Table Of ContentTHE MYCOPLASMAS
EDITORS
M. F. Barile
Mycoplasma Branch
Bureau of Biologies
Food and Drug Administration
Bethesda, Maryland
S. Razin
Biomembrane Research Laboratory
Department of Clinical Microbiology
The Hebrew University-Hadassah Medical School
Jerusalem, Israel
J. G. Tully
Mycoplasma Section
Laboratory of Infectious Diseases
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, Maryland
R. F. Whitcomb
Plant Protection Institute
Federal Research, Science and Education Administration
U.S. Department of Agriculture
Beltsville, Maryland
THE MYCOPLASMAS
VOLUME III
Plant and Insect
Mycoplasmas
Edited by
R. F. WHITCOMB
Plant Protection Institute
Federal Research, Science and Education Administration
U.S. Department of Agriculture
Beltsville, Maryland
and
J. G. TULLY
Mycoplasma Section
Laboratory of Infectious Diseases
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, Maryland
ACADEMIC PRESS New York San Francisco London 1979
A Subsidiary of Harcourt Brace Jovanovich, Publishers
COPYRIGHT © 1979, BY ACADEMIC PRESS, INC.
ALL RIGHTS RESERVED.
NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR
TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC
OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY
INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT
PERMISSION IN WRITING FROM THE PUBLISHER.
ACADEMIC PRESS, INC.
Ill Fifth Avenue, New York, New York 10003
United Kingdom Edition published by
ACADEMIC PRESS, INC. (LONDON) LTD.
24/28 Oval Road, London NW1 7DX
Library of Congress Cataloging in Publication Data
Main entry under title:
The Mycoplasmas.
Includes bibliographies.
CONTENTS: v.l. Cell biology.
v. 3. Plant and insect mycoplasmas.
1. Mycoplasmatales. 2. Mycoplasma diseases.
I. Barile, Michael Frederick, Date [DNLM:
1. Mycoplasma. QW143 M9973]
QR352.M89 589.9 78-20695
ISBN 0-12-078403-3 (v. 3)
PRINTED IN THE UNITED STATES OF AMERICA
79 80 81 82 9 8 7 6 5 4 3 2 1
LIST OF CONTRIBUTORS
Numbers in parentheses indicate the pages on which the authors' contributions begin.
J. M. Bove (83), I.N.R.A. and University of Bordeaux H, Laboratoire de
Biologie Cellulaire et Moléculaire, 33140 Pont de la Maye, France
E. C. Calavan (37), Department of Plant Pathology, University of
California, Riverside, California 92521
T. A. Chen (65), Department of Plant Biology, Cook College, Rutgers
University, New Brunswick, New Jersey 08903
H Fred Clark (155), The Wistar Institute of Anatomy and Biology,
Philadelphia, Pennsylvania 19104
M. J. Daniels (209), John Innes Institute, Norwich NR4 7UH, England
R. £. Daws (65), Beltsville Agricultural Research Center, Federal Re-
search, Science and Education Administration, U.S. Department
of Agriculture, Beltsville, Maryland 20705
Randolph F. McCoy (229), University of Florida Agricultural Research
Center, Fort Lauderdale, Florida 33314
G- N. Old field (37), Boy den Entomology Laboratory, Federal Research,
Science and Education Administration, U.S. Department of Agricul-
ture, Riverside, California 92521
Donald F. Poulson (175), Department of Biology, Yale University, New
Haven, Connecticut 06520
Lucy Balian Rorke (155), The Wistar Institute of Anatomy and Biology,
Philadelphia, Pennsylvania 19104
P. H. M. Saglio (1), Station de Physiopathologie Végétale, I.N.R.A.,
Boîte vaguemestre 1540, 21034 Dijon Cedex, France
Colette Saillard (83), I.N.R.A. and University of Bordeaux II,
Laboratoire de Biologie Cellulaire et Moléculaire, 33140 Pont de la
Maye, France
R. C. Sin ha (309), Chemistry and Biology Research Institute, Agriculture
Canada, Research Branch, Ottawa, Ontario K1A OC6, Canada
James H. Tsai (265), Agricultural Research Center, University of
Florida, Fort Lauderdale, Florida 33314
IX
X List of Contributors
R. F. Whitcomb (1), Plant Protection Institute, Federal Research, Science
and Education Administration, U.S. Department of Agriculture,
Belts ville, Maryland 20705
David L Williamson (175), Department of Anatomical Sciences, Health
Sciences Center, State University of New York, Stony Brook, New
York 11794
FOREWORD
A decade or so ago, the title of the present volume would have been
greeted with puzzlement or derision by all but a few cognoscenti. Myco-
plasmas in plant disease? Really! To disabuse one of such a wild notion, the
contemporary conventional wisdom concerning the sorts of plant patho-
gens would have been recited along the following lines: (1) with the excep-
tion of a few parasitic algae and seed plants, the causal agents of plant
diseases were nematodes, fungi, viruses, or bacteria; (2) among the bacter-
ial phytopathogens, only a few major sorts—emphatically not including
mycoplasmas—were involved; (3) these phytopathogenic bacteria were as-
sociated antagonistically only with plants (who ever heard of animals,
insects and man included, being harmed by plant bacteria?); (4) the often
insect-borne, sometimes filter-passing agents of plant disease, axenically
noncultivable and invisible under the light microscope, were surely all
viruses—most certainly none were bacteria. And the existence of a
plethora of viruses infecting insects, clearly distinct from the recognized
insect bacteria, appears to support such views.
