Acetylene Reduction by Symbiosomes and Free Bacteroids from Broad Bean (Vicia faba L.) Nodules (Role of Oxalate)

Abstract

and Rigaud, 1987), glutamate (Kahn et al., 1985), or Pro (Kohl et al., 1988) to be potential sources of energy for bacteroids. However, the preparation of intact symbiosomes from different legumes (Herrada et al., 1989; Udvardi and D~~, 1989;Rosendahl et 1992) has provided interesting infomation conceming the selectivity of the PBM and has lead to a reappraisal of the tyPe of substrates available to the bacteroid' Thusf the absence Of carriers for glutamate (Udvardi et 1988; Herrada et 1989) Or Pro (Udvardi et al.f 1990) on the PBM stronglY lifits the possibilitY that these mokcules are SOurceS of energy for bacteroids. In the same way, the abundance of certain carbohydrates in the nodule cytosol does not necessarily imply that it is utilized by the bacteroid. This situation occurs for &ate and benzoate, which is found in soybean (Glycine max L.) (Streeter, 1991), but these molecules are unable to cross the PBM (Herrada et al., 1989).In this paper we report the presence of high concentrationsOf oxalate in broad bean (Vicia fabQ L.1 nodules and examine the ability of oxalate to CrOSS the PBM and the bacteroid membranes. In addition, we studied the capacity for oxalate to support C2H2 reduction and respiration in symbiosomes and free bacteroids in the presence of leghemoglobin.We report the presence of oxalate in the organic acid fraction of broad bean (Vicia faba 1.) nodule cytosol. Using both highperformance liquid chromatography and enzymic assays, high levels of oxalate were detected (70.4 f 2.4 mM). The Rhizobium-legume symbiosis is characteked by numerous and complex interactions between the two partners. Besides the exchange of signals during the recognition (Long, 1989; Dénarié et al., 1992) and the differentiation of nodules (Truchet et al., 1991), the microsymbionts receive reduced C and, in retum, provide the host cell with ammonia. The infected cells contain large numbers of bacteroids that express nitrogenase, and a piasmalemma-type membrane that separates the bacteroids from the host cytosol. This PBM defines the bacteroid-containing compartment known as a 'symbiosome" (Roth et al., 1988).Studies of N2 fixation at the cellular leve1 in nodules have involved, until now, isolation of bacteroids and the provision of succinate or malate as the energy-yielding substrates (Bergersen and Tumer, 1975b). Besides the essential role played by organic acids to support N2 fixation (Day and Copeland, 1991; Streeter, 1991), studies have explored the ability of other molecules such as Glc (Trinchant et al., 1981; Trinchant MATERIALS AND METHODS ,,iant CultureBroad beans (Vicia faba L. var minor cv Soravi) were grown in a glasshouse in a sand:vermiculite mixture (3:1, v/v) under the conditions reported elsewhere (Guérin et al., 1990). Seedlings were inoculated 5 and 7 d after planting with a mixture of three strains of Rhizobium leguminosarum bv uiciae (FH 25, FH 34, and FH 20S1), kindly provided by N. Amarger (Institut National de la Recherche Agronomique, Dijon, France). Nodules appeared on the roots abo...

A Previously Unknown Oxalyl-CoA Synthetase Is Important for Oxalate Catabolism in Arabidopsis

“…In many plants, oxalate is not merely an intermediate in catabolic pathways. It has been observed to be synthesized in response to aluminum toxicity (Ma et al, 1997;Klug and Horst, 2010), as a carbon source for symbiotic nitrogen fixation (Trinchant et al, 1994), and, most broadly, for the production of calcium oxalate crystals in diverse plant species (Nakata, 2003;Franceschi and Nakata, 2005). In oxalate-accumulating plants, calcium oxalate crystal accumulation occurs in specialized idioblast cells.…”

Nutrient Sharing between Symbionts

“…Transport studies with symbiosomes isolated from soybean, P. vulgaris, and V. faba have failed to identify active amino acid transport across the symbiosome membrane (Udvardi et al, 1988;Herrada et al, 1989;Ouyang and Day, 1992;Trinchant et al, 1994). Many amino acid transporters are proton coupled and operate as symporters.…”

Microbial Relatives of the Seed Storage Proteins of Higher Plants: Conservation of Structure and Diversification of Function during Evolution of the Cupin Superfamily

“…In addition to this evidence for the existence of a GLP related to bacterial attachment to the wall of legume root tips, it is known that oxalate itself is found at the very high level of 70 mM in faba bean (Vicia faba) nodules (294). Application of water stress to such nodules increases the level of bacteroid OXO fourfold and reduces the level of oxalic acid by 55% (295).…”