Biomaterial Database

Nitrogen fixation and carbon metabolism in legume nodules. 2004

Neera Garg, and Ranju Singla, and Geetanjali

Department of Botany, Panjab University, Chandigarh 160014, India. gargneera@yahoo.co.in

A large amount of energy is utilized by legume nodules for the fixation of nitrogen and assimilation of fixed nitrogen (ammonia) into organic compounds. The source of energy is provided in the form of photosynthates by the host plant. Phosphoenol pyruvate carboxylase (PEPC) enzyme, which is responsible for carbon dioxide fixation in C4 and crassulacean acid metabolism plants, has also been found to play an important role in carbon metabolism in legume root nodule. PEPC-mediated CO2 fixation in nodules results in the synthesis of C4 dicarboxylic acids, viz. aspartate, malate, fumarate etc. which can be transported into bacteroids with the intervention of dicarboxylate transporter (DCT) protein. PEPC has been purified from the root nodules of few legume species. Information on the relationship between nitrogen fixation and carbon metabolism through PEPC in leguminous plants is scanty and incoherent. This review summarizes the various aspects of carbon and nitrogen metabolism in legume root nodules.

UI	MeSH Term	Description	Entries
D007887	Fabaceae	The large family of plants characterized by pods. Some are edible and some cause LATHYRISM or FAVISM and other forms of poisoning. Other species yield useful materials like gums from ACACIA and various LECTINS like PHYTOHEMAGGLUTININS from PHASEOLUS. Many of them harbor NITROGEN FIXATION bacteria on their roots. Many but not all species of "beans" belong to this family.	Afzelia,Amorpha,Andira,Baptisia,Callerya,Ceratonia,Clathrotropis,Colophospermum,Copaifera,Delonix,Euchresta,Guibourtia,Legumes,Machaerium,Pithecolobium,Stryphnodendron,Leguminosae,Pea Family,Pithecellobium,Tachigalia,Families, Pea,Family, Pea,Legume,Pea Families
D009586	Nitrogen Fixation	The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.	Diazotrophy,Diazotrophic Activity,Dinitrogen Fixation,N2 Fixation,Activities, Diazotrophic,Activity, Diazotrophic,Diazotrophic Activities,Fixation, Dinitrogen,Fixation, N2,Fixation, Nitrogen
D010730	Phosphoenolpyruvate Carboxylase	An enzyme with high affinity for carbon dioxide. It catalyzes irreversibly the formation of oxaloacetate from phosphoenolpyruvate and carbon dioxide. This fixation of carbon dioxide in several bacteria and some plants is the first step in the biosynthesis of glucose. EC 4.1.1.31.	Carboxylase, Phosphoenolpyruvate
D002244	Carbon	A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.	Carbon-12,Vitreous Carbon,Carbon 12,Carbon, Vitreous
D018517	Plant Roots	The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)	Plant Bulbs,Plant Root,Bulb, Plant,Bulbs, Plant,Plant Bulb,Root, Plant,Roots, Plant