Microbial Plant Pathogens-Detection and Disease Diagnosis:: Bacterial and Phytoplasmal Pathogens, Vol.2

280 Pages·2011·3.95 MB·English

by  P. Narayanasamy (auth.)

Microbial Plant Pathogens-Detection
and Disease Diagnosis
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Microbial Plant
Pathogens-Detection
and Disease Diagnosis
Bacterial and Phytoplasmal Pathogens,
Volume 2
P. Narayanasamy
Former Professor and Head, Department of Plant Pathology
Tamil Nadu Agricultural University, Coimbatore, India
P. Narayanasamy
Grand Parade Apartments
32 D Thilagar Street, R. S. Puram
Coimbatore 641002
India
[email protected]
ISBN 978-90-481-9768-2 e-ISBN 978-90-481-9769-9
DOI 10.1007/978-90-481-9769-9
Springer Dordrecht Heidelberg London New York
Library of Congress Control Number: 2010938430
© Springer Science+Business Media B.V. 2011
No part of this work may be reproduced, stored in a retrieval system, or transmitted in any
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Cover illustration:
Sesamum phyllody (Volume 2)
Symptoms of infection may be seen generally at the time of flowering. All floral parts
are converted into green leaf-like structures. The infected plants become partially or totally
sterile, depending on the time of infection.
(Courtesy of B. Sreenivasulu, Tamil Nadu Agricutlural University, Coimbatore, India)
Printed on acid-free paper
Springer is part of Springer Science+Business Media (www.springer.com)
Dedicated to the Memory of my Parents
for their Love and Affection
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Preface

Existence of prokaryotes including bacteria has been recorded several billions of
years ago. However, bacteria were demonstrated to be the causative agents of plant
diseases only in the last quarter of the 19th century. Now numerous plant diseases
are known to be due to the bacterial pathogens which induce symptoms distinct
from those induced by fungal pathogens. Diseases caused by phytoplasmas were
considered earlier to be due to viruses, because of the similarities in the modes of
transmission of these two pathogenic groups. But visualization of plemorphic
bodies without cell wall in the phloem tissues of the infected plants indicated the
nature of the causative agents and provided evidence that phytoplasmas are related
to bacteria and lack cell walls that are present in bacteria.
As the bacteria and phytoplasmas are much smaller than the fungal pathogens,
more powerful light microscopes and electron microscopes have to be employed for
the detection and differentiation of these disease-causing agents. As the morphological
characteristics have limited value for the differentiation of bacterial species, several
biochemical tests have to be performed for the detection and identification of bacterial
species causing the newly observed disease(s). The phytoplasma, on the other hand,
have not been successfully cultured in cell-free media and hence, their cultural
characteristics could not be studied. The biochemical tests are time-consuming,
labor-intensive and often yield inconsistent results. It is essential that rapid detection
and precise identification of bacteria and phytoplasmas have to be achieved within
short time to assess the extent of disease incidence. In order to successfully prevent
the spread of the bacterial and phytoplasmal diseases, techniques with greater
sensitivity, specificity, reproducibility and rapidity have to be applied. It has been
acknowledged that rapid detection and accurate identification of the microbial plant
pathogens up to subspecies/strain level form the basis for the development of short-
and long-term strategies for management of diseases caused by them. Immunoassays
and nucleic acid-based techniques have been demonstrated to be precise and reliable,
in addition to being amenable for automation and providing the results much earlier
when compared with the isolation-based conventional methods. Furthermore, these
modern molecular techniques have higher level of utility where the conventional
methods fail to detect the pathogens in asymptomatic plants and tissues containing
low concentration of bacteria and phytoplasmas. Hence, the molecular methods have
become the methods of choice for the researchers in the recent years.
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viii Preface
This volume presents exhaustive information based on extensive literature
search on various methods of detection of bacterial and phytoplasmal pathogens
and diagnosis of diseases caused by them. Comparative effectiveness of different
techniques is discussed critically to enable the researchers, teachers, extension
specialists and graduate students to choose the suitable techniques for their investi-
gations. Further, several protocols have been presented as appendix in appropriate
chapters to meet this requirement. This volume is expected to provide the necessary
platform for planning more critical studies that may improve the efficiency and
reliability of the existing methods that have been employed for simultaneous detec-
tion of two or more kinds of pathogens, without compromising the sensitivity and
specificity of detection of bacterial and phytoplasmal pathogens and diagnosis of
the diseases caused by them.
Coimbatore, India P. Narayanasamy
Acknowledgement
With a deep sense of humility, gratitude and reverence I bow to my Alma Mater that
continues to remain a source of inspiration for me for over five decades. I wish to
place on record appreciation to my colleagues and graduate students of the
Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore,
India for their suggestions and critical comments. I am thankful to Dr. T. Ganapathy,
Professor of Plant Pathology, for providing technical assistance requiring enormous
patience and skill. Permission granted by different copyright holders to reproduce
the figures published in various journals is gratefully acknowledged.
It is with great pleasure, I thank profusely my wife Mrs. N. Rajakumari who
showers her love and kindness, enabling me to devote my attention exclusively
for the preparation of this book. Expression of abundant affection and endless
encouragement of my family members Mr. N. Kumar Perumal, Mrs. Nirmala Suresh,
Mr. T. R. Suresh and Mr. S. Varun Karthik has been the source of support for all
my academic efforts during my career.
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