The phenotype upon (GlcNAc)_n accumulation is independent of the chitin receptor CERK1 and is unrelated to oxidative or ER stress. A, Left, stem length of NodC  OE lines pTGK42-10 and pTGK42-28 in the wild-type (WT) and cerk1 background. Right, extreme stem phenotype of NodC  OE line pTGK42-10 and pTGK42-10 × cerk1 compared with the wild type. B, Left, visualization of H₂O₂ production in 10-d-old Arabidopsis seedlings by incubating roots in DAB. Right, detail of the root tip. C, Glycosylation pattern of proteins of the wild type and NodC  OE lines. Proteins were extracted from fully developed leaves of rosette-stage plants. Blotting was performed using WGA-peroxidase (left) or ConA-peroxidase (right). Marker was the PageRuler Plus Prestained Protein Ladder. The molecular masses are indicated in kD. Asterisks indicate statistical significance compared with the wild type at P < 0.01 as determined by Student’s t test. Values are means ± sd.