Crassulacean acid metabolism: Biochemistry, ecophysiology and evolution

Cvassulacean Acid Metabolism: Biochemistry, Ecophysiology and Evolution Edited by K. Winter and J.A.C. Smith, Springer Verlag, Berlin, Price DM198 Crassulacean acid metabolism (CAM) is one of three CO2 assimilatory pathways found in vascular plants. Similar C, plants, CAM plants concentrate CO, by first assimilating it into an intermediate organic acid which is then decarboxylated releasing CO, for subsequent reassimilation by the classical C, pathway. CAM plants, however, partition these events temporally during the diurnal cycle as a means to increase efficient use of water (terrestrial plants) or to take advantage of increase CO, availability (aquatic plants). CO2 is incorporated into organic acids during the night and then assimilated after decarboxylation of the organic acids into sugars during the following light period. This strict pattern of CAM metabolism is exhibited most conspicuously by the desert cacti. Many other CAM plants, however, exhibit intermediate forms and can utilize both C, and CAM metabolism simultaneously or switch from C, to CAM metabolism by environmental or developmental induced changes. The phenotypic diversity of CAM metabolism is also reflected phylogenetically where it is displayed by 33 families of vascular plants ranging from aquatic ferns, tropical epiphytic ferns, and gymnosperms in addition to monocotyledons and dicotyledons. The diversity of CAM responses exhibited by an equally diverse set of plants have long interested biochemists, physiologists and ecologists. Despite this broad interest there have been few books devoted to this subject area. The last monograph devoted to CAM was published more than 12 years ago and, therefore, a book on this subject area is long overdue. This recent monograph is based on the International Workshop on Crassulacean Acid Metabolism held in March, 1993. Despite the rather long incubation period between the meeting and the publication of the proceedings of the workshop, this monograph is a welcome addition that will be useful to scientists working in the field and most importantly to advanced students. The monographs contains 26 chapters that are

divided into four sections; biochemistry of CAM metabolism. environmental and developmental control of CAM metabolism, ecophysiology and evolution of CAM metabolism, and a final section on current status and perspectives. Chapters in the first three sections are written by experts in specific areas and provide recent developments in the field (e.g., the formation of citrate instead of malate as the intermediate organic acid in some plants, the control of expression of CAM genes by environmental and developmental factors) or emphasize problems that remain unresolved (e.g. 0, and CO1 exchanges in CAM plants). The monograph will be of particular interest to advanced students who wish to gain more insight on the field. A strength of the book is that the editors have made a considerable effort to organize the chapters within each section as well as the four sections themselves into a comprehensive and cohesive unit. Standard abbreviations are used throughout the monograph. The monograph contains a general introduction chapter that precedes the four sections that succinctly discusses the nature of CAM metabolism, the plasticity in phenotypic responses exhibited by different plants, and ecophysiology and species diversity with specific references to individual chapters sprinkled throughout the text. Each section itself contains a short preface that successfully emphasizes the major highlights of each chapter contained within the section. The book finishes with a final chapter on current status and perspectives which discusses recent developments and new directions in research. Overall, this is a reference book which will be useful to scientists in the field and particularly to advanced students who wish to learn the more recent developments in CAM metabolism and future directions of the field. Thonzus W. Okitu Institute of Biological Chemistry Washington State University Pullman Washington USA P/f

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