Physiological and candidate gene analysis of RG5, a locus associated with a higher ratio of filled grains in rice (Oryza sativa L.)

In this report, we investigated physiological and genetic aspect of RG5, a locus increasing the ratio of filled grain in rice (Oryza sativa L). RG5 increased the accumulation of non-structural carbohydrates (NSCs) in the body, and NSCs might contribute to the development of grains after heading. With a chromosome segment substitution line containing ‘Kasalath’ RG5 in the genetic background of the japonica cultivar ‘Koshihikari’, RG5 might enlarge lower leaves and improve NSC supply to the sheath. Through the fine mapping using data plural mutans, we identified NBS-LRR protein (Os05g0380300) as a casual gene for expanding of lower leaves area by RG5. The single nucleotide polymorphism (SNP) of Kasalath caused a premature stop codon and lost function might increase the ratio of filled grains.