Expressed sequence tags from callus of Euphorbia tirucalli: A resource for genes involved in triterpenoid and sterol biosynthesis

We report generation of 9,301 expressed sequence tags (ESTs) derived from callus cells of Euphorbia tirucalli in search of candidate genes involved in the triterpenoid and sterol biosyntheses. After assembling 4,342 redundant ESTs into 1,252 clusters, a total of 6,211 non-redundant sequences were obtained. Database search revealed that 4,449 out of the 6,211 sequences shared significant similarities to known nucleotide or amino acid sequences, while the remaining 1,762 showed no significant matches and appear to represent novel genes in E. tirucalli. The annotations assigned to the hit database entries suggest that 48 of the unique sequences are involved in triterpenoid and sterol biosyntheses. Although functions of genes tagged by the 48 sequences are yet to be determined, the EST resource described here should contribute to identification of genes participating in the triterpenoid and sterol biosyntheses in E. tirucalli.