| Maize(Zea mays L.), one of the important crops, which can be sued as food, feed, and industrial raw material, is now in great demanding due to the following two facts: The increasing demand of agriculture and animal husbandry products caused by the improvement of people’s living quality, and the great need for clean energy such as ethanol caused by fossil shortage. These two facts is now exacerbating the global corn supply and demand tension(Keyzer et al 2005; Wirsenius et al 2010). Maize yields are determined by kernel number, Ear length, and ear row number. The improved of maize kernel number related traits is an effective way to improve corn production. The discovery and in-depth analysis of the genes related to kernel number per ear has important theoretical significance and practical value for marker-assisted selection in corn breeding. This research is studied as follows: Three elite inbred lines Mo17, TY6 and W138 were used to develop two bi-parental populations: Mo17×TY6 and W138×TY6, and then randomly chosen to generate two sets of F2:3 families through selfing. A whole genome scan for QTLs was conducted in the two sets of F2:3 families. a major QTL qEL1.10 was validated and also evaluate its breeding potential. Moreover, based on the previous positioning to the QTL qEL7.02, The fine mapping was performed, and the important candidate genes were analyzed to explore the important functional sites. The results are as follows:1. A total of 39 QTLs for ear length(EL), kernel number per row(KNR), ear row number(ERN) and ear weight(EW) traits were identified in the two populations. The QTL explained phenotypic variation 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 kernel number related traits were overlapped in a region on chromosome 1. This region was designated qEL1.10。2. To validated qEL1.10, we constructed a NIL-derived mapping population from W138×W138 TY6(carrying an allele of qEL1.10 from TY6) and Eight newly developed markers was also used. The QTL in the target region was explained 42%, 49% and 25% of the EL, KNR, and EW phenotypic variance. The additive effect of the W138TY6 allele was-1.58 cm for EL,-3.67 kernels for KNR and-8.9 g for EW.3. To evaluate the breeding value of qEL1.10, six elite inbred lines were selected to cross with two QTL-NILs(W138 and W138TY6). Analysis EL, KNR, and EW traits of Hybrid lines showed that the excellent allele from W138 can increase the 0.77 cm for EL, 1.42 kernels for KNR and 4.31 g for EW, indicating that the favorable allele of qEL1.10 from W138 has the potential to increase grain yield of breeding.4. Based on the previous positioning the qEL7.02 QTL to 6.3Mb foundation, using backcross population to select recombinant plants and using overlapped sub-NILs to narrowed the target QTL to about 605 Kb interval(based on B73 reference genome).5. Through bioinformatics analysis. It was found that the functional domain of Candidate gene 1 was homology with Id1. While the id1 homozygous mutant phenotypes for flowering developmental delays and with abnormal inflorescence structure. The Candidate gene 1 of SL17-1 and Ye478 were sequenced and analyzed, the difference between bi-parents was in the two regions upstream of ATG and the first exon, and totally found in 55 polymorphic loci, including 21 indels and 34 SNPs. the first exon have three polymorphic loci, 68 bp T/C, and 68 bp indel 6/0, finally cause a proline in Ye478 into leucine, threonine and arginine(SL17-1), the 111 bp T/C belongs to silent mutation. 2.3 Candidate gene association analysis showed that the first three polymorphism loci on the first exons of Candidate gene 1 affected day to heading, day to pollen and day to silk(In-68: P=0.0073; P=0.0009; P=0.0068), but did not detect the influence of ear length variant loci. |
PDF Full Text Request