Genome-Wide Association Study of Rice Rooting Ability at the Seedling Stage

Abstract

Background Rice rooting ability is a complex agronomical trait that displays heterosis and plays an important role in rice growth and production. Only a few quantitative trait loci (QTLs) have been identified by bi-parental population. More genes or QTLs are required to dissect the genetic architecture of rice rooting ability.Results To characterize the genetic basis for rice rooting ability, we used a natural rice population, genotyped by a 90K single nucleotide polymorphism (SNP) array, to identify the loci associated with rooting-related traits through the genome-wide association study (GWAS). Population structure analysis divided the natural population into two subgroups: indica and japonica. We measured four traits for evaluating rice rooting ability, namely root growth ability (RGA), maximum root length (MRL), root length (RL), and root number (RN). Combined with the association study in three panels consisting of one for the full population, one for indica, and one for japonica, 32 SNPs associated with rooting ability-related traits were identified. Through comparison of the relative expression levels and DNA sequences between germplasms with extreme phenotypes, results showed that LOC_Os05g11810 had non-synonymous variations at the coding region, which may cause differences in root number, and that the expression levels of LOC_Os04g09900 and LOC_Os04g10060 are closely associated with root length variation.Conclusions The goal of our research was to improve understanding of the genetic basis of rice rooting ability and provide useful molecular markers and germplasms for rice root breeding.