植物角质膜的结构、组成和生物学功能研究进展

植物角质膜是覆盖在植物最外层的一类有机混合物的总称,它是植物抵抗外界环境刺激的最后一道屏障,在植物生长发育过程中起重要作用。该文总结了近几十年来国内外关于角质膜的研究进展,通过植物角质膜的形态结构、化学组成、生物学功能等几个方面对角质膜的研究状况做系统综述,探讨目前研究中存在的一些问题,展望角质膜研究前景,以期为从事角质膜相关领域的研究提供可借鉴的参考依据。     

植物角质膜及其渗透性与抗旱性研究进展

角质膜覆盖于陆生植物的地上部分,是植物与外部环境之间的第一道屏障,保护植物免遭各种生物和非生物胁迫。本文就植物角质膜的结构、成分、生物合成的途径及机理、渗透性及温度、湿度、活性剂对角质膜渗透性的影响,角质膜与植物抗旱性关系的研究进展做系统综述,并对植物角质膜研究中存在的问题进行了探讨。     

植物次生代谢及其与环境的关系

人类对植物次生代谢产物（天然产物）的早期研究源于它们的应用价值,近些年来人们越来越认识到植物次生代谢产物广泛的生物学效应,开始重新评价这些化合物在植物生命活动以及生态系统中可能扮演的角色。植物的次生代谢是植物在长期进化中与环境（生物的和非生物的）相互作用的结果,次生代谢产物在植物提高自身保护和生存竞争能力、协调与环境关系上充当着重要的角色。介绍了植物次生代谢及其产物的特点,概述了植物次生代谢与温度、水分、光照、养分、CO2浓度、UV-B辐射、环境污染等非生物环境以及与化学防御、化感作用、菌根共生、微生物病害的关系。研究植物次生代谢与环境的关系,可以从更深的层次发掘植物与环境的内在联系,为全面、深入认识植物与环境的相互关系提供新的研究途径,同时也有利于人类更有效、合理地利用植物的次生代谢产物。     

我国资源植物化学与天然产物化学基础研究的现状与发展

本文从生物活性成分的筛选与分离、植物次生代谢产物生物合成及其分子调控、环境因子对植物次生代谢产物合成和积累的影响、植物体内生菌与植物次生代谢产物的关系等方面介绍了我国资源植物化学与天然产物化学领域基础研究的现状与发展。     

虫害诱导植物合成防御性次生代谢产物的研究进展

昆虫对植物的取食活动可以激活植物的防御反应,诱导植物通过调控自身的代谢网络合成防御性次生代谢产物,抵御外界不良刺激。虫害诱导植物合成防御性次生代谢产物及其机制研究已成为近年来的研究热点之一。现对虫害诱导的植物防御性次生代谢产物、昆虫危害产生的各类激发子、植物对激发子的识别、虫害应答相关的信号转导通路及其对次生代谢物质积累的调控进行了综述,可为虫害诱导植物合成防御性次生代谢产物的机制研究提供参考,为植物虫害防治研究、植物次生代谢物质的生产和利用提供理论依据。     

药用植物次生代谢的生物学作用及生态环境因子的影响

药用植物的很多有效成分为植物的次生代谢产物,包括生物碱、萜类、酚类、甙类等。这些次生代谢产物在植物的生理调节、自身保护、生存竞争、协调与环境关系等生命活动的许多方面均起着重要作用。各种生态环境因素包括光、温度、土壤、空气以及生物因素均影响到药用植物的次生代谢过程。对药用植物次生代谢成分与生态环境因素的关系进行研究有利于揭示药用植物药用有效成分地域性差异的原因,可为药用植物的育种、栽培提供理论依据。     

次生代谢产物与植物抗病防御反应

次生代谢产物是由植物次生代谢产生的许多结构不同的小分子有机化合物,它们广泛参与植物的生长、发育、防御等生理过程。次生代谢产物在植物的抗病防御反应中发挥着重要作用,可以作为生化壁垒防御病原物侵染,还可以作为信号物质参与植物的抗病反应;在植物与病原物互作中,植物合成新的抗菌物质植保素,原有的抗菌物质也会增加。植物次生代谢产物的积累受到病原物、发育,环境等多种因素的调节。本文重点介绍次生代谢产物在植物抗病防御中的相关作用以及影响其合成的各种因素。     

植物萜类次生代谢及其调控

植物次生代谢在植物生长发育、环境适应、抵御病虫害等方面发挥着重要作用,这些天然产物组成地球上最丰富的有机化合物的宝库．萜类是植物代谢产物中种类最多的一类,具有重要的生理和生态功能,一些成分还有应用价值．近十几年来,人们在萜类化合物的分离、鉴定、应用、生物合成、相关基因与基因族、酶蛋白结构和功能、代谢调控以及代谢工程等各方面取得了重大进展．本文概述了植物萜类化合物代谢及其调控领域的研究进展与发展趋势．     

