Transcriptome analysis of isoxaben-induced loss of cell wall integrity in Arabidopsis seedling liquid culture

Plant cells are surrounded by walls, which must often meet opposing functional requirements during plant growth and defense. The cells meet them by modifying wall structure and composition in a tightly controlled and adaptive manner. The modifications seem to be mediated by a dedicated cell wall integrity (CWI) maintenance mechanism. Currently the mode of action of the mechanism is not understood and it is unclear how its activity is coordinated with established plant defense signaling. We investigated both the responses to cell wall damage (CWD) compromising CWI and the underlying mechanism in Arabidopsis thaliana. A cellulose biosynthesis inhibitor isoxaben was used as a tool to induce the loss of cell wall integrity. Isoxaben was chosen because it only affects a certain cell type / differentiation stage, and weakens the cell walls indirectly by inhibiting a biosynthetic process, making CWD occurrence dependent on high turgor levels (allowing simultaneous manipulation of the responses by addition of osmotica like sorbitol, mannitol, etc.). Isoxaben treatment causes structural damage, induction of lesion formation, cell death, deposition of lignin and callose as well as production of jasmonic acid and salicylic acid. Isoxaben-resistant mutant ixr1-1 is included to ensure the specificity of the treatment. Overall design: Both genotypes (Col-0 and ixr1-1) were treated with either isoxaben or DMSO (mock). Three replicates of each sample were analyzed.

12