Lack of Galactose or Galacturonic Acid in Bradyrhizobium japonicum USDA 110 Exopolysaccharide Leads to Different Symbiotic Responses in Soybean

• DOI: 10.1094/mpmi-05-10-0122
• Publication Date: 2010-07-16T17:00:47Z
• Authors: Juan Ignacio Quelas; Elías J. Mongiardini; Adriana Casabuono; Silvina L. López-...; M. Julia Althabeg...; Julieta M. Covelli; Julieta Pérez-Gim...; Alicia Couto; Aníbal R. Lodeiro
• Keywords: Bradyrhizobium japonicum; Bradyrhizobium

Exopolysaccharide (EPS) and lipopolysaccharide (LPS) from Bradyrhizobium japonicum are important for infection nodulation of soybean (Glycine max), although their roles not completely understood. To better understand this, we constructed mutants in B. USDA 110 impaired galactose or galacturonic acid incorporation into the EPS without affecting LPS. The derivative LP 3010 had a deletion lspL-ugdH produced whereas 3013, with an insertion exoB, galactose. In addition, strain 3017, both mutations, devoid galactosides. missing galactosides were replaced by other sugars. defects different consequences. formed biofilms nodulated but was defective competitiveness nodulation; and, inside nodules, peribacteroid membranes tended to fuse, leading merging symbiosomes. Meanwhile, 3013 3017 unable form empty pseudonodules exoB suppressor obtained when plant inoculation supplemented wild-type EPS. Similar phenotypes observed all these G. soja. Therefore, lack each galactoside has functional effect on japonicum–soybean symbiosis.