Novel cell wall architecture of isoxaben‐habituated Arabidopsis suspension‐cultured cells: global transcript profiling and cellular analysis

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Abstract
The herbicide isoxaben is a highly specific and potent inhibitor of cellulose synthesis in plants. Nevertheless, suspension‐cultured cells can be habituated to grow in high concentrations of isoxaben, and apparently compensate for the disruption of cellulose synthesis by the modulation of other cell wall components. We have habituated Arabidopsis cells to isoxaben and characterized the cellular and genetic consequences. Near whole‐genome transcript profiling implicated novel genes in cell wall assembly and extended our understanding of the activity of known cell wall‐related genes including glycosyltransferases involved in cellulose and pectin biosynthesis. Habituation does not appear to be mediated by stress response processes, nor by functional redundancy within the cellulose synthase (AtCesA) family. Uniquely, amongst the cellulose synthase superfamily, AtCslD5 was highly upregulated and may play a role in the biosynthesis of the novel walls of habituated cells. In silico analysis of differentially expressed genes with unknown functions identified a putative glycosyltransferase and collagen‐like putative cell wall protein.