Transcriptional profile changes in grapevine (Vitis vinifera L.) cv. Malbec induced by UV-B radiation

LIJAVEZTKY D; PONTIN M; BOTTINI R; MARTÍNEZ ZAPATER JM; PICCOLI P

Adelaide, Australia

Congreso; Australian Meeting on Grape and Wine; 2008

ASGWR

Background and Aims: Ultraviolet-B radiation (UV-B) is a natural component of the solar radiation that affects plant growth and development. In Mendoza (Argentina), vineyards with top reputation for premium wines are those located at altitudes of 1500 m, where UV-B reaches high values, with consequences on berry growth and quality. An analysis of the transcriptional profile changes produced by different UV-B treatments on grapevine plants was undertaken.   Methods and Results: Grapevine cv. Malbec plants were grown in vitro 45 d under PAR (100 µmol m-2 s-1) and then subjected for one day to a UV-B dose similar to the radiation registered at 1500 m of altitude but with two different distributions. The treatments were: a) 16 h PAR without UV-B (control); b) 16 h PAR + 16 h UV-B (7,2 µW cm-2); c) 16 h PAR + 4 h UV-B (28,5 µW cm-2). Total RNA was isolated from apical leaves and used to hybridize grapevine custom Affymetrix GeneChips (developed by the GrapeGen project) containing 23000 probe-sets. For the “4 h” treatment, a total of 4029 genes were differentially expressed (p<0.05), while 1909 genes reached this threshold for the “16 h” treatment. Functional analysis of those genes was performed by means of the FatiGO web-tool (Al-Shahrour et al., 2008) and the MapMan software (Thimm et al., 2004). Up-regulation of genes responsible for the biosynthesis of flavonoids, phytoalexins and those involved in light and biotic stress response was common in both treatments, while a different sub-set of genes were exclusively up-regulated at “4 h” (biotic stress) and at “16 h” (water stress and ATPases). A different scenario was observed for the down-regulated genes, since just the auxin class was jointly repressed. Chromatin packaging and remodelling, cell growth and death and DNA metabolism classes were solely down-regulated in the “4 h” treatment, while genes for cell wall metabolism were down-regulated in the “16 h” treatment.   Conclusions: Our preliminary results suggest the existence of common and specific pathways in grapevine defence responses to high and low UV-B intensity treatments. While protective responses are evoked by both treatments, DNA damage and repair mechanisms are particularly affected by the high intensity UV-B application.   Significance of the study: This is the first study to analyze the global genome transcriptional changes in grapevine under UV-B radiation. The information generated will help to identify genes and pathways involved in grapevine defence and acclimation mechanisms triggered by UV-B stress.