Xyloglucan Fucosylation Modulates &ITArabidopsis&IT Cell Wall Hemicellulose Aluminium binding Capacity

Although xyloglucan (XyG) is reported to bind Aluminium (Al), the influence of XyG AXY3 (XYLOSIDASE1) function and consequent reduced levels of AXY8 (FUC95A) function and consequent increased levels of AXY3 transcript levels are strongly down regulated in response to 30 min Al treatment, whilst AXY8 transcript levels also repressed until 6 h following treatment onset. Mutants lacking AXY3 or AXY8 function exhibit opposing effects on Al contents of root cell wall and cell wall hemicellulose components. However, there was no difference in the amount of Al retained in the pectin components between mutants and WT. Finally, whilst the total sugar content of the hemicellulose fraction did not change, the altered hemicellulose Al content of the mutants is shown to be a likely consequence of their different XyG fucosylation levels. We conclude that variation in XyG fucosylation levels influences the Al sensitivity of Arabidopsis by affecting the Al-binding capacity of hemicellulose.