Genetic Basis of De Novo Appearance of Carotenoid Ornamentation in Bare Parts of Canaries
Genetic Basis of De Novo Appearance of Carotenoid Ornamentation in Bare Parts of Canaries
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DOI：
10.1093/molbev/msaa006
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发表时间：
2020-05-01
影响因子：
10.7
通讯作者：
Carneiro, Miguel
中科院分区：
文献类型：
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作者：
Gazda, Malgorzata Anna;Toomey, Matthew B.;Carneiro, Miguel
与野生和家养金丝雀（Serinus canaria）或Serinus属的三十几种雀中的任何一种不同，金丝雀的家养Urucum品种表现出明亮的红色喙和腿。这种新的特征提供了一个独特的机会，以了解鸟类裸部着色的机制。为了鉴定产生彩色表型的突变，我们对Urucum金丝雀的基因组进行了重新测序，并进行了一系列分析，以寻找基因组中基因型与表型的关联。我们发现了基因BCO 2（β-胡萝卜素加氧酶2，也称为BCDO 2）中的一个非同义突变，该酶参与全长类胡萝卜素切割和分解为短类胡萝卜素。蛋白质结构模型和体外功能测定表明，urucum突变废除类胡萝卜素切割活性的BCO 2。与预测的类胡萝卜素裂解活性的损失相一致，乌鲁科金丝雀往往有增加的水平，全长类胡萝卜素色素在票据组织和视网膜组织中的类胡萝卜素裂解产物（脱辅基类胡萝卜素）的水平降低相比，其他品种的金丝雀。我们推测，类胡萝卜素为基础的裸部分着色可能很容易获得，修改，或通过简单的开关在酶活性或调节的BCO 2和这个基因可能是一个重要的介体在鸟类之间的裸部分着色的进化。
Unlike wild and domestic canaries (Serinus canaria), or any of the three dozen species of finches in genus Serinus, the domestic urucum breed of canaries exhibits bright red bills and legs. This novel trait offers a unique opportunity to understand the mechanisms of bare-part coloration in birds. To identify the mutation producing the colorful phenotype, we resequenced the genome of urucum canaries and performed a range of analyses to search for genotype-to-phenotype associations across the genome. We identified a nonsynonymous mutation in the gene BCO2 (beta-carotene oxygenase 2, also known as BCDO2), an enzyme involved in the cleavage and breakdown of full-length carotenoids into short apocarotenoids. Protein structural models and in vitro functional assays indicate that the urucum mutation abrogates the carotenoid-cleavage activity of BCO2. Consistent with the predicted loss of carotenoid-cleavage activity, urucum canaries tended to have increased levels of full-length carotenoid pigments in bill tissue and reduced levels of carotenoid-cleavage products (apocarotenoids) in retinal tissue compared with other breeds of canaries. We hypothesize that carotenoid-based bare-part coloration might be readily gained, modified, or lost through simple switches in the enzymatic activity or regulation of BCO2 and this gene may be an important mediator in the evolution of bare-part coloration among bird species.