Radiation-induced mutants with increased cane number in sugarcane variety CoJ 85

Abstract

ABSTRACTCoJ 85 is an early-maturing, commercial sugarcane (Saccharum spp. complex) variety grown in Punjab, India. Farmers have adopted it because of its high sucrose content. However, it is shy in tillering and produces a low number of millable canes. It is also prone to lodging at maturity. Conventional breeding approaches are not feasible to further improve this variety, as it does not flower even under optimum tropical conditions. In this paper, we report on the use of gamma radiation-mediated in vivo mutagenesis to generate variation for cane number in CoJ 85.Contrary to general practice of irradiating tissue culture-derived calli (in vitro approach), single-bud cane setts (in vivo approach) of CoJ 85 were exposed to gamma rays to induce mutations for cane number. Our in vivo, standardized approach avoided tedious tissue culture cycles that cause undesirable somaclonal variation. Based on the germination data of buds, 25 Gy was found to be the 50% lethal dose (LD50). Thus, a mutant population of CoJ 85 was generated using 25 Gy gamma radiation and advanced to M1V2. The effects of different radiation doses were evaluated for number of tillers, number of millable canes, cane height (cm), cane weight (kg), and Brix (%) [Brix refers to total soluble solids content in juice; expressed in percentage) in the field-grown M1V2 population. A total of 38 elite mutant lines, which exhibited a significant increase in number of millable canes and Brix, were advanced for field evaluation and possible commercial use. We have demonstrated gamma rays-induced in vivo mutagenesis to be an effective method to generate stable mutants for increased cane number in CoJ 85.