The genus Jatropha is native of tropical America with more than 200 species that are widely distributed in tropics with a promise for use as an oil crop for biodiesel. This investigation was carried out to assess the genetic diversity of 12 Jatropha species based on random amplified polymorphic DNA markers. From 26 random primers used, 18 primers gave reproducible amplification banding patterns of 112 polymorphic bands out of 134 bands scored accounting for 80.2% polymorphism across the genotypes. Three primers viz., OPA 4, OPF 11, and OPD 14 generated 100% polymorphic patterns. The polymorphic information content was highest for the primer OPD 14 (0.50) followed by the primers OPF 11 and OPAD 11 (0.48). Jaccard's coefficient of similarity varied from 0.00 to 0.85, indicative of high level of genetic variation among the genotypes studied. UPGMA cluster analysis indicated three distinct clusters, one comprising all accessions of J. curcas L., while second included six species viz., J. ramanadensis Ramam., J. gossypiifolia L., J. podagrica Hook., J. tanjorensis J. L. Ellis et Saroja J. villosa Wight and J. integerrima Jacq. J. glandulifera Roxb. remained distinct and formed third cluster indicating its higher genetic distinctness from other species. The overall grouping pattern of clustering corresponds well with principal component analysis confirming patterns of genetic diversity observed among the species. The result provides valid guidelines for collection, conservation and characterization of Jatropha genetic resources.

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The selection of Jatropha based on morphological information and molecular markers is essential as it is more reliable and consistent. Hence, twelve Jatropha accessions from different geographical areas of India were screened for genetic diversity using 19 morphological traits and 21 ISSR primers. The analysis of morphological traits grouped the accessions into five clusters. The cluster I consisted of J. curcas (CJC 18), J. curcas (CJC 20), J. curcas (CJC 22), J. curcas (CJC21), and J. curcas (CJC 25), and contained the maximum number of accessions; clusters II and IV contained the minimum number of accessions. Among all the characters, the highest range was exhibited by plant height and the least value by the number of branches. The twenty-one ISSR primers generated 156 polymorphic alleles. The average number of ISSR alleles generated was 7.47 per primer. The ISSR primer UBC 884 was highly informative with the maximum of 12 alleles. The 12 genotypes were grouped into eight clusters. The cluster I contained the maximum number of accessions, namely J. curcas (CJC 18), J. curcas (CJC 20), J. curcas (CJC 22), J. curcas (CJC21), and J. curcas (CJC 25). The clusters II, III, IV, V, VI, VII, and VIII (J. tanjorensis, J. gossypiifolia, J. glandulifera, J. podagrica, J. ramanadensis J. villosa, and J. integerrima) contained the minimum number of accessions. Maximum diversity between J. villosa and J. integerrima was noticed and the least diversity between J. curcas (CJC21) and J. curcas (CJC 25) seen because the ISSR markers differentiated the Jatropha accession into a wide genetic diversity as compared to the morphological data. The species-specific diagnostic markers identified in the study such as 1000 bp alleles for J. glandulifera by the primer UBC 826 is suitable for discriminating species of Jatropha, and thus can be used for identifying a Jatropha species from any mixed population comprising other members of the Jatropha complex.

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