Departmento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Sevilla, 41012, España.
Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Sevilla, 41013, España.
BMC Plant Biol. 2024 Sep 30;24(1):905. doi: 10.1186/s12870-024-05481-y.
Polymorphisms are common in nature, but they are rarely shared among closely related species. Polymorphisms could originate through convergence, ancestral polymorphism, or introgression. Although shared neutral genomic variation across species is commonplace, few examples of shared functional traits exist. The blue-orange petal color polymorphisms in two closely related species, Lysimachia monelli and L. arvensis were investigated with UV-vis reflectance spectra, flavonoid biochemistry, and transcriptome comparisons followed by climate niche analysis.
Similar color morphs between species have nearly identical reflectance spectra, flavonoid biochemistry, and ABP gene expression patterns. Transcriptome comparisons reveal two orange-specific genes directly involved in both blue-orange color polymorphisms: DFR-2 specificity redirects flux from the malvidin to the pelargonidin while BZ1-2 stabilizes the pelargonidin with glucose, producing the orange pelargonidin 3-glucoside. Moreover, a reduction of F3'5'H expression in orange petals also favors pelargonidin production. The climate niches for each color morph are the same between the two species for three temperature characteristics but differ for four precipitation variables.
The similarities in reflectance spectra, biochemistry, and ABP genes suggest that a single shift from blue-to-orange shared by both lineages is the most plausible explanation. Our evidence suggests that this persistent flower color polymorphism may represent an ancestrally polymorphic trait that has transcended speciation, yet future analyses are necessary to confidently reject the alternative hypotheses.
多态性在自然界中很常见，但在亲缘关系密切的物种中很少共享。多态性可能起源于趋同进化、祖先多态性或基因渗入。尽管物种间存在共享的中性基因组变异，但共享的功能特征很少见。本研究通过紫外可见反射光谱、类黄酮生物化学和转录组比较，以及气候生态位分析，调查了两种亲缘关系密切的植物，如蔓长春花和铺地黍的蓝橙色花瓣颜色多态性。
相似的花色在物种间具有几乎相同的反射光谱、类黄酮生物化学和 ABP 基因表达模式。转录组比较揭示了两个橙色特异性基因直接参与了这两种蓝橙色颜色多态性：DFR-2 特异性将通量从矢车菊素重定向到天竺葵素，而 BZ1-2 用葡萄糖稳定天竺葵素，产生橙色天竺葵素 3-葡萄糖苷。此外，橙色花瓣中 F3'5'H 表达的减少也有利于天竺葵素的产生。两种花色形态的气候生态位在两个物种中对三个温度特征相同，但对四个降水变量不同。
反射光谱、生物化学和 ABP 基因的相似性表明，单一的蓝-橙颜色转变是最合理的解释。我们的证据表明，这种持久的花色多态性可能代表一个祖先多态性特征，已经超越了物种形成，但未来的分析仍然有必要来有把握地排除替代假说。
