Transient Silence of VvCSN5 Enhances Powdery Mildew Resistance in Grapevine (Vitis Vinifera)

As one of the most economically important fruit crops in the world, grapevine (Vitis vinifera) suffers significant yield losses from many pathogens including powdery mildew caused by Erysiphe necator. By contrast, several wild Chinese grapevines including Vitis pseudoreticulata accession ‘Baihe-35-1’ exhibit a high resistance to powdery mildew pathogen. Here, we identified a grapevine gene CSN5 (COP9 signalosome complex subunit 5), designated VvCSN5, which showed different expression patterns in ‘Baihe-35-1’ and in susceptible cultivar V. vinifera ‘Thompson Seedless’ during powdery mildew isolate En NAFU1 infection. Moreover, transient silence of VvCSN5 in ‘Thompson Seedless’ leaves enhanced resistance to En NAFU1, which is accompanied by cell wall deposition at the attempt sites, and hypersensitive response-like cell death of penetrated epidermal cells. Several defense-related marker genes (VvPR1, VvPR3, VvPAD4, and VvRBOHD) had higher basal expression levels in VvCSN5-silenced leaves. In addition, we found the structure and activity of CSN5 promoters in ‘Thompson Seedless’ and ‘Baihe-35-1’ were discrepant, which may be one of the reasons for their different resistance to powdery mildew infection. Taken together, these results imply that grapevine CSN5 plays an important role in the responses to powdery mildew.