Thaxtomin A affects CESA-complex density, expression of cell wall genes, cell wall composition, and causes ectopic lignification in Arabidopsis thaliana seedlings

• Published in: Journal of experimental botany Vol. 60; no. 3; pp. 955 - 965
• Main Authors: Bischoff, Volker, Cookson, Sarah Jane, Wu, Shuang, Scheible, Wolf-Rüdiger
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2009; Oxford Publishing Limited (England); Oxford University Press (OUP)
• Subjects: Arabidopsis; Arabidopsis - cytology; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis thaliana; Biological and medical sciences; Biosynthesis; callose; Carbon Isotopes; Cell Membrane; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Wall; Cell Wall - drug effects; Cell Wall - enzymology; Cell Wall - genetics; cell wall components; Cell walls; Cellulose; cellulose synthase; cytology; defence response; drug effects; Environmental Sciences; enzymology; Eubacteria; Fundamental and applied biological sciences. Psychology; gene expression regulation; Gene Expression Regulation, Plant; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant; genetics; Glucosyltransferases; Glucosyltransferases - metabolism; hemicellulose; Indoles; Indoles - pharmacology; isoxaben; Life Sciences; Lignification; Lignin; Lignin - metabolism; mechanism of action; metabolism; microscopy; microtubule; Microtubules; Mode of action; Multienzyme Complexes; Multienzyme Complexes - metabolism; pectins; pharmacology; phenotype; phytotoxin; Phytotoxins; Piperazines; Piperazines - pharmacology; Plant cells; Plant physiology; Plants; plasma membrane; RESEARCH PAPER; Research Papers; Seedlings; Seedlings - cytology; Seedlings - drug effects; Seedlings - enzymology; Streptomyces; thaxtomin; Vegetal Biology; callose; microtubule; defence response; cellulose; phytotoxin; isoxaben; thaxtomin; lignin; Lignin; Plant juvenile growth stage; Cellulose; Defensive response; Density; Cell wall; Actinomycetales; Arabidopsis thaliana; Lignification; Gene; Cruciferae; Dicotyledones; Angiospermae; Botany; Bacteria; Streptomycetaceae; Phytotoxin; Pesticides; Streptomyces; Herbicide; Callose; Benzamide derivatives; Actinomycetes; Spermatophyta; Microtubule; Experimental plant; Arabidopsis thaliana; callose; cellulose; defence response; isoxaben; lignin; microtubule; phytotoxin; Streptomyces; thaxtomin
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ern344

Thaxtomin A, a phytotoxin produced by Streptomyces eubacteria, is suspected to act as a natural cellulose synthesis inhibitor. This view is confirmed by the results obtained from new chemical, molecular, and microscopic analyses of Arabidopsis thaliana seedlings treated with thaxtomin A. Cell wall analysis shows that thaxtomin A reduces crystalline cellulose, and increases pectins and hemicellulose in the cell wall. Treatment with thaxtomin A also changes the expression of genes involved in primary and secondary cellulose synthesis as well as genes associated with pectin metabolism and cell wall remodelling, in a manner nearly identical to isoxaben. In addition, it induces the expression of several defence-related genes and leads to callose deposition. Defects in cellulose synthesis cause ectopic lignification phenotypes in A. thaliana, and it is shown that lignification is also triggered by thaxtomin A, although in a pattern different from isoxaben. Spinning disc confocal microscopy further reveals that thaxtomin A depletes cellulose synthase complexes from the plasma membrane and results in the accumulation of these particles in a small microtubule-associated compartment. The results provide new and clear evidence for thaxtomin A having a strong impact on cellulose synthesis, thus suggesting that this is its primary mode of action.