Abstract
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, an Arabidopsis ARF-GEF, is critical for cuticle formation and related leaf surface defense against the bacterial pathogen Pseudomonas syringae pathovar tomato (Pto). Our transmission electron microscopy and scanning electron microscopy studies indicate that the atmin7 mutant 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 in atmin7 mutant plants. Furthermore, the exogenous application of either of three plant hormones—salicylic acid, jasmonic acid, or abscisic acid—enhanced the cuticle formation in atmin7 mutant leaves and the related defense responses to the bacterial Pto infection. Thus, transport of cutin-related components by AtMIN7 may contribute to its impact on cuticle formation and related defense function.
Highlights
The plant cuticle is the outermost hydrophobic layer of the aerial plant surfaces which functions as a mechanical barrier to provide physical support, avoid organ fusion, and control the surface water status [1,2]
Despite many efforts to decipher the mechanisms of cuticle biosynthesis, transport, and regulation, little is known about the transport of the cuticular components to the plant surface
Previous reports have discovered that the trafficking of the intracellular wax components required a GNL1 and ECH dependent vesicle trafficking system [15]
Summary
The plant cuticle is the outermost hydrophobic layer of the aerial plant surfaces which functions as a mechanical barrier to provide physical support, avoid organ fusion, and control the surface water status [1,2]. The cuticle, which covers most of the plant tissues, including the leaves, fruits, flowers, and non-woody stems, is the first line to contact the outside environment [3,4,5]. The cuticle protects plants against various abiotic and biotic stresses, including extreme temperatures, drought, UV radiation, and attacks by pathogens and insects. The status of the cuticle varies with the stage of plant development as well as environmental factors. A pathogen’s entry into the plant tissue is the critical first step during the infection process, which leads to compositional and functional changes of the cuticle. Pathogens can sense the changes of the plant cuticle and adjust their pathogenesis and virulence [6,7]. The regulation and role of the cuticle in plant defense are still poorly understood
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