title: Activation of the signalling mucin MoMsb2 and its functional relationship with Cbp1 in Magnaporthe oryzae.
abstract: Various surface signals are recognized by Magnaporthe oryzae to activate the Pmk1 MAP kinase that is essential for appressorium formation and invasive growth. One of upstream sensors of the Pmk1 pathway is the MoMsb2 signalling mucin. However, the activation of MoMsb2 and its relationship with other sensors is not clear. In this study, we showed that the cleavage and transmembrane domains are essential for MoMsb2 functions. Cleavage of MoMsb2 was further confirmed by western blot analysis, and five putative cleavage sites were functionally characterized. Expression of the extracellular region alone partially rescued the defects of Momsb2 in appressorium formation and virulence. The cytoplasmic region of MoMsb2, although dispensable for appressorium formation, was more important for penetration and invasive growth. Interestingly, the Momsb2 cbp1 double mutant deleted of both mucin genes was blocked in Pmk1 activation. It failed to form appressoria on artificial surfaces and was non-pathogenic. In addition, we showed that MoMsb2 interacts with Ras2 but not with MoCdc42 in co-immunoprecipitation assays. Overall, results from this study indicated that the extracellular and cytoplasmic regions of MoMsb2 have distinct functions in appressorium formation, penetration and invasive growth, and MoMsb2 has overlapping functions with Cbp1 in recognizing environmental signals for Pmk1 activation.
authors: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.|Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors: Guanghui
authors: G
authors: Wang
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors: Guotian
authors: G
authors: Li
authors: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors: Shijie
authors: S
authors: Zhang
authors: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors: Cong
authors: C
authors: Jiang
authors: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.
authors: Jun
authors: J
authors: Qin
authors: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.|Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
authors: Jin-Rong
authors: JR
authors: Xu
mesh_terms: D002686:Chitin / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D020082:Magnaporthe / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009077:Mucins / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology*; D015398:Signal Transduction; D014774:Virulence / Q000235:genetics; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D009077:Mucins; D002686:Chitin; D020928:Mitogen-Activated Protein Kinases; C102726:Pmk1 protein, Magnaporthe grisea; D020764:cdc42 GTP-Binding Protein