VAMP725 and VAMP726 interact with cellulose synthase to support secondary cell wall formation

The formation of plant cell walls underpins morphogenesis, growth, and development of all plants. Cellulose is an essential and load-bearing cell wall polymer that is synthesized by Cellulose Synthase (CESA) protein complexes at the plasma membrane. In this study, we reveal that SNARE proteins Vesicle Associated Membrane Protein 726 (VAMP726) and VAMP725 associate with multiple CESA proteins. Consistent with these results, the VAMP726 is codelivered with the CESA proteins to the plasma membrane, and the proteins colocalize at intracellular compartments. We further show that the VAMPs, especially VAMP726, are important for CESA trafficking and sustenance of cellulose synthesis both in growing tissues and in secondary wall producing maturing tissues. Taken together, our study outlines an important intracellular process whereby VAMP proteins facilitate trafficking of CESA complexes during cellulose synthesis.