Mutagenic effects on frequency and spectrum of chlorophyll mutations in rice bean (Vigna umbellata Thunb, OHWI & OHASHI)

Abstract

An experiment was conducted to study the mutagenic effects on frequency and spectrum of chlorophyll mutations in M2 generation of rice bean (Vigna umbellata Thunb., Ohwi & Ohashi) treated with three doses each of gamma rays (150Gy, 200Gy and 250Gy) and Ethyl Methanesulphonate (EMS) (0.2%, 0.4% and 0.6%). Wide spectrum of chlorophyll mutations were induced which included chlorina, xantha, albina, viridis and sectorial. Among these, chlorina was the most frequent whereas, albina type appeared to be the least in treated populations indicating high mutability of the genes encoding chlorophyll biosynthesis. Total frequency of chlorophyll mutations was higher in gamma rays treatments as compared to EMS due to higher sensitivity of the genotype to gamma rays. Variation in magnitude of total chlorophyll frequency in different doses of mutagenic treatments clearly indicates the differential response of genotype to the doses in producing the chlorophyll mutations. Higher chlorophyll mutation frequency was recovered in lower doses of mutagens and this could be due to induction of minimum lethality at lower doses. The spectrum and frequency of chlorophyll mutations could serve as an index of induced genetic variations in M2 and follow-up generations.