Journal Article

Sinorhizobium fredii HH103 flgJ is a flagellar gene induced by genistein in a NodD1- and TtsI- dependent manner

Vinardell, José-María, López-Baena, Francisco-Javier, Fuentes-Romero, Francisco, Navarro-Gómez, Pilar, Alías-Villegas, Cynthia, Jiménez-Guerrero, Irene, Acosta-Jurado, Sebastián

2024

Overview

Background and aims Sinorhizobium fredii  HH103 is a broad host-range rhizobial strain able to induce the formation of nitrogen-fixing nodules in dozens of legumes, including soybean.  S. fredii  HH103 exhibits genistein-induced surface motility. The aim of this work has been to determine whether the  flgJ  gene, which is inducible by genistein and codes for a flagellar protein, is involved in this motility and is relevant for symbiosis with soybean. Methods We have generated two independent mutants in the  flgJ  gene of HH103 and analysed their phenotypes in motility, exopolysaccharide production, biofilm formation, soybean root colonization, symbiosis with soybean, and secretion of effector proteins. We have also further studied the regulation of the expression of  flgJ . Results We show that the expression of  flgJ  is driven by a  tts  box previously not detected, which accounts for its induction by flavonoids and the NodD1 and TtsI transcriptional activators. Inactivation of  flgJ  led to severe impairments in bacterial motility (swimming and genistein-induced surface motility) as well as to a significant reduction in symbiotic performance with soybean when bacteria are not directly inoculated onto the seedling roots. However, the absence of a functional FlgJ protein did not affect the bacterial ability to colonize soybean roots. Conclusion The  flgJ  gene of  S. fredii  HH103 connects the  nod  regulon with the genistein-induced surface motility exhibited by this rhizobial strain.

• Publisher: Springer International Publishing,Springer,Springer Nature B.V
• Subject: Agriculture / Bacteria / bacterial motility / Beans / biofilm / Biofilms / Biomedical and Life Sciences / Ecology / Environmental aspects / Exopolysaccharides / Fixation / Flagella / Flavonoids / Gene regulation / Genetic aspects / Genistein / host range / Legumes / Life Sciences / Mimosaceae / Motility / Nitrogen / Nitrogen fixation / Nitrogenation / Nodules / Phenotypes / Physiological aspects / Plant Physiology / Plant Sciences / Proteins / regulon / Research Article / Roots / secretion / Seedlings / Sinorhizobium fredii / soil / Soil microbiology / Soil Science & Conservation / Soybeans / Swimming / Symbiosis / transcription (genetics) / Transcription factors