The tight-adhesion proteins TadGEF of Bradyrhizobium diazoefficiens USDA 110 are involved in cell adhesion and infectivity on soybean roots

MONGIARDINI, EJ; PARISI, G; QUELAS, JI; LODEIRO, AR

MICROBIOLOGICAL RESEARCH

ELSEVIER GMBH

Año: 2016

0944-5013

Adhesion of symbiotic bacteria to host plants is an essentialearly step of the infection process that leads to the beneficialinteraction. In the Bradyrhizobium diazoefficiens-soybean symbiosis fewmolecular determinants of adhesion are known. Here we identified thetight-adhesion gene products TadGEF in the open-reading frames blr3941-blr3943 of the Bradyrhizobium diazoefficiens USDA 110 complete genomicsequence. Predicted structure of TadG indicates a transmembrane domainand two extracytosolic domains, from which the C-terminal has an integrinfold. TadE and TadF are also predicted as bearing transmembrane segments.Mutants in tadG or the small cluster tadGEF were impaired in adhesion tosoybean roots, and the root infection was delayed. However, nodulehistology was not compromised by the mutations, indicating that theseeffects were restricted to the earliest contact of the B. diazoefficiensand root surfaces. Knowledge of preinfection determinants is importantfor development of inoculants that are applied to soybean cropsworldwide.