Confirmation and Fine Mapping of the Resistance Locus <i>Ren9</i> from the Grapevine Cultivar ‘Regent’
2020
Daniel Zendler | Reinhard Töpfer | Eva Zyprian
Grapevine (<i>Vitis vinifera</i> ssp. <i>vinifera</i>) is a major fruit crop with high economic importance. Due to its susceptibility towards fungal and oomycete pathogens such as <i>Erysiphe necator</i> and <i>Plasmopara viticola,</i> the causal agents of powdery and downy mildew (PM and DM, respectively), grapevine growers annually face a major challenge in coping with shortfalls of yield caused by these diseases. Here we report the confirmation of a genetic resource for grapevine resistance breeding against PM. During the delimitation process of <i>Ren3</i> on chromosome 15 from the cultivar ‘Regent’, a second resistance-encoding region on chromosome 15 termed <i>Ren9</i> was characterized. It mediates a trailing necrosis associated with the appressoria of <i>E. necator</i> and restricts pathogen growth. In this study, we confirm this QTL in a related mapping population of ‘Regent’ × ‘Cabernet Sauvignon’. The data show that this locus is located at the upper arm of chromosome 15 between markers GF15-58 (0.15 Mb) and GF15-53 (4 Mb). The efficiency of the resistance against one of the prominent European PM isolates (EU-B) is demonstrated. Based on fine-mapping and literature knowledge we propose two possible regions of interest and supply molecular markers to follow both regions in marker-assisted selection.
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