Fine mapping of qKW7, a major QTL for kernel weight and kernel width in maize, confirmed by the combined analytic approaches of linkage and association analysis

Kernel weight (KWEI), a complex quantitative trait that is largely determined by kernel size, is a key component of grain yield in maize. In our previous studies, qKW7, a putative pleiotropic QTL associated with both KWEI and kernel width (KWID), was detected within the 7.02 bin region on chromosome 7 by both F-2:3 population and recombinant inbred line (RIL) population from a Ye478 and Huangzaosi cross. Therefore, a series of backcross populations from the same cross have been developed for fine mapping qKW7. By using a large BC3F4 segregation population, the qKW7 QTL was mapped to a physical interval of 647 Kb with several genes. An association panel with 627 diverse inbred lines was used to process the association analysis, and the results indicated that three KWEI- and KWID-related quantitative trait nucleotides (QTNs) were tightly linked to qKW7. Sequence analysis revealed that all three detected QTNs were located within the gene region of GRMZM2G114706, which encodes an ankyrin protein kinase that regulates endosperm development. Finally, the putative genes responsible for qKW7 are discussed.