The Study On Molecular Markers Linked To Fiber Color Of Brown Cotton

Brown cotton is a kind of natural colored cotton. Since it has less processing procedures, it is more healthful and economical for our daily life, comparing with the white cotton. But brown cotton's lower yield and poorer quality limit its use. In order to improve the yield and quality of brown cotton, the technique of molecular marker-assisted-selection for breeding is selected to speed up the breeding process. And the mark linked to the fiber color trait is studied.In the article, Zongcaixuan 1 was slected as a male parent,while Simian 3 was selected as a female parent. In 150 F2 populations from which plants with consistent color were chosen to construct DNA pools including brown colored cotton DNA pool and white colored cotton DNA pool. By the markers of RAPD,SRAP and EST-SSR, screened out the special mark which linked to the color trait of brown cotton from the DNA pool. The main results were as follows:1. 99 RAPD primers were analyzed through agarose gel electrophoresis. 78 primers produced clear bands, which accounted for 78.79%. A total of 351 bands were obtained and the average bands produced by per primer were 4.5. 20 primers showed polymorphic bands between two parents, which accounted for 20.20%. Zero primer showed polymorphism between two DNA pools among 20 primers which showed polymorphism between the parents.2. 88 SRAP primers were analyzed through agarose gel electrophoresis. 78 primers produced clear bands, which accounted for 88.60%. 60 primers were analyzed through polyacrylamide gel electrophoresis. A total of 2040 bands were obtained and the average bands produced by per primer were 34. 9 primers showed polymorphic bands between two parents, which accounted for 10.23%. Zero primer showed polymorphism between two DNA pools among 9 primers which showed polymorphism between the parents.3. To further screen specific markers closely linked to fiber color of brown cotton furtherly. I studied the relationship between the length of Gossypium hirsutum ESTs sequence and the characters of EST-SSR. The results showed that di-nucleotides were the main type repeats, accounting for 63.46% in all SSRs. Tri-nucleotide were the secondary type repeats, accounting for 34.04% of all SSRs. (AG)n, (AT)n, (AAG)n,(ACC)n, (ACT)n and (AAT)n were the most frequent motifs. Accordingly, 61 pairs of EST-SSR primers were exploited in order to find the marker linked to the color trait of brown cotton.4. The optimized reaction system was as follow: 25μL reaction system containing 30ng template, 2.0mmol/L Mg2+, 1.5μmol/L primers, 0.5mmol/L dNTPs and Taq polymerase 0.2μL. 61 EST-SSR primers were analyzed with this system. 48 primers produced clear bands.5. 48 EST-SSR primes were further selected. After identifying among parents,DNA pool and individual plant, a EST-SSR marker was obtained, which linked to fiber color of brown cotton. It was named W42, having 218 nucleotides. Through blasting and contrasting in GeneBank, an open reading frame which was homologous to other plant. For example, comparing with unknown protein in grape, the homology was 85%. And comparing with mitochondrial enzyme translocation in corn and arabidopsis thaliana, the homology was 84% and 67% respectively. Maybe the sequence was a partial sequence that could code mitochondrial translocation enzyme genes.