This book is another valuable contribution to the growing library of volumes in the Springer series ‘Advances in Photosynthesis and Respiration’ (almost 40 volumes and counting). While much of the present material has been covered in previous volumes, The Chloroplast seeks to take a unique approach. In the words of the editors, ‘this volume on the chloroplast is meant to provide the basis for chloroplast bioengineering and foster closer cooperation between scientists [in multiple disciplines] … and further the implementation of more efficient photosynthesis’ (Preface, p. xxviii). In doing so, the volume focuses on the bioengineering of improved photosynthetic efficiency as a method to increase agricultural plant productivity, improve biofuel production, and even support extra-terrestrial space colonization. The volume's contents can be arranged into several categories, as follows.
Chapter 1, as befitting its place, lays out the possible sources for the mismatch between the theoretical photosynthetic efficiency of 12 % and the actual measured efficiency of less than half a percent. It is that gap to which the volume editors seek to direct the attention of the reader and the researcher. Chapters 2–5 cover chlorophyll biosynthetic pathways, including synthesis of the vinyl side-chain, tetrapyrrole synthesis, interconversion of Chl a and b, and Mg2+ insertion. Chapter 6, an interesting, four-page piece titled, ‘The enigmatic chlorophyll a molecule in the cytochrome b6/f complex’, finds a home in this section. Chapters 7–10 focus on isoprenoids: their biosynthesis and connection to the isoprenoid-derived pigments (Chapter 7); the regulatory role of the MEP pathway in chloroplast isoprenoid production (Chapter 8); the role of protein geranylgeranylation in cellular metabolic control (Chapter 9); and the emission of a wide range of volatile terpenoid compounds from flowers and leaves of numerous plants (Chapter 10).
A comprehensive treatment of chloroplast lipids follows. Chapter 11 concerns engineering plastids for enhanced tocochromanols (vitamin E) production. The biosynthesis, function and importance of the four major chloroplast structural lipids are next covered in sequence: phosphatidylglycerol and sulfoquinovosylidiacylglycerol (Chapter 12), monogalactosyldiacylglycerol (Chapter 13) and digalactosyldiacylglycerol (Chapter 14).
The light-harvesting Chl-protein complex of photosystem II (LHCII) is treated in Chapter 15 (chemistry and biology) and Chapter 16 (folding and pigment binding). Both chapters do a fine job of bringing together structural and functional data on this important pigment–protein complex.
The heart of the subject matter that is the most pertinent to the research questions set out in the Preface and Chapter 1 – namely, chloroplast genomics and genetic engineering – is addressed in Chapters 17–20. This core portion of the volume begins with Chapter 17, a technical paper on increasing the resistance of plants and plant products to microbial attack. Up to 25 % of food is lost post-harvest, much of it through the action of food-degrading microbes. Engineering the plastic genome may hold the key to the introduction of disease-resistance genes and add an important layer of protection in the food production supply chain. Chapter 18 also focuses on chloroplast genetic engineering. The authors provide a review of available methods of plastid transformation and give examples of the successful production of chloroplast-derived vaccine antigens, biopharmaceutical proteins and industrially valuable biomaterials. Chapter 19 is a comprehensive case study of transforming tobacco chloroplasts with the sunflower Rubisco large and small subunits. Data are presented ranging from initial plastid transformation to eventual whole-leaf gas exchange measurements in mature Nicotiana leaves. The study identifies both hurdles encountered and achievements possible using this emerging experimental system. Chapter 20 is perhaps the signature chapter of the volume as it speaks directly to genetically engineering photosynthetic enzymes for the enhancement of photosynthetic efficiency. Gene shuffling of Chlamydomonas reinhardtii Rubisco genes was used to drive directed molecular evolution of increased carboxylase activity or CO2/O2 specificity. The experimental technique was extended to A. thaliana and generated several Rubisco variants with increased thermostability. The take-home message from these four chapters that focus on chloroplast genetic engineering is quite encouraging.
Finally, Chapters 21–25 expand the volume's coverage to include consideration of the chloroplast response in the face of environmental factors such as elevated CO2, elevated O3 and abiotic stress.
While the individual chapters are of a high standard, and the authors of well-earned international reputation, many of the contributions drifted significantly from the volume's stated goal of fully exploring how to bioengineer increased photosynthetic efficiency into chloroplasts in order to enhance food and biofuels production. The book is somewhat heavy on chloroplast basics (information that although well done, is available elsewhere in the literature), at the expense of a rather limited coverage of chloroplast applications. Beginning students will gain much from the review material and advanced researchers will find the chapters on direct applications to be very useful in guiding their thinking and future experiments.
In terms of presentation of the material, the inclusion of colour figures in the text, rather than collected at the front of the book as has been the norm with this series, is a definite improvement in the readability of the text.