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.
