Rice Blast Fungus Magnaporthe Oryzae Research Articles

A molecular mechanosensor for real-time visualization of appressorium membrane tension in Magnaporthe oryzae

The rice blast fungus Magnaporthe oryzae uses a pressurized infection cell called an appressorium to drive a rigid penetration peg through the leaf cuticle. The vast internal pressure of an appressorium is very challenging to investigate, leaving our understanding of the cellular mechanics of plant infection incomplete. Here, using fluorescence lifetime imaging of a membrane-targeting molecular mechanoprobe, we quantify changes in membrane tension in M. oryzae. We show that extreme pressure in the appressorium leads to large-scale spatial heterogeneities in membrane mechanics, much greater than those observed in any cell type previously. By contrast, non-pathogenic melanin-deficient mutants, exhibit low spatially homogeneous membrane tension. The sensor kinase ∆sln1 mutant displays significantly higher membrane tension during inflation of the appressorium, providing evidence that Sln1 controls turgor throughout plant infection. This non-invasive, live cell imaging technique therefore provides new insight into the enormous invasive forces deployed by pathogenic fungi to invade their hosts, offering the potential for new disease intervention strategies.

The RasGEF MoCdc25 regulates vegetative growth, conidiation and appressorium-mediated infection in the rice blast fungus Magnaporthe oryzae

Ras guanine nucleotide exchange factors (RasGEFs) can trigger Ras GTPase activities and play important roles in controlling various cellular processes in eukaryotes. Recently, it has been exhibited that RasGEF Cdc25 regulates morphological differentiation and pathogenicity in several plant pathogenic fungi. However, the role of RasGEFs in Magnaporthe oryzae is largely unknown. In this study, we identified and functionally characterized a RasGEF gene MoCDC25 in M. oryzae, which is orthologous to Saccharomyces cerevisiae CDC25. Targeted gene deletion mutants (ΔMocdc25) were completely nonpathogenic and were severely impaired in hyphal growth, conidiation and appressorium formation. The mutants exhibited highly sensitive response to osmotic, cell wall integrity or oxidative stresses. MoCdc25 physically interacts with the MAPK scaffold Mst50 and the putative Cdc42GEF MoScd1 in yeast two-hybrid assays. Moreover, we found that MoCdc25 was involved in regulating the phosphorylation of the MAP kinases (Pmk1, Mps1, and Osm1). In addition, the intracellular cAMP content in hyphae of the ΔMocdc25 mutants was significantly reduced compared to the parent strain Ku80 and the defect of appressorium formation of the mutants could be partially restored by the supplement of exogenous cAMP. Taken together, we conclude that the RasGEF MoCdc25 regulates vegetative growth, conidiation, appressorium formation and pathogenicity via MAPK and cAMP response pathways in M. oryzae.

Genome assemblies and gene models for 120 isolates of the rice blast fungus Magnaporthe oryzae

Genome assemblies and gene models for 120 isolates of the rice blast fungus Magnaporthe oryzae

Doxorubicin inhibits phosphatidylserine decarboxylase and confers broad-spectrum antifungal activity.

As phospholipids of cell membranes, phosphatidylethanolamine (PE) and phosphatidylserine (PS) play crucial roles in glycerophospholipid metabolism. Broadly, some phospholipid biosynthesis enzymes serve as potential fungicide targets. Therefore, revealing the functions and mechanism of PE biosynthesis in plant pathogens would provide potential targets for crop disease control. We performed analyses including phenotypic characterizations, lipidomics, enzyme activity, site-directed mutagenesis, and chemical inhibition assays to study the function of PS decarboxylase-encoding gene MoPSD2 in rice blast fungus Magnaporthe oryzae. The Mopsd2 mutant was defective in development, lipid metabolism, and plant infection. The PS level increased while PE decreased in Mopsd2, consistent with the enzyme activity. Furthermore, chemical doxorubicin inhibited the enzyme activity of MoPsd2 and showed antifungal activity against 10 phytopathogenic fungi including M. oryzae and reduced disease severity of two crop diseases in the field. Three predicted doxorubicin-interacting residues are important for MoPsd2 functions. Our study demonstrates that MoPsd2 is involved in de novo PE biosynthesis and contributes to the development and plant infection of M. oryzae and that doxorubicin shows broad-spectrum antifungal activity as a fungicide candidate. The study also implicates that bacterium Streptomyces peucetius, which biosynthesizes doxorubicin, could be potentially used as an eco-friendly biocontrol agent.

