Plant Microbe Symbiosis

This book provides an overview of the latest advances concerning symbiotic relationships between plants and microbes, and their applications in plant productivity and agricultural sustainability. Symbiosis is a living phenomenon including dynamic variations in the genome, metabolism and signaling network, and adopting a multidirectional perspective on their interactions is required when studying symbiotic organisms. Although various plant-microbe symbiotic systems are covered in this book, it especially focuses on arbuscular mycorrhiza (AM) symbiosis and root nodule symbiosis, the two most prevalent systems. AM symbiosis involves the most extensive interaction between plants and microbes, in the context of phylogeny and ecology. As more than 90% of all known species of plants have the potential to form mycorrhizal associations, the productivity and species composition, as well as the diversity of natural ecosystems, are frequently dependent upon the presence and activity of mycorrhizas. In turn, root nodule symbiosis includes morphogenesis and is formed by communication between plants and nitrogen-fixing bacteria. The biotechnological application of plant–microbe symbiosis is expected to foster the production of agricultural and horticultural products while maintaining ecologically and economically sustainable production systems. Designed as a hands-on guide, this book offers an essential resource for researchers and students in the areas of agri-biotechnology, soil biology and fungal biology.

Plants form mutualistic association with various microorganisms, particularly in the rhizosphere region. The association benefits both the partners in a number of ways. A single plant can support the growth of diverse microbes and in reciprocation these microbes help the plant in several ways. A great deal of knowledge is now available on the mechanisms of action of plant growth promoting microbes in forming association with their partner plant and benefitting it. With ever increasing population and to achieve food security it has become utmost necessary to utilize these friendly microbes to enhance the crop yield and quality in an ecofriendly and sustainable manner. We already know about the huge negative impact of chemicals used in agriculture on the humans and the ecosystems as whole. ‘Plant Microbes Symbiosis – Applied Facets’ provides a comprehensive knowledge on practical, functional and purposeful utility of plant-microbe interactions. The book reviews the utilization of beneficial microbes for crop yield enhancement and protection against diseases caused by phytopathogens and nutrient deficiencies. The tome also reviews the utility of plant growth promoting microbes in helping the plants to deal with abiotic stresses imposed by climate change and anthropogenic activities. The book showcases how plant-microbe interactions are or can be utilized for reclamation of stressed soils and degradation of pollutants in a most effective and environment friendly manner. It also ascertains the reasons for the below par performance of the microbial based inoculants. The utilization of biotechnological tools for development of next generation bioformulations to combat the new challenges and overcome past hurdles has been discussed. This wonderful association between plants and microbes if used properly will not only enhance the crop yields and reclaim barren lands but also make our planet a better place to live on for all of its habitants.

Plant microbe interaction is a complex relationship that can have various beneficial impacts on both the communities. An urgent need of today’s world is to get high crop yields in an ecofriendly manner. Utilization of beneficial and multifaceted plant growth promoting (PGP) microorganisms can solve the problem of getting enhanced yields without disturbing the ecosystem thus leading to sustainability. For this to achieve understanding of the intricate details of how the beneficial microbes form associations with the host plant and sustain that for millions of years must be known. A holistic approach is required wherein the diversity of microbes associated with plant and the network of mechanisms by which they benefit the host must be studied and utilized. ‘Plant Microbe Symbiosis – Fundamentals and Advances’ provides a comprehensive understanding of positive interactions that occur between plant and microorganisms and their utilization in the fields. The book reviews the enormous diversity of plant associated microbes, the dialog between plant-microbes-microbes and mechanisms of action of PGP microbes. Utilization of PGPRs as nutrient providers, in combating phytopathogens and ameliorating the stressed and polluted soils is also explained. Importantly, the book also throws light on the unanswered questions and future direction of research in the field. It illustrates how the basic knowledge can be amalgamated with advanced technology to design the future bioformulations.

The book addresses current public concern about the adverse effect of agrochemicals and their effect on the agro-ecosystem. This book also aims to satisfy and contribute to the increasing interest in understanding the co-operative activities among microbial populations and their interaction with plants. It contains chapters on a variety of interrelated aspects of plant-microbe interactions with a single theme of stress management and sustainable agriculture. The book will be very useful for students, academicians, researcher working on plant-microbe interaction and also for policy makers involved in food security and sustainable agriculture.

A description of of molecular techniques made accessible to final year students and postgraduates.

Recent years have seen tremendous progress in unraveling the molecular basis of different plant-microbe interactions. Knowledge has accumulated on the mecha nisms of the microbial infection of plants, which can lead to either disease or resistance. The mechanisms developed by plants to interact with microbes, whether viruses, bacteria, or fungi, involve events that can lead to symbiotic association or to disease or tumor formation. Cell death caused by pathogen infection has been of great interest for many years because of its association with plant resistance. There appear to be two types of plant cell death associated with pathogen infection, a rapid hypersensitive cell death localized at the site of infection during an incompatible interaction between a resistant plant and an avirulent pathogen, and a slow, normosensitive plant cell death that spreads beyond the site of infection during some compatible interactions involving a susceptible plant and a virulent, necrogenic pathogen. Plants possess a number of defense mechanisms against infection, such as (i) production of phytoalexin, (ii) formation of hydrolases, (iii) accumulation of hydroxyproline-rich glycoprotein and lignin deposition, (iv) production of pathogen-related proteins, (v) produc tion of oligosaccharides, jasmonic acid, and various other phenolic substances, and (vi) production of toxin-metabolizing enzymes. Based on these observations, insertion of a single suitable gene in a particular plant has yielded promising results in imparting resistance against specific infection or disease. It appears that a signal received after microbe infection triggers different signal transduction pathways.

This volume comprises the lectures of the speakers at the NATO Advanced Research Workshop held at the Congress Centre The Flevohof at Biddinghuizen, The Netherlands, May 11-16, 1986. The purpose of the workshop was to bring together experts in symbiosis, plant pathology and plant molecular biology in order to discuss recent progress in the field of microbe -plant re cognition at the molecular level, to promote integration of various disciplines, and to define recommendations for future research and applications. Plants have developed a variety of sophisticated defence mechanisms to cope with an environment in which many different microbes live. Most microbes which colonize plant tissues are harmless. Some microbes have developed ways to attack plants successfully, resulting in enormous losses of crop yields. Other microbes have reached an agreement with the host plant which is beneficial for both: these microbes live in symbiosis with the plant and provide their host plant for example with substantial amounts of atmospheric nitrogen. Chemical protection of crops is a necessity in modern crop management but this treatment has some negative effects as well. Therefore scientists are looking for alternative, biological, ways to control crop pests. Against this background specialists from eleven countries discussed the results of their most recent work on the molecular background of microbe -plant interactions. It appeared that, in order to capitalize the recent rapid progress made in the mole cular genetical studies on Rhizobium-legume and pathogen-host plant interactions, a multidisciplinary approach is required.