膜荚黄芪内生真菌次生代谢产物鉴定及抑菌活性

从膜荚黄芪(Astragalus membranaceus)叶中分离出一株内生真菌———瓶霉菌属(Phialophorasp.)。鉴定次生代谢产物中含有皂甙类、多糖类和黄酮类物质,并通过薄层层析证明内生真菌次生代谢产物的粗提物与黄芪植物水煎液的粗提物含有相同的成分。证明发酵液及菌丝体提取物对4种常见细菌具有不同程度的抑菌活性。     

bZIP转录因子调控植物次生代谢产物生物合成的研究进展

植物次生代谢产物是通过次生代谢产生的一类小分子有机化合物,是植物适应环境的表现,次生代谢产物也是重要药物和化工原料的来源。bZIP转录因子是普遍存在于真核生物中的一类多基因家族,可有效调控植物次生代谢产物的生物合成。本文概述了植物bZIP转录因子的结构和类型,重点阐述了bZIP转录因子调控萜类、黄酮类和生物碱等植物次生代谢产物生物合成的研究进展,并对研究前景进行了展望。深入探讨bZIP转录因子的调控机制,有助于利用基因工程技术优化植物次生代谢途径,提高次生代谢产物的含量,在新药创制、工农业生产等方面具有广泛的应用前景。     

植物角质层生物学特性及水分渗透性研究进展

植物角质层作为植物体与外界环境的第一道保护屏障, 其最主要的功能是防止植物体过度失水。揭示植物角质层的生物学功能及其原理将为现代农业的发展以及仿生材料的开发应用提供科学指导。该文综述了植物角质层的生物学特性及其与水分渗透性关系的研究进展, 并展望了角质层水分渗透研究的应用前景。     

Unraveling the complex network of cuticular structure and function

A hydrophobic cuticle is deposited at the outermost extracellular matrix of the epidermis in primary tissues of terrestrial plants. Besides forming a protective shield against the environment, the cuticle is potentially involved in several developmental processes during plant growth. A high degree of variation in cuticle composition and structure exists between different plant species and tissues. Lots of progress has been made recently in understanding the different steps of biosynthesis, transport, and deposition of cuticular components. However, the molecular mechanisms that underlie cuticular function remain largely elusive.     

CUTICULAR LIPIDS OF TERRESTRIAL PLANTS AND ARTHROPODS: A COMPARISON OF THEIR STRUCTURE, COMPOSITION, AND WATERPROOFING FUNCTION

1. Lipids deposited on the surface or embedded within the cuticle of terrestrial plants and arthropods are primarily responsible for the observed low rates of water loss through the cuticle. 2. These lipids are a mixture of long-chain compounds which include hydrocarbons (saturated, unsaturated, branched), wax esters, free fatty acids, alcohols, ketones, aldehydes, and cyclic compounds. 3. The cuticle of both plants and arthropods is a continuous, non-cellular multilayered membrane which overlies the epidermal cells. 4. In arthropods, horizontal division of the cuticle into layers is clearly visible. In plants, the layers comprising the cuticle are not sharply demarcated. 5. The substance responsible for the structural integrity of the plant cuticle (cutin) is composed of cross-esterified fatty acids; structural integrity in arthropod cuticle is provided by a chitin-protein complex. 6. Cuticular lipids are probably formed near the surface in both plants and arthropods; however, specific sites of synthesis are known for only a few species and little is known about their transport from these sites to the surface. The elaborate pore canal and wax canal system of arthropod cuticle is absent from plants. 7. The physical structure and arrangement of the lipid deposits on the cuticular surface that are so important in controlling water movement depend on both quantity and chemical composition, and are, in turn, specific to each species in relation to its environment. 8. Different lipid components are not equally efficient in reducing transpiration. Maximum waterproofing effectiveness is provided by long-chain, saturated, non-polar molecules containing few methyl branches. 9. Plants and arthropods can, within genetic constraints, alter the composition of their cuticular waxes to improve impermeability when conditions require increased water conservation. 10. None of the models proposed to explain the change in arthropod cuticular permeability which occurs at a species-specific temperature (‘transition temperature’) in many species is supported by the experimental data now available.     

Protecting against water loss: analysis of the barrier properties of plant cuticles

The cuticle is the major barrier against uncontrolled water loss from leaves, fruits and other primary parts of higher plants. More than 100 mean values for water permeabilities determined with isolated leaf and fruit cuticles from 61 plant species are compiled and discussed in relation to plant organ, natural habitat and morphology. The maximum barrier properties of plant cuticles exceed that of synthetic polymeric films of equal thickness. Cuticular water permeability is not correlated to the thickness of the cuticle or to wax coverage. Relationships between cuticular permeability, wax composition and physical properties of the cuticle are evaluated. Cuticular permeability to water increases on the average by a factor of 2 when leaf surface temperature is raised from 15 degrees C to 35 degrees C. Organic compounds of anthropogenic and biogenic origin may enhance cuticular permeability. The pathway taken by water across the cuticular transport barrier is reviewed. The conclusion from this discussion is that the bulk of water diffuses as single molecules across a lipophilic barrier while a minor fraction travels along polar pores. Open questions concerning the mechanistic understanding of the plant cuticular transport barrier and the role the plant cuticle plays in ensuring the survival and reproductive success of an individual plant are indicated.     

