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Plants and fungi: friends and enemies
BOOK
REVIEWS
The emphasis of the book as a whole is ecological, and Chapters 9–13 deal specifically with fungi in their environment and their parasitic and mutualistic interactions with other organisms. This is a mature synthesis of work over the past 40 years rather than a focused summary of recent work, much of which has been devoted to molecu-
lar systematics, endless restriction polymorphisms, RAPDs, gene fingerprint studies and in situ detection of fungi using molecular technologies. There is no better summary of fungal ecology than is found here. In conclusion, and despite my concern about the molecular biological limitations of Modern Mycology, it deserves its place as
an ideal text to introduce the fungi to biologists and undergraduate students.
Plants and fungi: friends and enemies
does well to encompass the full range of plant–fungus interactions while also describing the molecular biology of plant infection where known. The result is a richly diverse set of reviews that will be of general interest to plant pathologists and microbiologists alike. Plant Relationships is organized into two volumes, and the opening chapters follow the sequence of events from the time when a fungus first arrives at the plant surface to the resultant infection, colonization of plant tissue and production of disease symptoms. Fungi are unique among microorganisms in that they are able to breach intact plant cuticles and gain entry to underlying plant tissues. This is often achieved by the development of specialized infection structures called appressoria, which function either by applying mechanical force to the plant surface to rupture it or by secreting enzymes to dissolve the cuticle and epidermal cell wall layers. The elegance of the infection process is described in several chapters, which contain striking illustrations of these cells in action. Reviews of the plant colonization process are also complemented by a description of the plant defence reaction, which is often overlooked by fungal biologists and gives an impression of the dynamics of plant disease and the battle between host and pathogen. Part A of Plant Relationships provides an overview of the development of plant disease by fungi, but the number of diverse examples also underlines the impressive variety of fungal pathogens out there. There are also several complete research stories that show how a multidisciplinary approach involving biochemistry, genetics, molecular biology and
cell biology can rapidly clarify a plant–fungus interaction. The most notable of these is the description of the host-specific toxin-producing Cochliobolus species. Medical mycologists, who have been somewhat slower in adopting genetic analysis in their research, would do well to read this example of how a fungus–host interaction can be effectively dissected. A series of case histories of the most well-studied plant–fungus interactions follows in Part B and includes devastating diseases, such as rice blast, as well as endophytic interactions. This is followed by arguably the most challenging section, which describes the evolution of plant–fungus interactions and covers the recent evidence suggesting evolution of grass endophytes from their pathogenic relatives and also the genetic flexibility of pathogenic fungi revealed by genome-level analysis. The fact that this is discussed in a book containing chapters on lichen formation and mycorrhizal interactions shows how much we have yet to learn about the evolution of plant–fungus relationships. The lichens, for example, remain largely unexplored at the molecular level and yet may turn out to be the ‘Holy Grail’ for understanding plant– fungus recognition phenomena. I always have two primary concerns with a book of this sort. The first is how up to date the information covered is likely to be, given the lag time for publication. In this respect, Plant Relationships does surprisingly well, considering the current extensive activity in molecular plant pathology. In my opinion, the reviews are still contemporary, and any graduate student in fungal pathology should
The Mycota Vol. V: Plant Relationships Parts A and B edited by G.C. Carroll and P. Tudzynski Springer-Verlag, 1997. DM258.00/DM278.00 hbk (xviii 1 253/xix 1 288 pages) ISBN 3 540 58006 9/3 540 62018 4
F
ungi form a wide variety of interactions with plants, from benign forms of mutualism through to devastating crop diseases. Although plant diseases are well known and of continuing economic importance, the fact that plants seldom if ever, exist without fungal infection – either endophytic or mycorrhizal – is perhaps not so widely appreciated. The Mycota is a series of books planned to consist of ten volumes describing many aspects of fungal research, from the study of morphogenesis and mating interactions to industrial applications of fungi and their pathology. The overall aim of The Mycota has been to highlight the use of fungi as experimental organisms for studying basic biological processes. From the pioneering coupling of biochemistry and genetics by Beadle and Tatum to the first complete genetic inventory for a eukaryote, it is clear that fungi have played an extraordinary role in the progress of biological research. The Mycota also appears to have been something of a labour of love for the series editors Karl Esser and the late Paul Lemke, and the result is a beautifully crafted and extensive set of contemporary reviews on fungal biology. Volume V of The Mycota series explores Plant Relationships and
TRENDS
IN
MICROBIOLOGY
250
Neil A.R. Gow Dept of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK AB25 2ZD
VOL. 6 NO. 6 JUNE 1998
BOOK
REVIEWS
take a hint: if you are writing your thesis in the next two or three years, the core of your literature review is probably here. The second concern I have, however, is that the book is prohibitively expensive for most individual researchers. This is a shame because it is individual re-
search students who would benefit most by using this as a frequent reference book. I would therefore urge the publishers to consider a low-cost paperback edition or CDROM that would be in the price range of graduate students and researchers. This would allow the
book to be enjoyed far more than is otherwise likely.