Effects of irradiation treatments on genetic variation and damage repair in the rice blast fungus Magnaporthe oryzae

Effects of irradiation treatments on genetic variation and damage repair in the rice blast fungus Magnaporthe oryzae

RNAPII Degradation Factor Def1 Is Required for Development, Stress Response, and Full Virulence of Magnaporthe oryzae.

The RNA polymerase II degradation factor Degradation Factor 1 (Def1) is important for DNA damage repair and plays various roles in eukaryotes; however, the biological role in plant pathogenic fungi is still unknown. In this study, we investigated the role of Def1 during the development and infection of the rice blast fungus Magnaporthe oryzae. The deletion mutant of Def1 displayed slower mycelial growth, less conidial production, and abnormal conidial morphology. The appressoria of Δdef1 was impaired in the penetration into host cells, mainly due to blocking in the utilization of conidial storages, such as glycogen and lipid droplets. The invasive growth of the Δdef1 mutant was also retarded and accompanied with the accumulation of reactive oxygen species (ROS) inside the host cells. Furthermore, compared with the wild type, Δdef1 was more sensitive to multiple stresses, such as oxidative stress, high osmotic pressure, and alkaline/acidic pH. Interestingly, we found that Def1 was modified by O-GlcNAcylation at Ser232, which was required for the stability of Def1 and its function in pathogenicity. Taken together, the O-GlcNAc modified Def1 is required for hyphae growth, conidiation, pathogenicity, and stress response in M. oryzae. This study reveals a novel regulatory mechanism of O-GlcNAc-mediated Def1 in plant pathogenic fungi.

The regulatory subunit MoB56 of PP2A phosphatase regulates pathogenicity, growth and development in a protein complex with the atypical catalytic subunit Ppg1 in the rice blast fungus Magnaporthe oryzae

Protein phosphatase 2A (PP2A) is usually a heterotrimeric enzyme, consisting of a catalytic subunit (C) and a scaffolding subunit (A) associated with a third, variable regulatory subunit (B). Fungi usually carry a single gene for A and C subunits, and three genes for the B subunit. In addition, fungi contain a conserved atypical C subunit named Ppg1, which is essential to the pathogenicity of the rice blast fungus Magnaporthe oryzae. However, it remains largely unknown how the B subunit combinatorically assembles with the A and C subunits or Ppg1 to regulate fungal growth, development and pathogenicity. Here we report and functionally characterize one regulatory subunit of PP2A, named MoB56, in M. oryzae. We generated a MoB56 deletion mutant Δmob56, which was severely defective in vegetative growth, conidiation and septum formation, and had lost pathogenicity. The defects of Δmob56 could be rescued by introducing MoB56 fused with GFP (MoB56-GFP) at its C terminus. Fluorescence microscopic observations revealed that the MoB56-GFP signals were widely distributed in the cytoplasm and formed a dot-like structure at the center of the septum in conidia, appressoria and infection hyphae, supporting its function in septation. Further, we performed co-immunoprecipitation and pull-down assays, indicating that MoB56 forms a protein complex with the A subunit and Ppg1 in mycelial cells. The yeast two-hybrid assay showed that MoB56 could interact with the A subunit of PP2A but not with Ppg1, while Ppg1 could interact with the A subunit, suggesting that the A subunit ties MoB56 with Ppg1 for the protein complex formation. In addition, we revealed that MoB56 has multiple isoforms, which are likely originated from alternative splicing and sumoylation. This is the first report revealing that the regulatory subunit B56 is associated with the PP2A-like phosphatase Ppg1 in fungi. Importantly, this study showed that B56, like Ppg1, is essential to the pathogenicity of M. oryzae, offering a potential new lead to control this devastating fungal pathogen by targeting specific PP2A-like phosphatase. Together, this study provides important information for understanding how the regulatory subunit B56 of PP2A regulates fungal pathogenicity and for the control of rice blast disease.

