Molecular mapping of quantitative trait loci for grain moisture at harvest and field grain drying rate in maize (Zea mays L.).

Maize (Zea mays L.) grain moisture (GM) at harvest is an important trait that affects seed preservation during storage, grain quality and artificial drying costs. To date, most of the work on understanding GM dynamics in maize has focused on the grain filling period, while the period of postmaturity grain drying remains unexplored. The field grain drying rate (FDR) is one of the most important factors in determining GM at harvest. Therefore, understanding the genetic basis of FDR will be useful for obtaining low-GM varieties. In this study, a single-cross population (330 F2:3 -generation plants) derived from a cross of two divergent inbred lines was evaluated in two planting environments with a measurement method - Area under the Dry Down Curve (AUDDC). A high-density genetic linkage map of 2491 single nucleotide polymorphism (SNP) loci covering 2415.56 cM was constructed. Using composite interval mapping, four quantitative trait loci (QTL), q45dGM1-1, qHTGM2-2, qAUDDC2-1 and qAUDDC10-1, which were detected on chromosomes 1, 2 and 10, were stable across environments and could explain more than 10% of phenotypic variance. These may be the major QTLs, with non-significant environmental interactions for GM at 45 days, GM at harvest and FDR, respectively. Additionally, several predicted candidate genes for FDR were identified, including several transcription factors, hormone responsive genes, energy-related and DNA replication-related genes. These results will provide useful information for our understanding of the genetic basis of FDR, as well as providing tools for marker-assisted selection in maize breeding.