The Glycine-Glomus-Rhizobium Symbiosis

Abstract

Four consecutive trifoliate leaves of 56-day-old symbiotic or nonsymbiotic soybean plants were evaluated individually for CO2 exchange rates (CER), leaf area and dry weight, and leaf N, P, and starch concentrations. Plants had been inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae and Rhizobium japonicum, with either of the endophytes alone, or with neither at time of planting. Plants lacking one or both endophytes received N and/or P fertilizers to produce plants of equal total leaf dry weight in all four treatments. Photosynthetic P-use efficiency (CER per unit leaf P) was higher in the leaves of VAM plants than in P-fertilized plants regardless of the N source (N2 fixation or combined N). Photosynthetic N-use efficiency was also higher in VAM than in non-VAM plants, but it was affected by the N source, with higher CER in the nodulated plants. The greatest differences in CER, starch accumulation and leaf area were found between the nonsymbiotic plants and those with both endophytes. Statistical evaluations of leaf parameters for treatment or nutrient concentration (N and P) effects between the tripartite and the nonsymbiotic treatments showed significant changes in concentration of P, but not N, with decreasing leaf age. Both endophytes apparently enhance CO2 fixation at N and/or P concentrations lower than those of the nonsymbiotic plants. The effects of the endophytes on CO2 fixation were additive.

Glycine-Glomus-Bradyrhizobium Symbiosis

“…7A and 6B) or higher (Fig. 7C) WUE in VAM plants at lower leafP concentrations (Table I) confirms previous observations of higher P-use efficiency in VAM than in nonVAM plants (12). In view ofthe similar behaVior of CER and transpiration in VAM and nonVAM plants (Fig.…”

Facilitation of plant phosphate acquisition by arbuscular mycotrhizas from enriched soil patches

“…Greater CO, uptake for mycorrhizal plants has been shown for a variety of plant species (Lose! & Cooper, 1979;Brown & Bethlenfalvay, 1988;Cui & Nobel, 1992) and might be associated with improved leaf P status (Johnson, 1984;Brown & Bethlenfalvay, 1988) or increased carbohydrate sinks. Despite the significantly greater COj uptake rates, total biomass was only slightly greater for mycorrhizal plants than for non-mycorrhizal plants in our study.…”

Influência de fungos micorrízicos arbusculares, associada à adição de compostos fenólicos, no crescimento de mudas de maracujazeiro amarelo (Passiflora edulis f. flavicarpus)

“…O estabelecimento de FMAs no sistema radicular das plantas influencia fatores fisiológicos, tais como: redução da suscetibilidade a certos patógenos (Dehne, 1982;Guillemin et al, 1994), tolerância ao estresse hídrico (Koide, 1985) e alteração da capacidade fotossintética da planta (Brown & Bethlenfalvay, 1988). Todavia, o principal benefício do fungo para a planta hospedeira, observado quanto ao de melhor desenvolvimento e estado nutricional da planta, está associado à maior absorção de nutrientes, principalmente os de baixa mobilidade no solo, como o fósforo, potássio, zinco e cobre (Marschner & Dell, 1994).…”