Construction Of Genetic Map Using Genotyping Chips, QTL Detection Of Important Traits And Creating Of NILs

Wheat is one of the most important food crops in the world. Many important agronomic traits in wheat (flag leaf traits, panicle traits, seedle traits) and quality traits are confirmed to be controlled by quantitative traits. High density genetic maps is constructed in order to QTL analyze for agronomic and quality traits, indeed, which can provide reference to explore molecular markers, assisted selection for wheat breeding and excavate new gene in wheat. On the one hand,a RIL (recombinant inbred lines) population including 188 lines was analyzed using wheat 90k SNP genotyping chips technology. Subsequently,a high density genetic map was constructed. QTL for agronomic and quality traits were analyzed using MapQTL5.0 by multi-QTL model (MQM).The traits studied contained 29 agronomic traits (effective tillers, flag leaf length, kernel number, grain traits, etc.) and 9 quality traits (protein content, grain hardness, starch content, etc). altogether 38 traits were conducted to QTL mapping analysis; On the other hand,,two pairs of near-isogenic lines was established aiming at effective tillers according repeatedly self-intersection of F1 hybrids of H461×CN16. The main results obtained are as follows:1、A genetic map of wheat consisting of 43 linkage groups was constructed with 6573 polymorphism SNP markers, located in 18 chromosomes of the wheat genome except for 2D,5D,6D, covering 2647.02cM with an average interval distance of 0.4 cM.2696 SNP markers were from A genome, with 41% of total number, covering 1130.92cM,with an average interval distance of 0.42 cM,establishing 19 linkage groups; 3094 SNP markers were from B genome, with 47.1% of total number, covering 1164.82 cM,with an average interval distance of 0.38 cM, establishing 18 linkage groups; D genome contained 684 SNP markers,with 10.4% of total number,covering 330.44 cM, with an average interval distance 0.48 cM, establishing five linkage groups; Moreover,99 SNP makers located in 2A/2B/2D chromosomes simultaneously, constructing one linkage group.2、With the genetic map, QTL analyzing was processed using mapping software MapQTL5.0 MQM mapping method for the trait under two trials at Wenjiang and Ya’an in 2013、2014。Total additive 124 QTL were detected,distributed at the rest of 13 chromosomes excepte for 1A,3A,5A,7A,3B,3D,5D,6D,which explained phenotypic variance range from 6% to 19.5%, including 41 major effect QTL, of which 12 QTL were repeatable in Ya’an, Wenjiang.3、QTL of agronomic traits. We detected a total of 77 agronomic traits associated with the fields QTL, located in 2A,4A,6A,2B,4B,5B,2D,4D,7D.single QTL explained phenotypic variance of 7.4%-19.5%,62 QTL additive effects came from H461,and the rest from CN16. Of all the QTL,26 of which were major.Total of 12 QTL were detected in Wenjian and Ya’an simultaneously.New QTL loci were found from effective tiller number, flag leaf length, peduncle length, panicle length, spikelet number.Out of 19 grain traits,we detected 13 QTL, which were located in 1B,7B, 1D, single QTL explained 6.2%-10.7% of the phenotypic variation,5 QTL additive effects came from H461,8 were from CN16. Two major QTL were detected.4、QTL of quality traits.34 quality traits QTL were detected in 9 quality traits,Distributed in 3B,5B. Single QTL explained 7.9%-11.3% of the phenotypic variation rate,26 QTL additive effects from H461,8 were from CN16.13 major QTL were detected. New QTL were detected from grain hardness, zeleny sedimentation, dough development time, dough maximum resistance, loaf volume.5、"Pleiotropic Effects" QTL section.13 " pleiotropic effects" locis were formed On 7 chromosomes (2A,2B,2D,4B,5B,7B,7D),such as the loci of effective tillers, spikelets number, spikelets density; the loci of grain avgcurvedlength and avgprojarea; the loci of zeleny sedimentation and dough development time.6、Creating of NILs. Two NILs aiming at effective tiller were built,the low effective tiller lines showed a number of 1, whereas,the high one showed that of greater than 10.Research on the SNP assisted high-density genetic maps are less nowadays.The construction of the genetic population and the high density genetic map is successful, which is useful to analyze QTL of agronomy and quality traits, furthermore, which can provide reference to explore molecular markers, assisted selection for wheat breeding and excavate new gene in wheat;The discovery of new QTL can enrich the genetic and molecular markers in wheat breeding applications; " Pleiotropic Effects " sites can assist in gene pyramiding breeing of wheat; Creation of effective tiller number associated near-isogenic lines can eliminate the impact of genetic background,doing favors to the research of pleiotropic genes, at the same time,providing an ideal material for molecular markers tightly linked to genes.