植物褪黑素及其抗逆性研究

褪黑素(N-乙酰-5-甲氧基色胺)是脊椎动物的松果体产生的吲哚类激素,主要参与动物昼夜节律调节.现已证实褪黑素在高等植物中也普遍存在,但对其功能的研究还不甚深入.目前,植物中褪黑素的可能功能包括清除自由基、调节光周期、参与生长调节等.本文简述了植物中褪黑素的研究概况、含量及其合成途径,重点综述了其在提高植物抗逆性方面的功能,并对其研究前景进行展望.     

植物褪黑素研究进展

褪黑素最初是在动物中发现的一种吲哚类小分子,具有昼夜节律调节、清除自由基等多种生理功能,还具有改善睡眠的保健作用。后来在植物中也检测到了褪黑素,这表明植物也能合成褪黑素。随着对植物褪黑素的深入研究,发现褪黑素在调控植物生长发育、耐受干旱、高温、低温、高盐、重金属等非生物胁迫、抵御细菌和真菌病害方面具有重要作用。从植物褪黑素合成途径、生长发育调控和胁迫应答反应方面的研究进展进行了综述,以期为植物褪黑素研究提供参考。     

褪黑素与植物抗逆性研究进展

褪黑素广泛存在于植物体内,对植物生长和发育方面有着重要的作用。其中,最为人们关注的是褪黑素在植物抵御干旱、高盐、极端温度和氧化胁迫等不良影响中所发挥的重要功能。随着人们对褪黑素研究的深入,褪黑素在植物体中发挥的作用和功能也更加明确,国内外在褪黑素与植物抗逆性关系的研究也取得了丰硕的成果。主要从植物体中褪黑素的合成途径、褪黑素在植物抗性反应中的作用以及内源褪黑素含量与逆境等方面进行了综述,并提出今后的研究方向。可以归纳为:植物体内褪黑素的合成机制与动物体内相似,但是确切的生物合成途径和具体的合成位点尚未明确;外源褪黑素处理能够增强植物抵御逆境的能力;逆境胁迫能够促进植物自身合成褪黑素,过表达褪黑素合成相关基因能够增加植物体内褪黑素的含量。     

植物中褪黑素的研究进展

植物褪黑素自20世纪90年代被发现以来,初期的研究多为测定方法,而后褪黑素生理功能的研究成为热点。植物中褪黑素含量的测定方法有放射免疫测定(RIA)、高效液相色谱(HPLC)、气相色谱(GC)、高效液相色谱-质谱(HPLC-MS)和气相色谱-质谱(GC-MS)等,而高效液相色谱与荧光检测器(HPLC-FD)和电化学检测器(HPLC-EC)联用是植物中褪黑素定量研究的较常用方法。褪黑素含量因植物种类、器官不同而异,并以繁殖器官种子和花中较高。褪黑素在植物中具有调节光周期、促进植物种子萌发及生根、提高植物抵御外界环境压力如重金属、紫外辐射、温度变化等功能,而这些生理功能的作用机制、合成位点等尚待进一步研究。该文对国内外近年来有关褪黑素在植物中的检测方法、生物合成途径及生理功能等几个方面的研究进展进行综述,并提出今后的研究方向。     

盐胁迫盐芥和拟南芥褪黑素含量及合成相关基因表达模式分析

盐生植物盐芥（Eutrema salsugineum）耐盐适应性强且具备模式植物特征,是研究植物逆境适应机理的理想材料。作为一种多功能的激素信号分子,褪黑素在盐芥耐盐性中的作用仍不清楚。本研究以盐芥为主要材料,以拟南芥做对比,主要通过褪黑素酶联免疫以及实时荧光定量PCR分析,比较了二者在不同组织中褪黑素的积累和在响应盐胁迫过程中褪黑素合成、相关基因的表达模式以及外源褪黑素处理对其盐应答表型的影响。结果显示,两种植物的褪黑素合成均在幼叶中最高,盐芥本底褪黑素合成水平显著高于拟南芥,且盐胁迫诱导了两种植物中的褪黑素含量,但不同于盐芥,拟南芥在处理7 d后褪黑素合成明显下降。通过序列比对发现在不同植物中,盐芥和拟南芥褪黑素合成相关基因的亲缘关系较近。盐应答表达分析显示,盐芥SNAT1、ASMT和COMT在盐处理3 d表达上调,而拟南芥中的相关基因在处理1 d和3 d后受盐诱导,7 d后拟南芥中表达下降而盐芥中则无明显变化,表明两种植物相关基因响应盐信号的表达变化存在差异。此外,外源褪黑素处理明显缓解了两种植物在盐逆境下的胁迫表型。综上,褪黑素有效贡献于盐芥抗盐性,参与调节盐芥和拟南芥的耐盐适...     