An ATP Binding Cassette Transporter Is Required for Cuticular Wax Deposition and Desiccation Tolerance in the Moss Physcomitrella patens

The plant cuticle is thought to be a critical evolutionary adaptation that allowed the first plants to colonize land, because of its key roles in regulating plant water status and providing protection from biotic and abiotic stresses. Much has been learned about cuticle composition and structure through genetic and biochemical studies of angiosperms, as well as underlying genetic pathways, but little is known about the cuticles of early diverging plant lineages. Here, we demonstrate that the moss Physcomitrella patens, an extant relative of the earliest terrestrial plants, has a cuticle that is analogous in both structure and chemical composition to those of angiosperms. To test whether the underlying cuticle biosynthetic pathways were also shared among distant plant lineages, we generated a genetic knockout of the moss ATP binding cassette subfamily G (ABCG) transporter Pp-ABCG7, a putative ortholog of Arabidopsis thaliana ABCG transporters involved in cuticle precursor trafficking. We show that this mutant is severely deficient in cuticular wax accumulation and has a reduced tolerance of desiccation stress compared with the wild type. This work provides evidence that the cuticle was an adaptive feature present in the first terrestrial plants and that the genes involved in their formation have been functionally conserved for over 450 million years.     

The presence of cutan limits the interpretation of cuticular chemistry and structure: Ficus elastica leaf as an example

Plant cuticles have been traditionally classified on the basis of their ultrastructure, with certain chemical composition assumptions. However, the nature of the plant cuticle may be misinterpreted in the prevailing model, which was established more than 150 years ago. Using the adaxial leaf cuticle of Ficus elastica, a study was conducted with the aim of analyzing cuticular ultrastructure, chemical composition and the potential relationship between structure and chemistry. Gradual chemical extractions and diverse analytical and microscopic techniques were performed on isolated leaf cuticles of two different stages of development (i.e. young and mature leaves). Evidence for the presence of cutan in F. elastica leaf cuticles has been gained after chemical treatments and tissue analysis by infrared spectroscopy and electron microscopy. Significant calcium, boron and silicon concentrations were also measured in the cuticle of this species. Such mineral elements which are often found in plant cell walls may play a structural role and their presence in isolated cuticles further supports the interpretation of the cuticle as the most external region of the epidermal cell wall. The complex and heterogeneous nature of the cuticle, and constraints associated with current analytical procedures may limit the chance for establishing a relationship between cuticle chemical composition and structure also in relation to organ ontogeny.     

植物角质层蜡质的化学组成研究综述

角质层是植物与外界的第一接触面,而角质层蜡质则是由位于角质层外的外层蜡质和深嵌在角质层中的内层蜡质两部分构成。植物角质层蜡质成分极其复杂,具有重要的生理功能。综述了有关植物角质层蜡质的化学组成信息,探讨了目前植物角质层蜡质化学成分研究中存在的一些问题,展望了角质层蜡质成分的研究前景。     

Embryonic cuticle establishment: The great (apoplastic) divide

The plant cuticle, a dynamic interface between plants and their environment, is formed by the secretion of hydrophobic lipids and waxes into the outer wall of aerial epidermal cells. Cuticle formation is such a ubiquitous feature of epidermal cells, and is of such fundamental importance for plant survival, that identifying and understanding specific developmental roles for this structure has been a major challenge for plant scientists. In recent work, we have tried to understand the functional relationships between a signaling feedback loop required for epidermal cell specification in developing plant embryos, and a seed specific signaling cascade, involving components localized both in the embryo and in the embryo surrounding endosperm, and necessary for embryo cuticle function. Analysis of the strongly synergistic genetic relationships between these 2 independent pathways, combined with mathematical simulations of the behavior of the signaling feedback loop, have allowed us to propose an important, and hitherto unsuspected, role for the embryonic cuticle as an apoplastic diffusion barrier, necessary for preventing the excessive diffusion of developmentally important signaling molecules away from developing embryo into surrounding tissues.     

The biophysical design of plant cuticles: an overview

The outer surfaces of epidermal cell walls are impregnated with an extracellular matrix called the cuticle. This composite matrix provides several functions at the interface level that enable plants to thrive in different habitats and withstand adverse environmental conditions. The lipid polymer cutin, which is the main constituent of the plant cuticle, has some unique biophysical properties resulting from its composition and structure. This review summarizes the progress made towards understanding the biophysical significance of this biopolymer with special focus on its structural, thermal, biomechanical, and hydric properties and relationships. The physiological relevance of such biophysical properties is discussed in light of existing knowledge on the plant cuticle.