Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis

• DOI: 10.1038/srep23310
• Publication Date: 2016-03-17T10:45:50Z
• Authors: Dominik K. Großki...; Richard Tafner; María V. Moreno; Sebastian A. Sten...; Inés E. García de...; Louise M. Nelson; Ondřej Novák; Miroslav Strnad; Eric van der Graaff; Thomas Roitsch
• Keywords: Mechanisms of Plant Immune Response; 0301 basic medicine; biotic; Cytokinins; Integrated management; CYTOKININ PRODUCTION; Arabidopsis; Cytokinin; Pseudomonas syringae; Plant Science; Pseudomonas fluorescens; Microbiology; Biochemistry; Gene; Article; Agricultural and Biological Sciences; 03 medical and health sciences; Plant Growth Regulators; Tandem Mass Spectrometry; Plant beneficial microbes; https://purl.org/becyt/ford/1.6; Agronomía, reproducción y protección de plantas; Genetics; Plant Immunity; Auxin; https://purl.org/becyt/ford/1; Biology; Chromatography, High Pressure Liquid; GROWTH-PROMOTING RHIZOBACTERIA; Plant Diseases; 2. Zero hunger; Bacteria; Biological pest control; Pathogen; Genomics and Pathogenicity of Plant Pathogenic Bacteria; Mutant; Botany; Life Sciences; Strigolactone Signaling in Plant Interactions; Abiotic stress; SALICYLIC-ACID; Plant protection; PSEUDOMONAS FLUORESCENS; microbe; Plant Leaves; PLANT-GROWTH; FOS: Biological sciences; Salicylic Acid

AbstractPlant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.