Abstract
The exocyst, an evolutionarily conserved octameric protein complex, mediates tethering of vesicles to the plasma membrane in the early stage of exocytosis. Arabidopsis Exo70, a subunit of the exocyst complex, has been found to be involved in plant immunity. Here, we characterize the function of OsExo70B1 in rice. OsExo70B1 mainly expresses in leaf and shoot and its expression is induced by pathogen-associated molecular patterns (PAMPs) and rice blast fungus Magnaporthe oryzae (M. oryzae). Knocking out OsExo70B1 results in significantly decreased resistance and defense responses to M. oryzae compared to the wild type, including more disease lesions and enhanced fungal growth, downregulated expression of pathogenesis-related (PR) genes, and decreased reactive oxygen species accumulation. In contrast, the exo70B1 mutant does not show any defects in growth and development. Furthermore, OsExo70B1 can interact with the receptor-like kinase OsCERK1, an essential component for chitin reception in rice. Taken together, our data demonstrate that OsExo70B1 functions as an important regulator in rice immunity.
Highlights
Plants have evolved two layers of the innate immunity system, pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), to defend against pathogens [1,2,3,4]
In order to examine the subcellular localization of OsExo70B1, the OsExo70B1 fused with the green fluorescent protein (GFP) was expressed under the control of the 35S promoter in N. benthamiana leaves by agrobacterium-mediated genetic transformation
We observed clear fluorescence signals in the cytoplasm, nucleus, and plasma membrane (PM) (Figure 2), indicating that OsExo70B1 distributed throughout the whole cell, which is similar to some Exo70 members in Arabidopsis and H. villosa, such as AtExo70B1, Exo70D1-V and Exo70F2-V [20,39]
Summary
Plants have evolved two layers of the innate immunity system, pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), to defend against pathogens [1,2,3,4]. In PTI and ETI, many defense-related proteins must be transported to the suitable sites and exercise their function [5,6], which is partly dependent on the secretory trafficking system. The defense-related secretory trafficking is associated with three types of membrane vesicles: the trans-Golgi network/early endosome (TGN/EE), the multivesicular body (MVB), and the exocyst positive organelle (EXPO) [6]. Exo is a key member of the exocyst complex and has been found to be widely present in yeast, mammals and plants [13,14]. There is one Exo gene, while there are multiple copies of Exo genes in plants [15] ranging from 21 to 47 Exo members in potatoes, Arabidopsis, Populus trichocarpa, wheat and rice [16,17,18,19,20]. Exo genes have been duplicated independently in the moss, lycophyte and angiosperm lineages, and in the subsequent lineage-specific multiplications which are represented by nine subgroups (Exo70A–Exo70I) [15] and their function ranges from growth, development to biotic and abiotic stresses [21,22,23,24,25,26,27,28]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
