The Golgi Apparatus and the Plant Secretory Pathway

Edited by:
  • David Robinson
Blackwell Publishing 2003 £85.00/$139.95

When I learned biology at high school, the textbook clearly stated — as one of the many differences between animal and plant cells — that the Golgi apparatus is present in animal cells, whereas it is absent from plant cells. More than 30 years have passed, and today I hope that most cell biologists know that this is not so. Despite the fact that plant cells have the Golgi, there remains a large difference in our knowledge of animal and plant Golgi. Whereas its role as the protein-sorting centre in the cell has been established by studies on mammalian and yeast cells, our understanding of the plant Golgi has just begun to accumulate. The Golgi Apparatus and the Plant Secretory Pathway, published as an issue of Annual Plant Reviews, is very timely because it summarizes not only what we know but also what we do not know about the plant Golgi.

This book, edited by David Robinson (University of Heidelberg, Germany), consists of 14 chapters that have been contributed by many plant Golgi researchers. The first part is dedicated to a comparison of the structure and organization of the plant Golgi with those of the non-plant Golgi. Chapter 1, by B. Glick, on the yeast Golgi is a good introduction that serves to refresh our knowledge of Golgi structure and organization. Chapter 2, by M. Pavelka and D. Robinson, in addition to showing beautiful pictures of the plant Golgi that will appeal to many readers, discusses differences between animal and plant Golgi. The chapters that follow focus on pathways of vesicular trafficking between the endoplasmic reticulum and the Golgi and also between the Golgi and the vacuole, the plant counterpart of the mammalian lysosome. Separate chapters describe the role of the Golgi in protein glycosylation and its interaction with the cytoskeleton. Many components involved in trafficking have now been identified in plants and are similar to their non-plant counterparts, such as COPI and COPII subunits, Sar/Arf and Rab GTPases, and SNARE molecules. Discussions of these components demonstrate that many aspects of the structure and function of the plant organelle are quite similar to the animal and yeast Golgi, and research on the plant Golgi is quickly catching up.

One unique aspect of the plant Golgi is that its dynamic behaviour is clearly dependent on actin filaments; this is in contrast to the mammalian Golgi, whose localization to the perinuclear region is dependent on microtubules. The plant Golgi shows repetitive stop-and-go motion along the actin filament, which suggests a specific role for actin in the Golgi function. Possible interpretations of the significance of the motility of the plant Golgi are discussed in chapter 4 by C. Hawes and colleagues. The role of actin in traffic is also important in animal and yeast cells, but it tends to receive less attention than that given to microtubules in mammalian cells. Plant studies might therefore lead the field in this context. Classically, the plant Golgi was studied as a site of polysaccharide synthesis for the supply of cell wall components. It is still important to understand the plant Golgi from such a standpoint, but this aspect is not emphasized in this book, probably because the role of Golgi in trafficking is now appreciated as a more attractive question to study. Protein traffic along the major secretory pathway from the Golgi to the cell surface is an important topic, but it has not been studied extensively in plants and is not described in depth in this book. However, an exception is its role in cell plate formation during cytokinesis, which is described in the last chapter.

More than 100 years since Camillo Golgi discovered the apparatus named after him, it is still a mysterious and fascinating organelle for cell biologists. Its stacked structure continues to attract many researchers, although answers to the question of why and how those cisternae are organized as stacks still elude researchers. The beauty of the plant Golgi, which is arranged in separate stacks of cisternae, distinct from the unstacked Saccharomyces Golgi and the tangled cluster of the mammalian Golgi, presents a great advantage in probing the secrets of cisternal stacking and will continue to be a target of research for ambitious cell biologists.

This book provides a good opportunity to think about what the Golgi is and what it does, even though it is written from the viewpoints of plant researchers. The level of content is probably appropriate for graduate students but could also be interesting for undergraduate students, postdoctoral scientists and even the seasoned researcher. I would recommend this book not only to plant scientists but also to animal and yeast cell biologists who are interested in the Golgi itself and/or in the organization of protein trafficking.