Infection of Chinese cabbage by Plasmodiophora brassicae leads to a stimulation of plant growth: impacts on cell wall metabolism and hormone balance.

Abstract

The importance of plant hormones in clubroot infection has long been recognized. The morphological changes, such as cell division and cell elongation leading to gall formation are triggered in the early stages of infection. We analysed cell expansion by localizing Xyloglucan endoTransglucosylase/Hydrolase (XTH)-action and screened the endogenous concentrations of several classes of phytohormones by mass spectrometry in the early stages of Plasmodiophora brassicae infection in Chinese cabbage (Brassica rapa spp. pekinensis). Infected plants showed a general transient growth promotion early in infection. Furthermore a clear XTH action was visible in the epidermal layer of infected roots. Complex changes in the endogenous phytohormone profile were observed. Initially infection resulted in an increased total auxin pool. The auxin increase, together with an increased XTH action, results in wall loosening and consequently cell expansion. When the first secondary plasmodia are formed, thirteen days after infection (DAI), can be considered a switch point in phytohormone metabolism. Twenty-one DAI the plasmodia might act as a plant hormone sink resulting in a reduction in the active cytokinin pool and a lower indole-3-acetic acid content in the infected plants.

• Authors: Sylvie Devos, Kris Vissenberg, Jean-Pierre Verbelen, Els Prinsen
• Journal: The New phytologist (New Phytol) Vol. 166 Issue 1 Pg. 241-50 (Apr 2005) ISSN: 0028-646X [Print] England
• PMID: 15760367 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright New Phytologist (2004).

Chemical References

• Plant Growth Regulators

Topics

• Brassica rapa (growth & development, metabolism, microbiology)
• Cell Enlargement
• Cell Wall (metabolism)
• Fungi (physiology)
• Plant Growth Regulators (metabolism)