Screening ofBrassicagermplasm for resistance toPlasmodiophora brassicaepathotypes prevalent in Canada for broadening diversity in clubroot resistance

Abstract

Hasan, M. J., Strelkov, S. E., Howard, R. J. and Rahman, H. 2012. Screening of Brassica germplasm for resistance to Plasmodiophora brassicae pathotypes prevalent in Canada for broadening diversity in clubroot resistance. Can. J. Plant Sci. 92: 501–515. Clubroot disease of crucifers, caused by Plasmodiophora brassicae, poses a threat to the Canadian canola industry, and the development of resistant cultivars is urgently needed. Germplasm resistant to local pathotype(s) is the prime requirement for breeding clubroot-resistant cultivars. The objective of this study was to identify Brassica germplasm possessing resistance to P. brassicae pathotypes prevalent in Alberta. Pathotype-specific resistance was identified in the diploid species Brassica rapa (AA) and B. oleracea (CC), and in the amphidiploid B. napus (AACC). Among B. rapa genotypes, turnip was the most resistant, followed by winter type and spring type oilseed rape. The rutabaga group of B. napus, on the other hand, was homogeneous for resistance to Canadian P. brassicae pathotypes. The diploid species B. nigra (BB) also showed pathotype-specific resistance. However, the two amphidiploids carrying the B. nigra genome, B. juncea (AABB) and B. carinata (BBCC) were completely susceptible to clubroot.