Genetic Analysis And QTL Mapping On Several Important Agronomic Traits Of The Wheat Backbone Parent Mazhamai

Backbone parents had high combining ability and their genes expressed coordinately. They played an important role in developing new varieties in plant breedings. In China, some quality varieties were cultivated from backbone parents up to now. For example, Bimal-6 were derived from the backbone parent Mazhamai and another variety Quality. Bimal had been planted for hundreds millions acres. Bima4 was an important wheat backbone parent. All the quality cultivars produced many valuable materials. Mazhamai produced a lot of quality cultivars. What's the genetic basis for that? It's the important thing needing to be solved now.Genetic analysis and QTL mapping on plant height, fertile tillers number, spike length, spikelet number per spike, kernel number per spike and thousand kernels weight were conducted on the 185 individuals of the F2 population derived from Mazhamai×Quality in this study. It could be helpful for studying the genetic mechanism of backbone parents, selecting parents in wheat breeding and improving breeding efficiency.1. After analyzing the phenotype data of F2 population and their parents, we found that Mazhamai was superior to Quality in plant height and kernel number per spike.80.54% individuals in F2 population were better than mid-parent values in plant height,63.24% in kernel number per spike and 47.03% in both of them. It was indicated that Mazhamai made great contributions to F2 populations for plant height and kernel number per spike.2. A whole genomic scan was performed on the parents, Mazhamai and Quality. We screened 2899 SSR,EST-SSR and STS primers in all, including Xgwm, Xgdm, Xbarc, Xwmc, Xcfa, Xcfd, Xcfe, Swes, cnl, Dupw, For, Ksum and Mag series. There were 455 primers showed polymorphism between Mazhamai and Quality, and the average screening rate was 15.70%. The screening rates of Xgwm and Xbarc were the highest, higher than 30%. But polymorphisms of EST-SSR and STS primers were very low. 3. QTL mapping on chromosome 1A, 1B,2A,2B,5A,5B and 6B contained 96 primers was about plant height, fertile tillers number, spike length, spikelet number per spike, kernel number per spike and thousand kernels weight. We detected 9 QTLs in all. They distributed on chromosome 1 A, 1B,2A,5A and 5B. The number of QTLs on chromosomes was different. There were 3 QTLs on chromosome 1 A2 QTLs both on chromosome 1B and 2A,1 QTL both on chromosome 5A and 5B. And there were 5 main effect QTLs in all.3 fertile tillers number QTLs were located on chromosome 1A, 1B and 5A and 2 thousant kernels weight QTLs on chromosome 1A. The dominant effect values were positive for most of the QTLs, so the most effects came from the female parent, Mazhamai. It was indicated that Mazhamai made more contributions to the progenies for the hereditary effects of these QTLs.4. Compared with predecessors research results which were about Bima4 and other wheat backbone parents, we found that the QTLs on chromosome 1A and 5A were in the important parts of wheat chromosomes which were found by predecessors. On chromosome 1A, the fertile tillers number QTLs and thousand kernels weight QTLs were in the region of Xgwm357-Xbarc119-Xgwm135-Xwmc278 which was a region of high frequency of genetic alleles in Bima 4; on chromosome 5A, kernel number per spike QTLs were in the region of Xgwm415-Xcfa2250-Xbarc117-Xbarc186-Xgwm304 which was an important region about thousand kernels weight and other traits in Bima 4. So there were excellent gene clusters on chromosome 1A and 5A. This may be a reason to explain why Mazhamai was a kind of wheat backbone parents.