GAUT10 is required for Arabidopsis root cell differentiation and elongation

Abstract

Summary Cell wall properties of the root apical meristem (RAM) are poorly understood compared to the elongation and maturation zones of the developing root. GAUT10 is a pectin biosynthesizing enzyme that is post-transcriptionally regulated by auxin that influences Arabidopsis RAM size in a sucrose-dependent manner. Using live-cell microscopy, we have determined the short root phenotype of the gaut10 loss of function allele is due to a reduction in both RAM cell number and epidermal cell elongation. In addition, the absence of GAUT10 leads to a reduction in lateral root cap and epidermal cell marker line expression, indicating root cell differentiation defects in this mutant. GAUT10 is required for normal pectin and hemicellulose composition in primary Arabidopsis roots. Loss of GAUT10 leads to a reduction in galacturonic acid and xylose in primary cell walls and alters the presence of rhamnogalacturonan (RG) I and homogalacturonan (HG) polymers in the root. Auxin mediated gene expression and metabolism is altered in gaut10 roots, suggesting that cell wall composition may influence auxin pathways.