QTL Mapping For Su Sy Activity Of Island Cotton(G.barbadense L) And Development Of Functional Marker For Su Sy Gene During Secondary Cell Wall Deposition

In recent years, the improvement of fiber strength, length, has become an important goal of cotton breeding in China. Especially in cotton fiber secondary wall thickening stage, SuSy activity significantly affect to the cellulose synthesis and accumulation in the secondary wall deposition, and thus affect the cotton fiber strength, length and other fiber characteristics. This study used Pimas-7/5917S7 F2:4 group of island cotton and repeat groups F2:4B, and 193 varieties of Sea Island Cotton group named HDMa and its repeat group named HDMb as experimental materials. SuSy activity which is in secondary wall thickening stage of fiber cell and fiber quality index were measured, and make a correlation analysis between activity of SuSy and the index of fiber quality.Using Pimas-7/5917S7 F2:4 group, The location of SuSy activity QTL was made, and determined a major QTL.Analysis of the SuS3 gene in the activity of sea island cotton varieties of high, low SuSy between alleles.The main results obtained in this study are summarized below.1. In 5917S7/Pimas-7 F2:4A and F2:4B group, SuSy activity in cotton reached the peak at thirtieth days after flowering, and the varieties which has higher peak of activity of SuSy are higher than the varieties which has low peak of activity of SuSy in20-35 days after flowering.2.The characteristics of Pimas-7/5917S7 island cotton group F2:4 main fiber quality traits and the activity of SuSy in normal continuous distribution. 193 Sea Island Cotton Varieties Resources SuSy activity is different, a wide range of variation and selection potential. The activity of SuSy and the cotton fiber length, strength and elongation ratio showed a significant positive correlation.3.103 pairs of SSR markers were screened from1300 pairs of primers, A genetic linkage map of 5917s7/Pimas-7 F2:4 population was constructed, the map contains 26 linkage groups(LG1-LG26), the average distance of markers was 23.68 cM, the total length is 2153.88 cM, covering the whole cotton genome 29.02%.4. After the localization of QTL, 5 SuSy activity of QTL in the secondary wall thickening stage were detected In the Pimas-7/5917S7F2:4 group, Synergistic gene of 3 QTL are provided by high value SuSy activity parent 5917S7, Synergistic gene of the other 2 QTL from low value SuSy activity parent Pimas-7. The mode of action of 5 SuSy activity QTL is dominant or overdominant,which is Indicate that these the relationship of genes of SuSy activity QTL is allelic or non allelic interaction.5. A SuSy activity QTLwhich is named qSuS-18-1, is recognized as a main effect QTL,which is lie in A6 chromosome of cotton. A6 chromosome is located SuSy gene, suggesting that the SuSy gene itself is mainly genetically factor, which is determined SuSy activity.