Autophagy and cell wall integrity pathways coordinately regulate the development and pathogenicity through MoAtg4 phosphorylation in Magnaporthe oryzae.

Autophagy and Cell wall integrity (CWI) signaling are critical stress-responsive processes during fungal infection of host plants. In the rice blast fungus Magnaporthe oryzae, autophagy-related (ATG) proteins phosphorylate CWI kinases to regulate virulence; however, how autophagy interplays with CWI signaling to coordinate such regulation remains unknown. Here, we have identified the phosphorylation of ATG protein MoAtg4 as an important process in the coordination between autophagy and CWI in M. oryzae. The ATG kinase MoAtg1 phosphorylates MoAtg4 to inhibit the deconjugation and recycling of the key ATG protein MoAtg8. At the same time, MoMkk1, a core kinase of CWI, also phosphorylates MoAtg4 to attenuate the C-terminal cleavage of MoAtg8. Significantly, these two phosphorylation events maintain proper autophagy levels to coordinate the development and pathogenicity of the rice blast fungus.

Neuro-epithelial-ILC2 crosstalk in barrier tissues.

Group 2 innate lymphoid cells (ILC2s) contribute to the maintenance of mammalian barrier tissue homeostasis. We review how ILC2s integrate epithelial signals and neurogenic components to preserve the tissue microenvironment and modulate inflammation. The epithelium that overlies barrier tissues, including the skin, lungs, and gut, generates epithelial cytokines that elicit ILC2 activation. Sympathetic, parasympathetic, sensory, and enteric fibers release neural signals to modulate ILC2 functions. We also highlight recent findings suggesting neuro-epithelial-ILC2 crosstalk and its implications in immunity, inflammation and resolution, tissue repair, and restoring homeostasis. We further discuss the pathogenic effects of disturbed ILC2-centered neuro-epithelial-immune cell interactions and putative areas for therapeutic targeting.

AtSNU13 modulates pre-mRNA splicing of RBOHD and ALD1 to regulate plant immunity.

Pre-mRNA splicing is a significant step for post-transcriptional modifications and functions in a wide range of physiological processes in plants. Human NHP2L binds to U4 snRNA during spliceosome assembly; it is involved in RNA splicing and mediates the development of human tumors. However, no ortholog has yet been identified in plants. Therefore, we report At4g12600 encoding the ortholog NHP2L protein, and AtSNU13 associates with the component of the spliceosome complex; the atsnu13 mutant showed compromised resistance in disease resistance, indicating that AtSNU13 is a positive regulator of plant immunity. Compared to wild-type plants, the atsnu13 mutation resulted in altered splicing patterns for defense-related genes and decreased expression of defense-related genes, such as RBOHD and ALD1. Further investigation shows that AtSNU13 promotes the interaction between U4/U6.U5 tri-snRNP-specific 27 K and the motif in target mRNAs to regulate the RNA splicing. Our study highlights the role of AtSNU13 in regulating plant immunity by affecting the pre-mRNA splicing of defense-related genes.

Common carotid artery diameter and the risk of cardiovascular disease mortality: a prospective cohort study in northeast China.

