Development Of EST-SSR And SSR Markers And Application In Jatropha Curcas L.

Jatropha curcas (L.) is a newly energy plant and perennial shrub, belonging to the Euphorbiaceae family. This species is native of Central and South America but widely distributed in the tropics and subtropical area in the world. J. curcas can grow well under xerothermic climatic and sterile soil conditions by the form of wild or semi-cultivated type. The kernel contain high percentage of oleic and linoleic acid, and these unsaturated fatty acid has a semi-drying property, closing to petrochemical diesel fuel property, it may be developed as biodiesel. In recent years, the economic importance of J. curcas has been increasingly recognized as the potential use for biodiesel.But our understanding on this crop remains very limited as germplasm collection and basal research work are very limited. The present study aimed to identify a set of SSR markers transferability available from Manihot esculenta (cassava), a species in the same Eurphorbiacae family as Jatropha.241 SSR markers are transferred successfully,56 of which are used to study genetic diversity among 45 Jatropha accessions from collections in our germplasm bank and construct a primary molecule marker genetic linkage map of J. curcas. The results are addressed in this paper:1. A total of 302 EST-SSR and SSR markers were found to be amplifiable in J. curcas. Of them,241 SSR markers were polymorphic in five tested lines. In these polymorphic markers, including 187 EST-SSR markers and 54 SSR markers, their primer sequences and parameters of amplification are logged in the Genebank Database. Analysis of the nucleotide sequences of the polymorphic EST-SSRs and SSRs showed that, in J. curcas, the EST-SSRs corresponded to 57.75% trinucleotide repeats,26.20% dinucleotide repeats,8.56% pentanucleotide repeats, and 7.49% tetranucleotide repeats. In contrast, the SSRs were composed mainly of dinucleotide repeats (62.96%).2. Thirty-six EST-SSRs and twenty SSRs were chosen for detection of genetic diversity in 45 Jatropha accessions, and a total of 183 polymorphic loci have been revealed in the population. Based on the data of polymorphic loci, these germplasm were grouped into 6 clusters (including clusterâ… , clusterâ…¡, clusterâ…¢, clusterâ…£, clusterâ…¤and clusterâ…¥), which generally reflect their differences by the geographic origin. The intergroup genetic diversity index ranged from 0.4099 to 0.5022, and an estimated average of genetic diversity index (â… ) reached to 0.5572 suggested a considerable high genetic diversity in the Jatropha germplasm collection.3. A SSR linkage map is constructed using two high genetic diversity clones cross Yunnan clone YN049 and Hainan clone H001-31-1. The F1 segregating popultion is composed of 240 seedlings. Initially,31 EST-SSR primers were seclected to detect genetic polymorphism in the popultion. There are 45 loci accord to 1:1 or 3:1 segregation ratio among 83 polymorphic loci. The map is consist of 21 markers and be divided to 3 linkage groups by JoinMap3.0 software. The total distance of the map is 158.67cM. The average interval is 7.56cM. The genetic linkage map must be further completed in the future.