Understanding the aspartic proteases role in grapevine resistance against Plasmopara viticola

Mestrado em Biologia dos Recursos Vegetais / Instituto Superior de Agronomia. Universidade de Lisboa

Grapevine (Vitis vinifera L.) is one of the most important crops worldwide used mostly in wine production. Vitis vinifera cultivars are highly susceptible to downy mildew caused by the oomycete Plasmopara viticola (Berk. & M. A. Curtis) Berl. & De Toni. The damage caused by downy mildew is controlled with the intensive use of chemicals. Viticulturists and the scientific community are aiming for an optimization and reduction of pesticide usage in order to follow European Union guidelines. In Portugal, if the active substances at risk of exclusion by the EU are removed, it is estimated that downy mildew may cause a decline of 46% in the final production of wine grapes. To achieve a more sustainable viticulture practice, it is essential to understand this specific pathosystem. During plant-pathogen interaction, proteases play different roles in several layers of the activation of the immune response. The aim of this study was to identify and characterize the involvement of aspartic proteases (APs) in grapevine defense against P. viticola. We have conducted a genome wide search and bioinformatics characterization of V. vinifera AP gene family. A total of 81 APs proteins coded by 65 APs genes were found in V. vinifera genome. To investigate the phylogenetic relationship, we built a phylogenetic tree with 81 VviAPs and APs of other model plant species. Our results indicate that VviAPs can be divided into three categories, similar to those previously described for other plant models. Gene expression analysis of 12 selected VviAPs genes was conducted by quantitative real time PCR to further evaluate their role in the grapevine-P. viticola pathosystem. In the incompatible interaction, 5 VviAPs were significantly up-regulated, suggesting that VviAPs may have a role in grapevine defense against P. viticola

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