The QTL Preliminary Mapping Of Tassel Neck Length In Maize

The tassel of maize is an important organ, it is closely related to yield. Usually maize tassel produces pollen far more than the quantity of pollination needed, resulting in the loss of large amounts of energy; while there is a competitive relationship between male and female ear for photosynthetic products. A large tassel would consume much more energy. Emasculation will not only reduce nutrient consumption, but also can effectively prevent female parent loosing powder, improve the quality of seed production and yield. Mechanization emasculation is convenient, but effective mechanization emasculation mainly depends on the characteristics of female parent.The tassel neck length is a key part for maize mechanization emasculation, tassel neck length has a significant difference among different maize varieties. By means of molecular biology method, the gene mapping of the maize tassel neck length will promote the research on the improvement of maize plant type tassel trait, therefore provide a reference for maize mechanization emasculation and the breeding selection. In this study, correlation and path analysis between the spindle length of maize tassel, the internodes length above ear, plant height, ear length and tassel neck length were carried by 111 maize inbred lines, to investigate the effect of different traits on tassel neck length; then according to the survey results of maize tassel neck length of different inbred lines, select the inbred lines whose tassel neck length has significant difference(long tassel neck length inbred line 30153, short tassel neck length inbred line 40023) as parental inbred lines to construct F2 mapping population. Using SSR markers technology, combined with Bulk Segregant Analysis (BSA) screening maize tassel neck length linked markers for QTL Mapping. The main contents and results were as follows:1. The correlation analysis among traits of inbred lines showed that tassel neck length had a significant positive correlation with every trait and every trait each other at P< 0.01. The order of the correlation between the survey traits and the tassel neck length from large to small is:the first internode length>the second internode length>the third internode length> plant height> the forth internode length> the fifth internode length> the spindle length of maize tassel> ear length. The result of path analysis showed that the first internode length, the third internode length and plant height had fairly positive direct effect to tassel neck length; the effect of ear length on tassel neck length was not obvious. The fifth internode length and the forth internode length had less negative direct effect. The greatest effect of tassel neck length was caused by the first internode length(r=0.71**,p=0.5311), followed by the effects of the third internode length(r=0.65**,p=0.2873) and plant height(r=0.57*,p=0.2278). In order to obtain the maize varieties with long tassel neck length, attentions should be paid to increase the length of the first internode, the third internode and the height of the plant, meanwhile coordinate the relation between different traits.2.455 pairs of SSR primers which are uniformly distributed on the maize 10 linkage groups were selected from maize genome to screen parental polymorphism and 132 pairs of polymorphism markers were selected, account for 29.01%. BSA was used to detect the polymorphism for the two extreme pools of maize tassel neck length of F2 population. Three pairs of polymorphic primers were detected on chromosome 3, respectively phi053, bnlg1601, phi073.3. Selected and composited 30 pairs of SSR primers near the three markers to screen parental polymorphism, among them, umc2256、 phi104127、 umc1965、 bnlg1350、umc1528、 umc1825、 umc2174、 umc2152 showed polymorphism. Using the 11 markers to amplify the genome of F2 population respectively and recorded the corresponding banding patterns. Use QTL IciMapping 4.0 software for QTL analysis. The results showed that one major QTL was detected between the marks bnlg1350 and umc1528. The gene loci could explain 10.5% of the phenotypic variation rate. The linkage distance to bnlg1350 and umc1528 are 2.03cM and 9.91cM respectively.