Microbial Plant Pathogens-Detection and Disease Diagnosis:: Viral and Viroid Pathogens, Vol.3

343 Pages·2011·4.59 MB·English

by  P. Narayanasamy (auth.)

Microbial Plant Pathogens-Detection
and Disease Diagnosis

Microbial Plant
Pathogens-Detection
and Disease Diagnosis
Viral and Viroid Pathogens, Volume 3
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 641 002
India
[email protected]
ISBN 978-90-481-9753-8 e-ISBN 978-90-481-9754-5
DOI 10.1007/978-90-481-9754-5
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 form or by any
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Cover illustration:
Peanut bud necrosis (Volume 3)
Infected plants exhibit chlorotic ringspots on the young leaves and they show necrosis of the terminal
buds later. The plants may be killed, if they are infected in the early stages of growth.
(Courtesy of P. Narayanasamy, Tamil Nadu Agricultural 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

Preface
Viruses, although minute in size and primitive in structure, are capable of infecting
all life forms from prokaryotic bacteria to highly evolved humans. Occurrence
of diseases such as small pox and influenza, now known to be of viral origin,
was reported to affect human beings even before the recorded history. However,
the viral origin of diseases could be established only during the last decade of the
19th century by the researchers like Iwanowsky and Beijerinck working on tobacco
mosaic disease. The controversial status of virus, whether living or nonliving,
attracted the attention of not only the plant pathologists, but also biochemists, bio-
physicists and biotechnologists. Viruses and viroids form distinct groups of obli-
gate parasites and they have to be considered differently, while diagnosing the
diseases induced by them, because all steps of the Koch’s postulates cannot be
applied to prove them to be the causative agents of newly observed disease(s), as in
the case of fungal and bacterial plant pathogens.
As the viruses and viroids have only elementary constitutional features and no
physiological functions, application of methods based on the biological, morpho-
logical and biochemical characteristics may not yield precise results. Immunoassays
have been effectively employed for the detection, identification and differentiation
of viruses infecting various crops. However, the antigenic properties of the viruses
are governed by only a small portion of the viral genome. Hence, the differences in
the other segments of the viral genome cannot be detected by the immunoassays.
This situation makes the application of nucleic acid-based techniques to be
more appropriate for the detection, differentiation and quantification of plant virus
populations/strains in different host plant species and in different locations and
periods. Likewise, viroids, lacking the protein component, do not provide any better
option other than the nucleic acid-based techniques for their detection and diagnosis
of the diseases caused by them. Although bioindexing employing diagnostic plant
species has been adopted for long time, this approach requires large greenhouse
space and long time, in addition to the results being inconclusive frequently.
Nucleic acid-based techniques are preferred for the detection, identification, differen-
tiation and quantification of viruses and viroids because of their high levels of
sensitivity, specificity, reproducibility and rapidity. Furthermore, the feasibility of
automation to handle large number of samples and the possibility of simultaneous
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detection of several plant viruses by employing nucleic acid-based methods have
enhanced their utility for detection of plant viruses and viroids and diagnosis of the
diseases caused by these pathogens.
This volume presents exhaustive information based on extensive literature
search on various methods of detection of viral and viroid 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 procedures for their investigations. Several
protocols are presented as appendix in appropriate chapters to meet this require-
ment. 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 detection of two or more kinds
of pathogens, without compromising the sensitivity and specificity of detection of
viral and viroid 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 my 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 encou-
ragement 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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