Construction Of Transcriptome Map For Fiber Development In Interspecific Population Of Cotton

Cotton (Gossypium L.) is an important source of fiber. With the improvement of living standard and higher requirements for fiber yield and quality, people paid more attentions to improve the quality fiber yield and quality. Many researchers are trying to increase fiber production as well as the fiber quality. Conventional breeding method is difficult to achieve this goal, it is hard to break the negative correlationship of yield and quality.With the rapid development of molecular markers, and wide application of marker-assisted selection (MAS), it is no longer a fantasy to improve cotton fiber yield and quality. In the last decades, a lot of QTLs related to fiber yield and quality have been mapped by molecular markers, which is great helpful to improve fiber yield and quality. However, these researches are still in stage of theory, and most of them are on DNA level. With the development of functional markers, fiber formation mechanism can be analyzed on transcriptional level.This article conducted the analysis of transcriptional level from the following studies: (1) Search fiber development-related ESTs by differential display, and transferred them to functional markers; (2) Construct fiber transcriptome map, which will make a strong basis for QTL localization from DNA level to transcriptional level.1 Differential display of fiber from four developmental stages between Sea Island cotton and Upland cottonThis study chosed a simpliy cDNA-SRAP differential display technology to find differentially expressed sequences of fiber from four developmental stages (5DPA, 10DPA,15DPA,20DPA) between Emian22 and 3-79. Then the sequences were cloned and sequenced, we got 170 ESTs, which enriched cotton ESTs database. Exploited 104 functional markers based on differential sequences, and 6 polymorphic loci were integrated into our interspecific BC1 backbone genetic linkage map, and anchored in 6 chromosomes.2 Construction of transcriptome map for fiber development in interspecific population of cottonQTL mapping is an important part of marker-assisted selection breeding. There are many studies on the QTL related to cotton fiber yield and quality, but most of them based on a DNA level, which may appear some null QTL. However, QTL mapping based on transcriptome map at cDNA level can be more reliable.In this study, an interspecific transcriptome map of allotetraploid cotton was developed in a F2 population [Emian22×3-79] based on EST-SSRs, and we found the markers related to fiber expression at the developmental stage of 5DPA. This map contained 242 markers which distributed in 32 linkage groups (26 chromosomes). The full length of this map is 1938.72 cM, and the average length was 60.58 cM per linkage group. LG05, the maximal length of linkage group, was 132.74 cM consisting 15 markers; LG31, the minimum length of linkage group, was 2.33 cM consisting 2 markers. The mean distance of this map was 12.47 cM, and the density of markers in the linkage groups ranged from 0.01 cM (LG16/CHR11) to 36.12 cM (LG11/CHR09).Among the 242 markers in the constructed map, the functions of some ESTs have been annotated through searching homologous sequences. Some of the makers related to the differentiation and elongation of cotton fibrocytes, most of them related to basic metabolism. With the development of functional genome, we believe the function of the other ESTs must be studied clearly.This study constructed the transcriptome map for fiber using simple EST-SSRs, which is a strong tool for QTL mapping of fiber quality, and map cloning of important fiber traits related to fiber development. Meanwhile, it also has great significance to molecular assisted selection.