Abstract
Grain rate (GR) is a very important trait in maize ( Zea mays L.) breeding program related to yield. To realize its genetic basis, a recombinant inbred line (RIL) population and different nitrogen (N) regimes were used to map the quantitative trait loci (QTLs) for GR in maize. As a result, two QTLs were identified under high N regime and could explain a total of 14.84% of phenotypic variance. Due to additive effect, the QTL on chromosome 6 could decrease 0.029 of GR, while the QTL on chromosome 9 could increase 0.0203 of GR. Under low N regime, one QTL was mapped on chromosome 6 and could account for 9.52% of phenotypic variance, and owning to additive effect, the QTL could make GR decrease by 0.0234. The result in comparison with previous studies showed that the three QTLs in this present study were new quantitative loci associated with GR in maize. These results were beneficial for understanding the genetic basis of GR in maize. Key words : Maize ( Zea mays L.), grain rate, quantitative trait locus, recombinant inbred line, nitrogen.
Highlights
Grain rate (GR) is one of the most important traits in maize (Zea mays L.) breeding program (Yang et al, 2005) related to yield, but at present, the maize germplasm resources with high GR are quite lacking
The results investigated on GR showed that the tested lines presented variations
From the frequency distribution graphs of the recombinant inbred line (RIL) population under two N regimes (Figures 1 and 2), it was found that the two group data could not agree well with normal distribution, which suggested that the trait GR were probably controlled by few genes in maize
Summary
Grain rate (GR) is one of the most important traits in maize (Zea mays L.) breeding program (Yang et al, 2005) related to yield, but at present, the maize germplasm resources with high GR are quite lacking To resolve this problem, an effective solution is to utilize elite genes associated with high GR to improve the trait of maize, but this must depend on an understanding on its genetic basis and quantitative trait locus QTL) mapping is an efficient approach to realize genetic basis of agronomic trait (Liu et al, 2009). Recombinant inbred line (RIL) population is immortal and can be used again and again in different regions and time, due to homogenous individuals At present, this population has been widely used to identify QTLs in many plants (Geffroy et al, 2000; Wan et al, 2006; Ding et al, 2008). The studies on QTL mapping associated with GR using this kind of population were hardly reported in maize
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