Mapping QTLs for grain iron, zinc, and yield traits in advanced backcross inbred lines of Samba mahsuri (BPT5204)/Oryza rufipogon

Iron and zinc deficiency is a major problem among large populations in rice-consuming countries. Development micronutrient dense rice varieties with high yield is a key target area in breeding programmes and QTL mapping studies using backcross inbred lines to transfer beneficial genes from wild relatives is one of the potential strategy. In this study, 136 BC(4)F(1)0 backcross inbred lines (BILs) from BPT5204 x Oryza rufipogon WR119 were field evaluated for 3 years for nine yield related traits. Grain Fe and Zn were estimated using ED-XRF. In all, 11 major QTLs with phenotypic variance from 10 to 16.8% were identified for Fe, Zn, and 5 yield related traits. O. rufipogon alleles were trait-enhancing in 18% of all QTLs and an allele at qFe2.1 increased iron concentration. Major effect QTLs qFe1.1 for grain Fe and qZn5.1, qZn8.1, and qZn10.1 for grain Zn explained 11 to 16% PVE, qZn8.1 and qZn10.1 were co-located with QTLs for grain yield related traits. Seven chromosomal regions showed QTLs for more than two traits. QTLs were associated with several high priority candidate genes for grain Fe, Zn and yield. One elite BIL [IET 24775 RP4920-Bio51B] was tested in AICRIP bio fortification trials for 4 years [2014-2017], and three BILs [IET 28715 RP4920-Bio61-1B], [IET28706 RP4920-Bio83B] and [IET28695 RP4920-Bio88B] are evaluated for 2 years of trials. The significant BILs and QTLs are useful in rice bio fortification and for gene discovery.