Fig. 6

The neighbor-joining tree of selected lepidopteran desaturase genes, constructed using amino-acid sequences. Desaturases described in this study are indicated by different shapes (with signature motif displayed for the First Desaturase), followed by unigene expression levels in the gland and abdomen library, respectively (As_PG_FPKM /As_AB_FPKM). Desaturases in previous studies are named as follows: biochemical activities (if known) are indicated in connection to the species name, followed by accession number in parenthesis. Most of the desaturases used in here are First Desaturases that introduce double bond into saturated fatty acids. Among the First Desaturase, four distinctive groups formed that separate their biological functions. The ∆9 desaturases are usually used for normal fatty acid metabolism, with the “KPSE” group having preference on C16 and “NPVE” group mainly modifying C18. The ∆11,∆10 and bifunctional desaturases with the “xxxQ” motif (with a few exceptions having “xxxE” motif) exclusively involved in pheromone biosynthesis. The ∆5,∆6,∆14 group contain a mixture of different signature motifs derived from the ∆9 and ∆11 groups, and their biological function are also diverged. The tree was rooted on the ∆9-desaturase-KPSE (C16 > C18) functional class