Current Issues In Symbiotic Nitrogen Fixation

In the 100 years since the legume-Rhizobium symbiotic nitrogen fixation interaction was first described, interest in this field has grown rapidly. The types of studies have been cyclical in nature, involving a cross-section of disciplines. The availability of cheap nitrogenous fertilizers caused much of the biological nitrogen fixation research to become more theoretical in the developed world. The high cost of energy, coupled with environmental concerns and the interest in sustainable agriculture, has stimulated research in symbiotic nitrogen fixation. The development of modern genetic techniques has resulted in interdisciplinary research on plant-microbe interactions controlling nitrogen fixation. This has resulted in a better understanding of environmental factors influencing the nodulation process, chemical signalling between the symbiotic partners and the nature of the specificity between host plant and microsymbiotant. This volume summarizes the diverse research efforts in biological nitrogen fixation by presenting a collection of papers in the areas of physiology and metabolism, taxonomy and evolution, genetics and ecology.

During the past three decades there has been a large amount of research on biological nitrogen fixation, in part stimulated by increasing world prices of nitrogen-containing fertilizers and environmental concerns. In the last several years, research on plant--microbe interactions, and symbiotic and asymbiotic nitrogen fixation has become truly interdisciplinary in nature, stimulated to some degree by the use of modern genetic techniques. These methodologies have allowed us to make detailed analyses of plant and bacterial genes involved in symbiotic processes and to follow the growth and persistence of the root-nodule bacteria and free-living nitrogen-fixing bacteria in soils. Through the efforts of a large number of researchers we now have a better understanding of the ecology of rhizobia, environmental parameters affecting the infection and nodulation process, the nature of specificity, the biochemistry of host plants and microsymbionts, and chemical signalling between symbiotic partners. This volume gives a summary of current research efforts and knowledge in the field of biological nitrogen fixation. Since the research field is diverse in nature, this book presents a collection of papers in the major research area of physiology and metabolism, genetics, evolution, taxonomy, ecology, and international programs.

This volume discusses the most recent advances in biological nitrogen fixation, with chapters written by experts on the ecology, physiology, biochemistry and genetics of biological nitrogen fixation.

The core of the text is aimed at the research worker in the field of nitrogen fixation, but, despite its specialisation, does not lose the emphasis on teaching, both as a direct reference book and as a backbone for a graduate course on the subject.The closing part of the book includes a subject index and a glossary of terms. The latter was included not for the expert, for whom many of the definitions will be too general, but for the newcomer; the author hopes that the quick survey of key terms will help in the reading of this book.

The 14th International Nitrogen Fixation Congress was held in Beijing, China from October 27th through November 1st, 2004. This volume constitutes the proceedings of the Congress and represents a compilation of the presentations by scientists from more than 30 countries around the World who came to Beijing to discuss the progress made since the last Congress and to exchange ideas and information. This year marked the 30th anniversary of the first Congress held in Pullman, Washington, USA, in 1974. Since then, this series of Congresses has met five times in North America (three in the United States and once each in Canada and Mexico), once in South America (Brazil), four times in Western Europe (once each in Spain, The Netherlands, Germany and France), once in Eastern Europe (Russia), and once in Australia; and now for the first time in Asia. China was a most appropriate choice because China is a big country with the largest population in the World, about 1. 3 billion people, which is about 22% of the World’s population. It is traditionally an agricultural country, even though China has only 7% of the available farming land. This situation explains why agriculture and its productivity are major issues for the Chinese people, its government and the scientists in the field.

Biological Nitrogen Fixation is a comprehensive 3 volume work bringing together both review and original research articles on key topics in nitrogen fixation. Chapters across all three volumes emphasize molecular techniques and advanced biochemical analysis approaches applicable to various aspects of biological nitrogen fixation, but each volume also has a unique focus: Volume I explores the chemistry and biochemistry of nitrogenases, nif gene regulation, the taxonomy, evolution, and genomics of nitrogen fixing organisms, as well as their physiology and metabolism. Volume II covers the symbiotic interaction of nitrogen fixing organisms with their host plants, including nodulation and symbiotic nitrogen fixation. Volume III features chapters on the "omics" of nitrogen fixing organisms and host plants, nitrogen fixing cyanobacteria and archaea, nitrogen fixing plant growth promoting rhizobacteria and non-legumes, as well as field studies and nitrogen fixation in cereals. Covering the full breadth of current nitrogen fixation research and synthesizing it to point the way forward,Biological Nitrogen Fixation will be a one-stop reference for microbial ecologists and environmental microbiologists as well as plant and agricultural researchers working on crop sustainability.

The world population will grow more rapidly during the few coming years. This must be accompanied by a parallel increase in the agricultural production to secure adequate food. Sustainability considerations mandate that alternatives to chemical nitrogen fertilizers must be urgently sought. Biological nitrogen (N2) fixation, a microbiological process which converts atmospheric N2 into a plant-usable form, offers this alternative. Among these renewable sources, N2-fixing legumes offer an economically attractive and ecologically sound means of reducing external inputs and improving internal resources. Environmental factors such as drought, elevated temperature, salinity, soil acidity and rising CO2 are known to dramatically affect the symbiotic process and thus play a part in determining the actual amount of nitrogen fixed by a given legume in the field. Understanding how nodule N2 fixation responds to the environment is crucial for improving legume production and maintaining sustainability in the context of global change. In this thoughtful and provocative new Brief, we provide critical information on how current and projected future changes in the environment will affect legume growth and their symbiotic N2 fixing capabilities. Each section reviews the main drivers of environmental change on the legume performance that include drought, elevated temperature, salinity and rising CO2, and soil acidity. Importantly we discuss the molecular approaches to the analysis of the stress response in legumes and the possible biotechnological strategies to overcome their detrimental effects.