Genetic variation of Alternaria brassicae (Berk.) Sacc., causal agent of dark leaf spot of cauliflower and mustard in India

Cauliflower (Brassica oleracea L. var. botrytis) and mustard Brassica juncea (L.) Czern] are important cruciferous crops facing serious yield and quality loss in India from dark leaf spot disease caused by Alternaria brassicae (Berk.) Sacc. Genetic variation among 32 pathogenic A. brassicae isolates from both crops was analyzed with random amplified polymorphic DNA and inter-simple sequence repeat primers in which the mean similarity coefficient was found to be 0.73 and 0.84, respectively. Further internal transcribed spacer analysis showed all isolates are 90–100 % similar to each other, indicating genetic similarity among different A. brassicae isolates that vary pathogenically.