Genetic diversity in the Jatropha genus and its potential application

Jatropha curcas L., a drought tolerant, monoecious perennial shrub, has gained attention in the tropics and sub-tropics during the past decade as a potential biodiesel crop. Adequate genetic diversity for key agronomic traits is of fundamental importance in crop improvement programmes particularly for crops such as J. curcas, which are in the early stages of domestication. In J. curcas, genetic diversity in local populations and worldwide collections has been estimated using both dominant and co-dominant molecular markers systems such as random amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSRs), sequence-characterized amplified region (SCAR), amplified fragment length polymorphism (AFLP), simple sequence repeats (SSRs) and single-nucleotide polymorphism (SNPs), etc. Assessment of genetic variation using molecular markers unequivocally established the existence of rich genetic diversity in the germplasm from Central and South American regions and narrow genetic base in populations from Asia and Africa. Establishment of phylogenetic relationships among Jatropha species using molecular markers has been limited to species naturalized and distributed in India. Research expansion over the past decade has indicated the availability of considerable genetic variation in the genus Jatropha for vegetative and floral traits linked to productivity, seed oil content, fatty acid profiles, toxicity (phorbol esters, curcin), etc. The diverse genetic sources identified in J. curcas germplasm and the compatible wild species need to be exploited for genetic improvement of the crop through conventional breeding and interspecific gene transfer, which could be further accelerated through marker-aided selection.