The Construction Of Genetic Linkage Map By Composite Molecular Marker In Jute

Jute (Corchorus Capsularis)belonging to Corchorus in Tiliaceae is an important natural fibre crop, and also a characteristic cash crop in China, India and Bengal and so on. By now, the genetic map of jute has not been reported. The construction of genetic map can provide particular description of gene structure, and it lay the foundation of the development of genetic research in jute, which is an important field in the research of jute , and a theoretical basis of gene location and clone. In this study, the first genetic linkage map in jute was constructed by means of composite molecular markers including SRAP , ISSR and RAPD, The results were as follows:1.Creation of mapping population:Based on the cluster analysis of genetic diversity and relationships of 173 jute accessions worldwide by SPAP molecular markers, New NO.1 and Qiongyueqing were selected as hybridization parents for the generation of F1 progeny. 185 F2 individuals from the self-bred progeny of the F1 generation were used to construct a genetic linkage map;2.Optimization of extracting DNA:We improved the method of CTAB that extracted total DNA of the jute and obtained an optimal method for extracting DNA from the old leaves of the jute;3.Optimization of SRAP amplification system:We did the gradient experiments of SRAP amplification system in 6 aspects of DNA, dNTP, Mg2+, primer, Taq polymerase and annealing temperature and obtained an optimal SRAP amplification system for our sample;4.Screening of primers for polymorphism :By using New NO.1 and Qiong yueqing as templates for PCR amplification of the mapping population , 26 pairs of SRAP primers, 21 ISSR primers and 7 RAPD primers, which had preferable polymorphisms, were screened from 19×27 pairs of SRAP primers with 19 forward primers and 27 reverse primers, 60 ISSR primers and 26 SRAP primers;5.PCR amplification of the mapping population: to select three primer groups for Polymorphic primers, using three molecular markers including SRAP, ISSR, RAPD for PCR amplification of the mapping population , and these markers generated 157 polymorphic bands in the F2 population analysis,The average of polymorphic bands produced by one primer pair was 2.9 and the maximum was 6;6.Construction of the linkage map by maker3.0:A linkage map was constructed using Mapmaker/3.0. It consisted of 47 SRAP markers, 58 ISSR markers, 2 qualitative traint markers and 18RAPD markers, distributed into 10 linkage groups (LOD≥3.0) and spanned 2166.3 cM with an average interval of 17.33 cM between markers,the maximum distance between two markers was 42.7cM and the minimum was 0cM, each linkage group with a length between 0.6 and 573.8 cM had 2 to 33 markers;7.Analysis of segregation:The segregated rate (segregation 3:1) we constructed was 8.13%, and the relative segregation was low.8.Position of qualitative traint:There were 2 morphological markers in this map, M4 was the trait of the size of stipule and M5 was the strength of axillary bud,They were located in the linkage group 5, M4 linkaged with 807-220 and the genetic distance between them was 16.9 cM. M5 linkaged with M14E14-280 and the genetic distance was 26.4cM.