BACKGROUND: The association between the common carotid artery (CCA) diameter and cardiovascular disease (CVD) is recognized, but the precise nature of this link remains elusive. This study aimed to investigate the potential relationship between CCA diameter and the risk of CVD mortality in a large population in northeast China. METHODS: The current study included 5668 participants (mean age 58.9 ± 10.1 years) from a population-based study conducted in rural areas of northeast China between September 2017 and May 2018. Information on death was collected from baseline until July 31, 2022. The CCA inter-adventitial diameter was measured using ultrasound. Cox proportional-hazard models were employed to explore the relationship between the common carotid artery diameter and cardiovascular mortality. RESULTS: At baseline, the mean CCA diameter (mm) of subjects was 7.30 ± 0.99 and increased significantly with age, ranging from 6.65 ± 0.71 among people 40-49 years to 7.99 ± 1.04 among people ≥ 80 years. CCA diameter was significantly larger in males compared to females (7.51 ± 1.03 versus vs. 7.16 ± 0.94; P < 0.001). A total of 185 participants died of CVD during a median follow-up of 4.48 years. CCA diameters were divided into quartiles, and the highest quartile of carotid diameter (≥ 8.06 mm) had a 2.29 (95% confidence interval [CI]: 1.24, 4.22) times higher risk of CVD mortality than the lowest quartile (≤ 6.65 mm) (P < 0.01) in the fully adjusted model. Each increase in the diameter of the common carotid artery (per SD) raised the risk of cardiovascular death by 36% (hazard ratio [HR]: 1.36; 95% CI: 1.18, 1.57). The subgroup analysis results demonstrated that a per SD increase was associated with a 42% increased risk of CVD mortality in participants aged ≥ 64 years in the fully adjusted model (HR: 1.42; 95%CI: 1.21, 1.66). CONCLUSIONS: Our study indicates the possible incremental value of CCA diameter in optimizing the risk stratification of cardiovascular disease and provides essential insights into reducing the burden of cardiovascular disease.

Balancing of the mitotic exit network and cell wall integrity signaling governs the development and pathogenicity in Magnaporthe oryzae.

The fungal cell wall plays an essential role in maintaining cell morphology, transmitting external signals, controlling cell growth, and even virulence. Relaxation and irreversible stretching of the cell wall are the prerequisites of cell division and development, but they also inevitably cause cell wall stress. Both Mitotic Exit Network (MEN) and Cell Wall Integrity (CWI) are signaling pathways that govern cell division and cell stress response, respectively, how these pathways cross talk to govern and coordinate cellular growth, development, and pathogenicity remains not fully understood. We have identified MoSep1, MoDbf2, and MoMob1 as the conserved components of MEN from the rice blast fungus Magnaporthe oryzae. We have found that blocking cell division results in abnormal CWI signaling. In addition, we discovered that MoSep1 targets MoMkk1, a conserved key MAP kinase of the CWI pathway, through protein phosphorylation that promotes CWI signaling. Moreover, we provided evidence demonstrating that MoSep1-dependent MoMkk1 phosphorylation is essential for balancing cell division with CWI that maintains the dynamic stability required for virulence of the blast fungus.

The rice blast fungus MoRgs1 functioning in cAMP signaling and pathogenicity is regulated by casein kinase MoCk2 phosphorylation and modulated by membrane protein MoEmc2.

GTP-binding protein (G-protein) and regulator of G-protein signaling (RGS) mediated signal transduction are critical in the growth and virulence of the rice blast pathogen Magnaporthe oryzae. We have previously reported that there are eight RGS and RGS-like proteins named MoRgs1 to MoRgs8 playing distinct and shared regulatory functions in M. oryzae and that MoRgs1 has a more prominent role compared to others in the fungus. To further explore the unique regulatory mechanism of MoRgs1, we screened a M. oryzae cDNA library for genes encoding MoRgs1-interacting proteins and identified MoCkb2, one of the two regulatory subunits of the casein kinase (CK) 2 MoCk2. We found that MoCkb2 and the sole catalytic subunit MoCka1 are required for the phosphorylation of MoRgs1 at the plasma membrane (PM) and late endosome (LE). We further found that an endoplasmic reticulum (ER) membrane protein complex (EMC) subunit, MoEmc2, modulates the phosphorylation of MoRgs1 by MoCk2. Interestingly, this phosphorylation is also essential for the GTPase-activating protein (GAP) function of MoRgs1. The balance among MoRgs1, MoCk2, and MoEmc2 ensures normal operation of the G-protein MoMagA-cAMP signaling required for appressorium formation and pathogenicity of the fungus. This has been the first report that an EMC subunit is directly linked to G-protein signaling through modulation of an RGS-casein kinase interaction.

Glutathione and neodiosmin feedback sustain plant immunity.

