Evaluation of crucifer germplasm for black rot (Xanthomonas campestris pv. campestris) resistance

Black rot is a devastating bacterial disease caused by Xanthomonas campestris pv. campestris (Pam.) Dowson, inflicting 10–50% losses in cauliflower production. Therefore, 41 accessions/varieties of five crucifer species including Brassica oleracea var. botrytis L. (C genome), B. rapa (A genome), B. napus (AC genome), B. carinata (BC genome) and Eruca sativa were screened in field conditions against artificial inoculation of Xcc race 1. Mean disease severity and disease incidence (%) were observed in different accessions/varieties of cauliflower (7.51 to 8.46, 88 to 94), B. rapa (4.81 to 8.8, 66.33 to 98.00), B. carinata (0.07 to 6.48, 7.33 to 87), B. napus (1.46 to 7.33, 31.00 to 96.66) and E. sativa (7.10 to 7.24, 86 to 88.33), respectively. All the varieties/accessions of cauliflower and E. sativa were observed highly susceptible. Three accessions of B. rapa were found to be susceptible and remaining were classified into very susceptible types. Out of 16 accessions of B. carinata screened, 12 were susceptible, two were very susceptible, one was partially resistant and one was fully resistant. While in B. napus, three accessions as partial resistant, seven as susceptible and four were very susceptible against Xcc race 1. Newly identified Xcc resistant and partially resistant/tolerant sources can be used for breeding black rot resistant cole crops by introgressing gene(s) of interest into B. oleracea.