| Literature DB >> 10877796 |
X X Zhang1, S L Turner, X W Guo, H J Yang, F Debellé, G P Yang, J Dénarié, J P Young, F D Li.
Abstract
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 region was amplified by PCR from 24 rhizobial strains nodulating A. sinicus, which represented different chromosomal genotypes and geographic origins. No polymorphism was found in the size of PCR products, suggesting that the separation of nodA from nodBC is a common feature of A. sinicus rhizobia. Sequence analysis of the PCR-amplified nodA gene indicated that seven strains representing different 16S and 23S ribosomal DNA genotypes had identical nodA sequences. These data indicate that, whereas microsymbionts of A. sinicus exhibit chromosomal diversity, their nodulation genes are conserved, supporting the hypothesis of horizontal transfer of nod genes among diverse recipient bacteria.Entities:
Mesh：
Substances：
Year: 2000 PMID： 10877796 PMCID： PMC92101 DOI： 10.1128/AEM.66.7.2988-2995.2000
Source DB: PubMed Journal: Appl Environ Microbiol ISSN： 0099-2240 Impact factor: 4.792