Many organisms have complex pigmentation patterns. However, how these patterns are formed remains largely unknown. In wild carrot (Daucus carota subsp. carota), which is also known as Queen Anne’s lace, one or several purple central flowers occur in white umbels. Here, we investigated the unique central flower pigmentation pattern in wild carrot umbels. Using wild and cultivated carrot (Daucus carota subsp. sativus L.) accessions, transcriptome analysis, protein interaction, stable transformation, and CRISPR/Cas9-mediated knockout, a anthocyanin-activating R2R3-myeloblastosis (MYB) gene, Purple Central Flower (DcPCF), was identified as the causal gene that triggers only central flowers to possess the purple phenotype. The expression of DcPCF was only detected in tiny central flowers. We propose that the transition from purple to nonpurple flowers in the center of the umbel occurred after three separate adverse events: insertion of transposons in the promoter region, premature termination of the coding sequence (caused by a C-T substitution in the open reading frame), and the emergence of unknown anthocyanin suppressors. These three events could have occurred either consecutively or independently. The intriguing purple central flower pattern and its underlying mechanism may provide evidence that it is a remnant of ancient conditions of the species, reflecting the original appearance of Umbelliferae (also called Apiaceae) when a single flower was present.

中文翻译：

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花青素激活基因是野胡萝卜紫色中央花色素沉着的基础


许多生物体具有复杂的色素沉着模式。然而，这些图案是如何形成的仍然很大程度上未知。野胡萝卜（Daucus carota subsp. carota）也被称为安妮女王花边，一朵或多朵紫色的中央花出现在白色的伞形花序中。在这里，我们研究了野胡萝卜伞形花序独特的中央花色素沉着模式。使用野生和栽培胡萝卜 (Daucus carota subsp. sativus L.) 种质、转录组分析、蛋白质相互作用、稳定转化和 CRISPR/Cas9 介导的敲除，花青素激活 R2R3-成髓细胞病 (MYB) 基因，紫色中央花 (DcPCF) ），被确定为仅触发中心花具有紫色表型的因果基因。仅在微小的中央花中检测到 DcPCF 的表达。我们认为伞形花序中心从紫色花到非紫色花的转变发生在三个独立的不良事件之后：在启动子区域插入转座子、编码序列过早终止（由开放阅读框中的 C-T 替换引起）、以及未知花青素抑制剂的出现。这三个事件可以连续发生，也可以独立发生。有趣的紫色中央花朵图案及其潜在机制可能提供证据，表明它是该物种古代条件的残余，反映了伞形科（也称为伞形科）单花存在时的原始外观。