Differential Gene Expression in Anthonomus grandis Midgut: Studying Digestion Physiology

Cotton crop is one of the largest segments of the Brazilian agribusiness and is severely attacked by the cotton boll weevil (CBW), Anthonomus grandis. Among potential targets for insect pests control, the midgut is strategically important due to its involvement in functions such as digestion, mechanical protection, and immune defense. Functional genomics data were obtained from RNA-Seq experiments using different insect midgut tissue samples at third instar larvae. After cDNA libraries construction and Illumina sequencing, a reference transcriptome with 62,284 contigs was obtained by the assembly of 3,7 x 10⁹ nucleotides, showing the best top-hit species distribution with Dendroctonus ponderosae (30.6%) and Tribolium castaneum (14.5%). In silico differential expression analysis comparison of the anterior and posterior midgut transcripts profile resulted in more than 1,000 differentially expressed genes. Several contigs corresponding to genes related to plant cell wall degrading enzymes (PCWDE) were found, and the expression profile of 14 identified candidate genes was validated by RT-qPCR. The understanding of the digestion physiology of the CBW could contribute to identifying key RNAi pathways elements to control this insect pest.