QTL Mapping Of Plant Height And Fiber Quality In Upland Cotton And Explore The Salt Resistance Of Parents

Cotton is an important economic crop and textile raw material.On the one hand,the labor cost increases,the cotton planting area keeps declining.On the other hand,with the improvement of people's living standards,the market puts forward higher requirements on cotton fiber quality.In order to solve the above problems,the F₂ population and the F_2:3:3 family were constructed from the parental cotton cultivars CCRI 49 and 396289,which plant heights and fiber quality have differences,the parent and160 individuals were subjected to parental resequencing and progeny SLAF-simplified genome sequencing to construct high-density genetic maps.QTL mapping and functional annotation of related genes were performed on plant height and fiber quality.The purpose was to provide technical reference for fine mapping of QTL and to provides theoretical support for molecular marker assistance breeding.In addition,With the migration of cotton gradually to the northwest inland areas where the salt and alkali is more serious,this study also conducted indoor salt resistance tests on four land cotton materials including the parents,Zhongmian 44 and Zhongmian 571,hoping to understand the salt resistance of the material and explore its possible mechanism of salt resistance.Based on the above research,we have obtained the following conclusions:1)F₂ populations were constructed from cotton cultivars CCRI49 and 396289 in the Gossypium hirsutum strains?lines?.Parental and 160 F₂ individuals were genetically mapped using a strategy combining parental re-sequencing and offspring SLAF-simplified genome sequencing,and obtained4607 up-mapped SNPs with a total genetic distance of 3063 cM,and an average distance between adjacent markers of 0.898 cM.2)16 plant height-related QTLs were detected in four environments,which explained 2.07-19.04%phenotypic variation,and QTLs related plant height was found in ChrD05 for the first time.Using Mutmap-like correlation analysis,a candidate region related to plant height was obtained in each of ChrA07 and ChrD05.Combined with QTL mapping results,ChrD05 was finely mapped and 18candidate genes related to plant height were obtained.18 candidate genes were subjected to fluorescent quantitative PCR and 14 candidate genes that were significantly differently expressed between the parents were found.3)QTLs for fineness and maturity were mapped using high-density genetic maps.By QTL mapping of seven fiber qualities including fineness and maturity,a total of 157 QTLs related to fiber quality were obtained.These QTLs were distributed at 20 chromosomes,QTLs of 7 traits were distributed on A03,QTLs of 6 traits were distributed on A04 and D02,QTLs of 5 traits were distributed on A11 and D07,etc.,indicating that A03,A04,and D02,A11 and D07 are very likely to be the key chromosomes controlling the fiber quality traits.Of the 7 traits related to fiber quality,a total of 4763genes were annotated,and 2416,4188,and 2512 genes were annotated in COG,GO,and KEGG,respectively.Some of these genes may be closely related to fiber quality..4)Through the salt tolerance test at the seeding stage of CCRI 49,396289,CCRI44 and CCRI 571,it was found that the salt resistance capacity of the material was expressed as CCRI 571>CCRI 44>CCRI 49.For 396289,the germination rate and water content were relatively low,and potassium and sodium ions ratio were relatively high.It is speculated that 396289 may have produced a"salt avoidance mechanism,"in which the seeds are dormant under salt stress conditions,and the germination rate may be increased if the seeds are moved to the control.