| Ningmai9was originally called "Ning9312", it is hybridization breeding from "Yangmai6/Xifeng" by Jiangsu Academy of Agricultural Sciences. It has a high-quality, and is high-steady yield with good comprehensive resistance. Furthermore, it is the earliest breeding and large-scale used domestic high-quality weak gluten wheat variety at present. It was examined and approved by Jiangsu Crop Variety Approval Committee in October,1997and was listed in the National Agricultural Technology Across projects as the special wheat used for making high-quality biscuits, cakes in2000. Meanwhile, Ningmai9has bred Nannong0686, Ningmai13, Ningmai14, Ningmai16, Shengxuan6, Yangmai18, Yangfumai4, Zhenmai8, etc. as parent wheat variety, all of those above are different types of wheat varieties. Previous studies state that Ningmai9has a higher general combining ability on the yield and quality traits, so it is a good wheat parent variety. To further elucidate the genetic mechanism of Ningmai9, and make better use of this resource, it is necessary to study the molecular genetic mechanisms.A quantity of important agronomic and quality traits of wheat behave as genetic methods of quantitative traits controlled by multiple genes, and its phenotype is easily effected by environment. In recent years, with the development of genomics and the improvement of bio-statistical software, especially the wide use of molecular marker technology in the field of genetics and breeding, the method of association analysis based on linkage disequilibrium provides a new way for studying molecular genetic mechanism of quantitative traits in wheat, and also provides a new way of thinking for Molecular Design Breeding in crop. It could be verified and supplemented with the mapping results of quantitative trait locus based on linkage mapping.This study use the fine varieties and progenies by hybridization breeding or system selected breeding by Ningmai9as parent variety as studying materials, it studies the molecular genetic basis of good agronomic and quality traits of Ningmai9by Association analysis, and expects to provide a basis for Marker-assisted selection (MAS) The main results are as follows: 1.We study the3agronomic traits and11quality traits in Ningmai9and its derivative lines. The mean values of three yield traits, grains per spike, spike number per acreage and1000-grain weight are43,265thousand and42grams, Amplitudes are31-58,189-359thousand spike and28-51grams, coefficients of variation are12.08%,12.56%and9.59%respectively. And the mean value of Grain protein content and flour protein content means are11.50%and9.94%. Amplitudes are10.09-13.76%and8.36-12.44%, coefficient of variation is6.62%,7.00%. The mean values of the4indicators of Gluten strength (the mixing development time, peak height, peak width, eight minutes bandwidth) are1.45(min),64.47(cm),42.59(N/m),29.49(N/m). And the amplitude are0.55-3.81(min),47.01-93.08(cm),14.65-62.82(N/m),12.16-58.54(N/m). Coefficient of variations are47.55%,11.18%,20.85%,35.52%.2.We use172markers to do genetic diversity analysis and cluster analysis in Ningmai9and its derivative lines. A total of472allele sites, the average number of points for each marker alleles is2.77, genetic diversity is2.44, and the heterozygosity is0.006, polymorphism information content (PIC) is0.29. We use the method of NJ to do cluster analysis and separate Ningmai9and its derivative lines derived into3categories.3.We use the marker function of Pina and Pinb gene to do molecular testing for hardness gene in Ningmai9and its derivative lines, and the results show that:the soft wheat are in total of52accessions and all of their genotype is Pina-Dla/Pinb-Dla; the durum wheat are in total of53accessions and they are in2genotypes:48accessions belong to Pina-D1a/Pinb-D1b genotype and5accessions belong to Pina-D1b/Pinb-D1a genotype. There are another13accessions belong to mixed wheat, among which10accessions belong to Pina-D1a/Pinb-Dla,2accessions belong to Pina-D1b/Pinb-Dla, and1accession copy belongs to Pina-D1a/Pinb-D1b.4.We use the84microsatellite markers on the whole genome to do whole genome scan for the Ld and population structure of Ningmai9and its derivative lines, and construct association mapping population. According to the analysis of population genetic structure of SSR data based on Model, the group could be divided into three sub-groups. In the group analysis, Q values of each sample are greater than0.5, so when divide the groups, each kind of material relation is relatively simple, as Ningmai9and its derivative lines are used in this experiment, it has closer genetic relationship with Ningmai9, and most of them are the same backbone of breeding parents, there is no source of complexity, with mixed blood. The result of this experiment is also corresponding to the choice of material with genetic relationiship. And population structure analysis and cluster analysis are consistent to some extent.5.Among all the detected marks related to grains per spike, grain protein content, gluten strength and solvent retention capacity and other traits, some of them fall near the QTL in previous studies. For example, there are2QTL on6AL,2DS associated with protein content. The results based on the study on Ningmai9and derivative lines show that both Gwm539on2DS and Gwm508on6BL can explain more than10%of the phenotypic variation. Solvent retention capacity and other traits are also similar to the results of our study, And the explanation rate of some marks with high explanation, like Barc4on5B to Lactic acid SRC reaches (9.14%;12.17%).6.We do association analysis in markers and traits analysis through mixed linear model process by TASEEL (software),and we find a number of target traits have significant associated SSR loci, meanwhile, we do elite alleles analysis after getting those alleles related to traits, and calculate on every phenotypic effects value of each alleles, we find some elite allele related to low protein, weak gluten strength, low solvent retention capacity and high-yield traits, those allele sites has great contribution to the formation of their excellent quality and agronomic traits. For example:Wmc749-98has decreasing phenotype effect on sucrose SRC (-4.96;-5.10), Wmc577-112has decreasing phenotype effect for the mixing development time (-0.34;-0.28).The results above partly illustrate the molecular genetic mechanisms that Ningmai9as a good backbone parent.Meanwhile, the discovered numbers of allele sites related to traits provide some help to for Marker-assisted selection (MAS). |
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