Department of Chemistry and Biochemistry, The City College of New York, City University of New York (CUNY) and CUNY Institute for Macromolecular Assemblies, New York, NY, 10031, USA.
Department of Chemical Engineering, The City College of New York, CUNY, NY, 10031, USA.
Phytochemistry. 2021 Oct;190:112885. doi: 10.1016/j.phytochem.2021.112885. Epub 2021 Jul 31.
The growth and survival of terrestrial plants require control of their interactions with the environment, e.g., to defend against desiccation and microbial invasion. For major food crops, the protection conferred by the outer skins (periderm in potato) is essential to cultivation, storage, and marketing of the edible tubers and fruits. Potatoes are particularly vulnerable to bacterial infections due to their high content of water and susceptibility to mechanical wounding. Recently, both specific and conserved gene silencing (StNAC103-RNAi and StNAC103-RNAi-c, respectively) were found to increase the load of wax and aliphatic suberin depolymerization products in tuber periderm, implicating this NAC gene as a repressor of the wax and suberin biosynthetic pathways. However, an important gap in our understanding of StNAC103 silencing concerns the metabolites produced in periderm cells as antimicrobial defense agents and potential building blocks of the deposited suberin biopolymer. In the current work, we have expanded prior studies on StNAC103 silenced lines by conducting comprehensive parallel analyses to profile changes in chemical constituents and antibacterial activity. Compositional analysis of the intact suberized cell walls using solid-state C NMR (ssNMR) showed that NAC silencing produced an increase in the long-chain aliphatic groups deposited within the periderm cell walls. LC-MS of polar extracts revealed up-regulation of glycoalkaloids in both StNAC103-RNAi and StNAC103-RNAi-c native periderms but down-regulation of a phenolic amine in StNAC103-RNAi-c and a phenolic acid in StNAC103-RNAi native periderms. The nonpolar soluble metabolites identified using GC-MS included notably abundant long-chain alkane metabolites in both silenced samples. By coordinating the differentially accumulated soluble metabolites and the suberin depolymerization products with the ssNMR-based profiles for the periderm polymers, it was possible to obtain a holistic view of the chemical changes that result from StNAC103 gene silencing. Correspondingly, the chemical composition trends served as a backdrop to interpret trends in the chemical barrier defense function of native tuber periderms, which was found to be more robust for the nonpolar extracts.
陆生植物的生长和存活需要控制它们与环境的相互作用，例如，抵御干旱和微生物入侵。对于主要的粮食作物来说，外皮（马铃薯的周皮）提供的保护对于可食用块茎和果实的种植、储存和销售是必不可少的。由于马铃薯含水量高，容易受到机械损伤，因此特别容易受到细菌感染。最近，发现特异性和保守性基因沉默（分别为 StNAC103-RNAi 和 StNAC103-RNAi-c）均能增加块茎周皮中蜡质和脂肪族角质降解产物的负荷，这表明该 NAC 基因是蜡质和角质生物合成途径的抑制剂。然而，我们对 StNAC103 沉默的理解存在一个重要的空白，即周皮细胞中产生的代谢产物作为抗菌防御剂和潜在的沉积角质生物聚合物的构建块。在目前的工作中，我们通过进行全面的平行分析，对 StNAC103 沉默系进行了扩展研究，以分析化学成分和抗菌活性的变化。使用固态 C NMR（ssNMR）对完整的角质化细胞壁进行组成分析表明，NAC 沉默导致周皮细胞壁内沉积的长链脂肪族基团增加。极性提取物的 LC-MS 分析显示，StNAC103-RNAi 和 StNAC103-RNAi-c 天然周皮中的糖基生物碱上调，但 StNAC103-RNAi-c 中的酚胺和 StNAC103-RNAi 中的酚酸下调。使用 GC-MS 鉴定的非极性可溶代谢物包括在两个沉默样本中含量丰富的长链烷烃代谢物。通过将差异积累的可溶代谢物和角质降解产物与基于 ssNMR 的周皮聚合物图谱相结合，有可能全面了解 StNAC103 基因沉默所导致的化学变化。相应地，化学成分趋势为天然块茎周皮化学屏障防御功能的趋势提供了背景，非极性提取物的化学屏障防御功能更为稳健。
