Characterization of rice restorer lines for abiotic stress tolerance

Abstract

Rice, a dietary mainstay for over half of the global population, faces increasing threats from abiotic stresses, especially salinity and iron toxicity. These stresses are particularly severe in coastal and hilly regions, making the development of tolerant rice genotypes crucial for future food security. newlineHybrid rice offers a 15 20% yield advantage over inbred varieties under ideal conditions. In India, restorer lines are vital in hybrid rice development through three-line or two-line breeding systems. However, the success of hybrid rice in salt-affected and iron toxicity areas depends on the availability of restorer lines that are not only effective in fertility restoration but also possess tolerance to these stresses. newlineAn experiment was conducted during the 2024 kharif season at the Student Instructional Farm and Centre of Excellence using Augmented Block Design to evaluate 217 restorer lines at seedling and reproductive stages under both controlled and field conditions. newlineUnder artificial salinity stress, RR-40 and RR-45 exhibited superior physiological traits, while RR-122 emerged as the most promising line across all environments. Molecular characterization confirmed Saltol-positive genes in RR-40, RR-45, and RR-122 in artificial screening and in field screening in RR-16, RR-75, RR-92, RR-112, RR-122, RR-140, RR-164, RR-167, RR-169, RR-174, and RR-178. newline SMA linked AP3206 and RM10793 with shoot length; RM10825 and RM10852 with root length; G11A, RM3412, and RM10829 with both shoot and root traits; and RM10793 with chlorophyll content. These markers are useful for marker-assisted backcross breeding. newlineFor iron toxicity, RR-4 showed tolerance under both lab and field conditions, although molecular markers could not validate its performance genetically. Additional candidates like RR-9 and RR-58 demonstrated promising resilience. Overall, RR-122 stands out as a versatile restorer line with dual tolerance to salinity and moderate to iron toxicity, making it a potential source to develop climate-resilient rice hybrids. newline