Mechanisms of plant protection against two oxalate-producing fungal pathogens by oxalotrophic strains of Stenotrophomonas spp

MARINA M; ROMERO FM; VILLARREAL NM; MEDINA AJ; GÁRRIZ A; ROSSI FR; MARTINEZ GA; PIECKENSTAIN FL

PLANT MOLECULAR BIOLOGY

SPRINGER

Lugar: Berlin; Año: 2019

0167-4412

Oxalic acid plays a pivotal role in the virulence of the necrotrophic fungi Botrytis cinerea and Sclerotinia sclerotiorum. In this work, we isolated two oxalotrophic strains (OxA and OxB) belonging to the bacterial genus Stenotrophomonas from the rhizosphere of tomato plants. Both strains were capable to colonise endophytically Arabidopsis plants and protect them from the damage caused by high doses of oxalic acid. Furthermore, OxA and OxB protected Arabidopsis from S. sclerotiorum and B. cinerea infections. Bacterial inoculation induced the production of phenolic compounds and the expression of PR-1. Besides, both isolates exerted a protective effect against fungal pathogens in Arabidopsis mutants affected in the synthesis pathway of salicylic acid (sid2-2) and jasmonate perception (coi1). OxA and OxB induced callose deposition, which resulted crucial for bacterial protective effects. Moreover, B. cinerea and S. sclerotiorum mycelial growth was reduced in culture media containing cell wall polysaccharides from leaves inoculated with each bacterial strain. These findings suggest that cell walls from Arabidopsis leaves colonised by these bacteria would be less susceptible to pathogen attack. Results hereby indicate that these oxalotrophic bacteria protect plants against oxalate-producing pathogens by a combination of actions showing their potentiality to be used in biological control of fungal diseases in plants.