Background: Palmitoleic acid is a fatty acid that possesses nutritional, health, and industrial applications. However, it accumulates in the seed oil of few plant species that often lack agronomic value. A bioinformatics approach was developed as a complementary tool to effort- and time-consuming traditional methods to identify palmitoleic acid-accumulating plant species. The approach involved identifying acyl-ACP desaturases with a sequence variation linked to a switch in the substrate preference from stearic to palmitic acid.

Results: A PHI-BLAST analysis identified Handroanthus impetiginosus as a candidate species with two acyl-ACP desaturases with the desired sequence variation. A substrate docking analysis showed that the presence of phenylalanine at the bottom of the active site plays a similar structural role to that of tryptophan present in the same position in the divergent desaturase of the palmitoleic acid accumulator Dolichandra unguis-cati. The analysis of the genome of H. impetiginosus allowed the identification of four putative ferredoxins, three of which are heterotrophic type and have been linked to an increase in the activity of unusual acyl-ACP desaturases. RT-PCR results showed that both studied H. impetiginosus desaturases are expressed in the pod but not in the seeds, while all 4 ferredoxins are expressed in both tissues. GC–MS analysis confirmed the presence of palmitoleic acid in seed oil.

Conclusions: These results suggest that the proposed bioinformatic approach can be a valuable compliment to traditional methods for the identification of plant species that accumulate palmitoleic acid. However, further improvements are needed, such as predicting seed expression of desaturases.