ARS | Publication request: INDUCED SYSTEMIC RESISTANCE (ISR) IN ARABIDOPSIS AGAINST PSEUDOMONAS SYRINGAE PV. TOMATO BY 2,4-DIACETYLPHLOROGLUCINOL (DAPG)-PRODUCING PSEUDOMONAS FLUORESCENS.

Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2004
Publication Date: July 20, 2004
Citation: Weller, D.M., Van Pelt, J.A., Mavrodi, D.V., Pieterse, C.M., Bakker, P.H., Van Loon, L.C. 2004. Induced systemic resistance (isr) in arabidopsis against pseudomonas syringae pv. tomato by 2,4-diacetylphloroglucinol (dapg)-producing pseudomonas fluorescens. APS Annual Meeting. Phytopathology 94: S108.

Technical Abstract: Two-week-old Arabidopsis thaliana ecotype Col-0 seedlings were transferred into an autoclaved sand-soil mixture colonized by DAPG-producing P. fluorescens strain Pf-5 (rep-PCR genotype A), Q2-87 (B), Q8r1-96 (D) or HT5-1 (N) and the plants were challenge-inoculated with Pseudomonas syringae three weeks later. DAPG producers were not detected on the leaves. All DAPG producers induced resistance against P. syringae equivalent to the well studied Dutch strain P. fluorescens 417r. phlD or phlBC mutants of Q2-87 (DAPG minus) were significantly reduced in ISR activity. A phlF regulatory mutant (over-producer) had ISR activity equivalent to Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 'M four days before challenge inoculation induced resistance equivalent to or better than the bacteria. These results suggest that DAPG is a major mechanism of ISR by DAPG producers.