MYB46-related transcriptome analysis in Arabidopsis thaliana

In this study we show that the Arabidopsis transcription factor MYB46, previously described to regulate secondary cell wall biosynthesis in the vascular tissue of the stem, is pivotal for mediating disease susceptibility to the fungal pathogen Botrytis cinerea. We identified MYB46 by its ability to bind to a new cis element located in the 5´ promoter region of the pathogen-induced Ep5C gene which encodes a type III cell wall-bound peroxidase. We present genetic and molecular evidence indicating that MYB46 modulates the magnitude of Ep5C gene induction following pathogenic insults. Moreover, we demonstrate that different myb46 knock-down mutant plants exhibit increased disease resistance to B. cinerea, a phenotype that is accompanied by selective transcriptional reprogramming of a set of genes encoding cell wall proteins and enzymes, of which extracellular type III peroxidases are conspicuous. In essence our results substantiates that defense-related signaling pathways and cell wall integrity are interconnected, and MYB46 likely functions as a disease susceptibility modulator to B. cinerea through the integration of cell wall remodeling and downstream activation of secondary lines of defense. 10-15 days-old plants were collected, frozen in liquid nitrogen and stored at -80ºC. Independent replicates from 3 different experiments (separated in time) were used in the analysis. Samples from Col-0 and myb46-2 were compared.