Induced chlorophyll mutations in bell pepper (Capsicum annuum L. var. grossum)

An investigation entitled “Induced chlorophyll mutations in bell pepper (Capsicum annuum L. var. grossum)” was conducted during kharif (summer-rainy season) 2012 and 2013 at Experimental farm of the Department of Vegetable Science and Floriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, H.P., India. Healthy seeds of California Wonder of bell pepper were exposed to physical mutagen Gamma rays using 60CO as a source of radiation at Mutation Breeding Centre, Department of Biotechnology, BARC Trombay, Mumbai and chemical mutagen EMS (Ethyl Methane Sulphonate) to obtain the spectrum and frequency of chlorophyll mutations in M2 generation. The M1 generation was produced from these mutagen treated seeds. Several unique and interesting chlorophyll and viable mutants were obtained in M2 generation. In M2 generation, gamma rays induced higher proportion of chlorophyll mutants then EMS. A progressive increase in mutation frequency of chlorophyll mutations was observed with increasing doses/concentrations. Four different types of chlorophyll mutants namely xantha, yellow xantha, chlorina and viridis were induced. Out of these mutants, chlorina and viridis were most frequent and were produced even in lower doses/concentrations while yellow xantha was least frequent and produced only in higher doses. The highest frequency of chlorophyll mutations (18.8 %) was reported in the 22 kR of gamma dose, while the lowest (0.80 %) frequency of chlorophyll mutations was found in the treatment of 1.0 % EMS. There was a dose dependent increase in the spectrum and frequency of chlorophyll mutations. These chlorophyll mutants induced by gamma radiation and EMS could be used in mutation breeding programme for inducing viable mutations for improvement of bell pepper varieties

Expression analysis of hormonal pathways and defense associated genes in gamma-rays mutagenized wheat genotypes against combined stresses of spot blotch and terminal heat

Wheat (Tritium aestivum L.) productivity is severely hampered by various pathogens and changing climatic conditions. Spot blotch and terminal heat stress are the major constraints of wheat production in the eastern Gangetic plains of India. To identify novel breeding sources and to understand underlying resistance mechanisms, forty-four gamma rays mutagenized wheat genotypes, derived from three different parents were screened under favourable agro-ecological conditions for spot blotch and terminal heat stress. Ten mutants showed reduced spot blotch infection calculated based on Area Under Disease Progress Curve (AUDPC), than their respective parents. The mutant TAW41 had the least infection (AUDPC: 354.32), significantly lower than its parent HD2967 (AUDPC: 675.51) and other checks. TAW41 also had a higher Normalized Difference Vegetation Index (NDVI) and chlorophyll content than the parent. Gene expression analysis of TAW41 showed differential accumulation of transcripts involved in hormonal pathways (Salicylic acid, Jasmonic acid, and ethylene) and other defense-associated genes, indicating that TAW41 might have unique resistance mechanism that facilitates this genotype to perform better against the combined stress of spot blotch and terminal heat. Hence, mutant TAW41 has been identified as a novel source of resistance that could be exploited in wheat improvement programmes to enhance tolerance to spot blotch and terminal heat stress