Lucas William J, Ding Biao, VAN DER Schoot Chris
Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616, USA.
New Phytol. 1993 Nov;125(3):435-476. doi: 10.1111/j.1469-8137.1993.tb03897.x.
In the classical formulation of Münch (1930), plasmodesmata are considered to form simple cytoplasmic bridges between neighbouring plant cells to create the symplasm. This concept has dominated, if not monopolized, the thinking of plant biologists and in particular plant physiologists over the last few decades. Recent advances in ultrastructural, physiological and molecular studies on plasmodesmata indicate that this simple view is in need of revision. Structurally, the higher plant plasmodesma has been revealed to be a supramolecular complex consisting of membranes and proteins. Functionally, evidence is at hand that this complex structure appears to have evolved not only to control the size exclusion limit for intercellular diffusion of metabolites and small molecules, but also to potentiate and regulate intercellular trafficking of macromolecules, including proteins and nucleic acids. In this regard, plasmodesmal transport may share parallel regulatory mechanisms with nucleocytoplasmic transport. Based on these findings, we advance the hypothesis that plants function as supracellular, rather than multicellular, organisms. As such, the dynamics of the plant body, including cell differentiation, tissue formation, organogenesis and specialized physiological function(s), is subject to plasmodesmal regulation. Plasmodesmata presumably accomplish such regulatory roles by trafficking informational molecules which orchestrate both metabolic activity and gene expression. Current and future studies on the evolutionary origin(s) of plasmodesmata are likely to provide valuable information in terms of the genetic and molecular basis for the supracellular nature of plants. Contents Summary 435 I. Introduction 436 II. Plasmodesmal formation, structure and biochemistry 436 III. Evolution of plasmodesmata 445 IV. Symplasmic dynamics 452 V. Plasniodesmal trafficking of macromolecules: parallels with nucleocytoplasmic transport 457 VI. Role of plasmodesmata in plant development 464 VII. Concluding remarks 469 Acknowledgements 470 References 470.
在明希（1930年）的经典理论中，胞间连丝被认为是在相邻植物细胞之间形成简单的细胞质桥，从而构成共质体。在过去几十年里，这一概念即便没有完全垄断，也主导了植物生物学家尤其是植物生理学家的思维。最近在胞间连丝的超微结构、生理学和分子研究方面取得的进展表明，这种简单的观点需要修正。在结构上，高等植物的胞间连丝已被揭示为一种由膜和蛋白质组成的超分子复合体。在功能方面，有证据表明，这种复杂结构似乎不仅进化到可以控制代谢物和小分子细胞间扩散的大小排阻极限，还能增强和调节包括蛋白质和核酸在内的大分子的细胞间运输。在这方面，胞间连丝运输可能与核质运输具有平行的调控机制。基于这些发现，我们提出一个假说，即植物作为超细胞而非多细胞生物体发挥功能。因此，植物体的动态过程，包括细胞分化、组织形成、器官发生和特殊生理功能，都受胞间连丝的调控。胞间连丝大概是通过运输协调代谢活动和基因表达的信息分子来完成这种调控作用的。目前和未来关于胞间连丝进化起源的研究，很可能会在植物超细胞性质的遗传和分子基础方面提供有价值的信息。内容摘要435 一、引言436 二、胞间连丝的形成、结构与生物化学436 三、胞间连丝的进化445 四、共质体动态452 五、大分子的胞间连丝运输：与核质运输的平行关系457 六、胞间连丝在植物发育中的作用464 七、结语469 致谢470 参考文献470