Surviving starvation
conflicting, and at times poorly defined, concepts and terminology that have plagued the literature on oligotrophy and starvation of bacteria, and ends with an essay on how we should study and perceive the concept of energy of maintenance, or rather energy of survival as Morita puts it, as the fundamental topic that underlies the starvation survival lifestyle. Studies of the many varied oligotrophic habitats and the survival of a diverse range of bacteria in vitro and in situ are comprehensively reviewed in Chapters 2, 5 and 6, while the complex mechanisms by which organic matter becomes resistant to microbial utilization are detailed in Chapter 3. Chapter 4 not only deals with how we are facing a formidable challenge in estimating bioavailability and microbial activity in different ecosystems, but also highlights experimental pitfalls to help the microbial ecologist design meaningful experiments when assessing bacterial activity and growth in the field. Three chapters address more-contemporary research into starvation survival of bacteria and ecosystem consequences. These deal with the physiology (Chapter 7) and molecular determinants (Chapter 8) of bacterial starvation and the effects of host starvation on bacteriophage dynamics in the marine environment (Chapter 9). To me, the main strength of the book is the truly comprehensive way in which it presents the evolving field of starvation survival, including issues such as the early studies of long-term survival in various bacterial species, viable but nonculturable bacteria, the concept of maintenance energy, oligotrophic environments and bioavailability. Morita has managed to review an impressive number of publications (.2000) in the many subdisciplines that he covers and has succeeded in
producing a synthesis of many results, observations and models that have been published this century. However, given the wealth of information provided and the often disparate results and views, the weakness of the book is that, in places, it reads like an encyclopaedia, with much information that cannot or has not been provided in a conceptual or interpretative framework. It is likely that a reader new to the field will find it difficult to arrive at a consensus of the state of the art in a particular subdiscipline. The lack of follow-up explanations of complex sets of data in several chapters also makes the book less suitable as an undergraduate textbook. Although this is to some extent offset by a ‘Conclusions’ section for each of the chapters, the main audience of this book is therefore likely to be limited to scientists engaged in research in microbial ecology, in particular those who study marine ecosystems. It should also be noted that in several of the chapters there are few references to publications that have appeared in the literature in the past two years. However, because this book primarily provides a comprehensive background to the subject area, this fact does not undermine the significance and value of the text and, given the comprehensive research efforts of the author, it is likely that it will serve as the undisputed reference text in this area for a very long period of time.
Bacteria in Oligotrophic Environments: Starvation-survival Lifestyle by Richard Y. Morita Chapman & Hall, 1997. £69.00 hbk (xv 1 529 pages) ISBN 0 412 10661 2
I
n my preface to the book Starvation in Bacteria1, which was published in 1993, I made the point that several laboratories have contributed greatly to the progress made in ‘life-after-log’ research. One of these laboratories was that of Richard Morita, whose extensive pioneering work on starvation survival of marine Vibrio species paved the way for, in particular, the current surge in more-mechanistic studies of how nondifferentiating bacteria survive starvation conditions. Bacteria in Oligotrophic Environments: Starvation-survival Lifestyle is a testament to Morita’s longstanding interest in this topic and addresses his concern that the lack of available energy for heterotrophic bacteria in natural ecosystems is poorly studied in microbial ecology yet represents the most important environmental factor. Morita goes to some length to emphasize his beliefs that starvation survival physiology is the normal state of affairs in the environment and that to fully appreciate this biological response, and fully understand how ecosystems function, it is essential to address long-term starvation as well as the oligotrophic nature of ecosystems. Hence, a plea is made for introducing ecosystem-relevant and long-term starvation survival experiments and to further our studies on the bioavailability of organic matter in the environment. Eight of the ten chapters are written by Morita himself. The book begins with a review of the
TRENDS
IN
MICROBIOLOGY
251
Nicholas J. Talbot Dept of Biological Sciences, University of Exeter, Washington Singer Laboratories, Exeter, UK EX4 4QG
Staffan Kjelleberg School of Microbiology and Immunology, University of New South Wales, Sydney, NSW 2052, Australia Reference 1 Kjelleberg, S. (1993) Starvation in Bacteria, Plenum Press
VOL. 6 NO. 6 JUNE 1998
REVIEWS
The emphasis of the book as a whole is ecological, and Chapters 9–13 deal specifically with fungi in their environment and their parasitic and mutualistic interactions with other organisms. This is a mature synthesis of work over the past 40 years rather than a focused summary of recent work, much of which has been devoted to molecu-
lar systematics, endless restriction polymorphisms, RAPDs, gene fingerprint studies and in situ detection of fungi using molecular technologies. There is no better summary of fungal ecology than is found here. In conclusion, and despite my concern about the molecular biological limitations of Modern Mycology, it deserves its place as
an ideal text to introduce the fungi to biologists and undergraduate students.
