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Energetic aspects of sugar import and malate breakdown in the ripening berry
Rezk Shahood, Laurent Torregrosa, Matthieu Breil, Antoine Bigard, Stefania Savoi, Charles Romieu
To cite this version:
Rezk Shahood, Laurent Torregrosa, Matthieu Breil, Antoine Bigard, Stefania Savoi, et al.. Energetic aspects of sugar import and malate breakdown in the ripening berry. 12. International Conference on Grapevine Breeding and Genetics - GBG 2018, Jul 2018, Bordeaux, France. 2018. �hal-02735766�
Energetic aspects of Sugar import and Malate
breakdown in the ripening berry
Rezk Shahood
1
, Laurent Torregrosa
2
, Mathieu Breil, Antoine Bigard
2
,
Stefania Savoi
2
& Charles Romieu
2@
Sugar (M)
0.0
0.4
0.8
1.2
1.6
2.0
Ber
ry
wei
ght
(g)
0.0
0.3
0.6
0.9
1.2
1.5
1.8
-10
0
10
20
30
40
50
DAV
A
Present knowledge on berry metabolism is limited by fruit heterogeneity and asynchrony. More than 1000 Individual Pinot berries were harvested in order to characterize berry growth, sugar and acids at 10 days intervals.
Sugar (M)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Mala
te (mEq)
0
100
200
300
400
500
600
-10 0 10 20 30 40 50DAV
A
Sugar (M)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Mal
ate
(mEq)
0
100
200
300
400
500
600
(b)
-1
0
1
3-5
5-6
7-8
8-11
16-18
19-22
29-30
37-38
52-54
DAS
Heterogeneity in major solutes almost vanished when individual softening dates were considered. Malic acid was nearly consumed by Syrah in 10 days only, largely before technological maturity was reached
Hexoses ( mol Sucrose. n berries-1)
0.0 0.2 0.4 0.6 M a lic A cid ( m M o l H + .n b e rr ie s-1 ) 0 50 100 150 200 250 Pinot unsynch. > 0.8 Syrah unsynch. 1.2 Syrah synch. 1.5 DAS -10 0 10 20 30 40 50 Ma la te (mEq Id b err y -1 ) 0 50 100 150 200 S ug ar (mo l I d b err y -1 ) 0.0 0.2 0.4 0.6 0.8 1.0 O 2 u pta ke (µ mo l-1 .min -1 .kg -1 ) 18 21 24 27 30 33 36 39 42 A
Hexose accumulated 6 times faster than they can be oxidized by berry. In planta measurements showed that oxygen reduction was unaffected by the rate of phloem unloading, as confirmed upon detaching the berries. By contrast, respiration diminished simultaneously with the malic acid content.
Metabolic fluxes inferred from volume and concentration data initially fitted with net sucrose/H+ exchange at the tonoplast, but hexose virtually doubled after the completion of malate breakdown.
Cultivar H+/sucrose (t=0)
Aerobic fermentation triggered by temperature developed as malate breakdown was impaired and the net H+/sucrose exchange was quenched.
Discussion/ Conclusions
Sugar loading, malate breakdown and respiration have received considerable attention in ripening berries. Understanding the degrees of freedom of the underlying mechanisms would help to design the ideotypes of future grape varieties more resilient to global warming regarding berry acidity. In depth revisit of fundamental metabolic fluxes in individual berries led us to reveal new sub phases in the ripening process that were out of reach on conventional unsynchronized fruits samples. We show that despites its huge intensity, phloem unloading in the ripening berry essentially escapes respiratory energy coupling, which indicates in turn that H+ recirculation through sugar/H+ transporters and ATPases at the plasma and vacuolar membranes should be globally bypassed, therefore placing SWEETS as major contributors of berry ripening (Chong et al., 2014). VViHT6, induced at véraison (Terrier et al., 2001) appears as the privileged candidate for the net H+/sugar exchange induced at the tonoplast at the onset of ripening. In this respect, contrary to our previous interpretation, the initial release of vacuolar acidity is not the trigger of aerobic fermentation as a fail-safe mechanism against cytoplasmic acidosis, so the outgoing malic acid flow must be tightly adjusted to the oxidative capacity and neoglucogenesis during early ripening. Aerobic fermentation is induced precisely when net H+/sucrose exchange at the tonoplast becomes limited by malate availability, so H+ recirculation needs to be energized. Energy coupling was documented in mitochondria from mature grape (Romieu et Flanzy,1988), but the decrease in respiration, accompanied with greater propensity to aerobic fermentation, now raises question on respiratory complexes present in green stage, their evolution during ripening, and interaction with vacuolar function. Genetic variation in the malic acid/sugar pathway is under present investigation (Bigard et al., 2018)
35 S -VviHT6 –GFP fusion at the tonoplast of V. vinifera
Heary Roots
1
General Commission for Scientific Agricultural Research– Lattakia, Syrie
2
AGAP, Univ Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France.
Chong J, Piron MC, Meyer S, Merdinoglu D, Bertsch C, Mestre P. The SWEET family of sugar transporters in grapevine: VvSWEET4 is involved in the interaction with Botrytis cinerea. J Exp Bot. 2014 Dec;65(22):6589-601
Bigard, Antoine et al. 2018 Vitis Vinifera L. Fruit Diversity to Breed Varieties Anticipating Climate Changes. Frontiers in Plant Science 9 (2018): 455. PMC. Web. 11 July 2018.
Chong J, Piron MC, Meyer S, Merdinoglu D, Bertsch C, Mestre P. . 2014 The SWEET family of sugar transporters in grapevine: VvSWEET4 is involved in the interaction with Botrytis cinerea. J Exp Bot Dec;65(22):6589-601
Romieu C. & Flanzy C. 1988 Extraction des mitochondries des baies de raisin (Vitis vinifera L. ) Plant Physiol.Biochem,26-5 589-596
Terrier N, Sauvage FX, Ageorges A, Romieu C. Changes in acidity and in proton transport at the tonoplast of grape berries during development. Planta. 2001
