Micropropagation and Genetic Divergence Analysis in Jatropha Using RAPD markers

Abstract

Jatropha ( Jatropha curcas L. ) is an oil bearing crop growing in tropicaJ and subtropicaJ parts of the \Vorld. The present investigation \vas undertaken to development of protocol for micropropagation and assess the extent of genetic diversity in a representative set of twenty selected varieties of Jatropha curcas using random amplified polymorphic DNA (RAPD) markers. For micropropagation TriaJs with PGRs (auxins and cytokinins) alone or in different combinations and different explants have vividly evinced that none of the explants tried was amenable to m.icropropagation on any of PGR combination tried. However, these media supported callusing from different explants. Among different explants tried, leaf lamina is the best responding explants and MS medium supplemented with 5xl0-6 M each BAP and KIN and 2.5xl0-6 M ofNAA is the best callusing and growth supporting medium. Ten RAPD primers were used to assess molecular polymorphism in twenty Jatropha curcas genotypes. A total of 4 7 amplified products were obtained out of which 44 \vere polymorphic and 3 were monomorphic. Average polymorphism across twanty genotypes was found to be 93.61%. For the genotypes tested, 6 to 11 bands \vere obtained~ with an average of 7.83 bands per primer. The size of amplified fragments ranged from 200-3000 bp. All the genotypes were distinguishable with the combination of polymorphic bands generated by various primers. Some primers also produced unique alleles in specific genotypes which could be used to distinguish them. Analysis of this polymorphism profile, generated using suitable statistical programmes, grouped the twaty genotypes into two major clusters at a similarity coefficient of 0.62. The cluster-! comprised JC-4 and JC- genotypes. Cluster-IT comprised 16 genotypes. Cluster- II was divided into two subclusters at the similarity coefficient 0.65. Subcluster-! involved three varieties JC-8 and JC-17 and JC-19. The second sub-cluster contained all other genotypes. Genetic similarity matrices of the genotypes ranged from 0.88 to 0.93, indicating a moderate genetic variability among the genotypes. Genotypes JC-3 and JC-2 were genetically most similar with genetic similarity value of 0.88 \vhile the genotypes JC-8 and JC-I 7 were found out to be genetically most diverse, at a value of 0. 44. Similarity value for all other genotypes varied between these two extreme values. The results obtained indicated that RAPD markers are efficient for identification of Jatropha cure as genotypes and for determination of the genetic relationships among them. Fingerprint data obtained in this study can be further utilized in identification and development of improved Jatropha varieties for further use in breeding programmes.