Plants have evolved a two-layer immune system comprising pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) that is activated in response to pathogen invasion. Microbial patterns and pathogen effectors can be recognized by surface-localized pattern-recognition receptors (PRRs) and intracellularly localized nucleotide-binding leucine-rich repeat receptors (NLRs) to trigger PTI and ETI responses, respectively. At present, the metabolites activated by PTI and ETI and their roles and signalling pathways in plant immunity are not well understood. In this study, metabolomic analysis showed that ETI and PTI induced various flavonoids and amino acids and their derivatives in plants. Interestingly, both glutathione and neodiosmin content were specifically up-regulated by ETI and PTI, respectively, which significantly enhanced plant immunity. Further studies showed that glutathione and neodiosmin failed to induce a plant immune response in which PRRs/co-receptors were mutated. In addition, glutathione-reduced mutant gsh1 analysis showed that GSH1 is also required for PTI and ETI. Finally, we propose a model in which glutathione and neodiosmin are considered signature metabolites induced in the process of ETI and PTI activation in plants and further continuous enhancement of plant immunity in which PRRs/co-receptors are needed. This model is beneficial for an in-depth understanding of the closed-loop mode of the positive feedback regulation of PTI and ETI signals at the metabolic level.

Microbial volatile organic compounds 2-heptanol and acetoin control Fusarium crown and root rot of tomato.

Some microbial volatile organic compounds (mVOCs) can act as antagonistic weapons against plant pathogens, but little information is available on the contribution of individual mVOC to biocontrol and how they interact with plant pathogens. In this study, the Bacillus subtilis strain N-18 isolated from the rhizosphere of healthy plants grown in areas where Fusarium crown and root rot (FCRR) of tomato occurs could reduce the 30% of the incidence of FCRR. Moreover, the volatile organic compounds (VOCs) produced by N-18 had inhibitory effects on Fusarium oxysporum f. sp. radicis-lycopersici (FORL). The identification of VOCs of N-18 was analyzed by the solid-phase microextraction coupled to gas chromatography-mass spectrometry. Meanwhile, we conducted sensitivity tests with these potential active ingredients and found that the volatile substances acetoin and 2-heptanol can reduce the 41.33% and 35% of the incidence of FCRR in tomato plants. In addition, the potential target protein of acetoin, found in the cheminformatics and bioinformatics database, was F. oxysporum of hypothetical protein AU210_012600 (FUSOX). Molecular docking results further predicted that acetoin interacts with FUSOX protein. These results reveal the VOCs of N-18 and their active ingredients in response to FORL and provide a basis for further research on regulating and controlling FCRR.

Silica nanoparticles protect rice against biotic and abiotic stresses.

BACKGROUND: By 2050, the world population will increase to 10 billion which urged global demand for food production to double. Plant disease and land drought will make the situation more dire, and safer and environment-friendly materials are thus considered as a new countermeasure. The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice worldwide that seriously threatens rice production. Unfortunately, traditional breeding nor chemical approaches along control it well. Nowadays, nanotechnology stands as a new weapon against these mounting challenges and silica nanoparticles (SiO2 NPs) have been considered as potential new safer agrochemicals recently but the systematically studies remain limited, especially in rice. RESULTS: Salicylic acid (SA) is a key plant hormone essential for establishing plant resistance to several pathogens and its further affected a special form of induced resistance, the systemic acquired resistance (SAR), which considered as an important aspect of plant innate immunity from the locally induced disease resistance to the whole plant. Here we showed that SiO2 NPs could stimulate plant immunity to protect rice against M. oryzae through foliar treatment that significantly decreased disease severity by nearly 70% within an appropriate concentration range. Excessive concentration of foliar treatment led to disordered intake and abnormal SA responsive genes expressions which weaken the plant resistance and even aggravated the disease. Importantly, this SA-dependent fungal resistance could achieve better results with root treatment through a SAR manner with no phytotoxicity since the orderly and moderate absorption. What's more, root treatment with SiO2 NPs could also promote root development which was better to deal with drought. CONCLUSIONS: Taken together, our findings not only revealed SiO2 NPs as a potential effective and safe strategy to protect rice against biotic and abiotic stresses, but also identify root treatment for the appropriate application method since it seems not causing negative effects and even have promotion on root development.