Plants and fungi: friends and enemies
does well to encompass the full range of plant–fungus interactions while also describing the molecular biology of plant infection where known. The result is a richly diverse set of reviews that will be of general interest to plant pathologists and microbiologists alike. Plant Relationships is organized into two volumes, and the opening chapters follow the sequence of events from the time when a fungus first arrives at the plant surface to the resultant infection, colonization of plant tissue and production of disease symptoms. Fungi are unique among microorganisms in that they are able to breach intact plant cuticles and gain entry to underlying plant tissues. This is often achieved by the development of specialized infection structures called appressoria, which function either by applying mechanical force to the plant surface to rupture it or by secreting enzymes to dissolve the cuticle and epidermal cell wall layers. The elegance of the infection process is described in several chapters, which contain striking illustrations of these cells in action. Reviews of the plant colonization process are also complemented by a description of the plant defence reaction, which is often overlooked by fungal biologists and gives an impression of the dynamics of plant disease and the battle between host and pathogen. Part A of Plant Relationships provides an overview of the development of plant disease by fungi, but the number of diverse examples also underlines the impressive variety of fungal pathogens out there. There are also several complete research stories that show how a multidisciplinary approach involving biochemistry, genetics, molecular biology and
cell biology can rapidly clarify a plant–fungus interaction. The most notable of these is the description of the host-specific toxin-producing Cochliobolus species. Medical mycologists, who have been somewhat slower in adopting genetic analysis in their research, would do well to read this example of how a fungus–host interaction can be effectively dissected. A series of case histories of the most well-studied plant–fungus interactions follows in Part B and includes devastating diseases, such as rice blast, as well as endophytic interactions. This is followed by arguably the most challenging section, which describes the evolution of plant–fungus interactions and covers the recent evidence suggesting evolution of grass endophytes from their pathogenic relatives and also the genetic flexibility of pathogenic fungi revealed by genome-level analysis. The fact that this is discussed in a book containing chapters on lichen formation and mycorrhizal interactions shows how much we have yet to learn about the evolution of plant–fungus relationships. The lichens, for example, remain largely unexplored at the molecular level and yet may turn out to be the ‘Holy Grail’ for understanding plant– fungus recognition phenomena. I always have two primary concerns with a book of this sort. The first is how up to date the information covered is likely to be, given the lag time for publication. In this respect, Plant Relationships does surprisingly well, considering the current extensive activity in molecular plant pathology. In my opinion, the reviews are still contemporary, and any graduate student in fungal pathology should
The Mycota Vol. V: Plant Relationships Parts A and B edited by G.C. Carroll and P. Tudzynski Springer-Verlag, 1997. DM258.00/DM278.00 hbk (xviii 1 253/xix 1 288 pages) ISBN 3 540 58006 9/3 540 62018 4
F
ungi form a wide variety of interactions with plants, from benign forms of mutualism through to devastating crop diseases. Although plant diseases are well known and of continuing economic importance, the fact that plants seldom if ever, exist without fungal infection – either endophytic or mycorrhizal – is perhaps not so widely appreciated. The Mycota is a series of books planned to consist of ten volumes describing many aspects of fungal research, from the study of morphogenesis and mating interactions to industrial applications of fungi and their pathology. The overall aim of The Mycota has been to highlight the use of fungi as experimental organisms for studying basic biological processes. From the pioneering coupling of biochemistry and genetics by Beadle and Tatum to the first complete genetic inventory for a eukaryote, it is clear that fungi have played an extraordinary role in the progress of biological research. The Mycota also appears to have been something of a labour of love for the series editors Karl Esser and the late Paul Lemke, and the result is a beautifully crafted and extensive set of contemporary reviews on fungal biology. Volume V of The Mycota series explores Plant Relationships and
TRENDS
IN
MICROBIOLOGY
250
Neil A.R. Gow Dept of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK AB25 2ZD
VOL. 6 NO. 6 JUNE 1998
BOOK
REVIEWS
take a hint: if you are writing your thesis in the next two or three years, the core of your literature review is probably here. The second concern I have, however, is that the book is prohibitively expensive for most individual researchers. This is a shame because it is individual re-
search students who would benefit most by using this as a frequent reference book. I would therefore urge the publishers to consider a low-cost paperback edition or CDROM that would be in the price range of graduate students and researchers. This would allow the
book to be enjoyed far more than is otherwise likely.
