<i>In Vitro</i> Mutation Induction and Selection of Chrysanthemum (<i>Dendranthema Grandiflora</i> Tzelev) Lines with Improved Resistance to <i>Septoria Obesa</i> Syd

Abstract

This paper describes in vitro mutation selection technique for improved resistance in chrysanthemum (Den- dranthema grandiflora Tzelev) cv. Snow Ball against culture filtrate of Septoria obesa, a leaf spot pathogen. The callus was initiated fro m leaf exp lant on MS med iu m supplemented with 10 mg/ l kinetin and 1 mg/l NAA. Opt imal doses of gamma radiation and culture filtrate on the per cent survival of calli were standardized. The optimal dose of gamma radiation was 20 Gy and that of culture filtrate was 15%. The selection of the resistant calli was made at 15% cu lture filtrate concentration and the calli were subjected to two more cycles of selection (30 day cycle) to obtain resistant cell lines. 100% of the plants raised fro m cuttings had acquired resistance against the pathogen in the pot in greenhouse. The plants were maintained for four years without any symptoms with regular inoculation of fungal spore suspension. No phenotypic variation was observed in the resistant plants.