Identification Of QTL Related To Verticillium Wilt Resistance Of Cotton Based On F₂ And Ril Populations

Cotton is one of the main fiber crops in our country,which has a long planting history,and it is a strategic reserve material in China.It plays an important role in the stability and development of our country.The introduction and outbreak of Verticillium wilt seriously affected the rapid development of cotton in China,and caused great economic losses.Therefore,it is an urgent demand for cotton industry to cultivate cotton varieties with Verticillium wilt resistance.In this study,RIL and F₂ groups constructed by cotton varieties of resistant and susceptible to Verticillium wilt as the research materials,Use more than 10 thousand pairs of SSR primers to identify the genotypes and construct the genetic map.Then analyse and identify the QTL related to Verticillium wilt resistance in different environments to identify the stable QTL in many environments.At the same time,analyse the phenomenon of molecular marker segregation distortion in the process of map construction.In order to provide help for other construction of linkage maps,accurate location of QTL and locate the gametophyte genes that lead to segregation in cotton.Recombine inbred line?RIL?population contains 111 lines made up with two parents which show different resistance to Verticillium dahlia,the high resistant parent Changkangmian and the susceptible parent TM-1.F₂ population containing 232 single plants made up with two parents show different resistance to Verticillium dahlia,the high resistant parent Zhongzhimian2 and the susceptible parent Jimian11.Use 10 791 primers of different series SSR markers screen the 4 parents above preliminary,114 and 132 pairs polymorphic primers were obtained respectively,and the polymorphic rates were0.79%and 1.22%respectively.On this basis,2 genetic linkage maps of molecular markers were constructed.The RIL map contains 13 linkage groups,including 43 SSR markers,and a total length of212.5 cM.13 linkage groups were anchored on 11 chromosomes,chromosomes D07 and D09 anchored on 2 linkage groups respectively.The F₂ map contains 25 linkage groups,134 SSR markers,and a total length of 922.1 cM.After the chi square test,we found the segregation distortion rate of RIL population was much higher than that of F₂ population,and the separation distortion rate was 60.26%and 19.30%respectively.8 QTLs related to Verticillium wilt disease were detected in RIL by complete composite interval mapping?ICIM?with the datas of disease index of Verticillium wilt in multiple environments include different periods of Anyang field,Xinjiang seriously ill field,greenhouse and disease nursery.The LOD value is distributed between 2.51⁵.55,and the maximum contribution rate?PVE?is 20.34%,and the minimum is 6.93%.Among them,qVR-D05-1 was detected both in the analysis of disease index of Anyang in July 15,2015 and Xinjiang in July 9,2016,PVE were 12.96%and 20.34%respectively,and the marker BNL3452 also detected in F_2:3 group made up with Changkangmian and TM-1 using single marker analysis,which suggested that there may be a stable QTL site near this marker.6 QTLs were detected in the 2 groups of Verticillium wilt disease index in the QTL preliminary positioning.The minimum genetic distance between the 6 QTLs markers was 2.38 cM,the largest was22.83 cM.The LOD value is distributed between 2.74¹3.92,and the PVE is distributed between3.23²4.75.2 Of the 4 QTL are on the D05,and 1 is on the D05 homologous chromosome A05,and 1 is on the chromosome D09.qVF-D05-1 and qVF-D05-2 are detected both in the disease index of July 14,2017 and September 20,2017.