Development of Agrobacterium Tumefaciens C58-induced Plant Tumors and Impact on Host Shoots Are Controlled by a Cascade of Jasmonic Acid, Auxin, Cytokinin, Ethylene and Abscisic Acid

Planta. 2003 Jan;216(3):512-22. doi: 10.1007/s00425-002-0883-5. Epub 2002 Sep 7.

Abstract

The development of Agrobacterium tumefaciens-induced plant tumors primarily depends on the excessive production of auxin and cytokinin by enzymes encoded on T-DNA genes integrated into the plant genome. The aim of the present study was to investigate the involvement of additional phytohormone signals in the vascularization required for rapid tumor proliferation. In stem tumors of Ricinus communis L., free auxin and zeatin riboside concentrations increased within 2 weeks to 15-fold the concentrations in control stem tissue. Auxin and cytokinin immunolocalization revealed the highest concentrations within and around tumor vascular bundles with concentration gradients. The time-course of changes in free auxin concentration in roots was inversely correlated with that in the tumors. The high ethylene emission induced by increased auxin- and cytokinin correlated with a 36-fold accumulation of abscisic acid in tumors. Ethylene emitted from tumors and exogenously applied ethylene caused an increase in abscisic acid concentrations also in the host leaves, with a diminution in leaf water vapor conductance. Jasmonic acid concentration reached a maximum already within the first week of bacterial infection. A wound effect could be excluded. The results demonstrate the concerted interaction of a cascade of transiently induced, non-T-DNA-encoded phytohormones jasmonic acid, ethylene and abscisic acid with T-DNA-encoded auxin and zeatin riboside plus trans-zeatin, all of which are required for successful plant tumor vascularization and development together with inhibition of host plant growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism
  • Abscisic Acid / pharmacology
  • Agrobacterium tumefaciens / growth & development*
  • Cyclopentanes / metabolism
  • Cytokinins / metabolism
  • Cytokinins / pharmacology
  • Ethylenes / metabolism
  • Immunohistochemistry
  • Indoleacetic Acids / metabolism
  • Microscopy, Immunoelectron
  • Oxylipins
  • Plant Growth Regulators / metabolism*
  • Plant Growth Regulators / pharmacology
  • Plant Roots / drug effects
  • Plant Roots / growth & development
  • Plant Roots / microbiology
  • Plant Shoots / chemistry
  • Plant Shoots / growth & development
  • Plant Shoots / microbiology*
  • Plant Tumors / microbiology*
  • Ricinus / chemistry
  • Ricinus / growth & development
  • Ricinus / microbiology*
  • Time Factors

Substances

  • Cyclopentanes
  • Cytokinins
  • Ethylenes
  • Indoleacetic Acids
  • Oxylipins
  • Plant Growth Regulators
  • jasmonic acid
  • Abscisic Acid
  • ethylene