Identification of superior haplotype and haplotype combinations for UV-B stress-related genes in Rice (Oryza sativa L.)

Rice (Oryza sativa L.), a vital food crop, is significantly impacted by UV-B radiation, which limits growth and productivity. This study aimed to identify superior haplotypes of UV-B stress-responsive genes to improve rice tolerance to UV-B stress. A total of 417 rice accessions from diverse regions were analyzed for genetic variation, focusing on 10 genes associated with UV-B responsiveness. Using haplotype analysis, we identified significant genetic diversity in these genes, including OsCPDP, OsWRKY89, UTR319, OsUGT707A2, OsUGT706D1, OsbZIP48, OsRLCK160, and OsUVR8a. Phenotypic assessments of UV-B tolerance revealed several superior haplotypes linked to reduced leaf damage scores under UV-B exposure. Notably, haplotypes OsCPDP_Hap4, OsUGT707A2_Hap4, OsbZIP48_Hap2, OsRLCK160_Hap7, and OsUVR8a_Hap4 were identified as key contributors to UV-B stress resistance. Furthermore, haplotype combinations (HC), particularly HC21 and HC24, demonstrated the highest UV-B tolerance, offering potential targets for molecular breeding programs aimed at developing UV-B-resistant rice varieties. These findings highlight that haplotype-based breeding can be effectively utilized to develop rice varieties with improved tolerance to environmental stresses, particularly UV-B stress, thereby contributing to enhanced productivity and food security in the face of global challenges.