,

RGA GA pathway

FCA, FY,

FLD, FVE,

FPA, LD, FLK

Autonomous pathway

CLOCK

CO Light

LHA

CCA1

TOC1 GI

Photoperiod pathway COLD

FLC

FRI, FRL1,

FRL2, VIP3,

VIP4, ART1,

PIE1, ESD4

VIN3

VRN1

VRN2

Vernalization pathway

FT SOC1 LFY

AP1 LFY CAL

Floral meristem identity

Floral pathway integrators

TOE1, TOE2,

SMZ, SNZ,

FLM, SVP,

TFL1, TFL2,

EMF1, EMF2

Ambient

temperature

Nutrient

status

Activators Represors

Floral pathway

integrators

Flowering

Environmental signals

>200 genes are regulating flowering in Arabidopsis.


SAM

A mutation in the GA pathway causes flowering

» Association of dwarfism and

floral induction with a grape

'green revolution' mutation

» Single nucleotide change in

GAI gene results in

development of

inflorescences instead of

tendrils in grape

Boss and Thomas, Nature 416, 847-850 (25 April 2002)


Importance of winter


Winter Wheat Planted Acres by County for Selected States, 2010

Spring Wheat Planted Acres by County for Selected State, 2010

Importance for food production

» Winter wheat represents 70-80 percent of total U.S. production.

» Sown in the fall for summertime harvest.


Importance for fruit yield

Sufficient winter chilling = synchronised budbreak = more fruit


- HC + HC

Environmental impact

Dormancy releasing chemicals necessary in NZ conditions.


Plants can sense and measure temperature

» Seed germination

» Winter dormancy

» Flowering time

… all depend on temperature

Different plants use different types of

genes/proteins as outputs of

vernalization, but the mechanism is

the same: repression of a repressor. A

repressor of FT is de-activated by

cold, resulting in FT florigen activation.

Pin et al, Science 2010


FLC inactivation in response to cold

FLC represses FT

transcription in the leaf

Very complicated

regulation involving

anti-sense RNA and

modifications in

histones (proteins

packaging DNA)…

The genetic basis of flowering responses to seasonal cues Fernando Andrés & George Coupland Nature Reviews Genetics 13, 627-639 (September 2012)

http://www.nature.com/nrg/journal/v13/n9/full/nrg3291.htmlhttp://www.nature.com/nrg/journal/v13/n9/full/nrg3291.html


FT can be used to accelerate breeding

Many, many years…

Large plants need space… FT promotes maturity (first flowering)

Transgenic plum

Plum tree

Scorza lab, Kearneysville, WV


EF 5

>5

Fast breeding (heat resistance example)

Years

MAS (marker-assisted selection)


FT genes have other roles: tuberization, bulb

formation, fruit yield…

35S:AcFT4

WT


www.plantandfood.co.nz


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