Fine mapping of the sunflower resistance locus PlARG introduced from the wild species Helianthus argophyllus

Abstract

Downy mildew, caused by Plasmopara halstedii, is one of the most destructive diseases in cultivated sunflower (Helianthus annuus L.). The dominant resistance locus PlARG originates from silverleaf sunflower (H. argophyllus Torrey and Gray) and confers resistance to all known races of P. halstedii. We mapped PlARG on linkage group (LG) 1 of (cms)HA342 × ARG1575-2, a population consisting of 2,145 F2 individuals. Further, we identified resistance gene candidates (RGCs) that cosegregated with PlARG as well as closely linked flanking markers. Markers from the target region were mapped with higher resolution in NDBLOSsel × KWS04, a population consisting of 2,780 F2 individuals that does not segregate for PlARG. A large-insert sunflower bacterial artificial chromosome (BAC) library was screened with overgo probes designed for markers RGC52 and RGC151, which cosegregated with PlARG. Two RGC-containing BAC contigs were anchored to the PlARG region on LG 1. © 2010 The Author(s).