Muñoz-Gómez Sarita, Suárez-Baron Harold, Alzate Juan F, González Favio, Pabón-Mora Natalia
Facultad de Ciencias Exactas y Naturales, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia.
Centro Nacional de Secuenciación Genómica - CNSG, Sede de Investigación Universitaria, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia.
Front Plant Sci. 2021 Apr 9;12:633227. doi: 10.3389/fpls.2021.633227. eCollection 2021.
Flavonoids, carotenoids, betalains, and chlorophylls are the plant pigments responsible for floral color. Anthocyanins, a class of flavonoids, are largely responsible for the red, purple, pink, and blue colors. genes belonging to subgroup 6 (SG6) are the upstream regulatory factors of the anthocyanin biosynthetic pathway. The canonical members of these genes in include , , , and . The Aristolochiaceae is an angiosperm lineage with diverse floral groundplans and perianth colors. exhibits a biseriate perianth with green sepals and yellow petals. All other genera have sepals only, with colors ranging from green (in ) to a plethora of yellow to red and purple mixtures. Here, we isolated and reconstructed the SG6 gene lineage evolution in angiosperms with sampling emphasis in Aristolochiaceae. We found numerous species-specific duplications of this gene lineage in core eudicots and local duplications in Aristolochiaceae for and . Expression of SG6 genes examined in different developmental stages and plant organs of four Aristolochiaceae species, largely overlaps with red and purple pigments, suggesting a role in anthocyanin and flavonoid synthesis and accumulation. A directed RNA-seq analysis corroborated our RT-PCR analyses, by showing that these structural enzymes activate during perianth development in and that the regulatory genes are expressed in correlation with color phenotype. Finally, the reconstruction of the flavonoid and anthocyanin metabolic pathways using predicted peptides from transcriptomic data show that all pivotal enzymes are present in the analyzed species. We conclude that the regulatory genes as well as the biosynthetic pathway are largely conserved across angiosperms. In addition, the Aristolochiaceae emerges as a remarkable group to study the genetic regulatory network for floral color, as their members exhibit an outstanding floral diversity with elaborate color patterns and the genetic complement for SG6 genes is simpler than in core eudicot model species.
黄酮类化合物、类胡萝卜素、甜菜色素和叶绿素是决定花朵颜色的植物色素。花青素作为黄酮类化合物的一类，在很大程度上决定了红色、紫色、粉色和蓝色。6亚组（SG6）的基因是花青素生物合成途径的上游调控因子。这些基因的典型成员包括 、 、 和 。马兜铃科是一个被子植物谱系，具有多样的花基本结构和花被颜色。 具有双列花被，萼片绿色，花瓣黄色。所有其他属只有萼片，颜色从绿色（如 中）到大量的黄色，再到红色和紫色的混合色。在这里，我们分离并重建了被子植物中SG6 基因谱系的进化，重点采样了马兜铃科。我们发现在核心真双子叶植物中该基因谱系有许多物种特异性重复，在马兜铃科中 和 存在局部重复。在四种马兜铃科植物的不同发育阶段和植物器官中检测到的SG6 基因表达，在很大程度上与红色和紫色色素重叠，表明其在花青素和黄酮类化合物的合成与积累中发挥作用。一项定向RNA测序分析证实了我们的RT-PCR分析结果，表明这些结构酶在 花被发育过程中被激活，并且调控基因的表达与颜色表型相关。最后，利用转录组数据预测的肽段重建黄酮类化合物和花青素代谢途径表明，所有关键酶都存在于被分析的物种中。我们得出结论，调控基因以及生物合成途径在被子植物中基本保守。此外，马兜铃科作为一个研究花朵颜色遗传调控网络的显著类群出现，因为其成员表现出显著的花多样性，具有复杂的颜色模式，并且SG6 基因的遗传互补比核心真双子叶植物模式物种更简单。
