Polyamines produced by Sinorhizobium meliloti Rm8530 contribute to symbiotically relevant phenotypes ex planta and to nodulation efficiency on alfalfa.

Polyamines produced by Sinorhizobium meliloti Rm8530 contribute to symbiotically relevant phenotypes ex planta and to nodulation efficiency on alfalfa. Microbiology. 2020 Jan 14;: Authors: Becerra-Rivera VA, Arteaga A, Leija A, Hernández G, Dunn MF Abstract In nitrogen-fixing rhizobia, emerging evidence shows significant roles for polyamines in growth and abiotic stress resistance. In this work we show that a polyamine-deficient ornithine decarboxylase null mutant (odc2) derived from Sinorhizobium meliloti Rm8530 had significant phenotypic differences from the wild-type, including greatly reduced production of exopolysaccharides (EPS; ostensibly both succinoglycan and galactoglucan), increased sensitivity to oxidative stress and decreased swimming motility. The introduction of the odc2 gene borne on a plasmid into the odc2 mutant restored wild-type phenotypes for EPS production, growth under oxidative stress and swimming. The production of calcofluor-binding EPS (succinoglycan) by the odc2 mutant was also completely or mostly restored in the presence of exogenous spermidine (Spd), norspermidine (NSpd) or spermine (Spm). The odc2 mutant formed about 25 % more biofilm than the wild-type, and its ability to form biofilm was significantly inhibited by exogenous Spd, NSpd or Spm. The odc2 mutant formed a less efficient symbiosis with alfalfa, resulting in plants with significantly less biomass and height, more nodules but less nodule b...
Source: Microbiology - Category: Microbiology Authors: Tags: Microbiology Source Type: research