Identification of maize brace-root quantitative trait loci in a recombinant inbred line population

Abstract

Brace roots are vital constituents of the root system in maize. Their contribution to plant development is affected by brace-root traits (BRTs) including tier number (TN), root number (RN) and radius of the brace root (RBR). However, the genetic control of BRTs still remains elusive. Here, we have identified quantitative trait loci (QTLs) from 207 recombinant inbred lines of BY815/K22 grown in three environments to dissect the genetic architecture of BRTs in maize. All three of BRTs were highly heritable and were affected by genotype, environment and the interaction between them. RBR was positively correlated with both RN and TN. Eight QTLs were identified, 3 for TN, 3 for RN and 2 for RBR, and located on chromosome 1, 2, 9 and 10. They together explained 26.4% (TN), 21.5% (RN) and 13.4% (RBR) of phenotypic variation. Sixty of annotated genes were identified from the narrower QTLs by the bin-map method, including genes for signal transduction, gene expression regulation, and metabolism and related processes. The results also show that the interaction may occur between QTLs for BRTs. Our results can help to further study the genetic basis of BRTs and improve the approaches to control maize brace-root system through SNP marker-assisted selection.