SELECTION AND REGENERATION OF GROUNDNUT PLANTS RESISTANT TO THE PATHOTOXIC CULTURE FILTRATE OF CERCOSPORIDIUM-PERSONATUM THROUGH TISSUE-CULTURE TECHNOLOGY

Callus cultures were established from immature leaf explants of Arachi s hypogaea on MS medium supplemented with 2.0 mg/L of NAA and 0.5 mg/L of EAR of the susceptible cultivars namely VRI-2 and TMV-7. Three-wee k-old calli were subjected to mutagenic treatments (gamma rays: 50-250 Gy and EMS: 5-25 mM). Mutagen-treated calli were subcultured to fresh medium containing various concentrations (25-100% v/v) of pathotoxic culture filtrates. Calli were challenged in vitro with pathotoxic cult ure filtrate of the fungal pathogen and were assessed by visible growt h ratings expressed as the percent response to the doses/concentration s of mutagen. Selected mutagen-treated calli showed resistance in vitr o on media containing Cercosporidium personatum pathotoxic culture fil trate. Resistance calli were then transferred to MS regeneration mediu m supplemented with BAP (2.0 mg/L) and NAA (0.5 mg/L) for shoot bud re generation. The progeny of the plants produced 13 disease-resistant pl ants (R(2)) in both the cultivars. Among the eight R, populations stud ied, 70.2-82.5% of the plants exhibited enhanced resistance. This stud y suggested that groundnut plants with resistance to C, personatum can be selected from mutagen-treated callus of tikka leaf spot-susceptibl e cultivars using host-specific pathotoxic culture filtrates of C. per sonatum through in vitro technology.