褪黑素参与植物抗逆功能研究进展

褪黑素(N-乙酰基-5-甲氧基色胺)是一种生命必需的小分子吲哚胺类物质,广泛存在于动植物体内,对动植物的生长发育起至关重要的作用。随着植物褪黑素研究的逐渐深入,褪黑素在植物体内的合成途径及作用也更加明确。研究表明,褪黑素在提高植物抵抗非生物和生物胁迫能力等方面具有调控作用。该文对近年来有关植物褪黑素参与非生物和生物胁迫的研究进展进行总结,旨在为阐明褪黑素影响植物抵御逆境胁迫的调控机理提供参考。     

褪黑素对玉米幼苗根系发育和抗旱性的影响

褪黑素是一种在生物体内广泛存在的吲哚胺类化合物,参与植物的多种生理和生化过程.近年来研究认为褪黑素可以不同程度地增强植物的抗逆性,但对其作用机理仍知之甚少.通过两种褪黑素的施用方法,详细研究了褪黑素对于玉米根系发育和抗旱性的影响.首先,采用水培根灌褪黑素的方法对玉米幼苗的根系和生长状况进行分析,结果表明施加褪黑素显著提...     

植物体内一氧化氮合成途径研究进展

一氧化氮(NO)作为一种气体信号分子,在植物生理过程中发挥重要作用,它参与调节植物的生长、发育及对外界环境的应激反应.植物体内主要通过酶催化途径和非酶催化途径合成NO.酶催化途径合成NO的主要酶包括一氧化氮合酶(nitric oxide synthase,NOS)和硝酸还原酶(nitrate reductase,NR),以及在某些植物的特定组织或器官或在特殊环境条件下存在的一氧化氮氧化还原酶(nitric oxide oxidoreductase,Ni-NOR)和黄嘌呤氧化还原酶(xanthine oxidoreductase,XOR).非酶催化合成途径主要是在酸性和还原剂存在条件下将亚硝酸盐还原成NO.该文主要结合研究方法,综述了植物体内NO合成途径的研究进展,为植物体内NO信号的作用机理的深入研究提供信息资料.     

植物GSKs:新发现的具有多种重要功能的基因家族

糖原合成酶激酶 (GSK 3)是一种高度保守的丝氨酸 苏氨酸蛋白激酶 ,在动物中参与诸如糖原合成、胰岛素调节、多种蛋白的转录激活和发育调控等许多生命活动的信号转导。在植物中也分离到了GSK 3 Like基因 ,在拟南芥中的GSKs家族分为四种。GSKs家族在植物中也扮演着重要的角色 ,现有的证据表明 ,植物GSKs可能参与植物的渗透胁迫应答、伤害应答以及油菜素内酯信号转导 ,调节花的发育等等一系列生命活动进程。讨论植物GSKs的发现及其功能研究的最新进展。     

褪黑素调节卵巢功能及相关机制的研究进展

褪黑素是一种神经内分泌激素,在动物体内主要由松果体合成和分泌,具有调节昼夜节律的重要作用,包括卵巢生物钟系统。褪黑素在外周组织器官如女性生殖器官卵巢中也发挥重要生理作用。女性生殖过程中,卵泡不断产生并累积活性氧,进而造成组织细胞损伤。褪黑素可通过受体依赖或者受体非依赖的机制参与卵巢功能调节。最近研究发现,褪黑素还可通过调节细胞自噬机制发挥效应。该文就褪黑素对卵巢的保护作用及其相关机制的研究进展进行综述。     

Melatonin: A master regulator of plant development and stress responses

Melatonin is a pleiotropic molecule with multiple functions in plants. Since the discovery of melatonin in plants, numerous studies have provided insight into the biosynthesis, catabolism, and physiological and biochemical functions of this important molecule. Here, we describe the biosynthesis of melatonin from tryptophan, as well as its various degradation pathways in plants. The identification of a putative melatonin receptor in plants has led to the hypothesis that melatonin is a hormone involved in regulating plant growth,aerial organ development, root morphology, and the floral transition. The universal antioxidant activity of melatonin and its role in preserving chlorophyll might explain its anti-senescence capacity in aging leaves. An impressive amount of research has focused on the role of melatonin in modulating postharvest fruit ripening by regulating the expression of ethylene-related genes.Recent evidence also indicated that melatonin functions in the plant's response to biotic stress,cooperating with other phytohormones and wellknown molecules such as reactive oxygen species and nitric oxide. Finally, great progress has been made towards understanding how melatonin alleviates the effects of various abiotic stresses, including salt, drought, extreme temperature, and heavy metal stress. Given its diverse roles, we propose that melatonin is a master regulator in plants.     

