Molecular identification of differential expression genes associated with sex pheromone biosynthesis in Spodoptera exigua

Abstract

Species-specific sex pheromone is biosynthesized and released in most female moths as a chemical cue in mating communication. However, information on genes involved in this pathway is limited. The beet armyworm, Spodoptera exigua, is a cosmopolitan agricultural pest that causes severe economic losses to many crops. In China, the female sex pheromones in sex pheromone glands (PGs) of S. exigua have been measured which comprises (Z,E)-9,12-tetradecadienyl acetate, (Z)-9-tetradecen-l-ol, (Z)-9-tetradecenyl acetate, and (Z,E)-9,12-tetradecadien-1-ol in a ratio of 47:18:18:17. Fifty-nine putative genes related to sex pheromone biosynthesis were identified in the present study by sequencing and analyzing the sex pheromone gland (PG) transcriptome of S. exigua. Expression profiles revealed that two desaturase (SexiDes5 and SexiDes11) and three fatty acyl reductase (SexiFAR2, 3, and 9) genes had PG-specific expression, and phylogenetic analysis demonstrated that they clustered with genes known to be involved in pheromone synthesis in other moth species. Our results provide crucial background information that could facilitate the elucidation of sex pheromone biosynthesis pathway of S. exigua as well as other Spodoptera species and help identify potential targets for disrupting sexual communication in S. exigua for developing novel environment-friendly pesticides.

Transcriptional comparison between pheromone gland-ovipositor and tarsi in the corn earworm moth Helicoverpa zea

“…5) showed that FAR1 formed a clade with the identified FARs found in PGs of Helicoverpa (Hagstrom et al, 2012). FAR8 and FAR10 clustered with the Ostrinia FARs (Lassance et al, 2013), while the remaining FARs clustered with the FARs identified from the PG transcriptome data of Spodoptera (Zhang et al, 2015(Zhang et al, , 2017 and Agrotis (Gu et al, 2013;Ding and Löfstedt, 2015).…”

Multi-Functional Desaturases in Two Spodoptera Moths with ∆11 and ∆12 Desaturation Activities

“…The four full-length sequences of SexiDes5 (1017 bp), SexiDes7 (1116 bp), SexiDes11 (1062 bp) and SlitDes5 (1017 bp) were obtained from the pheromone gland cDNA library transcripts (Zhang et al 2017 ) and encoded proteins with 339 aa, 372 aa, 354 aa and 339 aa, respectively.…”

“…Desaturase sequences were obtained from pheromone gland transcriptome databases for S. exigua (Zhang et al 2017 ) and S. litura (Zhang et al 2015 ). A phylogenetic tree was constructed for desaturases from S. exigua (Zhang et al 2017 ) and S. litura (Zhang et al 2015 ), based on a dataset containing 3 amino acid sequences from S. exigua , 1 amino acid sequence from S. litura and 53 amino acid sequences from other insects (Table S2 ). Evolutionary history was inferred by using the maximum likelihood method based on the JTT matrix-based model (Jones et al 1992 ).…”

“…The desaturase-like SexiDes5 (GenBank accession number: KU755471), SlitDes5 (GenBank accession number: XP_022827905.1), SexiDes7 (GenBank accession number: AFO38465.1) and SexiDes11 (GenBank accession number: AFO38464.1), previously described to show pheromone gland-biased expression (Zhang et al 2017 ), were amplified by PCR on a Veriti Thermo Cycler with specific gene primers (Table S1 ) under the following conditions: 95 °C for 5 min, 35 cycles of 95 °C for 30 s, 55 °C for 30 s, 72 °C for 40 s, followed by a final extension for 10 min at 72 °C. The reactions were performed in a total volume of 50 μl, containing 25 μl of Maxima polymerase master mix (Thermo Scientific™), 2.5 μl for each primer (10 μM) (Table S1 ), 1 μl of sample cDNA (15 ng/μl), and 19 μl of sterilized H 2 O.…”

Identification of putative Type-I sex pheromone biosynthesis-related genes expressed in the female pheromone gland of Streltzoviella insularis

“…For instance, Δ9-desaturases have been divided into two groups: one with a substrate chain length preference of C16 >C18 (NPVE motif), and the other with a substrate chain length preference of C18 >C16 (KPSE motif) [22]. Subsequently, the unsaturated fatty acid is subjected to chain-shortening by β-oxidation, generating sex pheromone precursors of specific chain length [23], and the carbonyl carbon is modified to form an oxygenated functional group, such as an aldehyde, alcohol, or acetate ester, and these modifications involve some key biosynthesis enzymes; fatty acyl-CoA reductase (FAR) converts these acyl chains into fatty alcohols that act as actual sex pheromone components in various moths [24][25][26], but most fatty alcohols are either oxidized into the corresponding aldehyde by dehydrogenases [27][28] or esterified to form acetate esters by acetyltransferase (ATF) [29][30][31], resulting in the final functional groups.…”