摘要
There is increasing evidence shows that programmed cell death (PCD) can occur underphysiological, pathological or stress conditions in plants. The present review describes themorphological and biochemical characteristics, physiological functions, and the research significance ofplant PCD in detail as well as makes comparison betWeen these aspects with those in animals. Inaddition, this paper is also making exploration of the possible pathway for signal transduction, geneticregulation of plant PCD, origin and evolution of PCD and proposes a tactic for research on plant PCDalthough it is still in a preliminary stage.Compared to PCD in animals, PCD in plants under various conditions has revealed much greaterdifference in morphological and biochemical characteristics, which presents different essence far fromthe definition of apoptosis of animals. Nevertheless, no inflammation, specific fragmentation of DNAand rise of the activities of endonuclease and protease in plant PCD are still typical hallmarks fordistinguishing PCD from necrosis. On view of molecular level, as in animals, PCD in plants is alsoregulated by specific genes and involves signal transduction pathway with the involvement of a varietyof signal molecules.The physiological functions of plant PCD are similar to those in animals too. In the importantphysiological and pathological processes in plants, i.e., during reproduction, development, growth,senescenced disease-resistance, and stress-resistance against adverse circumstance conditions, PCDtakes on functions as important as proliferation throughout the whole life cycle of living organisms.Obviously, the research on PCD in plants is of vital importance that should not be ignored either intheory or in agricultural production.At present, the research on PCD in plants is focusing on collecting morphological and biochemicalevidences. But many molecules of initiation signal participating in plant PCD have been identified andseveral genes directly related to this process were isolated, which provide useful enlightenment forillustrating signal transduction pathway of PCD. Moreover, some conserved signal molecules andregulating genes were found in plant PCD, and caspase-like proteases have been detected in HR celldeath as well as in development-associated PCD. These data provide strong evidence at molecular levelfor conservation and the origin and evolution of PCD.1 The authors want to extend the sincerely thanks to Prof. Michele C. Heath (University of Toronto, Canada),Prof. Niroo Fukuda (University of Tokyo, Japan), Prof. Duran L. Nooden (University of Michigan, USA),Prof. Chris Lamb (Salk institute, California), Prof. Sarah Hake (Agricultural Research Service, USA), Prof.David L. Vaux (The Walter and Eliza Hall insititue of Medical Research, Post Office Royal MelbourneHospital, Australia), Associate Prof. Jeffrey L. Dangl (University of North Carolina, USA), Associate Prof.Eric Lain (The State University of New Jersey, USA), Dr. Maki Katsuhara (Okayama University, Japan),Prof. Sarah Hake (AgricultUral Research Service, USA), Dr. Peter P. Repetti (University of California,USA), Da Blazena Koukalova (Academy of Sciences of the Czech Republic, CZ), Dr. Iona Weir(Horticulture and Food Research Institute of New Zealand, New Zealand), Dr. Thorsten Jabs (Institute forBiology III, Germany), Dr. Hong Wang (University of California, USA) and Dr. Patrick Gallois (Universityof Perpignan, France) for their kind providing their personal latest data of their research concerned andoffering academic exchanges with us.This project is granted by the National Natural Science Foundation of China (No. 39870423) and by StateCommission of Education, Doctorate Spot Foundation.Author for correspondence. E-mail: ycsong@whu.edu.cn.Evidences in various aspects indicate that PCD origins from prokaryote, and various forms of PCD arefound along the phylogenic tree.Conclusion: A variety of endogenous and exogenous signals can break the homeostasis within plantbody and result in differentiation, proliferation, quiescence, or death of cell at length
近年来，越来越多的证据表明，植物细胞在生理、病理或逆境条件下可发生程序性死亡（ＰｒｏｇｒａｍｍｅｄＣｅｌｌＤｅａｔｈ，ＰＣＤ）。本文详细描述了植物ＰＣＤ的形态和生化特征、生理功能及其研究意义，并把这些方面与动物ＰＣＤ做了比较。另外，虽然植物ＰＣＤ的研究尚处于起步阶段，本文还是对其可能的信号传导机制、遗传调控以及ＰＣＤ的起源与进化作了探讨，并提出了植物ＰＣＤ的研究战略。具体说来有以下几个方面：１．形态和生化特征。目前，植物ＰＣＤ的研究主要还集中于形态和生化方面的描述。各种条件下的植物ＰＣＤ在形态和生化特征上都或多或少地与动物细胞凋亡存在差异，并不符合动物细胞凋亡定义的全部内容。并且不同植物ＰＣＤ类型相互之间也存在着较大的不同。尽管如此，动植物ＰＣＤ在形态和生化方面还是存在许多相似之处。无炎症反应、ＤＮＡ的特异片段化以及核酸内切酶和蛋白酶活性的升高在植物中也依然是区别ＰＣＤ与细胞坏死（ｎｅｃｒｏｓｉｓ）的形态和生化依据。２．分子水平上，植物ＰＣＤ也涉及到许多信号分子和特定基基参与调控的信号传导途径。但到目前为止，已分离的与植物ＰＣＤ直接相关的基因只有ＡＣＤ２、Ｄａｄ１等少数几个。
