Comparative metabolome analysis of seed kernels in phorbol ester-containing and phorbol ester-free accessions of Jatropha curcas L.

Abstract

Jatropha curcas L. (Jatropha) is a promising source of renewable bioenergy, since its abundant seed oil can readily be converted into biodiesel. However, industrial use of Jatropha seed oil is problematic; the toxicity of the seeds and oil endangers the oil users and prevents the use of byproducts, such as seed cakes. The most toxic compounds in Jatropha are phorbol esters (PEs), tetracyclic diterpenoids known for their tumor-promoting activity. It is important to utilize a non-toxic accession of Jatropha that lacks PEs in industrial feedstocks. Here, we used an LC-Orbitrap-MS system to characterize the metabolome of seed kernels from PE-containing and PE-free accessions of Jatropha. Among the more than 12,000 metabolites detected, 18 were specific to the PE-containing accession, and most of these appeared to be PEs or derivatives thereof. In contrast, only four ions were specific to the PE-free accession. These results indicate that PE-containing and PE-free Jatropha are broadly similar in their metabolism, but that the PE-containing accessions undergo PE biosynthesis.