title: Phosphorus homeostasis in legume nodules as an adaptive strategy to phosphorus deficiency.
abstract: Legumes have a significant role in effective management of fertilizers and improving soil health in sustainable agriculture. Because of the high phosphorus (P) requirements of N2-fixing nodule, P deficiency represents an important constraint for legume crop production, especially in tropical marginal countries. P deficiency is an important constraint for legume crop production, especially in poor soils present in many tropical degraded areas. Unlike nitrogen, mineral P sources are nonrenewable, and high-grade rock phosphates are expected to be depleted in the near future. Accordingly, developing legume cultivars with effective N2 fixation under P-limited conditions could have a profound significance for improving agricultural sustainability. Legumes have evolved strategies at both morphological and physiological levels to adapt to P deficiency. Molecular mechanisms underlying the adaptive strategies to P deficiency have been elucidated in legumes. These include maintenance of the P-homeostasis in nodules as a main adaptive strategy for rhizobia-legume symbiosis under P deficiency. The stabilization of P levels in the symbiotic tissues can be achieved through several mechanisms, including elevated P allocation to nodules, formation of a strong P sink in nodules, direct P acquisition via nodule surface and P remobilization from organic-P containing substances. The detailed biochemical, physiological and molecular understanding will be essential to the advancement of genetic and molecular approaches for enhancement of legume adaptation to P deficiency. In this review, we evaluate recent progress made to gain further and deeper insights into the physiological, biochemical and molecular reprogramming that legumes use to maintain P-homeostasis in nodules during P scarcity.
authors.affiliation: Department of Agronomy, Faculty of Agriculture, University of Khartoum, 13314 Shambat, Khartoum North, Sudan. Electronic address: saadsulieman@hotmail.com.
authors.forename: Saad
authors.initials: S
authors.lastname: Sulieman
authors.affiliation: Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science (CSRS), 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan. Electronic address: son.tran@riken.jp.
authors.forename: Lam-Son Phan
authors.initials: LS
authors.lastname: Tran
mesh_terms: D007887:Fabaceae / Q000378:metabolism*; D006706:Homeostasis; D010758:Phosphorus / Q000172:deficiency / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000378:metabolism*
chemical_list: D010758:Phosphorus
keywords: Acid phosphatase; Molecular adaptation; Nitrogenase activity; P deficiency; P homeostasis; Symbiosis capacity