Abstract：
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 (Dmg) was higher in flowering than vegetative plants. In vegetative plants, Dmg 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.
摘要：
茄科植物,比如茄子，产生类固醇糖苷（SGs）。叶SG轮廓在S.dulcamara个体之间有所不同，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,如果SG化学多样性在器官之间和个体发育中如何变化，这与SG代谢基因表达的关系尚不清楚。在器官和个体发育中，选择具有饱和（S）和不饱和（U）SG叶化学型的S.dulcamara植物并无性繁殖。根,从植物和开花植物收获茎和叶。使用非靶向LC-MS分析提取物。使用RT-qPCRs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，S.dulcamara的SG化学多样性在器官之间和个体发育中有所不同；开花中的SG丰富度（Dmg）高于营养植物。在营养植物中，叶子的Dmg高于根。在U型叶片中缺乏SdGAME25表达，虽然容易在根和茎中表达，表明SdGAME25在营养植物和开花植物的叶片化学型分化中的关键作用。通过充当个体发育依赖性化学型开关，SdGAME25的差分调节允许SGs的自适应分配，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，而不是他们的存在或不存在，解释了观察到的器官之间和整个个体发育中SG化学多样性的化学型变异。