Phosphorylation-guarded light-harvesting complex II contributes to broad-spectrum blast resistance in rice.

Environmental conditions are key factors in the progression of plant disease epidemics. Light affects the outbreak of plant diseases, but the underlying molecular mechanisms are not well understood. Here, we report that the light-harvesting complex II protein, LHCB5, from rice is subject to light-induced phosphorylation during infection by the rice blast fungus Magnaporthe oryzae We demonstrate that single-nucleotide polymorphisms (SNPs) in the LHCB5 promoter control the expression of LHCB5, which in turn correlates with the phosphorylation of LHCB5. LHCB5 phosphorylation enhances broad-spectrum resistance of rice to M. oryzae through the accumulation of reactive oxidative species (ROS) in the chloroplast. We also show that LHCB5 phosphorylation-induced resistance is inheritable. Our results uncover an immunity mechanism mediated by phosphorylation of light-harvesting complex II.

Different Fruit-Specific Promoters Drive AtMYB12 Expression to Improve Phenylpropanoid Accumulation in Tomato.

Tomato is an economically crucial vegetable/fruit crop globally. Tomato is rich in nutrition and plays an essential role in a healthy human diet. Phenylpropanoid, a critical compound in tomatoes, reduces common degenerative and chronic diseases risk caused by oxidative stress. As an MYB transcription factor, ATMYB12 can increase phenylpropanoid content by activating phenylpropanoid synthesis related genes, such as PAL, C4H, 4CL, CHS. However, the heterologous expression of AtMYB12 in tomatoes can be altered through transgenic technologies, such as unstable expression vectors and promoters with different efficiency. In the current study, the efficiency of other fruit-specific promoters, namely E8S, 2A12, E4, and PG, were compared and screened, and we determined that the expression efficiency of AtMYB12 was driven by the E8S promoter was the highest. As a result, the expression of phenylpropanoid synthesis related genes was regulated by AtMYB12, and the phenylpropanoid accumulation in transgenic tomato fruits increased 16 times. Additionally, the total antioxidant capacity of fruits was measured through Trolox equivalent antioxidant capacity (TEAC) assay, which was increased by 2.4 times in E8S transgenic lines. TEAC was positively correlated with phenylpropanoid content. Since phenylpropanoid plays a crucial role in the human diet, expressing AtMYB12 with stable and effective fruit-specific promoter E8S could improve tomato's phenylpropanoid and nutrition content and quality. Our results can provide genetic resources for the subsequent improvement of tomato varieties and quality, which is significant for human health.

Phosphatase-associated protein MoTip41 interacts with the phosphatase MoPpe1 to mediate crosstalk between TOR and cell wall integrity signalling during infection by the rice blast fungus Magnaporthe oryzae.

The type 2A (PP2A) and type 2A-like (PP4 and PP6) serine/threonine phosphatases participate in a variety of cellular processes, such as cell cycle progression, signal transduction and apoptosis. Previously, we reported that the PP6 catalytic subunit MoPpe1, which interacts with and is suppressed by type 2A associated protein of 42 kDa (MoTap42), an essential protein involved in the target of rapamycin (TOR) signalling pathway, has important roles in development, virulence and activation of the cell wall integrity (CWI) pathway in the rice blast fungus Magnaporthe oryzae. Here, we show that Tap42-interacting protein 41 (MoTip41) mediates crosstalk between the TOR and CWI signalling pathways; and participates in the TOR pathway via interaction with MoPpe1, but not MoTap42. The deletion of MoTIP41 resulted in disruption of CWI signalling, autophagy, vegetative growth, appressorium function and plant infection, as well as increased sensitivity to rapamycin. Further investigation revealed that MoTip41 modulates activation of the CWI pathway in response to infection by interfering with the interaction between MoTap42 and MoPpe1. These findings enhance our understanding of how crosstalk between TOR and CWI signalling modulates the development and pathogenicity of M. oryzae.

