Agroinfiltration by cytokinin-producing Agrobacterium sp. strain GV3101 primes defense responses in Nicotiana tabacum

Mol Plant Microbe Interact. 2014 Nov;27(11):1175-85. doi: 10.1094/MPMI-04-14-0114-R.

Abstract

Transient infiltrations in tobacco are commonly used in plant studies, but the host response to different disarmed Agrobacterium strains is not fully understood. The present study shows that pretreatment with disarmed Agrobacterium tumefaciens GV3101 primes the defense response to subsequent infection by Pseudomonas syringae in Nicotiana tabacum. The presence of a trans-zeatin synthase (tzs) gene in strain GV3101 may be partly responsible for the priming response, as the tzs-deficient Agrobacterium sp. strain LBA4404 only weakly imparts such responses. Besides inducing the expression of defense-related genes like PR-1 and NHL10, GV3101 pretreatment increased the expression of tobacco mitogen-activated protein kinase (MAPK) pathway genes like MEK2, WIPK (wound-induced protein kinase), and SIPK (salicylic acid-induced protein kinase). Furthermore, the GV3101 strain showed a stronger effect than the LBA4404 strain in activating phosphorylation of the tobacco MAPK, WIPK and SIPK, which presumably prime the plant immune machinery. Lower doses of exogenously applied cytokinins increased the activation of MAPK, while higher doses decreased the activation, suggesting a balanced level of cytokinins is required to generate defense response in planta. The current study serves as a cautionary warning for plant researchers over the choice of Agrobacterium strains and their possible consequences on subsequent pathogen-related studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agrobacterium tumefaciens / physiology*
  • Cytokinins / metabolism*
  • Cytokinins / pharmacology
  • Disease Resistance
  • Gene Expression Regulation, Plant* / drug effects
  • MAP Kinase Signaling System
  • Mitogen-Activated Protein Kinases
  • Plant Diseases / immunology*
  • Plant Diseases / microbiology
  • Plant Leaves / drug effects
  • Plant Leaves / genetics
  • Plant Leaves / immunology
  • Plant Leaves / microbiology
  • Plant Proteins / genetics
  • Promoter Regions, Genetic / genetics
  • Protoplasts
  • Pseudomonas syringae / physiology
  • Salicylic Acid / metabolism
  • Tobacco / drug effects
  • Tobacco / genetics
  • Tobacco / immunology
  • Tobacco / microbiology*

Substances

  • Cytokinins
  • Plant Proteins
  • Mitogen-Activated Protein Kinases
  • SA-induced protein kinase
  • Salicylic Acid