MPK4 negatively regulates the L-arabinose synthesis of cell wall in Arabidopsis

The mitogen-activated protein kinase (MAPK), as a major member in MAPK cascade, has been shown to play an important role in plant development and growth. However, little is known about the function of MAPK in regulating cell wall synthesis/metabolism. In this study, we found that the L-arabinose content in mpk4 mutant was much higher compared to those in wild type, mpk3 and mpk6 mutants, whereas overexpressing MPK4 in Arabidopsis obviously decreased the L-arabinose content of cell wall. Furthermore, loss of function in MPK4 significantly decreased the expression of L-arabinose synthesis/ metabolism-related gene MUR10, but did not affect the expressions of the other genes (MUR4, MUR5, UXT1 and ARAD1). Moreover, knock-out of MPK4 significantly decreased the cellulose content. These results suggest that MPK4 negatively regulates the L-arabinose synthesis of cell wall by likely modulating the expression of MUR10. (C) 2022 Elsevier Inc. All rights reserved.