Characterization and differential expression of complete coding sequence of Vitis vinifera L. sirtuin genes

The sirtuin/Sir2 (Silent information regulator 2) family of NAD+-dependent deacetylases and mono-ADP-ribosyltransferases plays an important role in several cellular processes including gene silencing, cell cycle regulation and life span extension in yeast and animals. Compared to other eukaryotes, plants have relatively fewer SIR2 related genes encoding only two putative SIR2 family proteins. Recently, two putative sirtuin genes were identified also in the grapevine genome. Starting from the predicted coding sequences present in the database, we have been able to obtain two truly expressed coding sequences from the start to the stop codon for both sirtuin genes that were named VvSRT1 and VvSRT2. The search for the expressed coding sequences was performed by comparing the predicted sequences with the recently available grape RNAseq database with the aim to develop the primers to be used in reverse trascriptase PCR reactions to amplify the genes of interest. Finally, in order to better understand the physiological role of both sirtuins, we investigated the expression of these genes in young leaves, mature leaves, and berries sampled at different growing stages. In leaves, usually it has been observed that VvSRT1 is less expresses than VvSRT2, moreover in young leaves VvSRT2 showed the higher expression during setting while in mature leaves during the flowering time. No particular variation have been observed concerning VvSRT1. In berries the two genes showed more similar expression level, and they showed the highest expression during the flowering time. Finally, the expression of VvSRT2 in berries is smaller than in leaves.