Anaia R A, Chiocchio I, Sontowski R, Swinkels B, Vergara F, van Dam N M
Molecular Interaction Ecology, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
Institute of Biodiversity, Friedrich Schiller University, Jena, Germany.
Plant Biol (Stuttg). 2025 Aug;27(5):651-668. doi: 10.1111/plb.13704. Epub 2024 Aug 16.
Solanaceous plants, such as Solanum dulcamara, produce steroidal glycosides (SGs). Leaf SG profiles vary among S. dulcamara individuals, leading to distinct phytochemical phenotypes ('chemotypes') and intraspecific phytochemical diversity ('chemodiversity'). However, if and how SG chemodiversity varies among organs and across ontogeny, and how this relates to SG metabolism gene expression is unknown. Among organs and across ontogeny, S. dulcamara plants with saturated (S) and unsaturated (U) SG leaf chemotypes were selected and clonally propagated. Roots, stems and leaves were harvested from vegetative and flowering plants. Extracts were analysed using untargeted LC-MS. Expression of candidate genes in SG metabolism (SdGAME9, SdGAME4, SdGAME25, SdS5αR2 and SdDPS) was analysed using RT-qPCRs. Our analyses showed that SG chemodiversity varies among organs and across ontogeny in S. dulcamara; SG richness (D) was higher in flowering than vegetative plants. In vegetative plants, D was higher for leaves than for roots. Lack of SdGAME25 expression in U-chemotype leaves, while readily expressed in roots and stems, suggests a pivotal role for SdGAME25 in differentiation of leaf chemotypes in vegetative and flowering plants. By acting as an ontogeny-dependent chemotypic switch, differential regulation of SdGAME25 enables adaptive allocation of SGs, thereby increasing SG chemodiversity in leaves. This indicates that differential expression and/or regulation of glycoalkaloid metabolism genes, rather than their presence or absence, explains observed chemotypic variation in SG chemodiversity among organs and across ontogeny.
茄科植物，如欧白英（Solanum dulcamara），会产生甾体糖苷（SGs）。欧白英个体之间的叶片SG谱存在差异，导致不同的植物化学表型（“化学型”）和种内植物化学多样性（“化学多样性”）。然而，SG化学多样性在不同器官间以及个体发育过程中是否存在差异，以及这与SG代谢基因表达有何关系尚不清楚。在不同器官间以及个体发育过程中，选择了具有饱和（S）和不饱和（U）SG叶片化学型的欧白英植株进行克隆繁殖。从营养期和花期植株上采集根、茎和叶。提取物采用非靶向液相色谱-质谱联用（LC-MS）分析。使用逆转录定量聚合酶链反应（RT-qPCR）分析SG代谢中候选基因（SdGAME9、SdGAME4、SdGAME25、SdS5αR2和SdDPS）的表达。我们的分析表明，欧白英的SG化学多样性在不同器官间以及个体发育过程中存在差异；开花期植株的SG丰富度（D）高于营养期植株。在营养期植株中，叶片的D值高于根。U化学型叶片中缺乏SdGAME25表达，而在根和茎中易于表达，这表明SdGAME25在营养期和花期植株叶片化学型分化中起关键作用。通过作为个体发育依赖的化学型开关，SdGAME25的差异调节能够实现SG的适应性分配，从而增加叶片中的SG化学多样性。这表明糖生物碱代谢基因的差异表达和/或调节，而非其存在与否，解释了在不同器官间以及个体发育过程中观察到的SG化学多样性的化学型变异。
