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The F8H Glycosyltransferase is a Functional Paralog of FRA8 Involved in Glucuronoxylan Biosynthesis in Arabidopsis
Lee, C., Q. TENG, W. Huang, R. Zhong, AND Z. H. Ye. The F8H Glycosyltransferase is a Functional Paralog of FRA8 Involved in Glucuronoxylan Biosynthesis in Arabidopsis. Plant and Cell Physiology. Oxford Journals, 50(4):812-827, (2009).
To study the impact of stressors on various species using NMR and other advanced analytical approaches to characterize changes in endogenous metabolites. The main focus is to define responses in ecologically-relevant organisms (e.g., small fish) upon exposure to potentially toxic xenobiotic chemicals.
The FRAGILE FIBER8 gene was previously shown to be required for the biosynthesis of the reducing end tetrasaccharide sequence of glucuronoxylan (GX) in Arabidopsis thaliana. Here, we demonstrate that F8H, a close homolog of FRA8, is a functional ortholog of FRA8 involved in GX biosynthesis. The F8H gene is preferentially expressed in xylem cells, in which the secondary walls contain abundant amount of GX, and the F8H protein is targeted to Golgi where GX is synthesized. Overexpression of F8H in the fra8 mutant completely complemented the fra8 mutant phenotypes including the secondary wall thickness of fibers and vessels, vessel morphology, GX content, and the abundance of the reducing end tetrasaccharide sequence of GX, indicating that F8H shares the same biochemical function as FRA8. Although the f8h mutant alone did not show any detectable cell wall defects, the f8h/fra8 double mutant exhibits an additional reduction in cell wall xylose level, a more severe deformation of vessels, and an extreme retardation in plant growth compared with the fra8 mutant. Together, our findings suggest that F8H and FRA8 are functional orthologs and they function redundantly in GX biosynthesis during secondary wall formation in Arabidopsis.