Rgs1 is a regulator of effector gene expression during plant infection by the rice blast fungus Magnaporthe oryzae

To cause rice blast disease, the filamentous fungus Magnaporthe oryzae secretes a battery of effector proteins into host plant tissue to facilitate infection. Effector-encoding genes are expressed only during plant infection and show very low expression during other developmental stages. How effector gene expression is regulated in such a precise manner during invasive growth by M. oryzae is not known. Here, we report a forward-genetic screen to identify regulators of effector gene expression, based on the selection of mutants that show constitutive effector gene expression. Using this simple screen, we identify Rgs1, a regulator of G-protein signaling (RGS) protein that is necessary for appressorium development, as a novel transcriptional regulator of effector gene expression, which acts prior to plant infection. We show that an N-terminal domain of Rgs1, possessing transactivation activity, is required for effector gene regulation and acts in an RGS-independent manner. Rgs1 controls the expression of at least 60 temporally coregulated effector genes, preventing their transcription during the prepenetration stage of development prior to plant infection. A regulator of appressorium morphogenesis is therefore also required for the orchestration of pathogen gene expression required for invasive growth by M. oryzae during plant infection.

The transcriptional landscape of plant infection by the rice blast fungus Magnaporthe oryzae reveals distinct families of temporally co-regulated and structurally conserved effectors.

The rice blast fungus Magnaporthe oryzae causes a devastating disease that threatens global rice (Oryza sativa) production. Despite intense study, the biology of plant tissue invasion during blast disease remains poorly understood. Here we report a high-resolution transcriptional profiling study of the entire plant-associated development of the blast fungus. Our analysis revealed major temporal changes in fungal gene expression during plant infection. Pathogen gene expression could be classified into 10 modules of temporally co-expressed genes, providing evidence for the induction of pronounced shifts in primary and secondary metabolism, cell signaling, and transcriptional regulation. A set of 863 genes encoding secreted proteins are differentially expressed at specific stages of infection, and 546 genes named MEP (Magnaportheeffector protein) genes were predicted to encode effectors. Computational prediction of structurally related MEPs, including the MAX effector family, revealed their temporal co-regulation in the same co-expression modules. We characterized 32 MEP genes and demonstrate that Mep effectors are predominantly targeted to the cytoplasm of rice cells via the biotrophic interfacial complex and use a common unconventional secretory pathway. Taken together, our study reveals major changes in gene expression associated with blast disease and identifies a diverse repertoire of effectors critical for successful infection.

Two nucleotide sugar transporters are important for cell wall integrity and full virulence of Magnaporthe oryzae.

Cell wall polysaccharides play key roles in fungal development, virulence, and resistance to the plant immune system, and are synthesized from many nucleotide sugars in the endoplasmic reticulum (ER)-Golgi secretory system. Nucleotide sugar transporters (NSTs) are responsible for transporting cytosolic-derived nucleotide sugars to the ER lumen for processing, but their roles in plant-pathogenic fungi remain to be revealed. Here, we identified two important NSTs, NST1 and NST2, in the rice blast fungus Magnaporthe oryzae. Both NSTs were localized in the ER, which was consistent with a function in transporting nucleotide sugar for processing in the ER. Sugar transport property analysis suggested that NST1 is involved in transportation of mannose and glucose, while NST2 is only responsible for mannose transportation. Accordingly, deletion ofNSTs resulted in a significant decrease in corresponding soluble saccharides abundance and defect in sugar utilization. Moreover, bothNSTs played important roles in cell wall integrity, were involved in asexual development, and were required for full virulence. The NST mutants exhibited decreasing external glycoproteins and exposure of inner chitin, which resulted in activation of the host defence response. Altogether, our results revealed that two sugar transporters are required for fungal cell wall polysaccharides accumulation and full virulence of M.oryzae.

