木栓质的结构组分、生物合成及其功能的研究进展

Progress on the structural components,biosynthesis and functions of suberin

木栓质是一种主要由含氧脂肪酸和芳香族化合物组成的疏水性生物聚合物.木栓质聚合物的合成起始于多种C16~C24链长度的脂肪酸,通过脂肪酸伸长和氧化还原过程,形成木栓质单体,经过内质网和质膜的运输,在细胞壁内侧沉积形成木栓层.木栓质主要沉积在根部的内皮层和周皮内,通过形成重要的机械屏障,控制根部水分和营养物质的运输,防止病原体的入侵和有毒气体的扩散等.木栓质的沉积可以帮助植物抵御各种胁迫,提高根系的保水能力,对植物适应复杂多样的外界环境从而保证其正常的生长发育等具有重要作用.本文系统综述了木栓质的沉积定位、化学成分分析与检测、生物合成及其调控的相关动态,重点总结了木栓质的生物功能,可为木栓质的深层次研究和开发应用提供重要的理论基础.

Through the long process of evolution,plants have dealt with complex and diverse external environmental conditions not only by regulating their physiological metabolism but also by adapting in structural ways.One of these structures is the hydrophobic barrier located on the inner side of the cell wall,which is made of suberin.Suberin is an oxygenated fatty acid and an aromatic compound found in the lipophilic biopolymer.It is heavily deposited on the aboveground and underground tissues of plants.In particular,the deposition of suberin is limited by tissue type and induced by various abiotic and biological stresses.During the primary growth stage of root endodermis,suberin mainly accumulates on its inner surface.During the secondary growth of mature tissues,suberin is usually present in the periderm,including wound periderm and other marginal tissues.In addition to the formation during the normal development of plants,the biosynthesis of suberin may also be stimulated under such environmental stresses as injury,pathogen invasion,and low temperature.Suberin is a polymer consisting of aliphatics(fatty acid derivatives),phenolics,and glycerol.The aliphatic parts of suberin mainly includeω-hydroxy fatty acids,α,ω-dicarboxylic acids,and primary fatty alcohols,often with a significant proportion of very-long-chain saturates.Phenolic components are mainly composed of hydroxycinnamic acids,usually ferulic acid,coumaric acid,and similar substances.The biosynthesis of suberin polymer begins with any of several fatty acids with a C16–C24 chain length.It forms suberin monomers through the process of fatty acid elongation and functionalization.Then suberin lamellae are deposited on the inner side of the cell wall after the transportation of the endoplasmic reticulum and plasma membrane.Suberin may control the transportation of water and nutrients in the roots and then prevent the invasion of pathogens and the diffusion of toxic gases as mechanical barriers after accumulating on the endodermis and exodermis of the root.Therefore,more and more attention and research have been devoted to suberin in recent years,especially into the mechanisms underlying monomer transportation and polymerization,the regulation of suberin biosynthesis,and its functions,which have greatly expanded our understanding of suberin.An in-depth study of suberin will help to better understand the stress resistance mechanism of plants and improve stress resistance,thus laying a good foundation for the development of crops in the future.In this review,we systematically used tissue localization,chemical composition analysis,and detection,biosynthesis,and regulation of suberin,with special emphasis on its biological functions.We believe this work provides valuable information for the in-depth research and utilization of suberin.