Deciphering the Novel Role of AtMIN7 in Cuticle Formation and Defense against the Bacterial Pathogen Infection.

The cuticle is the outermost layer of plant aerial tissue that interacts with the environment and protects plants against water loss and various biotic and abiotic stresses. ADP ribosylation factor guanine nucleotide exchange factor proteins (ARF-GEFs) are key components of the vesicle trafficking system. Our study discovers that AtMIN7, anArabidopsisARF-GEF, is critical for cuticle formation and related leaf surface defense against the bacterial pathogenPseudomonas syringaepathovar tomato (Pto). Our transmission electron microscopy and scanning electron microscopy studies indicate that theatmin7mutant leaves have a thinner cuticular layer, defective stomata structure, and impaired cuticle ledge of stomata compared to the leaves of wild type plants. GC-MS analysis further revealed that the amount of cutin monomers was significantly reduced inatmin7mutant plants. Furthermore, the exogenous application of either of three plant hormones-salicylic acid, jasmonic acid, or abscisic acid-enhanced the cuticle formation inatmin7mutant leaves and the related defense responses to the bacterialPtoinfection. Thus, transport of cutin-related components by AtMIN7 may contribute to its impact on cuticle formation and related defense function.