Legume Nitrogen Fixation in a Changing Environment: Achievements and Challenges

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.

Table of Contents:
Physiological responses of legume Nitrogen fixation to water limitation.- Salinity: physiological impacts on legume Nitrogen fixation.- How does high temperature affect legume nodule symbiotic activity.- Will elevated CO2 level amplify the benefits of symbiotic Nitrogen fixation in legumes.- Nodule physiological implications associated with soil acidity.

About the Author :

Dr. Lam-Son Phan Tran is Head of the Signaling Pathway Research Unit at RIKEN Center for Sustainable Resource Science, Japan. He obtained his MSc in Biotechnology in 1994 and PhD in Biological Sciences in 1997 from Szent Istvan University, Hungary. After doing his postdoctoral research at National Food Research Institute (1999-2000) and Nara Institute of Science and Technology of Japan (2001), from October 2001 he joined Japan International Research Center for Agricultural Sciences, to work on functional analysis of transcription factors and osmosensors in stress responses in Arabidopsis. In August 2007 he moved to University of Missouri-Columbia, USA as a Senior Research Scientist to coordinate a research team working on discovery of soybean genes for genetic engineering of drought-tolerant soybean plants. His current research interests are elucidation of the roles of phytohormones and their interactions in abiotic stress responses, as well as translational genomics of legume crops with the aim to enhance crop productivity under adverse environmental conditions. He has published over 80 peer-reviewed papers with more than 60 research and 20 review articles, contributed 7 book chapters to various book editions published by Springer, Wiley-Blackwell, and American Society of Agronomy, Crop Science Society of America and Soil Science Society of America. He has also edited four book volumes for Springer, including this one.

Dr. Saad Sulieman was graduated at the Faculty of Agriculture, University of Khartoum in 1998 with distinction in Agronomy and was awarded many prizes for being the best graduate. He joined the Department of Agronomy, Faculty of Agriculture, University of Khartoum as a Teaching Assistant in 1999. Subsequently, he was trained for MSc in Crop Sciences at the University of Khartoum (2002) and then for PhD in Agricultural Chemistry (2009) at Georg-August University of Göttingen, Germany with a PhD scholarship fromGerman Academic Exchange Service (DAAD). During his PhD pursuit, he focused on investigating the physiological characterization of symbioses contrasting tolerance in nitrogen fixation to major soil limitations (low soil bio-availability and excess of nitrate). After completing his PhD, he continued to work as a Research Assistant at the same institute for one and half year. He also worked as a Postdoctoral Fellow at RIKEN Center for Sustainable Resource Science (CSRS), Yokohama, Japan for one year (2013) with a Postdoctoral Fellowship from the Japan Society for the Promotion of Science (JSPS). Sulieman was promoted to Lecturer in 2005, Assistant Professor in 2009 and Associate Professor in 2013. He is actively involved in the teaching of undergraduate and postgraduate students, and throughout his career he trained many students to the level of BSc and MSc. Since 2014, he has been holding the position of Head of Department of Agronomy, University of Khartoum. Throughout the years of his research career, he has attended many domestic and international meetings, conferences, seminars and workshops. He has authored or co-authored more than 30 publications. The main thrust of his research is in the field of molecular plant physiology of abiotic stress.