LAUSR

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) (Pam.) is the most devastating disease of cauliflower (Brassica oleracea var. botrytis L.; 2n = 2x = 18), taking a heavy toll of the crop. In this study, a random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) derived sequence characterized amplified region (SCAR) markers linked to the black rot resistance locus Xca1bo were developed and evaluated as a screening tool for resistance. The RAPD marker OPO-04833 and ISSR marker ISSR-11635 were identified as closely linked at 1.6 cM distance to the black rot resistance locus Xca1bo. Both the markers OPO-04833 and ISSR-11635 were cloned, sequenced and converted into SCAR markers and validated in 17 cauliflower breeding lines having different genetic backgrounds. These SCAR markers (ScOPO-04833 and ScPKPS-11635) amplified common locus and showed 100% accuracy in differentiating resistant and susceptible plants of cauliflower breeding lines. The SCAR markers ScOPO-04833 and ScPKPS-11635 are the first genetic markers found to be linked to the black rot resistance locus Xca1bo in cauliflower. These markers will be very useful in black rot resistance marker assisted breeding.