Development And Morphology Of Cotton Fiber And Locating The Elite QTL Alleles Of G. Barbadense L. Fiber

Cotton is an important cash crop.The yield of upland cotton is higher than the yield of sea island cotton,but the fiber quality of upland cotton is inferior to sea island cotton.In order to Introgress the elite QTL alleles of G.barbadense L.for fiber quality into G.hirsutum L.and provid more new gerplasm resource for the variety development,the elite G.hirsutum variety 'CCRI36' and G.barbadense 'Hail' were respectively used as recurrent and donor parent to produce backcross populations,including the 1st(BC₁F₁ and BC₁S₁) and 2nd(BC₂F₁) backcross generations.QTL analysis of fiber quality traits on three phenotypic data were proceeded by Composite Interval Mapping.At the meanwhile,CCRI36 and Lumian19 were used as female and top-crossed with Hai7124 and Hai8577,the fiber character of 4 F₁ hybrids were observed by using of scanning electron microscope.The early development of the ovule was observed by microscope and scanning electron microscope in this study,it shows that the protuberance appeared at -1 DPA, the protuberance covered all over the ovule at 0 DPA,the protuberance grew into lint at 1 DPA.The fiber protuberance first appeared at the crest of the funiculus,then chalazal cap and middle parts of the ovule,and at the micropylar region at last.It could be also observed that there is lots of wrinkle in the mature fiber.The mature fiber has right-hand spiral wrinkle except its twisting after dehydration. The F₁ hybrids fiber not only have the parents' character,but also have a new character of bubble enlargement.They were more similar to parent of sea island cotton in morphology.A total of 3670 SSR primer pairs were used to screen polymorphism among two parents CCRI36,Hail and their F₁ progeny,which resulted in 261 poly-morphic primer pairs and 270 locus.They were used to screen the BC₁F₁ population.Linkage test indicated 212 of 270 locus derived from 261 primer pairs could be mapped to 42 linkage groups and covered a total genetic distance of 1780cM,approximate 40%of cotton genome.The average distance of markers was 8.39cM.32 linkage groups were assigned to corresponding chromosomes.25 QTLs for fiber quality traits were mapped in three generations.QTL numbers for fiber length,strength,micronaire,uniformity and elongation ratio were 7,1,5,5, 7,respectively.Each QTL could explain 7.0%～19.2%of phenotypic variance.Only one micronaire QTL could be detected in two of the three generations.