These notions had to be drastically revised in 1967. The first cases in the
rising epidemic of nosocomial diseases of man caused by plant-associated
bacteria were reported in that year. Beginning in the same year, plants
suffering from various yellows, dwarf, and witches'-broom diseases (con-
ventionally thought to be of viral etiology) were shown by electron micro-
scopy to contain peculiar wall-defective prokaryotic cells in infected, but
not in uninfected, tissues; moreover, such plant diseases could be con-
trolled by tetracyclines, the target of which is the bacterial ribosome, an
organelle that doesn't exist in a virus.
In addition to technical deficiencies, a number of historically determined
conceptual factors conspired to bring the community of plant pathologists
and microbiologists to this pre-1967 dogma. It might be instructive for this
general bacteriologist to review some of these factors briefly, almost
simplistically, in the hope that the next conceptual barriers might be
breached more promptly with these lessons from the past reiterated and
really learned.
Until about 1880, only fungi were commonly believed to cause diseases
of plants. This view had to be altered by the almost simultaneous demon-
stration in various parts of the world that several plant diseases (fireblight
xi
XII Foreword
of apples and pears, yellows disease of hyacinths, and olive knot) were
caused by bacteria rather than by fungi. By the end of the nineteenth
century, a score of plant diseases conclusively shown to be caused by
bacteria could be added to the list. But old dogmas die hard. The then-
dominant medical bacteriologists not only ignored this mounting evidence,
but some of them denied it most emphatically. For example, Alfred
Fischer, in his widely read German textbook of 1897, dismissed the facts
with these words (as given in the 1900 English edition): "[There is] no single
instance where bacteria . . . invade plants. All cases of so-called bacteriosis
in plants are primarily diseases of non-bacterial [that is, fungal] origin in
which the bacteria are present merely as accidental invaders/' Fischer's
view was eloquently challenged by Erwin Frink Smith, a towering Ameri-
can plant pathologist and bacteriologist, who had already published several
meticulous studies on plant diseases caused by bacteria. In the ensuing
public polemic between Smith and Fischer, which deserves to be read even
today by every scientist (it was published between 1899 and 1901 in the
Centralblatt fur Bakteriologie). Smith demolished for all time Fischer's
prejudiced notions. Bacteria do indeed cause disease of plants!
In the 1890s, Dmitri Ivanovski and Martinus Beijerinck independently
uncovered a plant disease agent, so small that it was not only invisible in the
available microscopes but also could pass through filters that retained all
the then-known bacteria. This improbable plant pathogen, the cause of
tobacco mosaic disease, provided the very first clearly stated concept and
demonstration of a plant virus. Acceptance of the concept that invisible
plant pathogens actually existed required a strong act of faith on the part of
the contemporary biologists who held this view.
Plant pathology entered the twentieth century with a difficult mixture of
causal agents of plant disease to deal with: nematodes, fungi, viruses, and
bacteria. The microbiological competence of most turn-of-the-century plant
pathologists centered about the fungi; few knew anything about bacteria or
viruses or, for that matter, nematodes. Only rarely were bacteriologists
associated with the study of plant diseases, and these few pioneers were
generally isolated from the mainstream of bacteriology. A sort of disciplinai
insularity was at that time (and, to a barely lessened extent, still is) in vogue
and was mirrored by a nomenclatural insularity. These trends culminated
in a notion, which persisted for half a century, to the effect that
phytopathogenic bacteria were a thing apart. Phytopathogenic bacteria
were the province mainly of plant pathologists, who rarely consorted with
general or medical bacteriologists; they were studied by often inappro-
priate methods, frequently derived from mycology; and they were placed in
a few genera separated from all other bacterial taxa solely on the basis of
phytopathogenicity. The same trends, albeit with differing manifestations,
Foreword χιιι
took place in virology: plant, animal, and later bacterial viruses. Each had
its own practitioners.
