QTL identification and epistatic effect analysis of seed size- and weight-related traits in Zea mays L

Seed size and weight are two seed physical traits showing high correlation to seed quality and grain yield. Here, we employed a maize F 2:3 population developed from a cross between inbred line 220 (herein named L220, small seed) and PH4CV (large seed) to identify loci that control the seed size traits of kernel length (KL), kernel weight (KW), kernel thickness (KT), projected area (PA), and kernel volume (KV) and the seed weight trait of hundred-kernel weight (HKW). A total of 20 QTL were identified with 2–5 for a trait to explain 3.97–13.77% phenotypic variances. Among them, 15 QTL were colocated within the following six chromosomal regions: chromosome 1 (Chr. 1), 195.2–195.8 Mb; Chr. 2, 7.6–10.6 Mb; Chr. 3, 8.9–9.6 Mb; Chr. 4, 188.3–193.2 Mb; Chr. 8, 18.8–24.4 Mb; and Chr. 9, 13.9–18.3 Mb. After collecting 1341 QTL related to seed physical traits from this work and previous publications, meta-QTL analysis revealed 8 mQTL, with 6 located in the abovementioned regions, suggesting high consistency of QTL localization across populations. Additionally, 10 pairs of epistatically interacting loci were identified for the 6 seed physical traits. Six QTL were found to be located within these interacting loci. Taken together, these results provide a foundation for further QTL fine mapping of the 8 mQTL and for the molecular-assisted breeding of maize with large seed size and weight.