Page 2 Plant-Bacteria Interactions Edited by Iqbal Ahmad, John ...

11
Rhamnolipid-Producing PGPR and Their Role in Damping-Off
Disease Suppression
Alok Sharma
Dedicated to Professor Bhavdish N. Johri on his 63rd birthday.
11.1
Introduction
In the course of industrialization, several problems have been created such as
excessive use of synthetic products to achieve greater crop yield and protect plants
from phytopathogens. This has resulted in the pollution of the environment,
while pathogens have adapted themselves to such chemicals. Realizing the severity
of the problem, several of these chemicals have been banned globally. Therefore, the
issue of sustainable agriculture, one that is based on the use of eco-friendly agents,
has gained more currency today. It is here that biological agents derived from
antagonistic and plant growth promoting rhizobacteria or as supplements to chemical
pesticides have been promoted in a system of integrated plant disease management,
acquiring considerable acceptance in recent times [1].
Over the past few years, agricultural policies in developing countries have undergone
major changes to meet the increased demand of food through diversification in
general and emphasis on sustainable production systems in particular. The latter is a
consequence of problems associated with nonjudicious use of fertilizers and pesticides,
as well as the low purchasing power of the marginal farmer. Intervention of
biotechnologies in development strategies is therefore of prime significance to crop
management. Biological control, using microorganisms to suppress plant diseases,
offers a powerful and inevitable alternative to the application of synthetic chemicals.
With the growing importance of such control systems in plant disease management,
study of the mechanisms involved is paramount [2,3]. Consequently, it is imperative
to establish the molecular basis behind the success of these approaches in the
context of their interaction with nature and their potential applicability. Despite
this complexity, benefits of biocontrol mechanisms and their growth promotion
attributes have been demonstrated in several plant systems [4–8].
The increasing use of chemical inputs causes several negative effects, development
of pathogen resistance to the applied agents and nontarget environmental
Plant-Bacteria Interactions. Strategies and Techniques to Promote Plant Growth
Edited by Iqbal Ahmad, John Pichtel, and Shamsul Hayat
Copyright Ó 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
ISBN: 978-3-527-31901-5
j213