Dai Zhan Wu, Meddar Messaoud, Renaud Christel, Merlin Isabelle, Hilbert Ghislaine, Delrot Serge, Gomès Eric
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France.
J Exp Bot. 2014 Aug;65(16):4665-77. doi: 10.1093/jxb/ert489. Epub 2014 Jan 29.
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.
葡萄浆果的发育和成熟受到浆果感知的营养物质、激素和环境信号的复杂调控。然而，这些调控类型背后的生化和分子机制仍知之甚少。一个能够轻松调节果实生长条件的简化但现实的模型系统将有助于解读这些机制。在此，通过结合温室结果插条的生产和体外器官培养技术，开发了完整离体葡萄浆果的体外培养系统。碳-13（¹³C）和氮-15（¹⁵N）标记实验表明，该系统能使完整离体浆果从培养基中积极吸收和利用碳和氮。该系统还进一步用于研究糖类对花青素积累的影响。在没有额外外源脱落酸的情况下，蔗糖浓度>2%可诱导花青素合成。蔗糖浓度越高，花青素积累的诱导越早。葡萄糖、果糖和蔗糖均可增加花青素积累，其中葡萄糖和果糖比蔗糖更有效。这种增加并非由于其前体水平的提高，因为高糖供应会降低苯丙氨酸含量。相反，全基因组转录组分析表明，糖诱导的花青素积累增强是由于调控基因和结构基因（特别是UDP-葡萄糖：花青素3-O-葡萄糖基转移酶）表达的改变，以及信号转导途径的大量重编程所致。这个体外系统可用于研究浆果成分对营养因子和激素的反应，以及它们与环境因子（如光照和温度）的相互作用，所有这些都可以进行精细调节和控制。
