Genetic dissection of stage-dependent dry matter accumulation in maize (Zea mays L.) kernel

Abstract

Dry matter accumulation (DMA) in kernels is critical for high-yield maize harvesting. However, the genetic mechanism by which DMA affects grain weight remains elusive. We conducted a quantitative trait locus (QTL) analysis of DMA using a recombinant inbred line population at different grain filling stages under three environmental conditions. For most maize inbred lines, about 90% of DMA was completed within 45 days after pollination (DAP). Using 0–45 DAP as an active grain-filling period, we identified 13 DMA QTLs, each explaining 7.11–23.64% of the total phenotypic variation. Four of them, qDMA5.2, qDMA6.4, qDMA7.2, and qDMA9.2, were consistently detected in at least two of three field trials. At the next grain-filling stage after 45 DAP when the DMA is leveling-off, a total of 18 QTLs were identified, accounting for 8.49–28.66% of the total phenotypic variation, of which only qDMA1.2 was consistently observed for two years. Since consistent DMA QTLs were discovered at either the active grain-filling stage (0–45 DAP) or at the later stage after 45 DAP, it is hypothesized that the genetic regulation of DMA proceeds in a stage-dependent manner. Our results will aid in deciphering the genetic basis of grain yield development and provide insight into grain yield improvement in maize.