Toxicity of Jatropha curcas L. as a biofuel crop and options for management

There are high expectations of Jatropha curcas L. as a new crop for biofuel production in the tropics and sub-tropical areas, as evidenced by the forecast expansion of its cultivation in various areas, especially in Asia. The definitive confirmation of the crop as realistic and suitable feedstock for biodiesel will come about when it is able to exploit the vast marginal areas present in many countries, demonstrating the economic sustainability of the whole Jatropha biodiesel chain. Increasing seed yield and oil content remain the main goals, but a valorization of the extruded seed cake, as animal feed, currently prevented by the presence of phorbol esters (PE) toxins, could contribute to a significant improvement in the economic sustainability of the crop. At present, the only reliable process is the seed cake detoxification by washing treatments with solvents and by biotransformation, but these treatments are expensive, not environmentally friendly and difficult to apply in developing countries. In the near future, the solution may come from non-toxic J. curcas accessions, which can be used in breeding programmes to recombine non-toxic traits into elite toxic varieties. In general, a plant free of PE would be more acceptable, opening additional market opportunities for the farmers. Strategies for breeding improved non-toxic varieties could be accelerated by DNA-based molecular marker technology, utilizing the simple sequence repeat (SSR) markers associated with toxicity. The whole genome of plant was recently sequenced and this important acquisition is expected to accelerate the process of molecular breeding in J. curcas.