Identification of powdery mildew resistance in wild grapevine (Vitis vinifera subsp. sylvestris Gmel Hegi) from Croatia and Bosnia and Herzegovina.

Wild grapevine (Vitis vinifera subsp. sylvestris) is widely recognized as an important source of resistance or tolerance genes for diseases and environmental stresses. Recent studies revealed partial resistance to powdery mildew (Erysiphe necator, PM) in V. sylvestris from Central Asia. Here, we report resistance to PM of V. sylvestris collected from different regions of Croatia and in seedling populations established from in situ V. sylvestris accessions. Ninety-one in situ individuals and 67 V. sylvestris seedlings were evaluated for PM resistance according to OIV 455 descriptor. Three SSR markers (SC47-18, SC8-071-0014, and UDV-124) linked to PM resistance locus Ren1 were used to decipher allelic structure. Nine seedlings showed resistance in in vivo evaluations while leaf disk assays revealed three PM-resistant accessions. One V. vinifera cultivar used as a control for PM evaluations also showed high phenotypic resistance. Based on the presence of one or two resistance alleles that are linked to the Ren1 locus, 32 resistant seedlings and 41 resistant in situ genotypes were identified in the investigated set. Eight seedlings showed consistent phenotypic PM resistance, of which seven carried one or two alleles at the tested markers. This study provides the first evidence of PM resistance present within the eastern Adriatic V. sylvestris germplasm.