RESUMO
A link between the T3SS and inhibition of swimming motility by the transcriptional regulator TtsI in Mesorhizobium japonicum MAFF303099 has been previously reported. Here, we show that mutants in T3SS components display impaired biofilm formation capacity, indicating that a functional T3SS, or at least pili formation, is required for this process. As a first approach to the cdiG regulation network in this bacterium, we started a study of the second messenger cdiG by overexpressing or by deleting some genes encoding cdiG metabolizing enzymes. Overexpression of two putative PDEs as well as deletion of various DGCs led to reduced biofilm formation on glass tubes. Mutation of dgc9509 also affected negatively the nodulation and symbiosis efficiency on Lotus plants, which can be related to the observed reduction in adhesion to plant roots. Results from transcriptional nopX- and ttsI-promoter-lacZ fusions suggested that cdiG negatively regulates T3SS expression in M. japonicum MAFF303099.
Assuntos
Mesorhizobium , Simbiose , Mesorhizobium/genética , Membrana Celular , BiofilmesRESUMO
The in vitro growth of Bradyrhizobium diazoefficiens USDA 110 strain is inhibited by glyphosate. The herbicide affects 5-enolpyruvylshikimic acid-3-phosphate synthase, a key enzyme for aromatic aminoacid synthesis. In this study, site-directed mutagenesis was used to change only two nucleotides of the coding region of phosphoenolpyruvate binding site. This change improved the in vitro growth of B. diazoefficiens USDA 110 in the presence of glyphosate, without affecting its normal growth in the absence of the herbicide. Plant co-inoculation experiments demonstrated a better competitiveness of the glyphosate-resistant strain for soybean nodulation in the presence of glyphosate.