OsDGL1, a Homolog of an Oligosaccharyltransferase Complex Subunit, is Involved in N-Glycosylation and Root Development in Rice

A leaky rice mutant was isolated from an ethylmethane sulfonate (EMS)-mutagenized rice library based on its short root phenotype. The map-based cloning results showed that the mutant was due to a point mutation in the intron of OsDGL1 (LOC_Os07g10830), which encodes the dolichyl-diphosphooligosaccharide-protein glycosyltransferase 48 kDa subunit precursor. The mutation results in premature termination of protein synthesis. OsDGL1 is an ortholog of Arabidopsis DGL1, human OST48 and yeast WBP1, an essential protein subunit of the oligosaccharyltransferase (OST) complex, which is involved in N-glycosylation in eukaryotes. The leaky rice mutant, Osdgl1, displayed a change of matrix polysaccharides in its root cell wall, shorter root cell length, smaller root meristem and cell death in the root. Consistent with the known function of the OST complex in eukaryotes, the Osdgl1 mutation leads to a defect in N-glycosylation in the root. It was also found that reactive oxygen species (ROS) may be involved in this process.