The seven transmembrane domain protein MoRgs7 functions in surface perception and undergoes coronin MoCrn1-dependent endocytosis in complex with Gα subunit MoMagA to promote cAMP signaling and appressorium formation in Magnaporthe oryzae.

Regulator of G-protein signaling (RGS) proteins primarily function as GTPase-accelerating proteins (GAPs) to promote GTP hydrolysis of Gα subunits, thereby regulating G-protein mediated signal transduction. RGS proteins could also contain additional domains such as GoLoco to inhibit GDP dissociation. The rice blast fungus Magnaporthe oryzae encodes eight RGS and RGS-like proteins (MoRgs1 to MoRgs8) that have shared and distinct functions in growth, appressorium formation and pathogenicity. Interestingly, MoRgs7 and MoRgs8 contain a C-terminal seven-transmembrane domain (7-TM) motif typical of G-protein coupled receptor (GPCR) proteins, in addition to the conserved RGS domain. We found that MoRgs7, but not MoRgs8, couples with Gα MoMagA to undergo endocytic transport from the plasma membrane to the endosome upon sensing of surface hydrophobicity. We also found that MoRgs7 can interact with hydrophobic surfaces via a hydrophobic interaction, leading to the perception of environmental hydrophobiccues. Moreover, we found that MoRgs7-MoMagA endocytosis is regulated by actin patch-associated protein MoCrn1, linking it to cAMP signaling. Our studies provided evidence suggesting that MoRgs7 could also function in a GPCR-like manner to sense environmental signals and it, together with additional proteins of diverse functions, promotes cAMP signaling required for developmental processes underlying appressorium function and pathogenicity.

The Golgin Protein RUD3 Regulates Fusarium graminearum Growth and Virulence.

Golgins are coiled-coil proteins that play prominent roles in maintaining the structure and function of the Golgi complex. However, the role of golgin proteins in phytopathogenic fungi remains poorly understood. In this study, we functionally characterized the Fusarium graminearum golgin protein RUD3, a homolog of ScRUD3/GMAP-210 in Saccharomyces cerevisiae and mammalian cells. Cellular localization observation revealed that RUD3 is located in the cis-Golgi. Deletion of RUD3 caused defects in vegetative growth, ascospore discharge, deoxynivalenol (DON) production, and virulence. Moreover, the Δrud3 mutant showed reduced expression of tri genes and impairment of the formation of toxisomes, both of which play essential roles in DON biosynthesis. We further used green fluorescent protein (GFP)-tagged SNARE protein SEC22 (SEC22-GFP) as a tool to study the transport between the endoplasmic reticulum (ER) and Golgi and observed that SEC22-GFP was retained in the cis-Golgi in the Δrud3 mutant. RUD3 contains the coiled coil (CC), GRAB-associated 2 (GA2), GRIP-related Arf binding (GRAB), and GRAB-associated 1 (GA1) domains, which except for GA1, are indispensable for normal localization and function of RUD3, whereas only CC is essential for normal RUD3-RUD3 interaction. Together, these results demonstrate how the golgin protein RUD3 mediates retrograde trafficking in the ER-to-Golgi pathway and is necessary for growth, ascospore discharge, DON biosynthesis, and pathogenicity in F. graminearumIMPORTANCEFusarium head blight (FHB) caused by the fungal pathogen Fusarium graminearum is an economically important disease of wheat and other small grain cereal crops worldwide, and limited effective control strategies are available. A better understanding of the regulation mechanisms of F. graminearum development, deoxynivalenol (DON) biosynthesis, and pathogenicity is therefore important for the development of effective control management of this disease. Golgins are attached via their extreme carboxy terminus to the Golgi membrane and are involved in vesicle trafficking and organelle maintenance in eukaryotic cells. In this study, we systematically characterized a highly conserved Golgin protein, RUD3, and found that it is required for vegetative growth, ascospore discharge, DON production, and pathogenicity in F. graminearum Our findings provide a comprehensive characterization of the golgin family protein RUD3 in plant-pathogenic fungus, which could help to identify a new potential target for effective control of this devastating disease.

