Abstract
Increasing effective panicle number per plant (EPN) is one approach to increase yield potential in rice. However, molecular mechanisms underlying EPN remain unclear. In this study, we integrated map-based cloning and genome-wide association analysis to identify the EPN4 gene, which is allelic to NARROW LEAF1 (NAL1). Overexpression lines containing the Teqing allele (TQ) of EPN4 had significantly increased EPN. NIL-EPN4TQ in japonica (geng) cultivar Lemont (LT) exhibited significantly improved EPN but decreased grain number and flag leaf size relative to LT. Haplotype analysis indicated that accessions with EPN4-1 had medium EPN, medium grain number, and medium grain weight, but had the highest grain yield among seven haplotypes, indicating that EPN4-1 is an elite haplotype of EPN4 for positive coordination of the three components of grain yield. Furthermore, accessions carrying the combination of EPN4-1 and haplotype GNP1-6 of GNP1 for grain number per panicle showed higher grain yield than those with other allele combinations. Therefore, pyramiding of EPN4-1 and GNP1-6 could be a preferred approach to obtain high yield potential in breeding.
