Transcriptome Profiling of Two Male Reproductive Tissues of a Major Apple Pest, the Codling Moth Cydia pomonella

The codling moth Cydia pomonella is a world-wide pest infesting apple and other fruit trees. It has not been characterized at the genomic level. In this study, we sequenced de novo the first transcriptomes of male testis and accessory gland. Our aim was to identify and catalog expressed genes potentially involved in spermatogenesis as well as putative seminal fluid proteins (SFPs) sequences, which are essential for mating success and considered to play potential roles in sexual selection and speciation. Reads from 1/2 picotiter plate per sample were generated by 454 pyrosequencing and assembled into 44,108 non-redundant unigenes (contigs and singletons) for testis and 19,522 for accessory gland. Surprisingly, accessory glands have only about 1.8 % of transcripts in common with testis to which they are connected, while 15.1 % are splice variants. BLAST analysis (e-value < 10^-3) against non-redundant protein databases retrieved hits of only 35% of total unigenes for testis and 17% for accessory gland, with most hits and top hits both from the Monarch butterfly Danaus plexippus. Gene ontology analysis of both tissues revealed a broad class of biological properties such as reproduction, biological regulation/adhesion, developmental processes, response to stimulus, immune system process, and notably, viral replication. In testis, a large number of genes involved in spermatogenesis and copulation are identified, as well as several sex-specific isoforms of genes in the sex determination cascade. Over 300 putative SFPs were identified from accessory gland, with an additional small repertoire (13) from testis.