Castells E, Sanchez-Martinez P
Departament de Farmacologia, Terapèutica i Toxicologia, Universitat Autònoma de Barcelona, Catalonia, Spain.
CREAF, Catalonia, Spain.
Plant Biol (Stuttg). 2025 Aug;27(5):761-772. doi: 10.1111/plb.13731. Epub 2024 Oct 25.
Plants synthesize a broad array of specialized chemical compounds that mediate their interactions with the surrounding environment. Some of this chemical diversity is functional and subject to natural selection, but the factors underlying chemical evolution at the intraspecific level remain largely unknown. Here, we combined chemical, environmental and genetic data to investigate the effect of aridity on the expression of chemotypes in the invasive shrub Senecio pterophorus. We studied the variation in pyrrolizidine alkaloids (PAs), a group of specialized metabolites widespread across the families Boraginaceae, Asteraceae and Fabaceae, from native populations spanning a cline of aridity and from three cross-continental introductions, under natural and common garden conditions. We examined whether the relationship between chemistry and aridity was compatible with a process of adaptive differentiation using a method that partitions the variance and covariance by controlling for the population neutral genetic structure. We found a consistent shift from retrorsine-like to seneciphylline-like compounds under increasing aridity in both natural and controlled conditions in coherence with the biosynthetic pathways. This pattern was independent of the neutral genetic structure and occurred along the environmental gradient in the native range and in a convergent manner in all nonnative regions, which suggests adaptive differentiation in response to aridity. Our findings show that the diversity of PAs in S. pterophorus has been partially shaped by aridity. Investigating how abiotic factors influence chemical evolution is key to elucidating the plant responses in future climate scenarios and the cascading effects on other trophic levels.
植物合成了种类繁多的特殊化合物，这些化合物介导了它们与周围环境的相互作用。这种化学多样性中的一些具有功能性并受到自然选择的影响，但种内水平化学进化的潜在因素在很大程度上仍然未知。在这里，我们结合化学、环境和遗传数据，研究干旱对入侵灌木翼齿千里光化学型表达的影响。我们研究了在自然和普通园圃条件下，来自跨越干旱梯度的本地种群以及三个跨大陆引入种群的吡咯里西啶生物碱（PAs）的变异情况，PAs是一类广泛存在于紫草科、菊科和豆科的特殊代谢产物。我们使用一种通过控制种群中性遗传结构来划分方差和协方差的方法，检验化学与干旱之间的关系是否与适应性分化过程相符。我们发现，在自然和受控条件下，随着干旱程度的增加，反式千里光碱样化合物向异叶千里光碱样化合物发生了一致的转变，这与生物合成途径一致。这种模式与中性遗传结构无关，并且在原生范围内沿着环境梯度出现，在所有非原生区域以趋同的方式出现，这表明是对干旱的适应性分化。我们的研究结果表明，翼齿千里光中PAs的多样性部分是由干旱塑造的。研究非生物因素如何影响化学进化是阐明植物在未来气候情景中的反应以及对其他营养级的级联效应的关键。
