Characterization of fatty acyl-coA reductases involved in the sex pheromone biosynthesis of the cotton leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae)
B. Antony*, S. A. Aldosari, and A. S. Aldawood1
King Saud University, Chair of Date Palm Research, College of Food and Agriculture Sciences, Riyadh, Saudi Arabia 11451
1 King Saud University, EERU, College of Food and Agriculture Sciences, Riyadh, Saudi Arabia 11451
Pheromone gland specific fatty acyl reductase (pgFAR) form an evolutionary conserved category of enzyme involved in sex pheromone biosynthesis, has recently been characterized from insects, which catalyses the conversion of fatty acyl precursor to the corresponding alcohol with distinct stereo-specificities, and a major gene that contribute the pheromone based reproductive isolation in moth. The cotton leaf-worm female moth, Spodoptera littoralis, use a pheromone blend composed of several C14 acetates with different degrees of unsaturation, including (Z)-9, (Z)-11 and (E)-11-tetradecenyl, and (Z,E)-9,11 and (E,E)-10,12-tetradecadienyl acetates as a sex pheromone. Biosynthesis of this
pheromone blend occurs by combined chain-shortening and desaturation reactions of acyl-CoA intermediates followed by reduction and acetylation to produce acetate pheromone. At a step in the pheromone biosynthetic pathway, fatty-acyl precursors are converted to corresponding alcohols by an enzyme, fatty-acyl reductase (FAR). Here we report the cloning of FAR-like genes expressed in the pheromone gland of female S. littoralis, and the characterization of a single pgFAR. As many as eight FAR-like genes were expressed in the pheromone gland of S. littoralis; however, only one (pgFAR) was pheromone gland specific. The deduced amino acid sequence of S. littoralis pgFAR predicted a 456-aa protein with a conserved Pfam domains including NAD (P)H binding domain, sterile domain and epimerase domain; showing overall homology of 45-51% with the pgFAR of Heliothine and Yponomeuta moths. A gene tree was constructed using a set of FAR sequences from arthropod, mammalian and lepidopteran FARs including the lepidopteran-specific pgFAR group and S. littoralis pgFAR clustered within the lepidopteran pgFAR clade (Bombyx mori, Ostrinia spp., Yponomeuta spp., Heliothis spp. and Helicoverpa spp.) that contains FARs involved in sex pheromone biosynthesis. This study is the first report of pgFAR from Spodoptera moth.
Keywords: Fatty acyl reductase, pgFAR, Pheromone gland, Spodoptera