VAMP Proteins Facilitate Cellulose Synthase for Secondary Cell Wall Build-up

Plant cell walls, which are essential for growth and biomechanics, depend on cellulose synthesized by cellulose synthase (CESA) complexes localized at the plasma membrane. These CESAs are delivered to the cell surface via vesicles, a process that requires coordinated protein machinery. Vesicle membrane fusion is primarily mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. In Arabidopsis, vesicle-associated membrane proteins (VAMPs) are key SNARE members. However, whether VAMPs mediate cell wall deposition and the molecular mechanisms involved remain largely unknown.

This study demonstrates that the SNARE protein VAMP726, together with its close homolog VAMP725, associates with CESAs and regulates their trafficking during both primary and secondary cell wall formation. Mutations in these VAMPs disrupt CESA dynamics, reduce cellulose and lignin deposition, and impair vascular development. More specifically, VAMP726, likely acting in concert with VAMP725, binds to CESAs and modulates their delivery to—and possibly retrieval from—the plasma membrane. This function appears particularly pronounced during secondary cell wall synthesis, a process critical for plant stature and the ability to transport water from roots to shoots. These findings uncover an important trafficking process in plant cell biology and offer potential targets for engineering plants with enhanced structural integrity and biomass yield.

This study, entitled "VAMP725 and VAMP726 Interact with Cellulose Synthase to Support Secondary Cell Wall Formation," was recently published in PNAS. Assistant Researcher ZHENG Wenna (South China Botanical Garden, CAS) and Associate Professor LIU Guoyong (China Agricultural University) share co-first authorship, while Researcher ZENG Yonglun and Professor Staffan Persson (University of Copenhagen) serve as corresponding authors. Additional contributors include Dr. GAO Yihong (Institute of Genetics and Developmental Biology, CAS), Dr. LIU Zengyu (Shanghai Jiao Tong University), ZHENG Shuai (University of Copenhagen), GUO Yan (China Agricultural University), and ZHOU Yihua (Institute of Genetics and Developmental Biology, CAS). Dr. DAI Guangyi, from the Institutional Center for Shared Technologies and Facilities of South China Botanical Garden-CAS and the Center for Advanced Bioimaging (CAB) Denmark, provided microscopy support. This work was supported by grants from the National Natural Science Foundation of China, the Guangdong Province Pearl River Talent Plan, the Guangdong Science and Technology Plan Project, Science and Technology Projects in Guangzhou, the Villum Investigator program, the DNRF Chair, and Novo Nordisk.

Figure. VAMP725 and VAMP726 impact secondary cell wall composition and thickness.（Image by ZHENG Wenna）