MoLrp1-mediated signaling induces nuclear accumulation of MoMsn2 to facilitate fatty acid oxidation for infectious growth of the rice blast fungus

Fatty acid β-oxidation is critical for fatty acid degradation and cellular development. In the rice blast fungus Magnaporthe oryzae, fatty acid β-oxidation is reported to be important mainly for turgor generation in the appressorium. However, the role of fatty acid β-oxidation during invasive hyphal growth is rarely documented. We demonstrated that blocking peroxisomal fatty acid β-oxidation impaired lipid droplet (LD) degradation and infectious growth of M. oryzae. We found that the key regulator of pathogenesis, MoMsn2, which we identified previously, is involved in fatty acid β-oxidation by targeting MoDCI1 (encoding dienoyl-coenzyme A [CoA] isomerase), which is also important for LD degradation and infectious growth. Cytological observations revealed that MoMsn2 accumulated from the cytosol to the nucleus during early infection or upon treatment with oleate. We determined that the low-density lipoprotein receptor-related protein MoLrp1, which is also involved in fatty acid β-oxidation and infectious growth, plays a critical role in the accumulation of MoMsn2 from the cytosol to the nucleus by activating the cyclic AMP signaling pathway. Our results provide new insights into the importance of fatty acid oxidation during invasive hyphal growth, which is modulated by MoMsn2 and its related signaling pathways in M. oryzae.

Sucrose preferentially promotes expression of OsWRKY7 and OsPR10a to enhance defense response to blast fungus in rice.

Sucrose controls various developmental and metabolic processes in plants. It also functions as a signaling molecule in the synthesis of carbohydrates, storage proteins, and anthocyanins, as well as in floral induction and defense response. We found that sucrose preferentially induced OsWRKY7, whereas other sugars (such as mannitol, glucose, fructose, galactose, and maltose) did not have the same effect. A hexokinase inhibitor mannoheptulose did not block the effect of sucrose, which is consequently thought to function directly. MG132 inhibited sucrose induction, suggesting that a repressor upstream of OsWRKY7 is degraded by the 26S proteasome pathway. The 3-kb promoter sequence of OsWRKY7 was preferentially induced by sucrose in the luciferase system. Knockout mutants of OsWRKY7 were more sensitive to the rice blast fungus Magnaporthe oryzae, whereas the overexpression of OsWRKY7 enhanced the resistance, indicating that this gene is a positive regulator in the plant defense against this pathogen. The luciferase activity driven by the OsPR10a promoter was induced by OsWRKY7 and this transcription factor bound to the promoter region of OsPR10a, suggesting that OsWRKY7 directly controls the expression of OsPR10a. We conclude that sucrose promotes the transcript level of OsWRKY7, thereby increasing the expression of OsPR10a for the defense response in rice.

Disentangling the complex gene interaction networks between rice and the blast fungus identifies a new pathogen effector.

