NAC1 Directs CEP1-CEP3 Peptidase Expression and Modulates Root Hair Growth in Arabidopsis

The study explores how the NAC1 transcription factor and CEP1-CEP3 peptidases influence root hair growth in Arabidopsis. It was discovered that NAC1 activates the expression of AtCEP1 and AtCEP2, which in turn negatively regulate root hair growth. Double mutants of AtCEP1 and AtCEP3 showed a 20% increase in root hair growth compared to wild-type plants, indicating that these peptidases act as growth inhibitors. The study also found that reduced AtCEP activity in mutants led to changes in EXT insolubilization in root hair cell walls, which is associated with cell wall remodeling. The conclusion is that NAC1 directly regulates AtCEP1 and AtCEP2 expression, which suppresses cell expansion in root hairs, and that AtCEP1-AtCEP3 may be involved in a protein quality control system for EXT and related proteins. This research sheds light on the molecular components of the NAC1-AtCEPs-EXT O-glycosylation pathway that are essential for polar growth in root trichoblasts.