Drought Tolerance in Irradiated Wheat Mutants Studied by Genetic and Biochemical Markers

Abstract

Mutation breeding is an alternative method for developing agriculturally important crops. A large set of Sagittario bread wheat seeds (Triticum aestivum L. cv.) were exposed to gamma ray irradiation (200 Gy) to obtain drought-tolerant mutant lines. To study drought tolerance, polyethylene glycol (PEG) 6000 was applied to the M-2 and M-3 individuals under in vitro conditions. Except in well-watered (100%) control plants, drought stress was triggered by a 50% decrease in the irrigation water applied to M-3 and M-4 plants in a greenhouse. Afterwards, 11 candidate drought-tolerant lines were obtained at the M-4 stage and subjected to molecular analysis. The highest percentage of polymorphisms (72.4%) was detected with Retrotransposons Microsatellite Amplified Polymorphism (REMAP) markers followed by Inter-Simple Sequence Repeat (ISSR; 62.07%) and Inter-Retrotransposon Amplified Polymorphism (IRAP) markers (52.94%). A dendrogram tree and a principal coordinate analysis (PCoA) plot classified the experimental samples into three distinctive groups. Additionally, the activities of several antioxidant enzymes were evaluated in both vegetative and flowering stages, and mutant lines showing the highest biochemical performance under stress were detected in the same group through phylogenetic analysis. Gamma ray irradiation was used to improve drought-tolerant wheat lines for forward/reverse genomic studies and marker-assisted selection in crops.