QTL Analysis Of Important Traits Of Winter Wheat Pindong34 And Application Of Yr62 Gene

Wheat stripe rust caused by Puccinia striiformis f.sp.tritici（Pst）,is one of the most devastating diseases in wheat.Serious impact on wheat production.It has become an important problem for researchers and breeders to find new genetic loci for agronomic traits,disease resistance,yield and other important traits from excellent wheat varieties and apply them in breeding new varieties with high disease resistance,high and stable yield and good adaptability.In this study,the 90K single nucleotide polymorphism（SNP）chip data from whole genome,disease resistance and major agronomic traits（1000-grain weight,plant height,grain number per spike,tiller number and spike length）were obtained from the cross progeny of wheat variety Pingdong 34 and Mingxian 169,and QTL analysis was conducted to identify the loci controlling the related traits.The disease resistance gene Yr62 derived from PI 660060 was introduced into four wheat varieties with excellent agronomic traits（Lunxuan 987Bainongaikang 58 Zhengmai 9023 and Hanmai 6172）,and new wheat lines with excellent agronomic traits and high level of disease resistance was selected by combining the phenotypes of agronomic traits.This study enriched the germplasm resources of wheat disease resistance and high yield,and provided theoretical,material,technology,method and empirical support for the control of wheat stripe rust and the genetic improvement of wheat disease resistance varieties in China.The main results obtained in this study are as follows:1.The disease resistance of Pindong 34,Mingxian 169 and its F₈population was identified by applying stripe rust race CYR34 in greenhouse and field.The results showed that Pindong 34 have both all-stage resistance（ASR）gene and adult-plant resistance（APR）QTLs.2.Through field experiment,the recombinant inbred lines（RIL）of Pindong 34 and Mingxian 169 infection type（IT）,disease severity（DS）and grain length（GL）,grain width（GW）,length-width ratio（LWR）,plant height（PH）,spike length（SL）,grain number per spike（GPS）and thousand kernel weight（TGW）value in Yangling and Mianyang two locations all showed a trend of continuous variation,suggesting that the genes controlling the above traits from Pindong 34 are quantitative traits.Variance analysis showed that the phenotypes differed significantly in different families,environment,duplication and genotype-environment interaction（P<0.05）,and the generalized heritability was 0.97.The results showed that the expression of the gene loci controlling each trait was stable,and the phenotypic contribution rate was high,and it was easy to transfer the excellent traits to other breeding materials.3.By genotyping 120 F₆populations using 90K single nucleotide polymorphism（SNP）gene array chip,four ASR genes and 11 APR QTLs were found on wheat chromosome 1A,1B,1D,2A,2B,3A,6B,6D,7A and 7D.Among the 11 APR resistance QTLs,QYrpd.swust-1BL（9.24-13.33%）,QYrpd.swust-3AL.2（11.54-17.0%）,QYrpd.swust-6BL（9.39-12.78%）,QYrpd.swust-6DL（9.52-16.36%）,QYrpd.swust-7AL（9.09-17.0%）and QYrpd.swust-7DL（8.87-11.38%）were detected in more than 5 test environments.QYrpd.swust-1AS（11.05-12.72%）,QYrpd.swust-1DL（9.81-13.05%）,QYrpd.swust-2BL.1（9.69-10.57%）,QYrpd.swust-2BL.2（10.36-12.97%）and QYrpd.swust-2BL.3（9.54-13.15%）was detected in some environments.Four ASR QTLs,including QYrpd.swust-2AS（9.69-13.58%）,QYrpd.swust-2BL.4（9.49-12.07%）,QYrpd.swust-3AL.1（11.41-14.80%）and QYrpd.swust-7AS（16.16%）,were detected by QTL analysis using the identification data of CYR34 Pst varieties.Among the 15 QTLs detected in Pindong 34,the all-stage resistance gene Yr61（QYrpd.swust-7AS）of Pindong 34 was located on the short arm of chromosome7A.These QTLs and their closely linked molecular markers are of great significance for breeding wheat cultivars resistant to stripe rust.4.QTL analysis was performed by combining the phenotypic data of Pingdong 34’s agronomic traits with SNP genotype data obtained by scanning 120 F₆populations with 90K SNP chip.Results showed that eight QTLs:QGLpd.swust-1BL（13.79-14.92%）,QGLpd.swust-2BL（11.74-18.09%）,QGLpd.swust-3B.1（9.93-15.57%）,QGLpd.swust-3B.2（11.35-17.6%）,QGLpd.swust-5DL（9.95-13.95%）,QGLpd.swust-6A（15.21-17.06%）,QGLpd.swust-6DL.1（17.23-21.33%）and QGLpd.swust-6DL.2（10.84-15.16%）which regulate wheat grain length were detected in several test environments.Two QTLs:QGWpd.swust-3B（11.44-14.58%）and QGWpd.swust-6DL（9.81-13.05%）which regulate grain width were detected;Two QTLs:QLWRpd.swust-7AS.1（10.88-11.63%）and QLWRpd.swust-7AS.2（11.16-11.61%）which regulate the length-width ratio were detected;Five QTLs:QPHpd.swust-2DL（14.81-17.36%）,QPHpd.swust-3AL（15.22-19.27%）,QPHpd.swust-5AL（11.30-17.15%）,QPHpd.swust-6BL（13.38-16.88%）and QPHpd.swust-7BS（14.06-14.96%）for regulating plant height were identified on 2D,3A,5A,6B and 7B,respectively.A QTL for spike length regulating:QSLpd.swust-3AL（16.08-17.55%）was detected on 3A.On chromosome 6D,a QTL regulating grains per spike,QGPSpd.swust-6DS（11.37-13.75%）was detected.A QTL regulating 1000-grain weight:QTGWpd.swust-6BS（14.13-16.20%）was detected on 6B.5.By crossing stripe rust resistant line PI 660060 with Chinese staple cultivars Lunxuan 987,Bainongaikang 58,Zhengmai 9023 and Hanmai 6172,the F₁generation seeds from these four cross was harvested.The four populations seeds were then mix sown in the test field and mix harvested until F₅generation respectively,and then manually screened according to stripe rust resistance and agronomic traits.As a result,a total of 45 single plants were screened with stripe rust resistance,moderate plant height and full spikes.6.Through QTL detection,a total of 28 lines were selected from 45 F₆lines that successfully introduced the resistance QTL Yr62.The relationship between molecular markers Xgwm251and Xgwm192 closely linked to Yr62 was verified.The data of yield-related agronomic traits such as plant height（PH）,spike grain number（GPS）,spike length（SL）,tiller number（TN）,1000-grain weight（TGW）,and phenotypic data of response type（IT）and severity（DS）were obtained through the evaluation of these 45 F₆lines for agronomic traits in the field and the identification of disease resistance combined with the results of QTL detection,six lines were finally screened for successful introduction of the target gene Yr62 with excellent agronomic traits and disease resistance.