Cyclophilin: a downy mildew resistance gene candidate in grapevine
Plasmopara viticola is the pathogen responsible for one of the most important diseases in viticulture. Vitis vinifera cultivars show almost no resistance to this pathogen except some new cultivars like ‘Regent’, which achieved resistance through introgression. The molecular mechanisms of resistance are still unknown. A cyclophilin cDNA, denoted as VviCyP was isolated in grapevine. Real time PCR analysis was used to evaluate VviCyP mRNA accumulation at several time-points (0 h, 6 hpi, 12 hpi, 18 hpi, 24 hpi and 48 hpi) following infection. The field resistant cultivar ‘Regent’ accumulates more VviCyP transcripts at early time-points (0 h, 6 hpi and 12 hpi) whereas the sensitive cultivar ‘Trincadeira’ only accumulates it after the 18 hpi time-point. These results suggest that VviCyP may play an important role in the ‘Regent’ defence mechanism and that ‘Regent’ resistance capabilities are probably due to a faster perception and activation of the defence mechanism upon infection with the downy mildew pathogen.