Genetic variations of EMS-induced chili peppers (Capsicum annuum) cv. Gelora generate geminivirus resistant mutant lines

Abstract

A mutation breeding program was conducted to improve chili pepper (Capsicum annuum) resistance to Geminivirus caused by Pepper yellow leaf curl virus (PepYLCV). The disease can cause significant yield losses on chili pepper. This study was conducted to enhance genetic variation in pepper cv. Gelora using ethyl methanesulphonate (EMS) to obtain mutant lines resistant to PepYLCV. Exposure to an EMS solution of 0.5% (v/v) for 30 minutes was used for mutagenizing shoot tips to produce the first population (M1). After the treatment, shoot tips were cultured on MS medium to regenerate planlets that were subsequently acclimatized to produce M2 population. A set of 2,955 mutant lines (M2) were screened in a greenhouse by inoculating PepYLCV isolate Segunung using white flies (Bemisia tabaci) as the virus vector. Six weeks after inoculation, the M2 population was examined for symptoms of Geminivirus and was verified for the presence of PepYLCV infection by PCR using specific primer. The greenhouse assay successfully selected 47 lines (1.6%) of M2 mutant population that showed no symptoms and no infection to PepYLCV compared to Gelora and Tanjung-2 varieties. Subsequent field test of M3 mutant lines in Geminivirus endemic area in Lembang, West Bandung, revealed that 15 out of 47 lines showed high resistance to PepYLCV and have good agronomic characters including yield components. A set of primers corresponding to the PepYLCV infection which produced 678 bp in size indicated its good amplification in the susceptible mutant lines, confirming the PepYLCV resistance of 15 selected mutant lines. The resistant mutants were immune to PepYLCV and had potential to be released as improved varieties in the future.