Grimplet Jérôme, Ibáñez Sergio, Baroja Elisa, Tello Javier, Ibáñez Javier
Instituto de Ciencias de la Vid y del Vino (CSIC, Universidad de La Rioja, Gobierno de La Rioja), Logroño, Spain.
Front Plant Sci. 2019 Jan 7;9:1917. doi: 10.3389/fpls.2018.01917. eCollection 2018.
Previous studies showed that the number of berries is a major component of the compactness level of the grapevine clusters. Variation in number of fruits is regulated by events occurring in the fruitset, but also before during the flower formation and pollination, through factors like the initial number of flowers or the gametic viability. Therefore, the identification of the genetic bases of this variation would provide an invaluable knowledge of the grapevine reproductive development and useful tools for managing yield and cluster compactness. We performed the phenotyping of four clones (two compact and two loose clones) of the Tempranillo cultivar with reproducible different levels of cluster compactness over seasons. Measures of reproductive performance included flower number per inflorescence, berry number per cluster, fruitset, coulure, and millerandage indices. Besides, their levels of several hormones during the inflorescence and flower development were determined, and their transcriptomes were evaluated at critical time points (just before the start and at the end of flowering). For some key reproductive traits, like number of berries per cluster and number of seeds per berry, clones bearing loose clusters showed differences with the compact clones and also differed from each other, indicating that each one follows different paths to produce loose clusters. Variation between clones was observed for abscisic acid and gibberellins levels at particular development stages, and differences in GAs could be related to phenotypic differences. Likewise, various changes between clones were found at the transcriptomic level, mostly just before the start of flowering. Several of the differentially expressed genes between one of the loose clones and the compact clones are known to be over-expressed in pollen, and many of them were related to cell wall modification processes or to the phenylpropanoids metabolism. We also found polymorphisms between clones in candidate genes that could be directly involved in the variation of the compactness level.
先前的研究表明，浆果数量是葡萄串紧实度水平的一个主要组成部分。果实数量的变化受坐果期发生的事件调控，但在花形成和授粉之前及期间也受诸如花的初始数量或配子活力等因素的影响。因此，鉴定这种变异的遗传基础将为葡萄生殖发育提供宝贵的知识，并为管理产量和果串紧实度提供有用的工具。我们对丹魄品种的四个克隆株（两个紧实克隆株和两个松散克隆株）进行了表型分析，这些克隆株在不同季节具有可重复的不同果串紧实度水平。生殖性能的测量指标包括每花序的花数、每串的浆果数、坐果率、落花落果率和无籽小果率指数。此外，我们测定了它们在花序和花发育过程中几种激素的水平，并在关键时间点（开花开始前和结束时）对它们的转录组进行了评估。对于一些关键的生殖性状，如每串的浆果数和每粒浆果的种子数，松散果串的克隆株与紧实克隆株表现出差异，且彼此之间也存在差异，这表明每个克隆株在产生松散果串时遵循不同的途径。在特定发育阶段观察到克隆株之间脱落酸和赤霉素水平存在差异，赤霉素水平的差异可能与表型差异有关。同样，在转录组水平上也发现了克隆株之间的各种变化，主要是在开花开始前。已知其中一个松散克隆株和紧实克隆株之间的几个差异表达基因在花粉中过度表达，其中许多与细胞壁修饰过程或苯丙烷类代谢有关。我们还在可能直接参与紧实度水平变异的候选基因中发现了克隆株之间的多态性。
