Enhanced disease resistance to Botrytis cinerea in myb46 Arabidopsis plants is associated to an early downregulation of CesA genes

The cell wall is a protective barrier of paramount importance for the survival of plant cells. Monitoring the integrity of the cell wall allows plants to quickly activate defense pathways to minimize pathogen entry and reduce the spread of disease. Counter-intuitively, however, pharmacological effects as well as genetic lesions that affect cellulose biosynthesis and content confer plants with enhanced resistance against necrotrophic fungi. These kind of pathogens target cellulose for degradation to facilitate penetration and to generate glucose units as a food source. Our results point towards the existence of a transcriptional reprogramming mechanism in genes encoding cellulose synthases (CesAs) that occurs very soon after Botrytis cinerea attack and that result in a temporary shut down of some CesA genes. Interestingly, the observed coordinated downregulation of CesA genes is more pronounced, and occurs earlier in myb46 mutant plants. In the resistant myb46 plants, pathogen infection induces transient downregulation of CesA genes that concur with a selective transcriptional reprogramming in a set of genes encoding structural cell wall proteins and extracellular remodeling enzymes. Together with previous indications, our results favor the hypothesis that CesAs are part of a surveillance system of the cell wall integrity that senses the presence of a pathogen and transduces that signal into a rapid transcriptional reprogramming of the affected cell.