High-Throughput Sequencing to Reveal Genes Involved in Reproduction and Development in Bactrocera dorsalis (Diptera: Tephritidae)

BackgroundTephritid fruit flies in the genus Bactrocera are of major economic significance in agriculture causing considerable loss to the fruit and vegetable industry. Currently, there is no ideal control program. Molecular means is an effective method for pest control at present, but genomic or transcriptomic data for members of this genus remains limited. To facilitate molecular research into reproduction and development mechanisms, and finally effective control on these pests, an extensive transcriptome for the oriental fruit fly Bactrocera dorsalis was produced using the Roche 454-FLX platform. ResultsWe obtained over 350 million bases of cDNA derived from the whole body of B. dorsalis at different developmental stages. In a single run, 747,206 sequencing reads with a mean read length of 382 bp were obtained. These reads were assembled into 28,782 contigs and 169,966 singletons. The mean contig size was 750 bp and many nearly full-length transcripts were assembled. Additionally, we identified a great number of genes that are involved in reproduction and development as well as genes that represent nearly all major conserved metazoan signal transduction pathways, such as insulin signal transduction. Furthermore, transcriptome changes during development were analyzed. A total of 2,977 differentially expressed genes (DEGs) were detected between larvae and pupae libraries, while there were 1,621 DEGs between adults and larvae, and 2,002 between adults and pupae. These DEGs were functionally annotated with KEGG pathway annotation and 9 genes were validated by qRT-PCR. ConclusionOur data represent the extensive sequence resources available for B. dorsalis and provide for the first time access to the genetic architecture of reproduction and development as well as major signal transduction pathways in the Tephritid fruit fly pests, allowing us to elucidate the molecular mechanisms underlying courtship, ovipositing, development and detailed analyses of the signal transduction pathways.背景 实蝇科（Tephritidae）果实蝇属（Bactrocera）昆虫在农业领域具有重大经济意义，对果蔬产业造成可观损失。目前尚无理想的害虫防控方案。分子手段是当前害虫防控的有效途径，但该属物种的基因组或转录组数据仍较为匮乏。为推动该类害虫繁殖与发育机制的分子研究，最终实现其有效防控，本研究依托罗氏454-FLX（Roche 454-FLX）测序平台，构建了东方果实蝇（Bactrocera dorsalis）的大规模转录组。 结果 本研究从不同发育阶段的东方果实蝇整虫样本中获取了超过3.5亿碱基的互补脱氧核糖核酸（complementary DNA, cDNA）序列。单次测序共获得747,206条测序读段（sequencing reads），平均读长382 bp。经组装后得到28,782个重叠群（contig）与169,966个单例序列（singleton），重叠群平均长度为750 bp，且组装得到大量近乎全长的转录本。此外，本研究鉴定出大量参与繁殖与发育过程的基因，以及几乎覆盖后生动物所有主要保守信号转导通路的基因，例如胰岛素信号转导通路。进一步对发育过程中的转录组变化进行分析：幼虫与蛹文库间共检测到2,977个差异表达基因（differentially expressed genes, DEGs），成虫与幼虫文库间检测到1,621个DEGs，成虫与蛹文库间则检测到2,002个DEGs。所有差异表达基因均通过KEGG通路完成功能注释，并选取9个基因通过qRT-PCR进行了验证。 结论 本研究获得的序列资源为东方果实蝇提供了目前最为全面的序列数据，首次揭示了实蝇科害虫繁殖、发育的遗传架构以及主要信号转导通路，为阐明求偶、产卵及发育的分子机制，以及深入解析信号转导通路提供了重要研究基础。