Ion distribution across the cortex of soybean nodules: possible involvement in control of oxygen diffusion
1994
Minchin, F.R. | Thomas, B.J. | Mytton, L.R.
X-ray microanalysis was used to study ion distribution in nodules of soybean [Glycine max (L.)] cv. Clarke formed with two strains of Bradyrhizobium japonicum; RCR3407 and RCR3442. Previous studies have shown that the oxygen diffusion barrier in nodules of the RCR3442 symbiosis has slower responses to acetylene and increased external oxygen than those of the RCR3407 symbiosis and this variation is correlated with differences in glycoprotein content. X-ray maps and cross-cortical cell counts of nodules formed by either strain show very similar zonal distributions of Mg, K, S and Ca across the cortex. Levels of K appear to be similar but levels of Mg, S and Ca seem to be lower in nodules of the RCR3442 symbiosis. These results suggest that the content and distribution of Mg, S and Ca reflect an involvement in the operation of the cortical diffusion barrier.
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