Pollination: A key event controlling the expression of genes related to phytohormone biosynthesis during grapevine berry formation

Berry formation is the process of ovary conversion into a functional fruit, and is characterized by abrupt changes in the content of several phytohormones, associated with pollination and fertilization. Much effort has been made in order to improve our understanding of berry development, particularly from veraison to post-harvest time. However, the period of berry formation has been poorly investigated, despite its importance. Phytohormones are involved in the control of fruit formation; hence it is important to understand the regulation of their content at this stage. Grapevine is an excellent fleshy-fruit plant model since its fruits have particularities that differentiate them from those of commonly studied organisms. For instance, berries are prepared to cope with stress by producing several antioxidants and they are non-climacteric fruits. Also its genome is fully sequenced, which allows to identify genes involved in developmental processes. In grapevine, no link has been established between pollination and phytohormone biosynthesis, until recently. Here we highlight relevant findings regarding pollination effect on gene expression related to phytohormone biosynthesis, and present results showing how quickly this effect is achieved

Sugar and abscisic acid signaling orthologs are activated at the onset of ripening in grape

The onset of ripening involves changes in sugar metabolism, softening, and color development. Most understanding of this process arises from work in climacteric fruits where the control of ripening is predominately by ethylene. However, many fruits such as grape are nonclimacteric, where the onset of ripening results from the integration of multiple hormone signals including sugars and abscisic acid (ABA). In this study, we identified ten orthologous gene families in Vitis vinifera containing components of sugar and ABA-signaling pathways elucidated in model systems, including PP2C protein phosphatases, and WRKY and homeobox transcription factors. Gene expression was characterized in control- and deficit-irrigated, field-grown Cabernet Sauvignon. Sixty-seven orthologous genes were identified, and 38 of these were expressed in berries. Of the genes expressed in berries, 68% were differentially expressed across development and/or in response to water deficit. Orthologs of several families were induced at the onset of ripening, and induced earlier and to higher levels in response to water deficit; patterns of expression that correlate with sugar and ABA accumulation during ripening. Similar to field-grown berries, ripening phenomena were induced in immature berries when cultured with sucrose and ABA, as evidenced by changes in color, softening, and gene expression. Finally, exogenous sucrose and ABA regulated key orthologs in culture, similar to their regulation in the field. This study identifies novel candidates in the control of nonclimacteric fruit ripening and demonstrates that grape orthologs of key sugar and ABA-signaling components are regulated by sugar and ABA in fleshy fruit

Verbesserung der Fruchtschalenfarbe und des Phenolgehaltes durch unterschiedliche Vorerntebehandlungen bei der Tafeltraubensorte (V. vinifera L.) ‘Red Globe’

Foliar sprayings of grapevines with different plant growth regulators or chemicals were evaluated for determining grape skin color and phenolic compounds content and enhancing table grape quality characteristics of cv. Red Globe in this study. Grape skin color is one of the most important quality factors for table grapes. Sometimes, it can be viewed difficulties in skin coloration of some red table grape cultivars grown in various grape growing regions of the world and poor skin coloration of red table grapes is a frequent trouble that reduces production efficiency. Despite the fact that it is utilized from some canopy management practices; plant growth regulators, chemicals with plant hormones and hormone-like compounds as active ingredients can be recently used for improving anthocyanin accumulation in growing of some table grape cultivars. In current study, nine different preharvest treatments were used for improving quality parameters of cv. Red Globe, including 1aEuroControl (C), 2-300 mg/L Abscisic acid (ABA), 3-300 mg/L Ethephon (Eth), 4-30% Ethanol (EtOH), 5-300 mg/L ABA + 300 mg/L Eth, 6-300 mg/L ABA + 30% EtOH, 7-300 mg/L Eth + 30% EtOH, 8-300 mg/L ABA + 300 mg/L Eth + 30% EtOH and 9aEuroCluster tip cutting (CTC). Although the best results from total phenolic compounds content and total anthocyanin content of cv. Red Globe were obtained in CTC treatment in all preharvest treatments, Eth+ETOH treatment especially gave rise to the best results among the preharvest chemical treatments