Marker assisted selection (MAS) for powdery mildew resistance in a grapevine hybrid family

Introduction: Fungal disease resistance became a cardinal point of the grape breeding in the 19th century, when pathogens such as powdery mildew (Uncinula or Erysiphe necator Schwein) and downy mildew (Plasmopara viticola Berk. et Curtis ex. de Bary Berl. et de Toni) were carried to Europe from North America. European viticulture faced a new challenge and a significant environmental risk factor because of the necessity of repeated fungicide applications during the vegetation period, since traditional cultivars of Vitis vinifera origin do not carry any resistance to the mildew fungi. All sources providing high or partial resistance to these pathogens are low-quality wild Vitis species, therefore introgression of the resistance genes from them requires many back-crosses with Vitis vinifera in order to produce high quality cultivars (FISCHER et al. 2004). Muscadinia rotundifolia was described as totally resistant to powdery mildew (PM) species due to a single locus called Run1 (for Resistance to Uncinula Necator 1). This dominant gene was introduced into the V. vinifera genome using a pseudo-backcross strategy (BOUQUET 1986). Molecular markers closely linked to Run1 locus have been identified (PAUQUET et al. 2001; DONALD et al. 2002), allowing MAS to be used in a breeding program. Our research aimed at the application and validation of molecular markers linked to Run1 PM resistance locus in BC5 individuals based on the results of DONALD et al. (2002) and BARKER et al. (2005) with PCR-RFLP (GLP112P1-P3), and SSR (simple sequence repeat) markers (VMC4f3.1, VMC8g9), respectively. The objective of the involvement of the SSR markers was to find a one-step way for identification of the PM resistant lines beside the reliable two-step PCR-RFLP.