Studies focused solely on single organisms can fail to identify the networks underlying host-pathogen gene-for-gene interactions. Here, we integrate genetic analyses of rice (Oryza sativa, host) and rice blast fungus (Magnaporthe oryzae, pathogen) and uncover a new pathogen recognition specificity of the rice nucleotide-binding domain and leucine-rich repeat protein (NLR) immune receptor Pik, which mediates resistance to M. oryzae expressing the avirulence effector gene AVR-Pik. Rice Piks-1, encoded by an allele of Pik-1, recognizes a previously unidentified effector encoded by the M. oryzae avirulence gene AVR-Mgk1, which is found on a mini-chromosome. AVR-Mgk1 has no sequence similarity to known AVR-Pik effectors and is prone to deletion from the mini-chromosome mediated by repeated Inago2 retrotransposon sequences. AVR-Mgk1 is detected by Piks-1 and by other Pik-1 alleles known to recognize AVR-Pik effectors; recognition is mediated by AVR-Mgk1 binding to the integrated heavy metal-associated (HMA) domain of Piks-1 and other Pik-1 alleles. Our findings highlight how complex gene-for-gene interaction networks can be disentangled by applying forward genetics approaches simultaneously to the host and pathogen. We demonstrate dynamic coevolution between an NLR integrated domain and multiple families of effector proteins.

MoMaf1 Mediates Vegetative Growth, Conidiogenesis, and Pathogenicity in the Rice Blast Fungus Magnaporthe oryzae.

In eukaryotes, Maf1 is an essential and specific negative regulator of RNA polymerase (Pol) III. Pol III, which synthesizes 5S RNA and transfer RNAs (tRNAs), is suppressed by Maf1 under the conditions of nutrient starvation or environmental stress. Here, we identified M. oryzae MoMaf1, a homolog of ScMaf1 in budding yeast. A heterogeneous complementation assay revealed that MoMaf1 restored growth defects in the ΔScmaf1 mutant under SDS stress. Destruction of MoMAF1 elevated 5S rRNA content and increased sensitivity to cell wall agents. Moreover, the ΔMomaf1 mutant exhibited reduced vegetative growth, conidiogenesis, and pathogenicity. Interestingly, we found that MoMaf1 underwent nuclear-cytoplasmic shuffling, through which MoMaf1 accumulated in nuclei under nutrient deficiency or upon the interaction of M. oryzae with rice. Therefore, this study can help to elucidate the pathogenic molecular mechanism of M. oryzae.

Type 2C Protein Phosphatases MoPtc5 and MoPtc7 Are Crucial for Multiple Stress Tolerance, Conidiogenesis and Pathogenesis of Magnaporthe oryzae.

Protein kinases and phosphatases catalyze the phosphorylation and dephosphorylation of their protein substrates, respectively, and these are important mechanisms in cellular signal transduction. The rice blast fungus Magnaporthe oryzae possesses 6 protein phosphatases of type 2C class, including MoPtc1, 2, 5, 6, 7 and 8. However, only very little is known about the roles of these phosphatases in filamentous fungi. Here in, we deployed genetics and molecular biology techniques to identify, characterize and establish the roles of MoPtc5 and MoPtc7 in M. oryzae development and pathogenicity. We found that during pathogen-host interaction, MoPTC7 is differentially expressed. Double deletion of MoPTC7 and MoPTC5 suppressed the fungal vegetative growth, altered its cell wall integrity and reduced its virulence. The two genes were found indispensable for stress tolerance in the phytopathogen. We also demonstrated that disruption of any of the two genes highly affected appressorium turgor generation and Mps1 and Osm1 phosphorylation levels. Lastly, we demonstrated that both MoPtc5 and MoPtc7 are localized to mitochondria of different cellular compartments in the blast fungus. Taken together, our study revealed synergistic coordination of M. oryzae development and pathogenesis by the type 2C protein phosphatases.