Surviving starvation
conflicting, and at times poorly defined, concepts and terminology that have plagued the literature on oligotrophy and starvation of bacteria, and ends with an essay on how we should study and perceive the concept of energy of maintenance, or rather energy of survival as Morita puts it, as the fundamental topic that underlies the starvation survival lifestyle. Studies of the many varied oligotrophic habitats and the survival of a diverse range of bacteria in vitro and in situ are comprehensively reviewed in Chapters 2, 5 and 6, while the complex mechanisms by which organic matter becomes resistant to microbial utilization are detailed in Chapter 3. Chapter 4 not only deals with how we are facing a formidable challenge in estimating bioavailability and microbial activity in different ecosystems, but also highlights experimental pitfalls to help the microbial ecologist design meaningful experiments when assessing bacterial activity and growth in the field. Three chapters address more-contemporary research into starvation survival of bacteria and ecosystem consequences. These deal with the physiology (Chapter 7) and molecular determinants (Chapter 8) of bacterial starvation and the effects of host starvation on bacteriophage dynamics in the marine environment (Chapter 9). To me, the main strength of the book is the truly comprehensive way in which it presents the evolving field of starvation survival, including issues such as the early studies of long-term survival in various bacterial species, viable but nonculturable bacteria, the concept of maintenance energy, oligotrophic environments and bioavailability. Morita has managed to review an impressive number of publications (.2000) in the many subdisciplines that he covers and has succeeded in
producing a synthesis of many results, observations and models that have been published this century. However, given the wealth of information provided and the often disparate results and views, the weakness of the book is that, in places, it reads like an encyclopaedia, with much information that cannot or has not been provided in a conceptual or interpretative framework. It is likely that a reader new to the field will find it difficult to arrive at a consensus of the state of the art in a particular subdiscipline. The lack of follow-up explanations of complex sets of data in several chapters also makes the book less suitable as an undergraduate textbook. Although this is to some extent offset by a ‘Conclusions’ section for each of the chapters, the main audience of this book is therefore likely to be limited to scientists engaged in research in microbial ecology, in particular those who study marine ecosystems. It should also be noted that in several of the chapters there are few references to publications that have appeared in the literature in the past two years. However, because this book primarily provides a comprehensive background to the subject area, this fact does not undermine the significance and value of the text and, given the comprehensive research efforts of the author, it is likely that it will serve as the undisputed reference text in this area for a very long period of time.
Bacteria in Oligotrophic Environments: Starvation-survival Lifestyle by Richard Y. Morita Chapman & Hall, 1997. £69.00 hbk (xv 1 529 pages) ISBN 0 412 10661 2
I
n my preface to the book Starvation in Bacteria1, which was published in 1993, I made the point that several laboratories have contributed greatly to the progress made in ‘life-after-log’ research. One of these laboratories was that of Richard Morita, whose extensive pioneering work on starvation survival of marine Vibrio species paved the way for, in particular, the current surge in more-mechanistic studies of how nondifferentiating bacteria survive starvation conditions. Bacteria in Oligotrophic Environments: Starvation-survival Lifestyle is a testament to Morita’s longstanding interest in this topic and addresses his concern that the lack of available energy for heterotrophic bacteria in natural ecosystems is poorly studied in microbial ecology yet represents the most important environmental factor. Morita goes to some length to emphasize his beliefs that starvation survival physiology is the normal state of affairs in the environment and that to fully appreciate this biological response, and fully understand how ecosystems function, it is essential to address long-term starvation as well as the oligotrophic nature of ecosystems. Hence, a plea is made for introducing ecosystem-relevant and long-term starvation survival experiments and to further our studies on the bioavailability of organic matter in the environment. Eight of the ten chapters are written by Morita himself. The book begins with a review of the
TRENDS
IN
MICROBIOLOGY
251
Nicholas J. Talbot Dept of Biological Sciences, University of Exeter, Washington Singer Laboratories, Exeter, UK EX4 4QG
Staffan Kjelleberg School of Microbiology and Immunology, University of New South Wales, Sydney, NSW 2052, Australia Reference 1 Kjelleberg, S. (1993) Starvation in Bacteria, Plenum Press
VOL. 6 NO. 6 JUNE 1998