The Isolation and Fixation of Wholly Mutant Plant from Sectorial Chimera Induced by Gamma Irradiation in Begonia rex

Abstract

A possibility of the application of the pruning techniques for the isolation, fixation and propagation of wholly mutant plant from a small sectorial mutation induced by gamma irradiation on Begonia rex has been investigated.
Among the irradiated Begonia plants, variety‘Winter Queen’, partially changed plants each having a small green chimeric mutation with a number of small silver- white spots on leaf were found and one of these plants was employed throughout the present experiments (Fig. 1).
For extending and fixing the mutation, this plant was subjected to repeated cutting-back, layering and division in order to accelerate the development of axillary or adventitious buds and to grow them up to the shoots having the wider mutated area (Figs. 2-4). After the application of these techniques, the wholly mutated shoot was finally obtained (Fig. 4). This changed shoot was layerd and grown to the wholly changed plant (Fig. 5). The leaf color of new plants was green with a number of small silver-white spots as that of the original small sector (Figs. 6 and 9, and Table 1). The procedures of these experiments are illustrated in Figs. 7 and 8.
From this investigation, it is suggested that the combination of irradiation and various pruning techniques can be useful in the breeding of horticultural crops, which are propagated vegetatively, under ordinary cultural conditions.\