De novo transcriptome sequencing of Cryptotermes domesticus and comparative analysis of gene expression in response to different wood species.

The drywood termite Cryptotermes domesticus is an important worldwide pest with limited genomic resources that causes substantial damage to dry timber and structural lumber. Here, we performed transcriptome sequencing for Cr. domesticus pseudergate using Illumina paired-end sequencing technology. A total of 108,745,470 clean reads were collected and assembled into 302,979 contigs with an average length of 648bp and an N50 length of 893bp. A total of 185,248 unigenes and 100,680 proteins were identified among the assembled contigs. Of these, there were 152,317 (50.27%) contigs with significant similarity to publicly available databases. To understand how the termites respond to phylogenetically diverse wood species, variations in gene expression were examined among pseudergates feeding on three wood species from different plant families, Casuarina equisetifolia (CE), Koompassia excelsa (KE) and Myristica sp. (MS). A total of 417 (118 up-regulated/299 down-regulated), 599 (148 up-regulated/451 down-regulated) and 505 (223 up-regulated/282 down-regulated) differentially expressed genes were detected in KE vs. CE, KE vs. MS and CE vs. MS, respectively. Digital gene expression analysis indicated that different wood species played an important role in the expression of termite genes, such as genes involved in carbohydrate metabolism, and proteins with catalytic activity and hydrolase activity. Additionally, the genes encoding cellulase were identified and analyzed. This study provides the first primary transcriptome of Cr. domesticus and lays a foundation for future functional genomics studies in the feeding responses.