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

Ethylene induced Regu egulation on of of gr grape e bud d dor ormancy cy macromolecule rel elea ease catabolism – the switch required for bud meristem growth The Bud resumption? Dormancy team Dr. Etti tti O Or Volca cani cen center er Agricu culture R e Resea esearch ch Organization Isr srael el

Chemical and physical stress agents induce bud dormancy release hydrogen cyanamide (HC) and Heat Shock (HS) 120 100 Control-6.11 80 HS-6.11 60 HC-3%-6.11 HC-4%-6.11 40 HC-5%-6.11 20 0 7 14 18 21 24 27 32 35 Azid (AZ) Hypoxia

Our initial model for the molecular cascade that activate dormancy release (based on years of comparative analyses of 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 Pang et al., 2007, JExBot Halali et al., 2008, Planta Ophir et al.,2009, PMB

Azid, HC and HS temporarily induce anaerobic A respiration, to face energy shortage caused by 2011-12 12 120 Dormancy cycle impaired aerobic respiration 10 100 םיעקפ תצירפ %) ( 80 80 60 60 Etha hano nol 160 C C 40 40 140 HC Etha hano nol Concentration (ppm) 20 20 120 HS 100 0 80 Az Azid 60 Con ontrol ol 40 H Pyruvate Decarboxylase 20 35000 0 Normalized Reads 30000 3 6 12 24 48 25000 20000 Time from treatment 15000 10000 Anaerobiosis induce bud dormancy release 5000 0 Temporary induction 100 of fermentation also L Buds break (%) Alcohol DH 80 occure under 12000 Normalized Reads 60 10000 vineyard conditions 8000 40 6000 during deep Control 4000 20 2000 Nitrogen dormancy, indicative 0 0 of an energy crisis. 7d 11d 14d 18d 21d 25d 28d Ophir et al.,2009, PMB Days after treatment Or, unpublished

D Hexokinase2 1600 Normalized Reads 1400 1200 1000 800 600 400 200 0 Sucrose Degradation Glycolysis Sucrose synthesis G Pyruvate kinase Sucrose Suc 6500 65 00 25000 6000 60 00 55 5500 00 l(IS) Normalized Reads 20000 5000 50 00 itol( atio 4500 45 00 Rat ibit 15000 lite/Rib 4000 40 00 rea R 3500 35 00 Peak Are 30 3000 00 10000 Metabolit 2500 25 00 2000 20 00 5000 1500 15 00 1000 10 00 0 500 50 0 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) •

VvACO Vv VvACO Vv Ethylene biosynthesis 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

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

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 Up regulated (11) Down regulated (22) RNAseq of AZ, HC, Ethylene, hypoxia and NBDHC treated buds

ABA delay bud break and reduce the enhancing effect of HC, HS, Azid and hypoxia on dormancy release. A B 100 100 80 80 60 60 40 40 Buds break (%) 20 20 0 0 HS Control HC Control ABA-HC ABA ABA-HS ABA C D 100 100 80 80 60 60 40 40 20 20 0 0 AZ Control Hypoxia Control ABA-AZ ABA ABA-Hypoxia ABA 7 11 14 18 21 25 28 7 11 14 18 21 25 28 Zheng et al., 2015, JExBot 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.

HC lead to reduction of ABA levels Natural dormancy cycle and increase of level of ABA degradation products in the buds Down-regulation of VvNCED1 and up-regulation of VvA8H-CYP707A4 levels by HC may be responsible together for decreased ABA level and increased ABA catabolites level Zheng et al., 2015, JExBot in response to HC. Zheng et al., 2018, PCE

cuttings test The OE VvA8H- CYP707A4 grapevine lines presented significantly improved rate and level of dormancy release 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 on of of gr grape e bud d dor ormancy cy The Bud rel elea ease Dormancy team Thank you and thanks to… Dr. Etti tti O Or Volca cani cen center er Agricu culture R e Resea esearch ch Organization Isr srael el