Radiation Genetics of Sesame Part III

Abstract

I. Introduction Since 1953, the author has been studying the cytogenetical effects on and the production of mutants in sesame (Sesamum indicum L.) by using several ionizing radiations; some results obtained have already been reported (Kobayashi 1954-1958). The present study deals with the morphological changes as well as with the characteristics of mutants induced by radiation treatments. It is found that the type of morphological changes and the occurrence of mutants induced by radiation are closely related to the evolution of sesame. Some important facts are; Alteration of phyllotaxis and leaf shape, development of nectary or differentiation to functional flower or capsule containing fertile seeds, alteration of number of loculus per capsule, etc. Thus, among the induced mutant types there are found the same types of morphology as found in cultivated types in Japan. The fact that the nectary of sesame used in the present study is proved to be homologous with the flower bud may be noteworthy in the field of experimental morphology. These obtained facts may contribute to finding the role of ionizing radiation in morphogenesis and, further, to reveal the mechanism of sesame evolution. II. Materials and methods Three diploid forms of cultivated sesame (Sesamum indicum L.), BID (BAN-type), WD(3B0-type), and WD8(QAN-type)*, were selected as materials for the present experiment. Since 1947, each of the three types was selfed and bred true. These three