MicroRNA-like milR236, regulated by transcription factor MoMsn2, targets histone acetyltransferase MoHat1 to play a role in appressorium formation and virulence of the rice blast fungus Magnaporthe oryzae.

MicroRNAs (miRNAs) play important roles in various cellular growth and developmental processes through post-transcriptional gene regulation via mRNA cleavage and degradation and the inhibition of protein translation. To explore if miRNAs play a role in appressoria formation and virulence that are also governed by the regulators of G-protein signaling (RGS) proteins in the rice blast fungus Magnaporthe oryzae, we have compared small RNA (sRNA) production between several ΔMorgs mutant and the wild-type strains. We have identified sRNA236 as a microRNA-like milR236 that targets the encoding sequence of MoHat1, a histone acetyltransferase type B catalytic subunit involved in appressorium function and virulence. We have also found that milR236 overexpression induces delayed appressorium formation and virulence attenuation, similar to those displayed by the ΔMohat1 mutant strain. Moreover, we have shown that the transcription factor MoMsn2 binds to the promoter sequence of milR236 to further suppress MoHAT1 transcription and MoHat1-regulated appressorium formation and virulence. In summary, by identifying a novel regulatory role of sRNA in the blast fungus, our studies reveal a new paradigm in the multifaceted regulatory pathways that govern the appressorium formation and virulence of M. oryzae.

Diagnosis of triple negative breast cancer based on radiomics signatures extracted from preoperative contrast-enhanced chest computed tomography.

BACKGROUND: To explore the diagnostic value of radiomics features of preoperative computed tomography (CT) for triple negative breast cancer (TNBC) for better treatment of patients with breast cancer. METHODS: A total of 890 patients with breast cancer admitted to our hospital from June 2016 to January 2018 were analyzed. They were diagnosed by surgery and pathology to have mass and invasive breast cancer and had contrast-enhanced chest CT examination before operation. 300 patients were randomly selected for the study, including 100 TNBC and 200 non-TNBC (NTNBC) patients. Among them 180 were used in discovery group and 120 were used in validation group. The molecular subtypes of breast cancer in the patients were determined immunohistochemistrially. Radiomics features were extracted from three dimensional CT-images. The LASSO logistic method was used to select image features and calculate radiomics scores. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value of radiomics scores for TNBC. RESULTS: Five image features were found to be related to TNBC subtype (P < 0.001). These image features based-radiomic signatures had good predictive values for TNBC with the areas under ROC curve (AUC) of 0.881 (95% CI: 0.781-0.921) in the discovery group and 0.851 (95% CI: 0.761-0.961) in the validation group, respectively. The sensitivities and specificities were 0.767, and 0.873 in the discovery group and 0.785 and 0.915 in the validation group. CONCLUSIONS: Radiomic signature based on preoperative CT is capable of distinguishing patients with TNBC and NTNBC. It adds additional value for conventional chest contrast-enhanced CT and helps plan the strategy for clinical treatment of the patients.

MoEnd3 regulates appressorium formation and virulence through mediating endocytosis in rice blast fungus Magnaporthe oryzae.

Eukaryotic cells respond to environmental stimuli when cell surface receptors are bound by environmental ligands. The binding initiates a signal transduction cascade that results in the appropriate intracellular responses. Studies have shown that endocytosis is critical for receptor internalization and signaling activation. In the rice blast fungus Magnaporthe oryzae, a non-canonical G-protein coupled receptor, Pth11, and membrane sensors MoMsb2 and MoSho1 are thought to function upstream of G-protein/cAMP signaling and the Pmk1 MAPK pathway to regulate appressorium formation and pathogenesis. However, little is known about how these receptors or sensors are internalized and transported into intracellular compartments. We found that the MoEnd3 protein is important for endocytic transport and that the ΔMoend3 mutant exhibited defects in efficient internalization of Pth11 and MoSho1. The ΔMoend3 mutant was also defective in Pmk1 phosphorylation, autophagy, appressorium formation and function. Intriguingly, restoring Pmk1 phosphorylation levels in ΔMoend3 suppressed most of these defects. Moreover, we demonstrated that MoEnd3 is subject to regulation by MoArk1 through protein phosphorylation. We also found that MoEnd3 has additional functions in facilitating the secretion of effectors, including Avr-Pia and AvrPiz-t that suppress rice immunity. Taken together, our findings suggest that MoEnd3 plays a critical role in mediating receptor endocytosis that is critical for the signal transduction-regulated development and virulence of M. oryzae.

