Phenotypic and genotypic variability of F2 plants derived from Jatropha curcas × integerrima hybrid

Phenotypic and genotypic variability were evaluated in a population of 227 F2 plants derived from an interspecific cross between Jatropha curcas (cv. “Chai Nat”) and Jatropha integerrima (local dwarf ornamental type) from Thailand. The objective of this study was to assess the range of variability for 13 phenotypic characters and 16 EST-SSR markers observed in the population. A high variation was found in morphological characters showing many superior genotypes over the J. curcas parent. The results of molecular parameters also suggested a high level of genetic variability in the current population with 100% of polymorphic loci (PPL) for all 16 SSR primers used. The mean numbers of observed alleles (Na) and effective alleles (Ne) were 2.13 and 1.81, respectively. The polymorphic information index (PIC) ranged from 0.17 to 0.55 with an average of 0.34. The average values of Nei's genetic diversity (He), observed heterozygosity (Ho), and Shannon's information index (I) were 0.43, 0.47, and 0.64, respectively. Jaccard's similarity coefficient ranged from 0.51 to 0.96 with a continuous distribution. The UPGMA-based dendrogram could not classify the F2 plants into clusters, but separated them into three sub-groups and seven distinct plants at 61% similarity. The information generated from the current research will be of great benefit to jatropha breeding program; providing a new gene source to the currently low variation in J. curcas.