Mechanisms and Adaptation Strategies of Tolerance to Phosphorus Deficiency in Legumes
Mohamed Lazali, Jean Jacques Drevon
Abstract
Legumes are well recognized for their nutritional and health benefits as well as for their impact in the sustainability of agricultural systems, due to their ability to form a symbiosis with N2-fixing microorganisms. Nevertheless, legume N2 fixation has a high energy cost, and phosphorus (P) deficiency strongly hampers legume production, especially in low-P soils typical of most of the tropical regions. P-deficiency limits N2 fixation, since it has been described to have a strong impact on the growth and survival of both rhizobia and host plant. Legumes have evolved strategies at both morphological and physiological levels to adapt to P-deficiency. The maintenance of symbiotic N2 fixation seems to be a key aspect to assure legume productivity in low-P environments. During the last decades, physiological components and molecular players underlying P-deficiency adaptation responses have been elucidated. Hence, in order to design strategies to develop elite cultivars able to produce high-quality seeds and efficiently fix N2 under P-deficiency, it is important to understand how legumes cope with this nutritional constraint. In this review, we discuss future directions and research priorities that may lead to a better understanding of the physiological and molecular adaptations that allow the legumes to thrive under conditions of P-deficiency.