Department of Ecology and Evolutionary Biology, University of Colorado, 1900 Pleasant Street 334 UCB, Boulder, CO 80309-0334, USA.
Proc Biol Sci. 2023 Jul 12;290(2002):20230275. doi: 10.1098/rspb.2023.0275. Epub 2023 Jul 5.
The structure and function of biochemical and developmental pathways determine the range of accessible phenotypes, which are the substrate for evolutionary change. Accordingly, we expect that observed phenotypic variation across species is strongly influenced by pathway structure, with different phenotypes arising due to changes in activity along pathway branches. Here, we use flower colour as a model to investigate how the structure of pigment pathways shapes the evolution of phenotypic diversity. We focus on the phenotypically diverse Petunieae clade in the nightshade family, which contains 180 species of and related genera, as a model to understand how flavonoid pathway gene expression maps onto pigment production. We use multivariate comparative methods to estimate co-expression relationships between pathway enzymes and transcriptional regulators, and then assess how expression of these genes relates to the major axes of variation in floral pigmentation. Our results indicate that coordinated shifts in gene expression predict transitions in both total anthocyanin levels and pigment type, which, in turn, incur trade-offs with the production of UV-absorbing flavonol compounds. These findings demonstrate that the intrinsic structure of the flavonoid pathway and its regulatory architecture underlies the accessibility of pigment phenotypes and shapes evolutionary outcomes for floral pigment production.
生物化学和发育途径的结构和功能决定了可获得的表型范围,而表型是进化变化的基础。因此,我们预计物种间观察到的表型变异强烈受到途径结构的影响,不同的表型是由于途径分支活性的变化而产生的。在这里,我们以花色为模型,研究色素途径的结构如何塑造表型多样性的进化。我们专注于茄科中表型多样化的矮牵牛族,该族包含 180 种和相关属,作为理解类黄酮途径基因表达如何映射到色素产生的模型。我们使用多元比较方法来估计途径酶和转录调节剂之间的共表达关系,然后评估这些基因的表达与花色色素变化的主要轴之间的关系。我们的结果表明,基因表达的协调变化可以预测总花青素水平和色素类型的转变,而这反过来又会与产生吸收紫外线的类黄酮化合物产生权衡。这些发现表明,类黄酮途径的内在结构及其调控结构是色素表型可及性的基础,并塑造了花色色素产生的进化结果。