Ready to fire: Secretion in plant immunity.

Effective recognition of pathogens and rapid execution of immune responses are essential for the survival of living organisms. Cell-autonomous immune responses of animal and plant cells rely on pattern recognition receptors that can distinguish self from non-self structures and that are able to activate a molecular execution machinery that ultimately terminates most pathogen attacks. Reminiscent of the situation in mammalian T cells, accumulating evidence points to a key role of vesicle trafficking and exocytosis in plant innate immunity. In this context, our recent finding that ternary soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) complexes comprising PEN1, SNAP33 and VAMP721/722 function at pathogen entry sites is instrumental in understanding the execution of plant immune responses at the cell periphery. Our study further revealed unexpected overlapping functions of the same SNARE complexes in disease resistance and development. Here, we discuss the potential identity of cargo delivered through the PEN1-SNAP33-VAMP721/722-dependent secretory pathway and the necessity for a tight regulation of SNARE complex formation to avoid unintentional release of toxic load.