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）蝴蝶的翅型模式多样性，为探究自然遗传变异如何驱动复杂适应性表型的进化提供了独一无二的研究契机。此前的图位克隆（positional cloning）与候选基因研究，已鉴定出少量参与袖蝶翅型模式变异的调控基因与色素沉着基因，但对于这些基因相互作用以构建翅型模式的完整发育调控网络，目前仍所知甚少。本研究采用大规模转录组学方法，旨在鉴定参与袖蝶翅型模式发育与变异的基因调控网络。具体而言，我们使用了超过140张转录组微阵列（transcriptome microarrays）芯片，对红带袖蝶（Heliconius erato）不同发育阶段、不同翅型模式的解剖翅型结构中的基因表达情况进行了检测。

研究结果：本研究鉴定出多个具备颜色模式相关表达结构域的潜在早期预模式基因；同时还筛选得到51个与自然颜色模式变异显著相关的差异表达基因（differentially expressed genes）。其中，此前已被报道的颜色模式"开关基因"optix，是首个表现出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（pupal development）后期进行转录，且主要参与角质层形成（cuticle formation）或色素合成（pigment synthesis）过程，其中包含此前未被报道的与眼色素（ommochrome）沉着相关的转运蛋白基因。此外，我们观察到在非黑色素化翅型模式中，ebony与Dat1等黑色素抑制基因（melanin-repressing genes）呈现上调表达。

研究结论：本研究鉴定出多个参与蝴蝶翅型模式发育的全新基因，并为解析驱动颜色模式进化的基因变异所影响的基因数量与类型提供了新的认知视角。