Library Open Repository

Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity

Downloads

Downloads per month over past year

Tegg, RS and Gill, WM and Thompson, HK and Davies, NW and Ross, JJ and Wilson, CR (2008) Auxin-Induced Resistance to Common Scab Disease of Potato Linked to Inhibition of Thaxtomin A Toxicity. Plant Disease, 92 (9). pp. 1321-1328. ISSN 0191-2917

[img]
Preview
PDF
Tegg_et_al_2008.pdf | Download (347kB)
Available under University of Tasmania Standard License.

Abstract

Production of the phytotoxin thaxtomin A by pathogenic Streptomyces spp. is essential for induction of common scab disease in potato. Prior studies have shown that foliar application of sublethal concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and other auxin or auxin-like compounds significantly reduced severity and occurrence of common scab in subsequently produced tubers. However, the means of disease suppression by these compounds was not known. We confirm the disease suppressive activity of 2,4-D. Detailed tuber physiological examination showed that lenticel numbers, lenticel external dimensions, and periderm thickness and structure, physiological features believed to be critical to Streptomyces scabiei infection, were not substantially changed by 2,4-D treatments, negating a possible mechanism for disease suppression through alteration of these structures. In contrast, our studies show accumulation of 2,4-D in tubers of treated plants occurs and is associated with an enhanced tolerance to thaxtomin A. Applying 2,4-D to cultures of S. scabiei did not significantly alter in vitro growth of the pathogen. Thaxtomin A production by the pathogen was inhibited by 2,4-D, but only at the highest rate tested (1.0 mM), which is at least 200-fold more than is found in 2,4-D treated tubers. These data suggest 2,4-D has no direct effect on the pathogen or its virulence. Confirmatory evidence from studies with Arabidopsis thaliana seedlings demonstrated that the auxins 2,4-D and IAA ameliorate thaxtomin A toxicity. The evidence presented whereby auxin treatment inhibits toxicity of thaxtomin A secreted by the pathogen suggests a novel indirect means of disease suppression.

Item Type: Article
Journal or Publication Title: Plant Disease
Page Range: pp. 1321-1328
ISSN: 0191-2917
Identification Number - DOI: 10.1094/PDIS-92-9-1321
Additional Information: Copyright © 2008 The American Phytopathological Society
Date Deposited: 10 Feb 2012 05:13
Last Modified: 18 Nov 2014 04:27
URI: http://eprints.utas.edu.au/id/eprint/12560
Item Statistics: View statistics for this item

Repository Staff Only (login required)

Item Control Page Item Control Page