Transcriptome Characterization Analysis of Bactrocera minax and New Insights into Its Pupal Diapause Development with Gene Expression Analysis

Abstract

Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal diapause duration of this fly is a major bottleneck for artificial rearing and underlying mechanisms remain unknown. Genetic information on B. minax transcriptome and gene expression profiles are needed to understand its pupal diapause. High-throughput RNA-seq technology was used to characterize the B. minax transcriptome and to identify differentially expressed genes during pupal diapause development. A total number of 52,519,948 reads were generated and assembled into 47,217 unigenes. 26,843 unigenes matched to proteins in the NCBI database using the BLAST search. Four digital gene expression (DGE) libraries were constructed for pupae at early diapause, late diapause, post-diapause and diapause terminated developmental status. 4,355 unigenes showing the differences expressed across four libraries revealed major shifts in cellular functions of cell proliferation, protein processing and export, metabolism and stress response in pupal diapause. When diapause was terminated by 20-hydroxyecdysone (20E), many genes involved in ribosome and metabolism were differentially expressed which may mediate diapause transition. The gene sets involved in protein and energy metabolisms varied throughout early-, late- and post-diapause. A total of 15 genes were selected to verify the DGE results through quantitative real-time PCR (qRT-PCR); qRT-PCR expression levels strongly correlated with the DGE data. The results provided the extensive sequence resources available for B. minax and increased our knowledge on its pupal diapause development and they shed new light on the possible mechanisms involved in pupal diapause in this species.

Pupal diapause termination in Bactrocera minax: an insight on 20-hydroxyecdysone induced phenotypic and genotypic expressions

“…Although pupal diapause intensity is gradually decreased with the pupal development22, our results indicate that the diapause intensity could be different in different individuals. As a result, only those pupae that have lower diapause intensities could successfully emerge in January in the control group.…”

Environmental history impacts gene expression during diapause development in the alfalfa leafcutting bee,Megachile rotundata

“…Global gene expression techniques have greatly expanded our ability to understand the molecular regulation of diapause (Emerson et al, 2010;Ragland et al, 2010Ragland et al, , 2011Poelchau et al, 2011Poelchau et al, , 2013aGong et al, 2013;Dong et al, 2014;Huang et al, 2015;Qi et al, 2015;Yocum et al, 2015;Hao et al, 2016;Kang et al, 2016;Meyers et al, 2016;Koštál et al, 2017). Observed similarities in specific gene expression patterns between species has led a number of research teams to propose the existence of a conserved 'diapause genetic toolkit' (Ragland et al, 2010;Poelchau et al, 2013a;Huestis and Lehmann, 2014;Amsalem et al, 2015;Yocum et al, 2015;Ragland and Keep, 2017).…”

Insight into the possible mechanism of the summer diapause ofDelia antiqua(Diptera: Anthomyiidae) through digital gene expression analysis

“…Insect diapause is a dynamic process consisting of several successive phases (Kostal, 2006) and involves intricate molecular regulations controlled by an internal clock mechanism and hormones. Recent studies suggest that the molecular regulation of diapause processes show some important similarities across insect species, in spite of their different diapause states (Wolschin & Gadau, 2009;Lu & Xu, 2010;Poelchau et al, 2013;Dong et al, 2014). However, the mechanisms that induce, maintain and terminate diapause are poorly understood.…”