Abstract
L-Arabinofuranosyl (L-Araf) residues are constituent of plant cell wall polysaccharides and glycoproteins. L-Araf residues are synthesized from UDP-L-Araf by arabinofuranosyltransferases. UDP-L-Araf is itself synthesized from UDP-L-arabinopyranose by UDP-L-arabinopyranose mutase (UAM). To elucidate the role of L-Araf residues in rice cell walls, we used RNA interference to down-regulate the expression of rice UAM1. The expression level of UAM1 in transgenic lines was reduced by approximately 90% compared with that of control lines. In addition, these transgenic lines showed reduction of UAM activity. The cell wall composition and glycosidic linkage analyses revealed that L-Araf residues in rice cell walls were reduced by approximately 50% compared with these of control lines. Moreover, these transgenic lines were more susceptible with cellulase compared with the control lines. On the other hand, some of the transgenic lines with a drastically reduced L-Araf residues were dwarf and infertile. These results suggest that the reduced L-Araf residues cause an aberrant formation of cell wall networks, resulting in effect on growth and reproduction.
