QTL mapping reveals different set of candidate genes governing stable and location specific QTLs enhancing zinc and iron content in rice

Rice is a cornerstone of global food security. Addressing contemporary dual challenge of global food and nutritional security, this study focuses on identification of genomic regions/QTLs that control uptake and translocation of micronutrients (Zn and Fe) in rice. Using mapping population derived from a cross between URG 30 (Zn 32.2 ppm and Fe 15.3 ppm) and Rajendra Kasturi (Zn 19.2 ppm and Fe 9.5 ppm), evaluated at three locations, we identified 8 QTLs each for grain Zn and Fe content distributed across 8 chromosomes. Notably 3 major QTLs for grain Zn content (chromosomes 1, 5 and 6) and 1 major QTL for grain Fe content (chromosome 3) were identified with phenotypic variance (PV) ranging from 10.7 to 15.19% for Zn and 12.10% for Fe. Two stable QTLs for grain Zn content (PV 5.89–8.98% and 3.18–13.62%) and one for Fe content (PV 1.84–7.59%) were consistently identified at two locations. Seven transgressive segregants for yield and Zn content are identified at two locations. Correlation analysis uncovered significant positive associations between grain Zn and Fe content. We also interpreted the functional role of 24 candidate genes including key candidates OsZIP1 , OsSPR1 , OsZIP2 , OsPEZ1 , OsZIP6 , OsNAS1 , OsNAS2 , OsYSL3 underlying stable and location specific QTLs in the context of mineral uptake strategies utilized by rice. The research supports marker assisted breeding efforts towards substantial nutritional enhancement in rice grain.