AgNPs-Triggered Seed Metabolic and Transcriptional Reprogramming Enhanced Rice Salt Tolerance and Blast Resistance

Seeds are facing harsher environments due to the changing climate. Improving seeds' stress resilience is critical to reduce yield loss. Here, we propose that using ROS-generating nanoparticles (NPs) to prestimulate seeds would enhance the stress resilience of seeds and seedlings through triggering stress/immune responses. We examined this hypothesis by exposing AgNPs-primed rice (Oryza sativa L.) seeds under salt conditions (NaCl). The results showed that primed seeds exhibit accelerated germination speed, increased seedling vigor (from 22.5 to 47.6), biomass (11%), and root length (83%) compared to seeds with hydropriming treatment. Multiomics (metabolomics and transcriptomics) analyses reveal that AgNPs-priming triggered metabolic and transcriptional reprogramming in rice seeds. Signaling metabolites, such as salicylic acid, niacinamide, and glycerol-3-phosphate, dramatically increased upon AgNPs-priming. KEGG pathway analysis reveals that AgNPs-priming activated stress signaling and defense related pathways, such as plant hormone signal transduction, glutathione metabolism, flavone and flavonol biosynthesis, MAPK signaling pathway, and plant-pathogen interaction. These metabolic and transcriptional changes indicate that AgNPs-priming triggered stress/immune responses. More importantly, this "stress memory" can last weeks, providing protection to rice seedlings against salt stress and rice blast fungus (Magnaporthe oryzae). Overall, we show that prestimulated seeds with ROS-generating AgNPs not only enable faster and better germination under stress conditions, but also increase seedling resistance to biotic and abiotic stresses. This simple nanobiostimulant-based strategy may contribute to sustainable agriculture by maintaining agricultural production and reducing the use of pesticides.

The Calcium Chloride Responsive Type 2C Protein Phosphatases Play Synergistic Roles in Regulating MAPK Pathways in Magnaporthe oryzae.

Reversible protein phosphorylation is essential in cellular signal transduction. The rice blast fungus Magnaporthe oryzae contains six putative type 2C protein phosphatases, namely MoPtc1, MoPtc2, MoPtc5, MoPtc6, MoPtc7, and MoPtc8. The major functions of MoPtc1 and MoPtc2 have been reported recently. In this communication, we found that MoPtc1 and MoPtc2 were induced by calcium chloride. We also found that the deletion of both MoPtc1 and MoPtc2 resulted in the overstimulation of both the high-osmolarity glycerol (Hog1) and pathogenicity MAP kinase 1 (Pmk1) pathways in M. oryzae. MoPtc1 was recruited directly to Osm1 (the osmotic stress-sensitive mutant) by the adaptor protein MoNbp2 to inactivate the Osm1 during hypoosmotic stress, distinct from the budding yeast. Moreover, we showed that MoPtc1 and MoPtc2 were localized in different cellular compartments in the fungal development. Taken together, we added some new findings of type 2C protein phosphatases MoPtc1 and MoPtc2 functions to the current knowledge on the regulation of MAPK signaling pathways in M. oryzae.

Membrane component ergosterol builds a platform for promoting effector secretion and virulence in Magnaporthe oryzae.

The plasma membrane (PM) functions as a physical border between the extracellular and cytoplasmic environments that contribute to the interaction between host plants and pathogenic fungi. As a specific sterol constituent in the cell membrane, ergosterol plays a significant role in fungal development. However, the role of ergosterol in the infection of the rice blast fungus Magnaporthe oryzae remains unclear. In this study, we found that a sterol reductase, MoErg4, is involved in ergosterol biosynthesis and the regulation of plasma membrane integrity in M.oryzae. We found that defects in ergosterol biosynthesis disrupt lipid raft formation in the PM and cause an abnormal distribution of the t-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein MoSso1, inhibiting its interaction with the v-SNARE protein MoSnc1. In addition, we found that MoSso1-MoSnc1 interaction is important for biotrophic interface complex development and cytoplasmic effector protein secretion. Our findings suggested that ergosterol-enriched lipid rafts constitute a platform for interactions among various SNARE proteins that are required for the development and pathogenicity of M.oryzae.

The Amino Acid Permease MoGap1 Regulates TOR Activity and Autophagy in Magnaporthe oryzae.

