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Abstract:
Vitis vinifera cv. Carignan Noir likely originated in Aragon region (Spain), close to the town of Cariñena. Its late budding and ripening, high acidity and high anthocyanin content are characteristics which make this cultivar suitable to grow under conditions of global warming. However, Carignan Noir is losing popularity because of its high susceptibility to Erysiphe necator (powdery mildew, PM). The main objective of this study was the selection of Carignan Noir clones with increased tolerance to PM as well as identifying the genetic variation underlying their tolerance. Carignan Noir prospection from vineyards at the Cariñena designation of origin (DO) area resulted in 1119 true-to-type virus-free accessions. We selected three individuals showing different susceptibility to PM in the field. We confirmed their differential susceptibility in in vitro inoculated leaves. The most extreme susceptible and tolerant lines were compared in an RNA-seq transcriptome analysis in healthy apices and PM-infected adult leaves. The tolerant line showed upregulation of wax and lipid synthesis genes and specific pathogen response genes in both healthy and infected samples. Wax synthesis and a polygalacturonase gene upregulation could provide a physical barrier to powdery mildew, as well as a pathogen-related protein precursor (PRP1). On the other hand, the sensitive line presented upregulation of phenylpropanoid and flavanol synthesis genes. These results provide candidate genes for which to study their possible involvement in conferring tolerance to PM.
