Abstract— Rapeseed-mustard crops in general, show low average productivity due to the prevalence of various biotic and abiotic stresses. Among biotic stresses, Alternaria blight caused by Alternaria brassicae (Berk.) Sacc. is an important and a widespread destructive disease. In the present study, an attempt was made to isolate Alternaria blight resistant mutants in the susceptible variety ‘Jayanti’ of Ethiopian mustard (Brassica carinata A. Braun) using in vivo and in vitro mutagenic techniques. Dry and uniform coloured seeds were mutagenised by gamma rays (50, 60, 70, 80, 90, 100 and 110kR) in 60Co gamma cell and Ethyl Methyl Sulphonate (EMS, 0.3%, 0.4% and 0.5%). About 46 mutants in M2 generation were isolated which showed segregation for Alternaria brassicae resistance. Ten mutants showed very less sporulation intensity along with less halo and concentric ring diameter. Screening of different mutagenised population under Alternaria-sick plots resulted in the isolation of two mutants viz., P(4)2 in 80kR and P13 in 100kR doses exhibiting moderate resistance/tolerance (PDI <25.0 %, scale 2) compared to the parental check ‘Jayanti’. The resistance of theses mutants was further confirmed by in vitro studies using cultural filtrate and detached leaf techniques. The Alternaria blight tolerant mutants also exhibited dwarfness and earliness in comparison to parental variety while the yield potential of both tolerant mutants remained at par with the checks used in the study. Thus, the induced mutagenesis through irradiation and EMS treatments could be effectively used for the induction of Alternaria blight tolerance and the isolated mutants can be the potential genetic stocks for breeding Ethiopian mustard lines with tolerance to Alternaria blight coupled with earliness and dwarfness.
Keywords— Culture filtrate, irradiation, EMS, Alternaria brassicae (Berk.) Sacc., mutation, resistance, Brassica carinata A. Braun.
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