Claudine Elmerich - Böcker

The refinement of molecular techniques and the development of new probes of the phylogeny of diazotrophs has revealed an extreme biodiversity among the nitrogen fixers, which helps explain the role that nitrogen fixation plays in maintaining life on Earth. The most efficient ecosystems are those in which the bacteria are associated with a plant in differentiated organs to benefit crop productivity. Most short-term benefit from fundamental research on nitrogen fixation is likely to result in the improvement of existing nitrogen-fixing symbiotic or associative systems. Longer-term efforts are aimed at extending the nitrogen-fixing capacity to other organisms, including transfer of the genetic information for efficient nitrogen fixation into the plant genome and using current knowledge of microbe-plant interactions to extend symbiosis to cereals and, in particular, to rice. Related challenges in sustainable agriculture and forestry include the creation of new nitrogen-fixing associations. All of these topics were discussed at the 11th International Congress on Nitrogen Fixation, held in Paris in July 1997, the proceedings of which are presented in this book.

This self-contained volume covers fundamental and applied aspects of nitrogen-fixation research. The book describes milestones in the discovery of the associative and endophytic nitrogen-fixing bacteria found involved with cereal crops, forage grasses, and sugar cane.

The 14th International Nitrogen Fixation Congress was held in Beijing, China from October 27th through November 1st, 2004.

Poverty is a severe problem in Africa, Asia, South America and even in pockets of the developed world. Addressing poverty alleviation via the expanded use of biological nitrogen fixation in agriculture was the theme of the 15th International Congress on Nitrogen Fixation. Because nitrogen-fixation research is multidisciplinary, exploiting its benefits for agriculture and environmental protection has continued to attract research by diverse groups of scientists, including chemists, biochemists, plant physiologists, evolutionary biologists, ecologists, agricultural scientists, extension agents, and inoculant producers. The 15th International Congress on Nitrogen Fixation was held jointly with the 12th International Conference of the African Association for Biological Nitrogen Fixation. This joint Congress was hosted in South Africa at the Cape Town International Conv- tion Centre, 21–26 January 2007, and was attended by about 200 registered participants from 41 countries world-wide. During the Congress, some 100 oral and approximately 80 poster papers were presented. The wide range of topics covered and the theme of the Congress justifies this book’s title, Nitrogen Fixation: Applications to Poverty Alleviation.

Associative and Endophytic Nitrogen-fixing Bacteria and Cyanobacterial Associations This book is part of the seven-volume series that was launched a few years ago with the ambitious objectives of reviewing the field of nitrogen fixation from its earliest beginnings through the millennium change and of consolidating the relevant information - from fundamental to agricultural and environmental aspects – all in one place. Volume 5 covers the biology of bacteria that associate with n- leguminous plants. The subject matter includes a wide range of associations; it covers the bacterial species that associate either with the surface or within the tissues of grasses (often referred as plant growth-promoting rhizobacteria) and also the symbiotic associations that cyanobacteria form with fungi, algae, and both lower and higher plants. This volume does not deal with the Frankia-actinorhizal plant associations, which is the topic of Volume 6. The book is divided in 13 chapters, each of which is the work of well-known scientists in the field. Just like in the other volumes of this series, the first chapter is th an historical perspective. It describes how, as early as the end of the 19 century, it was shown that plant exudation favoured the proliferation of soil bacteria in the rhizosphere, and how the first nitrogen-fixing bacteria, including cyanobacteria were isolated. The chapter covers the landmarks and scientific concepts that arose from more than one century of research in this area.

This volume covers all aspects of fundamental and applied nitrogen-fixation research, extending from biochemistry and chemistry through genetics, regulation and physiology to agricultural practice and environmental impact. It describes recent progress on studies of potential catalysts for nitrogen fixation; how the N2-fixing process is regulated in living cells; the use and impact of genetics and genomics on our understanding of the biological process; the wide variety of associations of nitrogen-fixing microbes with plants, including the formalized Rhizobium-legume and actinorrhizal associations as well as the less formalized associative and endophytic interactions; and the impact of nitrogen fixation in agriculture and forestry, including its effect on the environment. This volume provides an up-to-date referenced source, which can be readily accessed by all practicing and otherwise interested proponents of nitrogen fixation research, including those with related interests in the areas of plant and microbial science, genomics, plant-microbe interactions, genetics and regulation, plant growth and biocontrol, agriculture, forestry, ecology, taxonomy and evolution.

This volume covers recent developments in both fundamental and applied research in biological nitrogen fixation. It emphasizes the application of biological nitrogen fixation for sustainable agriculture, which should lead to poverty alleviation, environmental protection, and good agricultural practices generally. The roles of, and advances in, plant breeding, plant molecular biology, nodule physiology, and symbiotic and associative interactions between plants and microbes in sustaining agricultural productivity and soil fertility are described. The evolution of symbioses and nitrogen fixation are also covered in this volume. To ensure high agricultural productivity, while protecting the environment (both soil and water resources), requires plant cultivars that also respond to beneficial microbes. The volume, therefore, describes the physiology and genomics of nitrogen-fixing bacteria together with the biochemistry and molecular genetics of the nitrogenase enzyme that actually fixes atmospheric nitrogen to a usable form.This volume, which covers the most recent data on the role of nitrogen fixation in agriculture and forestry and on the biology of both plants and nitrogen-fixing microbes, is intended to serve as a useful reference for students and researchers, both in the laboratory (academic and commercial) and in the field.