QTL Location Of Earliness And Fiber Quality In Cotton Using Rils

Cotton, one of the most important economic crops in the world, is the most important fiber crop for the textile industry and the third important oil crop. It is also a model plant species for the research of cell development and the origin and evolution of polyploids. With the increase of the population of China, the competition between food crops and cotton became more and more fierce, and the arable land decreased more and more seriously. So it is necessary to study on the cotton’s early maturity and growth period to adjusting for new cropping systems.In this study, a shorted-season upland cotton and another upland cotton with island cotton chromosome segment substitution (CCRI36×G2005) were used to built recombinant inbred lines which contained192lines. Combined with three years and five environmental tests, we studyed the QTLs of important agronomic trait. There are significant differences between the two parents in growth period, fiber-quality and other traits. The research lay a theoretical foundation for fine mapping early maturity and fiber-quality trait-related QTL, marker-assisted selection (MAS) breeding and gene cloning in upland cotton.1. A total of16517pairs of SSR primers were used to screen polymorphism between two parents, which resulted511pairs of polymorphic primers, of which363pairs of primers were detected polymorphism in the population.2. Using the mapping software (Joinmap4.4),261polymorphic loci derived from363primer pairs could be mapped60. The map covered a genetic distance of908.96cM, accounting for20.38%of the total length of the cotton genome, and the largest linkage group contained44loci,52.6cM in length, while the smallest linkage group included2loci.3. The correlation analysis about three years and five environmental tests of the population’s traits relating to early maturity and fiber-quality showed the results as follows:①for the early maturity traits, there was a significant positive correlation between plant type (plant height, height of the first fruiting branch, location of the first fruiting branch) and the traits relating to growth period (growth period, sowing to flowering, flowering and boll-setting period, bud period),②there was a significant negative correlation between early maturity traits and fiber length and micronair. Therefore, selecting the material whose fiber length and micronair have a good performance to breeding early-maturing varieties can reduce influence of the early-maturing materials on fiber quality.4. The widely used QTL location analysis software WinQTLCartographer2.5was applied by Compose Interval Mapping (CIM) method. There were13traits including bud period, flowering and boll-setting period, sowing to flowering, growth period, height of the first fruiting branch, location of the first fruiting branch, plant height, boll weight, fiber length, fiber uniformity, micronair, fiber strength and fiber elongation scanned QTL, and a total of53QTL were deteced under five environmental tests, including43QTLs related to early maturity traits and10QTLs related to fiber quality.5. Eleven higher contribution rate of phenotypic QTL were detected. There were1bud period-related QTL:qBP-10J-2-1;2QTLs related to sowing to flowering: qSF-10J-38-1, qSF-12A-24-1;3QTLs related to flowering and boll-setting period: qFBP-10J-38-1, qFBP-10X-2-1and qFBP-10X-16-1;1QTL related to growth period: qGP-10X-2-1;1QTL related to location of the first fruiting branch:qLFB-12A-24-1;2QTLs related to plant height:qPH-10X-31-1, qPH-11A-13-1;1QTL related to fiber strength:qFS-11A-11-1。6、10QTLs were detected in multiple environments. QTL related to flowering and boll-setting period and growth period were detected in3different environments, QTL related to bud period, location of the first fruiting branch, plant height, boll weight, fiber length, fiber uniformity were detected in2different environments, and expect for the QTL related to bud period, sowing to flowering, growth period, plant height, fiber length were detected in multiple environments. The QTLs with phenotype variation above10%will be further studied.