Regu egulation on of of gr grape e bud d dor ormancy cy - - PowerPoint PPT Presentation

Regu egulation

• n of
• f gr

grape e bud d dor

• rmancy

cy rel elea ease

• Dr. Etti

tti O Or Volca cani cen center er Agricu culture R e Resea esearch ch Organization Isr srael el The Bud Dormancy team Ethylene induced macromolecule catabolism – the switch required for bud meristem growth resumption?

20 40 60 80 100 120 7 14 18 21 24 27 32 35 Control-6.11 HS-6.11 HC-3%-6.11 HC-4%-6.11 HC-5%-6.11

Chemical and physical stress agents induce bud dormancy release

hydrogen cyanamide (HC) and Heat Shock (HS) Azid (AZ) Hypoxia

Pang et al., 2007, JExBot Halali et al., 2008, Planta Ophir et al.,2009, PMB

Our initial model for the molecular cascade that activate dormancy release (based on years of comparative analyses

• f response to dormancy release stimuli…)

Here we bring on the tip of the fork support for the model and suggest that Ethylene induced catabolism may be a central switch of dormancy release

C

20 40 60 80 100 120 140 160 3 6 12 24 48 Time from treatment Concentration (ppm) C HC HS

Etha hano nol

20 40 60 80 100 7d 11d 14d 18d 21d 25d 28d Buds break (%) Days after treatment

Control Nitrogen

Anaerobiosis induce bud dormancy release Azid, HC and HS temporarily induce anaerobic respiration, to face energy shortage caused by impaired aerobic respiration

2000 4000 6000 8000 10000 12000

Normalized Reads

Alcohol DH

L

5000 10000 15000 20000 25000 30000 35000

Normalized Reads

Pyruvate Decarboxylase H

20 20 40 40 60 60 80 80 10 100 12 120

םיעקפ תצירפ%)(

2011-12 A

Dormancy cycle

Az Azid Con

• ntrol
• l

Etha hano nol Ophir et al.,2009, PMB Or, unpublished

Temporary induction

• f fermentation also
• ccure under

vineyard conditions during deep dormancy, indicative

• f an energy crisis.

50 500 10 1000 00 15 1500 00 20 2000 00 25 2500 00 30 3000 00 35 3500 00 40 4000 00 45 4500 00 50 5000 00 55 5500 00 60 6000 00 65 6500 00

Metabolit lite/Rib ibit itol( l(IS) Peak Are rea R Rat atio

Suc Sucrose

Sucrose Degradation Sucrose synthesis

• Sucrose degradation is activated during deep dormancy
• It is probably induced in response to enhanced Glycolysis needed to supply

pyruvate for anaerobic respiration

• Sucrose degradation decrease during dormancy release in parallel with

increased sucrose synthesis capacity and sucrose level

• Similar regulation appears in response to HC and additional stimuli (not shown)

5000 10000 15000 20000 25000

Normalized Reads

Pyruvate kinase

G

Glycolysis

200 400 600 800 1000 1200 1400 1600

Normalized Reads

Hexokinase2

D

• HC and AZ upregulate

Ethylene synthesis by temporary induction of ethylene synthesis genes (ACS, ACO)

• Ethylene induce dormancy

release

• Temporary increase in

ethylene biosynthesis capacity is also regulated at the transcription level during the natural dormancy cycle

• Inhibition of ethylene

signaling inhibit bud break and the effect is timing dependent Shi et al, 2018, submitted

Vv VvACO Vv VvACO

Ethylene biosynthesis

Ethylene signaling We formerly identified ERF genes, which are known sensors of energy crisis and activate hypoxic response

• As expected, they accumulates in response to hypoxia
• Less expected, they directly respond to HC induced signal
• They are positively regulated during deep dormancy in transcript or protein level

Ophir et al.,2009, PMB Shi et al, in preparation

RNAseq of AZ, HC, Ethylene, hypoxia and NBDHC treated buds Down regulated (22) Up regulated (11) We identified all the ERFs, as well as other genes that are regulated by HC, Azid, hypoxia AND ethylene….assuming that they are primary regulators of the cascade

ABA delay bud break and reduce the enhancing effect

• f HC, HS, Azid and hypoxia on dormancy release.

20 40 60 80 100

HC Control ABA-HC ABA

Buds break (%)

20 40 60 80 100

HS Control ABA-HS ABA

7 11 14 18 21 25 28 20 40 60 80 100

AZ Control ABA-AZ ABA

7 11 14 18 21 25 28 20 40 60 80 100

Hypoxia Control ABA-Hypoxia ABA

A B C D

Days after treatment

Recovery from the inhibition was demonstrated in the combined ABA-HC treatment whereas no recovery was evident in the ABA-treated, compared to the control.

Zheng et al., 2015, JExBot

HC lead to reduction of ABA levels and increase of level of ABA degradation products in the buds Down-regulation

• f

VvNCED1 and up-regulation of VvA8H-CYP707A4 levels by HC may be responsible together for decreased ABA level and increased ABA catabolites level in response to HC. Natural dormancy cycle

Zheng et al., 2015, JExBot Zheng et al., 2018, PCE

The OE VvA8H- CYP707A4 grapevine lines presented significantly improved rate and level of dormancy release

cuttings test All vine test

Zheng et al., 2018, PCE

Profiling the expression of GA metabolism throughout the natural dormancy cycle suggests during endodormancy release:

• levels of active GA biosynthetic

enzymes increased

• levels of active GA degradation

enzyme decreased These results are in agreement with the initial model However… In reality, things appears to be more complicated…

Zheng et al., 2018, JExBot

During initial steps of meristem activation, GA has a strong inhibiting

• effect. Once meriatem is activated, GA has an enhancing effect,

probably on primordia growth

Regu egulation

• n of
• f gr

grape e bud d dor

• rmancy

cy rel elea ease

• Dr. Etti

tti O Or Volca cani cen center er Agricu culture R e Resea esearch ch Organization Isr srael el

Thank you and thanks to…

The Bud Dormancy team