The Physiological Function of Melatonin in Plants

Melatonin (N-acetyl-5-methoxytryptamine), a well-known animal hormone, was discovered in plants in 1995 but very little research into it has been carried out since. It is present in different parts of all the plant species studied, including leaves, stems, roots, fruits and seeds. This brief review will attempt to provide an overview of melatonin (its discovery, presence and functions in different organisms, biosynthetic route, etc.) and to compile a practically complete bibliography on this compound in plants. The common biosynthetic pathways shared by the auxin, indole-3-acetic, and melatonin suggest a possible coordinated regulation in plants. More specifically, our knowledge to date of the role of melatonin in the vegetative and reproductive physiology of plants is presented in detail. The most interesting aspects for future physiological studies are presented.Key Words: antioxidant, auxin, flowering, growth, IAA, melatonin, plant hormone, reproductive development, rooting, vegetative developmentMelatonin (N-acetyl-5-methoxytryptamine), an “old friend” and well known as an animal hormone but “new” to plant biology is arousing great interest due to its broad distribution in the biological kingdom and the recent data on its possible physiological role in plants. Many studies on melatonin, as a phytochemical compound with potentially interesting health-related properties, have recently appeared, but no more than 15–20 papers with a plant physiological focus have been published since 1995. Besides mentioning the most interesting data on melatonin related with plants, this review will hopefully trigger more studies into this molecule to deepen our understanding of the different physiological roles that it might play in plants. We shall briefly look at the well-known function of melatonin in vertebrates, its discovery in plants and other organisms, and its presence in plants as a possible medicinal phytochemical. The joint biosynthetic pathways of melatonin and the auxin indole-3-acetic acid (IAA) will be described. Thus, we reveal the new and emerging field of melatonin studies in plants, the limited physiological data available and its possible role in plants.     

Regulation of the biosynthesis of plant hormones by cytochrome P450s

 Cytochrome P450 monooxygenases are a large group of heme-containing enzymes, most of which catalyze hydroxylation reactions. Since the discovery of cytochrome P450 in plants, more than 500 forms have been found, and they appear to be involved in the biosynthetic pathways of a large variety of primary and secondary metabolites. In particular, cytochrome P450s are involved in the biosynthesis of plant hormones, and play important roles in the regulation of plant growth and development. Recent genetic and functional analyses of cytochrome P450s in plants have significantly improved our understanding of not only the biosynthetic pathways themselves, but also of plant development from the perspective of hormonal control of morphogenesis. This review summarizes the present status of research on cytochrome P450s' roles in regulating the biosynthesis of plant hormones. Received: January 30, 2002 / Accepted: March 4, 2002     

Rhythm and soul in the avian pineal

The avian pineal gland, like that of mammals, displays a striking circadian rhythm in the synthesis and release of the hormone melatonin. However, the pineal gland plays a more prominent role in avian circadian organization and differs from that in mammals in several ways. One important difference is that the pineal gland in birds is relatively autonomous. In addition to making melatonin, the avian pineal contains photoreceptors and a circadian clock (thus, an entire circadian system) within itself. Furthermore, avian pineals retain their circadian properties in organ or dispersed cell culture, making biochemical components of regulatory pathways accessible. Avian pinealocytes are directly photosensitive, and novel candidates for the unidentified photopigments involved in the regulation of clock function and melatonin production, including melanopsin, pinopsin, iodopsin, and the cryptochromes, are being evaluated. Transduction pathways and second messengers that may be involved in acute and entraining effects, including cyclic nucleotides, calcium fluxes, and protein kinases, have been, and continue to be, examined. Moreover, several clock genes similar to those found in Drosophila and mouse are expressed, and their dynamics and interactions are being studied. Finally, the bases for acute and clock regulation of the key enzyme in melatonin synthesis, arylalkylamine N-acetyltransferase (AA-NAT), are described. The ability to study entrainment, the oscillator itself, and a physiological output in the same tissue at the same time makes the avian pineal gland an excellent model to study the bases and regulation of circadian rhythms.     

植物蛋白质亚细胞定位相关研究概述

蛋白质在植物细胞内的定位是了解蛋白质功能、 基因调控和蛋白质-蛋白质相互作用的关键.近年来随着各种蛋白质亚细胞定位方法的快速发展和技术的不断提升,蛋白质亚细胞定位实现了高通量、活体动态研究.本文总结了植物蛋白质亚细胞定位的常用技术,以及常用细胞器特异性标记的研究进展,并对此领域研究的发展前景做出了展望.     

植物多胺代谢途径研究进展

多胺是一类小分子生物活性物质,广泛存在于生物体内,与植物的生长发育、衰老及抗逆性都有着密切的联系。目前,在植物中的多胺合成途径已经基本揭示,其生理作用在分子水平上逐步得到阐明。对多胺合成突变体和各种转基因植物的研究也使得人们更深入地了解了多胺以及其合成代谢相关酶在植物生长发育等生理过程中的重要作用。以下概述了植物多胺代谢途径,重点综述了代谢途径中各基因的功能及遗传操作的最新进展,并对将来的研究方向尤其是相关基因在植物抗逆境 (包括生物和非生物逆境) 基因工程方面的应用作了讨论。