Mapping for yield related traits in rice reveals major effect QTL qFLA1.1 from Oryza nivara increases flag leaf area

A stable back cross introgression line IL65 (IET22161) (Swarna/O. nivara-BC₂F₆) of rice was used to map flag leaf related traits in F₂ and F₃ populations. A total of 12 QTLs were mapped on two chromosomes with each QTL explaining 3 to 21% phenotypic variance (PV). Interestingly, a novel 12 Mb QTL cluster (RM8094—RM9) that controls 7 traits was identified on long arm of chromosome 1 where QTLs qSPAD1.2, qSPAD1.3 for SPAD, qFLL1.1, qFLL1.2 for flag leaf length, qFLW1.1, qFLW1.2 for flag leaf width, qFLA1.1, qFLA1.2 for flag leaf area, qPH1.1, qPH1.2 for plant height, qDTF1.2, qDTF1.3 for days to flowering and qHI1.2, qHI1.3 for harvest index were co-located. Among these, one major effect QTL qFLA1.1 for flag leaf area explaining 12.7% PV was identified in a 9 Mb region between RM8094 and RM5638. There was an adjacent minor effect QTL qFLA1.2 with 7% PV in a 3 Mb region between RM5638 and RM9. Together, these two QTLs from O. nivara explained 19.7% PV of leaf area. The QTL for flag leaf related traits can be fine mapped and considered for breeding rice varieties with higher flag leaf area, photosynthetic rate and grain yield.