Genetic association of crown rust resistance gene Pc68, storage protein loci, and resistance gene analogues in oats

Segregating F(3) families, derived from a cross between oat cultivar Swan and the putative single gene line PC68, were used to determine the association of seed storage protein loci and resistance gene analogues (RGAs) with the crown rust resistance gene Pc68. SDS-PAGE analysis detected three avenin loci, AveX, AveY, and AveZ, closely linked to Pc68. Their diagnostic alleles are linked in coupling to Pc68 and were also detected in three additional lines carrying Pc68. Another protein locus was linked in repulsion to Pc68. In complementary studies, three wheat RGA clones (W2, W4, and W10) detected restriction fragment length polymorphisms (RFLPs) between homozygous resistant and homozygous susceptible F(3) DNA bulks. Four oat homologues of W2 were cloned and sequenced. RFLPs detected with two of them were mapped using F(3) and F(4) populations. Clone 18 detected a locus, Orga2, linked in repulsion to Pc68. Clone 22 detected several RFLPs including Orga1 (the closest locus to Pc68) and three RGA loci (Orga22-2, Orga22-3, and Orga22-4) loosely linked to Pc68. The diagnostic RFLPs linked in coupling to Pc68 were detected by clone 22 in three additional oat lines carrying Pc68 and have potential utility in investigating and improving crown rust resistance of oat.