Maping QTL For Yield And Fiber Quality Traits From G.hirsutum Cultivar × G. Hirsutum Race Palmeri Population

Cotton is an important commercial crop.Upland cotton?Gossypium hirsutum?is the most widely cultivated species in the world.However,the poor genetic diversity among cultivars limited the improvement of upland cotton.G.hirsutum race is the original type of upland cotton,which is closely related to cultivars and easy to cross.Moreover,G.hirsutum race is rich in genetic diversity and contains many excellent characteristics which wasn?t found in upland cotton,such as resistance to diseases and insects,high fiber strength,excellent quality,drought tolerance,and salt resistance.It is important to identify the favorable alleles of agronomic trait loci?QTL?for upland cotton improvement.This study constructed the genetic map from?G.hirsutum cultivar CCRI 35×G.hirsutum race palmeri TX-832?F₂ population and detected QTL controlling fiber quality and yield traits.The main results are as follows:1.The phenotypic analysis of yield and fiber quality traitsThe phenotypic data of fiber quality traits presented a wide range of variation and distributed continuously in the four environments.Correlation analysis showed that the fiber elongation extremly positively correlated with seed index,fiber length,fiber uniformity,fiber strength,and extremly negatively correlated with Micronaire.Micronaire extremly negatively correlated with seed index,fiber length,fiber uniformity and fiber strength.Fiber strength extremly positively correlated with seed index,boll weight,fiber length,fiber uniformity,and extremly significant negatively correlated with lint percentage.Fiber uniformity extremly positively correlated with seed index,lint percentage,boll weight,fiber length.Boll weight extremly positively correlated with seed index.Lint percentage extremly negatively correlated with seed index.2.Polymorphism and population genotypingA total of 22258 SSR primers pairs were used to screen the polymorphism between CCRI35 and TX-832.Finally 1038 effective polymorphic primers pairs were obtained with a polymorphism ratio of 4.04%.The polymorphic primers were used to genotype92 individuals from F₂ population,and generated 1054 loci,16 polymorphic primers had double loci.3.Genetic map constructionA genetic map consisted of 1026 polymorphic loci,covered 4149.04 cM,which occupies approximately 90%of G.hirsutum genome.The average distance between markers is 4.04 cM.A-genome contained 450 markers covering a length of 2109.17 cM with an average genetic distance between markers of 4.69 cM.The D-genome contained576 markers and covered a length of 2039.87 cM,with a average genetic distance between markers of 3.51 cM.4.QTL maping yield and fiber quality traitsIn total,52 QTL for fiber quality traits and 38 QTLs for yield traits were detected,these QTL explained 7.1–24.4%of the phenotypic variance.Forteen fiber length QTL distributed on 10 chromosomes and explained the phenotypic variation between 9.6%and 15.6%.Nine fiber strength QTL distributed on 7 chromosomes and explained the phenotypic variation between 9.6%and 15.6%.Ten fiber micronaire QTL distributed on10 chromosomes and explainedthe phenotypic variation between 9.9%and 20.4%.Nine fiber uniformity QTL distributed on 7 chromosomes and explainedthe phenotypic variation 10.2%and 19.0%.Ten fiber elongation QTL distributed on 10 chromosomes,and explainedthe phenotypic variation between 9.9%and 15.9%.Ten boll weight QTL distributed on 8 chromosomes,and explained the phenotypic variation between 9.8%and 18.2%.Fifteen lint percentage QTL distributed on 12 chromosomes and explained the phenotypic variation between 9.8%and 24.1%.Thirteen QTL seed index distributed on 13 chromosomes and explained the phenotypic variation between 7.1%and 18.7%.Eleven QTL clusters were distributed on 10 chromosomes.8 stable QTL were detected in more than two environments.qLP17.1 and qFM17.1were detected in three environments.qFL02.1,qFU16.2,qBW02.2,qLP18.1,qLP23.1,qSI18.1 were detected in two environments.