Abstract
The kernel number is a grain yield component and an important maize breeding goal. Ear length, kernel number per row and ear row number are highly correlated with the kernel number per ear, which eventually determines the ear weight and grain yield. In this study, two sets of F2:3 families developed from two bi-parental crosses sharing one inbred line were used to identify quantitative trait loci (QTL) for four kernel number-related traits: ear length, kernel number per row, ear row number and ear weight. A total of 39 QTLs for the four traits were identified in the two populations. The phenotypic variance explained by a single QTL ranged from 0.4% to 29.5%. Additionally, 14 overlapping QTLs formed 5 QTL clusters on chromosomes 1, 4, 5, 7, and 10. Intriguingly, six QTLs for ear length and kernel number per row overlapped in a region on chromosome 1. This region was designated qEL1.10 and was validated as being simultaneously responsible for ear length, kernel number per row and ear weight in a near isogenic line-derived population, suggesting that qEL1.10 was a pleiotropic QTL with large effects. Furthermore, the performance of hybrids generated by crossing 6 elite inbred lines with two near isogenic lines at qEL1.10 showed the breeding value of qEL1.10 for the improvement of the kernel number and grain yield of maize hybrids. This study provides a basis for further fine mapping, molecular marker-aided breeding and functional studies of kernel number-related traits in maize.
Highlights
Maize is one of the most widely grown crops worldwide
Due to the increased kernel rows on the ears of TY6, TY6 exhibited a greater kernel number and ear weight relative to Mo17 (P = 7.12E-15 and P = 1.26E-06, respectively) and W138 (P = 3.15E-15 and P = 5.89E-12, respectively) (Fig 1)
The analysis of variance showed that the four traits exhibited significant genetic differences among families and high broad-sense heritability that ranged from 75.5% for EW to 88.7% for ear row number (ERN) in the MT F2:3 families and from 75.5% for EW to 84.1% for EL in the WT F2:3 families
Summary
Maize is one of the most widely grown crops worldwide. The rapidly expanding global demand for maize as a food, feed and industrial crop has led to intense pressure to improve the maize grain yield, which is an extremely complex quantitative trait controlled by quantitative trait loci (QTLs)[1,2,3]. The genetic complexity and low heritability impede our understanding of the genetic basis and molecular mechanisms underlying grain yield. The maize grain yield is composed of yield components that include kernel number per ear (KN) and kernel weight (KW). Kernel number is composed of the ear row number (ERN) and kernel number per row (KNR). The yield components exhibit higher heritability and better stability across
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