QTL Detection And Analysis For Zn, Fe And Phytic Acid Content In Maize Seeds

The research work of improving the micronutrient content of the main crops,which aims at solving the shortage of international micronutrients , is the hotspot of the crop genetic and breeding research in the domestic and overseas. Maize is the main grain, feedstuff and economic crops in our country, and improving the micronutrients content and availability is especially important for deceloping economics and enhancing the quality of life. Therefore, through the variation analysis on the content of Zn ,Fe and phytic acid and QTL detection of DH,RILs and F2 populations, this study revealed the genetic mechanism of Zn ,Fe and phytic acid content of maize , the number of the gene that controlling the micronutrient and phytic acid content , the locationof these gene on the chromosome and their contribution rate. It is expected to provid foundation for the selecting and breeding of the new hybrid maize and molecule marker assist select breeding. The main results were as follows:1.Two maize double haploid(DH)populations DH8×DH40 and DH86×S137 were used in this study to detect the variation of Zn, Fe and PA to conduct the analysis of quantitative trait loci (QTLs)for these traits. The results showed that the variation of the Zn, Fe and PA contents were very large in theses populations and unstable in 2007 and 2008. The variations of these traits in two populations were continuous and the distributions were normal. Through the QTL Mapper1.6 ,6 QTL of these traits were detected for A populations in 2007, explaining 9.41%~65.61% variation respectively. In 2008, there are which 3 QTL were detected for A population. They were Zn ,Fe and PA respectively , and the same QTL was not found the two years. Through QTL analyses of these traits in B populations, a total of 17 QTL distributed on 9 chromosomes were detected excepting the 5 chromosome , in which 12 QTLwere detected in 2007 and 5 QTL in 2008 , only 1 QTL in both 2007 and 2008. The one QTL that controls Zinc content locates on chromosome 3(between markers p-umc1399-p-bnlg1605).2.Under two levels of nitrogen fertilizer (0 kg N/hm2 and 180 kg N/hm2), genetic analysis for phytic acid content of maize seeds were identified in 2006 and 2007 using a set of 184 recombinant inbred line (RIL)population derived from 478 and wu312 through continous selfing for seven or eight generations.The study show that, the phytic acid content is low when the nitrogen content is high . 3.Under two levels of nitrogen fertilizer (0 kg N/hm2 and 180 kg N/hm2), QTLs for phytic acid content of maize seeds were identified in 2006 and 2007 using a set of 184 recombinant inbred line (RIL) population derived from 478 and wu312 through consecutive selfing for seven or eight generations. Through the Composite Interval Mapping (CIM) a total of 18 QTLs distributed on seven chromosomes were detected. In 2006, 4 QTLs were found under 180 kg N/hm2 treatment and 4 QTLs in 0 kgN/hm2 treatment , and 1 QTL was detected in two treatments at the same time, which was on chromosome 6 (between markers umc2162-umc2165). In 2007, 9 QTLs were found in 180 kg N/hm2 treatment and 1 QTLs in 0 kg N/hm2 treatment. 1 QTL was detected in two years at the same time, which was on chromosome 6 ( between markers bnlg1732-umc2162).4.Under the normal managerial skills of the QTL for Zn and Fe content of maize seeds were identified in 2009 using a set of F2 population drived from a cross between the high Zn 178 and low Zn P53. Through the test, QTL of Zn was found on 2,2,5 and 10 chromosome , explaining 6.29%,5.85%,17.57% and 7.10% variation respectively ; and QTL of Fe was found on the 5 chromosome , explaining 16.89% variation respectively.5.Through comparing the QTL results of the three population , and also the QTL mapping maize. we concluded that the location p-bnlg1520-bnlg198 on the 2 chromosome contains 1 QTL of the Zn content and the location between the bnlg198-umc1252 on the 2 chromosome contains 1 QTL of the Fe content, the p-phi227562-bnlg2238 on the 1 chromosome,the p-bnlg1520-bnlg198 on the 2 chromosome and p-umc1587-p-bnlg389 of the 5 chromosome respectively contains 1 QTL of the PA content.This result provided evidence for specific QTL of the content of Zn ,Fe and PA content in maize seeds and the correlative gene clone.