Rice is an important food crop all over the world. It can be infected by the rice blast fungus Magnaporthe oryzae, which results in a significant reduction in rice yield. The infection mechanism of M. oryzae has been an academic focus for a long time. It has been found that G protein, AMPK, cAMP-PKA, and MPS1-MAPK pathways play different roles in the infection process. Recently, the function of TOR signaling in regulating cell growth and autophagy by receiving nutritional signals generated by plant pathogenic fungi has been demonstrated, but its regulatory mechanism in response to the nutritional signals remains unclear. In this study, a yeast amino acid permease homologue MoGap1 was identified and a knockout mutant of MoGap1 was successfully obtained. Through a phenotypic analysis, a stress analysis, autophagy flux detection, and a TOR activity analysis, we found that the deletion of MoGap1 led to a sporulation reduction as well as increased sensitivity to cell wall stress and carbon source stress in M. oryzae. The ΔMogap1 mutant showed high sensitivity to the TOR inhibitor rapamycin. A Western blot analysis further confirmed that the TOR activity significantly decreased, which improved the level of autophagy. The results suggested that MoGap1, as an upstream regulator of TOR signaling, regulated autophagy and responded to adversities such as cell wall stress by regulating the TOR activity.

The Paxillin MoPax1 Activates Mitogen-Activated Protein (MAP) Kinase Signaling Pathways and Autophagy through MAP Kinase Activator MoMka1 during Appressorium-Mediated Plant Infection by the Rice Blast Fungus Magnaporthe oryzae.

Paxillin is a focal adhesion-associated protein that functions as an adaptor to recruit diverse cytoskeleton and signaling molecules into a complex and plays a crucial role in several signaling pathways in mammal cells. However, paxillin-mediated signal pathways are largely unknown in phytopathogenic fungi. Previously, Pax1 of Magnaporthe oryzae (MoPax1), a paxillin-like protein, has been identified as a crucial pathogenicity determinant. Here, we report the identification of a mitogen-activated protein (MAP) kinase (MAPK) activator, Mka1 of M. oryzae (MoMka1), that physically interacts with MoPax1. Targeted gene deletion of MoMKA1 resulted in pleiotropic defects in aerial hyphal growth, conidiation, appressorium formation, and pathogenicity in M. oryzae. MoMka1 interacts with Mst50, an adaptor protein of the Mst11-Mst7-Pmk1 and Mck1-Mkk2-Mps1 cascades. Moreover, the phosphorylation levels of both Pmk1 and Mps1 in aerial hyphae of the ΔMomka1 mutant were significantly reduced, indicating that MoMka1 acts upstream from the MAPK pathways. Interestingly, we found that MoMka1 interacts with MoAtg6 and MoAtg13. Deletion of MoMKA1 led to impaired MoAtg13 phosphorylation and enhanced autophagic flux under nutrient-rich conditions, indicating that MoMka1 is required for regulation of autophagy in M. oryzae. Taken together, the paxillin MoPax1 may activate MAP kinase signaling pathways and autophagy through MAP kinase activator MoMka1 and play important roles during appressorium-mediated plant infection by the rice blast fungus. IMPORTANCE Paxillin, as an adaptor recruiting diverse cytoskeleton and signaling molecules into a complex, plays a crucial role in several signaling pathways in mammal cells. However, paxillin-mediated signal pathways are largely unknown in phytopathogenic fungi. Here, we identified that MoMka1 physically interacts with MoPax1. Furthermore, MoMka1 acts upstream from the MAPK pathways through interacting with Mst50, a key protein of the Mst11-Mst7-Pmk1 and Mck1-Mkk2-Mps1 cascades. Meanwhile, MoMka1 interacts with both MoAtg6 and MoAtg13 and controls autophagy initiation by influencing the phosphorylation level of MoAtg13. In summary, we describe a model in which MoPax1 activates MAP kinase signaling pathways and autophagy through MoMka1 during appressorium-mediated plant infection by M. oryzae.