Several intertwined factors have conspired to slightly splinter this collec-
tion of disciplinai cocoons during the past decade or so. One factor was the
recognition that certain microorganisms possess the capacity to associate
antagonistically with both plants and animals, a capacity I have labeled
ambilateral harmfulness. Ambilaterally harmful bacteria and fungi are
nowadays well-known causes of nosocomial infections of compromised
human hospital patients. In fact, plant-associated bacteria are among the
most common bacterial nosocomial pathogens. A second factor was the
breaching of disciplinai insularity to some extent. Nowadays, bac-
teriologists are appointed to plant pathology departments; plant
pathologists attend meetings of microbiological societies and vice versa;
and bacteriologists, virologists, and plant pathologists interact and even
collaborate with one another. A third factor was acceptance of the view,
still not widespread, that there are many more genera to which
phytopathogenic bacteria might be assigned than the five or six in vogue
until the 1950s.
All of which brings us finally to the advancing frontier of etiology of plant
disease recorded in this book: the discovery that mycoplasmas and other
peculiar prokaryotes can cause diseases of plants. The facts, laid out compe-
tently in great detail in this volume, can be summarized in a lengthy
sentence. Several sorts of plant diseases, the causes of which had long been
ascribed to viruses (because the agents were filterable, axenically uncultiv-
able, invisible in the light microscope, and sometimes insect-borne) were
shown actually to be caused by prokaryotes (by electron microscopy;
sensitivity to drugs that have targets only in bacteria and not in viruses;
and, in an increasing number of cases, by actual axenic cultivation). Proba-
bly, some of these lessons could not have been learned before about 1950,
at which time electron microscopes became generally available (so the
mycoplasmas could be visualized), the use of antibiotics and knowledge of
their modes of action became routine, and the understanding of mycoplas-
mal biology became sufficiently extensive so that a bacteriologically alert
plant pathologist would even entertain the concept that mycoplasmas
might have something to do with causing insect-borne plant diseases. And,
that is what this book is all about (together with insect mycoplasmas,
regarding which I have nothing sensible to say).
The conceptual lessons seem to have been learned well and quickly, as
shown in this volume. And, possibly based on this precedent, it is almost a
commonplace today to read about yet more novel prokaryotes causing
plant and animal diseases: the previously uncultivable so-called rick-
ettsialike plant pathogens are metamorphosing, on the basis of interdisci-
XIV Foreword
plinary efforts, into several sorts of fastidious bacteria, some of which can
indeed be cultivated; the plant spiroplasmas are providing all sorts of
titillation for the general and medical bacteriologists. Let's continue to
break down disciplinai barriers (perhaps it wasn't the worst idea in the
world to expose this general bacteriologist to the task of writing this
Foreword!) It is indeed important to recognize that a capacity like ambilat-
eral harmfulness might exist. Above all, we must keep our minds open to
historically determined conceptual factors such as those recited here.
Mortimer P. Starr
PREFACE
'The Mycoplasmas," a comprehensive three-volume series, encom-
passes the various facets of mycoplasmology, emphasizing outstanding
developments made in the field during the past decade. The pronounced
information explosion in mycoplasmology was prompted primarily by the
discovery of insect and plant mycoplasmas and mycoplasma viruses in the
early 1970s, which attracted many new workers from different disciplines.
During this period significant progress in the field of animal and human
mycoplasmas was also made, providing important new insights into the
nature of host-parasite relationships and into the mechanisms by which
mycoplasmas infect and cause disease in man and animals.
Mycoplasmas are the smallest and simplest self-replicating microorgan-
isms, and their use as models for the study of general biological problems
has contributed considerably to our understanding of cell biology, particu-
larly in the field of biological membranes. Volume I deals with the cell
biology of the mycoplasmas, largely concentrating on problems regarding
their classification, phylogenetics, and relatedness to wall-covered bac-
teria; their unique molecular biology, energy metabolism, transport mech-
anisms, antigenic structure, and membrane biochemistry. The characteri-
zation, ultrastructure, and molecular biology of the mycoplasma viruses,
as well as the special properties of several groups of mycoplasmas, are also
included.
Volume II is concerned with host-parasite relationships of mycoplasmas
in man and animals. In part, emphasis is placed on recent developments in
the study of classical mycoplasmal diseases of animals, such as cattle,
sheep, goats, swine and chickens. On the other hand, new information on
the host range of mycoplasmas made it necessary to describe the myco-
plasma flora of hosts not previously known to harbor mycoplasmas (for
example, equines) or to document the increasing number of new myco-
plasmas found in some other animal hosts (as observed in canines, felines,
and nonhuman primates). This volume also offered the opportunity to
record current knowledge about mycoplasmal diseases of man, including
those involving the respiratory and genitourinary tracts. Humoral and
cellular immune responses to mycoplasmas, which are assuming an ever-
increasing significance in our understanding of the pathogenesis of human
and animal mycoplasmal diseases, are covered in detail. The volume closes
XV
