[The role of iron-uptake factor PiuB in pathogenicity of soybean pathogen Xanthomonas axonopodis pv. glycines].

ABSTRACT

Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe3+, Cu2+, Zn2+ and Mn2+ was significantly enhanced. Additionally, the H2O2 resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe3+ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe3+, and is necessary for Xag to be pathogenic in host soybean.