Genetic improvement for drought tolerance in rice using mutation induction

Abstract

Thirty-three percent of the world's farmland is subject to drought, making it the most difficult abiotic stress on rice production. Ten different M4-rice mutants were tested, along with three check varieties (Giza 179, Sakha 107, and IET1444 - International check variety for drought stress), to see how well they fared in drought conditions. These genotypes were tested in well-watered (WW: irrigation every 4 days), water-stressed (WS1: irrigation every 8 days), and severe water-stressed (WS2: irrigation every 12 days) conditions across generations M5 to M8. Drought stress was measured regarding its effect on agronomic traits and drought tolerance indices. Of the ten tested mutants, seven high-tillering mutants had higher yields under normal and stress conditions than the check varieties did in the field. The STI, MP, YI, and GMP indices show that, compared to IET444 (DT check variety), the mutant EN25 performed best under drought stress, followed by the mutant EN27. According to the data analysis of SCoT markers, only 34 of the 46 primers used amplified 377 bands (alleles) across 53 different markers. There was a wide range of genetic similarities among mutants, parents, and the check varieties, and it ranged from 17% to 78%. These seven mutants shared 13 common bands with the most drought-tolerant check variety (IET444) using SCoT markers, which indicates that these mutants carried some drought-tolerant genes. Hence, these mutants hold great potential for use in drought-stressed rice breeding programs.