Data from: Transcriptome analysis reveals novel patterning and pigmentation genes underlying Heliconius butterfly wing pattern variation

BACKGROUND: Heliconius butterfly wing pattern diversity offers a unique opportunity to investigate how natural genetic variation can drive the evolution of complex adaptive phenotypes. Positional cloning and candidate gene studies have identified a handful of regulatory and pigmentation genes implicated in Heliconius wing pattern variation, but little is known about the greater developmental networks within which these genes interact to pattern a wing. Here we took a large-scale transcriptomic approach to identify the network of genes involved in Heliconius wing pattern development and variation. This included applying over 140 transcriptome microarrays to assay gene expression in dissected wing pattern elements across a range of developmental stages and wing pattern morphs of Heliconius erato. RESULTS: We identified a number of putative early prepattern genes with color-pattern related expression domains. We also identified 51 genes differentially expressed in association with natural color pattern variation. Of these, the previously identified color pattern “switch gene” optix was recovered as the first transcript to show color-specific differential expression. Most differentially expressed genes were transcribed late in pupal development and have roles in cuticle formation or pigment synthesis. These include previously undescribed transporter genes associated with ommochrome pigmentation. Furthermore, we observed upregulation of melanin-repressing genes such as ebony and Dat1 in non-melanic patterns. CONCLUSIONS: This study identifies many new genes implicated in butterfly wing pattern development and provides a glimpse into the number and types of genes affected by variation in genes that drive color pattern evolution.

研究背景：袖蝶属（Heliconius）蝴蝶的翅型多样性为探究自然遗传变异如何推动复杂适应性表型的演化提供了独特契机。此前通过位置克隆与候选基因研究，已确定少量参与袖蝶翅型变异的调控基因及色素沉着相关基因，但对于这些基因协同塑造翅型所依托的更大规模发育调控网络，目前仍知之甚少。本研究采用大规模转录组学策略，旨在解析参与袖蝶翅型发育与变异的基因调控网络。我们使用超过140套转录组微阵列，对不同发育阶段、不同翅型变体的红带袖蝶（Heliconius erato）的解剖翅型元件开展基因表达谱检测。
研究结果：本研究鉴定出一批具备颜色模式相关表达结构域的潜在早期预模式基因。同时筛选得到51个与自然翅型变异显著相关的差异表达基因。其中，此前已报道的翅型“开关基因”optix成为首个被检出具有颜色特异性差异表达的转录本。绝大多数差异表达基因在蛹发育后期转录，且参与角质层形成或色素合成过程，包括此前未被报道的与眼黄素（ommochrome）色素沉着相关的转运蛋白基因。此外，我们观察到在非黑色素型翅型中，黑色素抑制基因如ebony与Dat1呈现上调表达。
研究结论：本研究鉴定出诸多参与蝴蝶翅型发育的新基因，并揭示了驱动翅型演化的基因变异所影响的基因类别与数量，为相关领域的后续研究提供了重要参考。