Effect of common bean seed exudates on growth, lipopolysaccharide production, and lipopolysaccharide transport gene expression of .

Lipopolysaccharide (LPS) is essential for successful nodulation during the symbiosis of rhizobia and legumes. However, the detailed mechanism of the LPS in this process has not yet been clearly elucidated. In this study, the effects of common bean seed exudates on the growth, lipopolysaccharide production, and lipopolysaccharide transport genes expression () of were investigated. exposed to exudates showed changes in LPS electrophoretic profiles and content, whereby the LPS band was wider and the LPS content was higher in treated with seed exudates. Exudates enhanced cell growth of in a concentration-dependent manner; exposed to higher doses of the exudate showed faster growth. Seven genes of were amplified and sequenced. Sequences of six genes, except for , were the same as those found in previously analyzed strains, while shared low sequence similarity with other strains. Exposure to the exudates strongly stimulated the expression of all genes. Approximately 6.7- () to 301-fold () increases in the transcriptional levels were observed after only 15 min of exposure to exudates. These results indicate that seed exudates affect the LPS by making the cell wall structure more conducive to symbiotic nodulation.