Irradiation of hexaploid wheat (Triticum aestivum L.) seeds with varying doses of gamma radiation leads to novel mutants

The plateauing wheat yield and its narrow genetic diversity warrants modifying wheat to meet the global food demand from the growing population. Gamma radiation-based mutagenesis is a widely used technique to develop or improve crops like wheat. However, optimizing radiation dose level and the response of wheat genetic background to radiation dose are the two key challenges. This study was conducted to assess the effect of different gamma radiations doses (0 Gy, 100 Gy, 150 Gy, 200 Gy and 250 Gy) on early growth, development and yield related attributes of six wheat genotypes (AZRC Dera, RK2022, landrace-49, landrace-52, black wheat and Kashmiri landrace), and to screen out mutants with promising growth, developmental and yield related attributes. Eighteen different traits (early growth, phenology and yield of the wild type and M1 mutants) of the six wheat genotypes revealed differences (p < 0.01) among genotypes (wheat) and treatment (gamma radiation doses), underscoring the genetic diversity and differential radio-sensitivity of the wheat genotypes. Additionally, all the eighteen traits among all genotypes were negatively (p < 0.01) affected at high dose of 250 Gy, while optimum dose of 150 Gy positively impacted early growth and yield related traits. Kashmiri landrace exhibited improved superior yield related attributes such as early maturity, longer spike, greater spikelets per spike, greater number of seeds per spike and superior seed weight per spike, making it an ideal genetic material for mutation breeding programs. Hierarchical clustering revealed five distinct clusters of genotypes, Kashmir landrace and black wheat being the most distinct genotypes. Gamma radiation mutagenesis produced a vast array of radio morphs such as double spikes per tiller, high tillering, dwarfing and altered spike architecture. These mutants provide novel and valuable genetic resources for wheat breeding.