Early changes in apoplast composition associated with defence and disease in interactions between Phaseolus vulgaris and the halo blight pathogen Pseudomonas syringae Pv. phaseolicola

Brendan M. O'Leary, Helen C. Neale, Christoph Martin Geilfus, Robert W. Jackson, Dawn L. Arnold, Gail M. Preston*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)
86 Downloads (Pure)

Abstract

The apoplast is the arena in which endophytic pathogens such as Pseudomonas syringae grow and interact with plant cells. Using metabolomic and ion analysis techniques, this study shows how the composition of Phaseolus vulgaris leaf apoplastic fluid changes during the first six hours of compatible and incompatible interactions with two strains of P. syringae pv. phaseolicola (Pph) that differ in the presence of the genomic island PPHGI-1. Leaf inoculation with the avirulent island-carrying strain Pph 1302A elicited effector-triggered immunity (ETI) and resulted in specific changes in apoplast composition, including increases in conductivity, pH, citrate, γ-aminobutyrate (GABA) and K+, that are linked to the onset of plant defence responses. Other apoplastic changes, including increases in Ca2+, Fe2/3+ Mg2+, sucrose, β-cyanoalanine and several amino acids, occurred to a relatively similar extent in interactions with both Pph 1302A and the virulent, island-less strain Pph RJ3. Metabolic footprinting experiments established that Pph preferentially metabolizes malate, glucose and glutamate, but excludes certain other abundant apoplastic metabolites, including citrate and GABA, until preferred metabolites are depleted. These results demonstrate that Pph is well-adapted to the leaf apoplast metabolic environment and that loss of PPHGI-1 enables Pph to avoid changes in apoplast composition linked to plant defences.

Original languageEnglish
Pages (from-to)2172-2184
Number of pages13
JournalPlant Cell and Environment
Volume39
Issue number10
Early online date30 May 2016
DOIs
Publication statusPublished - Oct 2016

Keywords

  • apoplastic washing fluid
  • citrate
  • GABA
  • leaf apoplast
  • metabolic footprinting
  • metabolomics
  • plant defence response
  • plant–microbe interactions

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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