Construction Of A Primary Molecular Genetic Map In Rubber Tree (Hevea Brasiliensis)

The rubber tree (Hevea brasiliensis) is an economic woody crop in family Euphorbiaceae. Produced natural rubber is an important ir-replaceable strategic matter to development of our country. The paradox of increasing demand and decreasing self-supply faced us a hard task to enhance productivity by biotechnology. Construction of molecular linkage map will lead to molecular breeding and accelerate genomics research in rubber tree. Using a selected segregation F1 population (GT1×IAN873) with no inbred parents of 180 plant lines to find polymorphic DNA markers with SSR,SRAP and AFLP analysis methods, the results of molecular genetic map construction is as followings:A modified CTAB was developed to get high quality DNA sample of rubber tree against to problem of rich protein in leaf. The abstracted DNA showed neat bands with concentration of 60～100ng/μL, and molecular size was about 50Kb.Simple sequence repeat (SSR) analysis indicated that 13 of 30 SSR primers can amplify out diversity alleles in the population. There were 35 diversity alleles shown in total of 13 alleles. The polymorphic frequency ratio reach to 94.6 percentage. And a stable SSR amplification system was established based on suitable annealing temperature 51～54℃.Total of 180 individuals were analyzed by SRAP (sequence-related amplified Polymorph- ism) markers. There is 166 amplified fragments and 113 polymorphic fragments that were detected by applying 20 SRAP primer combinations.The polymorphic fragment percentage was 68.1%.The number of amplified fragments and polymorphic fragments per primer combination were 8.3 and 5.65.A SRAP amplification reaction system has been bettered by land PCR machine. A new AFLP analysis and screening system in rubber tree was set up. Full set of EcoRI/MseI primers and adaptors were synthesized. From the quality of template DNA, pre-amplification, selective amplification, gel-electronphorsis to silver staining, all factors probable affected the AFLP were tried and modified produced an useful protocol. The result will provide a powerful tool to construct genetic linkage group and gene mapping.All 148 polymorphic markers include of 113 SRAP markers and 35 SSR markers, were used for construction of molecular linkage groups in rubber tree by JoinMap 3.0 Software. A primary map consisted in 18 linkage groups and located in 61 SRAP markers and 7 SSR markers has been finished. This map covers a total genetic distance of 774 cM, with average map distance of 11.38 cM per marker, and length of each group varied from 51 to 85cM, the number of markers linked to each group ranged from 2 to 8, corresponding to 0.5～25.5 cM per marker. There were 18 markers shown bias segregation occupied 26.47% of the total markers.This primary rubber tree genetic map should be enriched or used for construction of a consensus genetic map integrated with the published map data although it still is valuable to gene or QTL mapping presently. The reasonable factors to the molecular map and how to utilize it have been discussed in the paper.