AtSYP71 Is Important for Plant Cell Wall Biosynthesis and Stress Adaptation.

Background: SYP71, the plant-specific Qc-SNARE protein, is reported to regulate vesicle trafficking. SYP71 is localized on the ER, endosome, plasma membrane and cell plate, suggesting its multiple functions. Lotus SYP71 is essential for symbiotic nitrogen fixation in nodules. AtSYP71, GmSYP71 and OsSYP71 are implicated in plant resistance to pathogenesis. To date, SYP71 regulatory role on plant development remain unclear.Results: AtSYP71-knockout mutant atsyp71-4 was lethal at early development stage. Early development of AtSYP71-knockdown mutant atsyp71-2 was delayed, and stress response was also affected. Confocal images revealed that protein secretion was blocked in atsyp71-2. Transcriptomic analysis indicated that metabolism, response to environmental stimuli pathways and apoplast components were influenced in atsyp71-2. Moreover, the contents of lignin, cellulose and flavonoids as well as cell wall structures were also altered.Conclusion: Our findings suggested that AtSYP71 is essential for plant development. AtSYP71 probably regulates plant development, metabolism and environmental adaptation by affecting cell wall homeostasis via mediating secretion of materials and regulators required for cell wall biosynthesis and dynamics.