Induction of Alternaria blight resistance using in vivo and in vitro mediated mutagenic techniques in Ethiopian mustard (Brassica carinata A. Braun)

Rapeseed-mustard crops are the important oilseed crops grown on North western Himalayan region of India comprising the states of Himachal Pradesh, Jammu and Kashmir, and Uttarakhand. In Himachal Pradesh, the crops account for about 57% of total oilseeds area and contribute nearly 60% to total oilseeds production. In general, all brassica crops are attacked by a variety of pathogens culminating in huge losses in seed yield. Alternaria blight caused by Alternaria brassicae (Berk.) Sacc. is an important and a widespread destructive disease of rapeseed-mustard which causes considerable reduction in quantity and quality of harvested brassica products (Kumar et al., 2014). Depending upon its severity in India, the yield losses to the extent of 70 % have been reported (Kolte, 1985; Chahal, 1986; Gupta et al., 2003). The present grown commercial varieties of rapeseed-mustard are susceptible to Alternaria blight and no resistant source has been identified so far amongst a wide array of rapeseed-mustard germplasm. Consequently, development of resistant cultivars appears to be the most efficient, sustainable and eco-friendly approach for the management of this disease. There are a number of reports on the existence of variability in this pathogen on the basis of morphology, sporulation, growth and cultural characteristics and reaction on a set of host differentials.

 Ethiopian mustard (Brassica carinata A. Braun) (BBCC, 2n=4x=34) is a natural allopolyploid between B. nigra L. (BB, 2n=2x=16) and B. oleracea L. (CC, 2n=2x=18). The variety ‘Jayanti’ is high yielding and very well suited to dry land farming but, is susceptible to Alternaria blight caused by Alternaria brassicae. Induced mutagenesis is one of the important tools to create genetic variability not available in the gene pool or to correct specific deficiency of an otherwise outstanding genotype (Bhat et al., 2001). Induced mutations have been extensively used for genetic enhancement of the oilseed crops and for improvement of some economic and quality traits in short duration of time (Manjaya and Nandanwar, 2007; Singh and Verma, 2015). In vitro mutagenesis mediated selection technique involves the use of pathogen toxins to select resistant Page | 5 International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-6, June- 2016] variants in culture and has attracted considerable attention due to its simplicity and ease in exposing a large number of cells to a uniform dose of toxins (Chawla and Wenzel, 1987; Toyoda et al., 1988). Tissue and cell culture techniques have been utilized to induce variability in many crop plants including brassica crops (Kharb et al., 2002; Larkin and Scowcroft, 1981; Jain et al., 1990; Katiyar, 1997; Javier et al., 2011). Although, these approaches have resulted in the development of resistant plants in some crops but, there is no report on the induction of Alternaria blight resistance in Ethiopian mustard. Therefore, aim of the present study was to induce Alternaria blight resistance/tolerance in a susceptible variety ‘Jayanti’ through in vivo and in vitro mediated mutagenic techniques followed by in vitro screening of the induced mutants for disease resistance/tolerance.