In vitro isolation of red coloured mutant from chimeric ray florets of chrysanthemum induced by gamma-ray

Abstract

Mutation breeding played a pivotal role in generating genetic variation in chrysanthemum. As a result of gamma radiation large numbers of novel mutants appear in the form of chimeras that differ in flower colour, shape and size. Isolation of such types of mutated tissue is impossible through conventional techniques. Therefore, all such novel mutants appear as a result of mutation is lost every year due to lack of suitable means to isolate them through conventional propagation methods. Therefore, an effort was made to develop efficient regeneration system from ray florets of a chrysanthemum mutant in order to isolate, purify and field establish the novel mutant. The maximum survival of cultures were found when the ray florets were per-treated with mancozeb-45 (0.2%) + carbendazim (0.2%) + 8-HQC (200 mg/l) for 3 h followed by surface sterilized with HgCl2 (0.1%) for a duration of four minutes. The callus induction was maximum on Murashige and Skoog (MS) medium supplemented with BAP (4.0 mg/l) and NAA (1.0 mg/l). The maximum regeneration of microshoots (95.56%) from the ray floret induced callus was recorded on MS medium fortified with BAP (4.0 mg/l) and NAA (0.1 mg/l). MS medium supplemented with BAP (5.0 mg/l) + NAA (0.1 mg/l) + GA3 (0.2 mg/l) gave the highest microshoot proliferation (100.0%). In vitro rooting ideal (99.0%) on half-strength MS medium fortified with 0.5 mg/l NAA. The hardening of rooted plantlets was successfully achieved after 3-4 weeks of acclimatization. The isolated mutant produced flowers that were true-to-type to the original red mutant, i.e., solid mutant.