Defects in Cell Wall Differentiation of the Arabidopsis Mutant Is Dependent on Cyclin-Dependent Kinase CDK8.

Plant cells are encapsulated by cell walls whose properties largely determine cell growth. We have previously identified the mutant, which shows defects in seedling root and shoot development. is affected in the () and shows alterations in the structures of Rhamnogalacturonan I (RG I) and RG II, two rhamnose-containing pectins. The data presented here shows that root tissue of the mutant fails to properly differentiate the cell wall in cell corners and accumulates excessive amounts of callose, both of which likely alter the physical properties of cells. A () mutant was identified that alleviates the cell growth defects in . The cell wall differentiation defect is re-established in the mutant and callose accumulation is reduced compared to . The mutation is an allele of the (), which encodes a component of the mediator complex that influences processes central to plant growth and development. Together, the identification of the mutant suggests that changes in cell wall composition and turnover in the mutant have a significant impact on cell growth and reveals a function of CDK8 in cell wall architecture and composition.