Inheritance of necrotic mutants of groundnut (Arachis hypogaea L.)

In groundnut, parent Dharwad Early Runner on treatment with ethyl methane sulphonate and 5-azacytidine (a demethylating agent) resulted in two independent lesion mimic mutants namely, Necrotic 1 and Necrotic 2 belonging to Spanish (var. vulgaris) and Valencia (var. fastigiata) type, respectively. Inheritance studies involving Non-necrotic 1, Non-necrotic 2 (Non-necrotic versions of Necrotic 1 and Necrotic 2) and parent Dharwad Early Runner as ovule parents and Necrotic 1 and Necrotic 2 as pollen parents indicated that necrosis phenotype is under the control of five genes.Though the two necrotic mutants were isolated independently and belongs to different botanical groups, they are essentially similar with respect to necrotic phenotype and genotype. But, Non-necrotic 1, Non-necrotic 2 and parent Dharwad Early Runner differ for their allelic constitution in two or three genes. Response to 5azacytidine (a demethylating agent) suggested that Dharwad Early Runner is in hypermethylated state, necrotic mutants viz., Necrotic 1 and Necrotic 2 are in moderately-methylated state, while non-necrotic variants and Dharwad Early Runner like variants are in hypomethylated state. Results indicate the possible ‘epigenetic’ nature of these necrotic mutants.