Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI 48823, USA.
Department of Plant Biology, Michigan State University, 612 Wilson Road, East Lansing, MI 48823, USA.
Plant Physiol. 2024 Oct 1;196(2):1231-1253. doi: 10.1093/plphys/kiae279.
Solanaceae (nightshade family) species synthesize a remarkable array of clade- and tissue-specific specialized metabolites. Protective acylsugars, one such class of structurally diverse metabolites, are produced by ACYLSUGAR ACYLTRANSFERASE (ASAT) enzymes from sugars and acyl-coenzyme A esters. Published research has revealed trichome acylsugars composed of glucose and sucrose cores in species across the family. In addition, acylsugars have been analyzed across a small fraction of the >1,200 species in the phenotypically megadiverse Solanum genus, with a handful containing inositol and glycosylated inositol cores. The current study sampled several dozen species across subclades of Solanum to get a more detailed view of acylsugar chemodiversity. In depth characterization of acylsugars from the clade II species brinjal eggplant (Solanum melongena) led to the identification of eight unusual structures with inositol or inositol glycoside cores and hydroxyacyl chains. Liquid chromatography-mass spectrometry analysis of 31 additional species in the Solanum genus revealed striking acylsugar diversity, with some traits restricted to specific clades and species. Acylinositols and inositol-based acyldisaccharides were detected throughout much of the genus. In contrast, acylglucoses and acylsucroses were more restricted in distribution. Analysis of tissue-specific transcriptomes and interspecific acylsugar acetylation differences led to the identification of the brinjal eggplant ASAT 3-LIKE 1 (SmASAT3-L1; SMEL4.1_12g015780) enzyme. This enzyme is distinct from previously characterized acylsugar acetyltransferases, which are in the ASAT4 clade, and appears to be a functionally divergent ASAT3. This study provides a foundation for investigating the evolution and function of diverse Solanum acylsugar structures and harnessing this diversity in breeding and synthetic biology.
茄科（茄科）物种合成了一系列显著的类群和组织特异性的特殊代谢物。保护酰基糖，是一类结构多样的代谢物，由糖和酰基辅酶 A 酯的酰基糖基转移酶（ASAT）产生。已发表的研究揭示了在茄科植物中，毛状体酰基糖由葡萄糖和蔗糖核心组成。此外，酰基糖已经在表型多样化的茄属的一小部分超过 1200 种物种中进行了分析，其中少数含有肌醇和糖基化肌醇核心。本研究在茄属的几个亚属中采样了几十种物种，以更详细地了解酰基糖的化学多样性。对茄属 II 种茄子（茄子）酰基糖的深入表征导致鉴定出了八种具有肌醇或肌醇糖苷核心和羟基酰基链的不寻常结构。对茄属 31 种附加种的液相色谱-质谱分析显示，酰基糖具有惊人的多样性，有些特征局限于特定的类群和物种。酰肌醇和基于肌醇的酰基二糖在该属的大部分地区都有发现。相反，酰基葡萄糖和酰基蔗糖的分布更为局限。组织特异性转录组分析和种间酰基糖乙酰化差异分析导致鉴定出茄子茄子 ASAT3-LIKE 1（SmASAT3-L1；SMEL4.1_12g015780）酶。这种酶与以前表征的酰基糖乙酰转移酶不同，以前的酰基糖乙酰转移酶属于 ASAT4 分支，而这种酶似乎是一种功能上不同的 ASAT3。本研究为研究不同茄属酰基糖结构的进化和功能以及在育种和合成生物学中利用这种多样性提供了基础。
