Long-term in vitro culture of grape berries and its application to assess the effects of sugar supply on anthocyanin accumulation.
Grape berry development and ripening are under complex regulation by the nutrients, hormones, and environment cues sensed by the berry. However, the biochemical and molecular mechanisms underlying these types of regulation are poorly understood. A simplified but realistic model system that enables fruit growth conditions to be modulated easily will facilitate the deciphering of these mechanisms. Here, an in vitro culture system of intact detached grape berries was developed by coupling the production of greenhouse fruiting-cuttings and in vitro organ culture techniques. (13)C and (15)N labelling experiments showed that this system enables the intact detached berries actively to absorb and utilize carbon and nitrogen from the culture medium. It was further used to study the effects of sugars on anthocyanin accumulation. A sucrose concentration >2% could induce anthocyanin synthesis in the absence of additional exogenous abscisic acid. The higher the sucrose concentration, the earlier was the induction of anthocyanin accumulation. Glucose, fructose, and sucrose increased anthocyanin accumulation, with glucose and fructose being more effective than sucrose. This increase was not due to an increase in its precursor level, since the phenylalanine content was decreased by a high sugar supply. Instead, genome-wide transcriptome analysis suggests that the sugar-induced enhancement of anthocyanin accumulation results from altered expression of regulatory and structural genes (especially UDP-glucose:anthocyanidin 3-O-glucosyltransferase), together with massive reprogramming in signalling transduction pathways. This in vitro system may serve to study the response of berry composition to nutrient factors and hormones, and their interaction with environmental factors (e.g. light and temperature), which can all be finely tuned and controlled.
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France zhanwu.dai@bordeaux.inra.fr.
Zhan Wu
ZW
Dai
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Messaoud
M
Meddar
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Christel
C
Renaud
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Isabelle
I
Merlin
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Ghislaine
G
Hilbert
Université de Bordeaux, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Serge
S
Delrot
Université de Bordeaux, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
Eric
E
Gomès
D000040:Abscisic Acid / Q000494:pharmacology; D000596:Amino Acids / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism*; D002241:Carbohydrates / Q000494:pharmacology*; D002244:Carbon / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005632:Fructose / Q000494:pharmacology; D005638:Fruit / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D009584:Nitrogen / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D013997:Time Factors; D046509:Tissue Culture Techniques / Q000379:methods*; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D027843:Vitis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D000596:Amino Acids; D000872:Anthocyanins; D002241:Carbohydrates; D005632:Fructose; D013395:Sucrose; D000040:Abscisic Acid; D002244:Carbon; D005947:Glucose; D009584:Nitrogen
Anthocyanins; Vitis.; grape quality; in vitro; secondary metabolism; sugar signalling