New insights in the role of protein N-glycosylation in root development

Plant roots have the potential capacity to grow almost indefinitely if meristematic and lateral branching is sustained. We have identified a novel and viable allele of LEW3 called limited root growth (lrg1), which has affected the protein N-glycosylation. This mutant shows defects in cell division and elongation in the root meristem and reduces the positive interaction between Arabidopsis and Piriformosa indica. We found that lrg1 short root phenotype correlates with a high content in reactive oxygen species and low pH in the apoplast. Interestingly, lrg1 mutation causes a synonymous substitution that alters the correct splicing of the fourth intron in LEW3, causing a mix of wild type and truncated protein. LRG1 RNA missplicing in roots and short root phenotypes in lrg1 are light-intensity dependent, generating a light-stress conditional mutant. This mutation disrupts a GC-base pair in a three-base-pair stem with a four-nt loop that seems to be necessary for correct LEW3 RNA splicing. Our work highlights for the first time the important role of N-glycosylation for root growth and development.