The nodulation genes of Mesorhizobium sp. (Astragalus sinicus) strain 7653R were cloned by functional complementation of Sinorhizobium meliloti nod mutants. The common nod genes, nodD, nodA, and nodBC, were identified by heterologous hybridization and sequence analysis. The nodA gene was found to be separated from nodBC by approximately 22 kb and was divergently transcribed. The 2. 0-kb nodDBC ...

An ultrasensitive bioassay system for the detection of N-acylhomoserine lactones (AHLs) was constructed in Agrobacterium tumefaciens by using the T7 expression system to overproduce the AHL receptor TraR. This strain detected many diverse AHLs, some at extremely low concentrations. We used this strain to detect for the first time AHLs made by Mesorhizobium huakuii, which symbiotically fixes nit...

1. ATP sulphurylases were partially purified (20-40-fold) from leaf tissue of Astragalus bisulcatus, Astragalus racemosus (selenium-accumulator species) and Astragalus hamosus and Astragalus sinicus (non-accumulator species). Activity was measured by sulphate-dependent PP(i)-ATP exchange. The enzymes were separated from pyrophosphatase and adenosine triphosphatase activities. The properties of ...

Astragalus sinicus (Chinese Milk vetch), a green manure leguminous plant, harbors Mesorhizobium huakuii subsp. rengei strain B3 in the root nodules. The visualization of symbiotic plasmid of strain B3 showed the presence of one sym plasmid of about 425 kbp. Curing of sym plasmid by temperature and acrydine orange was studied. Growing rhizobial cells at high temperature (37 degrees C) or treatin...

We expressed the Arabidopsis thaliana gene for phytochelatin synthase (PCS(At)) in Mesorhizobium huakuii subsp. rengei B3, a microsymbiont of Astragalus sinicus, a legume used as manure. The PCS(At) gene was expressed under the control of the nifH promoter, which regulates the nodule-specific expression of the nifH gene. The expression of the PCS(At) gene was demonstrated in free-living cells u...