Heat-Shock Proteins MoSsb1, MoSsz1, and MoZuo1 Attenuate MoMkk1-Mediated Cell-Wall Integrity Signaling and Are Important for Growth and Pathogenicity of Magnaporthe oryzae.

The mitogen-activated protein kinase (MAPK) MoMkk1 governs the cell-wall integrity (CWI) pathway in rice blast fungus Magnaporthe oryzae. To understand the underlying mechanism, we have identified MoSsb1 as one of the MoMkk1-interacting proteins. MoSsb1 is a stress-seventy subfamily B (Ssb) protein homolog, sharing high amino acid sequence homology with the 70-kDa heat shock proteins (Hsp70s). Hsp70 are a family of conserved and ubiquitously expressed chaperones that regulate protein biogenesis by promoting protein folding, preventing protein aggregation, and controlling protein degradation. We found that MoSsb1 regulates the synthesis of nascent polypeptide chains and this regulation is achieved by being in complex with other members of Hsp70s MoSsz1 and 40-kDa Hsp40 MoZuo1. MoSsb1 is important for the growth, conidiation, and full virulence of the blast fungus and this role is also shared by MoSsz1 and MoZuo1. Importantly, MoSsb1, MoSsz1, and MoZuo1 are all involved in the regulation of the CWI MAPK pathway by modulating MoMkk1 biosynthesis. Our studies reveal novel insights into how MoSsb1, MoSsz1, and MoZuo1 affect CWI signaling that is involved in regulating growth, differentiation, and virulence of M. oryzae and highlight the conserved functional mechanisms of heat-shock proteins in pathogenic fungi.

MoMip11, a MoRgs7-interacting protein, functions as a scaffolding protein to regulate cAMP signaling and pathogenicity in the rice blast fungus Magnaporthe oryzae.

The rice blast fungus Magnaporthe oryzae has eight regulators of G-protein signaling (RGS) and RGS-like proteins (MoRgs1 to MoRgs8) that exhibit both distinct and shared regulatory functions in the growth, differentiation and pathogenicity of the fungus. We found MoRgs7 with a unique RGS-seven transmembrane (7-TM) domain motif is localized to the highly dynamic tubule-vesicular compartments during early appressorium differentiation followed by gradually degradation. To explore whether this involves an active signal perception of MoRgs7, we identified a Gbeta-like/RACK1 protein homolog in M. oryzae MoMip11 that interacts with MoRgs7. Interestingly, MoMip11 selectively interacted with several components of the cAMP regulatory pathway, including Gα MoMagA and the high-affinity phosphodiesterase MoPdeH. We further showed that MoMip11 promotes MoMagA activation and suppresses MoPdeH activity thereby upregulating intracellular cAMP levels. Moreover, MoMip11 is required for the response to multiple stresses, a role also shared by Gbeta-like/RACK1 adaptor proteins. In summary, we revealed a unique mechanism by which MoMip11 links MoRgs7 and G-proteins to reugulate cAMP signaling, stress responses and pathogenicity of M. oryzae. Our studies revealed the multitude of regulatory networks that govern growth, development and pathogenicity in this important causal agent of rice blast.

Functional analysis of MoSnf7 in Magnaporthe oryzae.

Snf7 is the core subunit protein of the yeast endosomal sorting complex required for transport (ESCRT) complex, which plays important roles in endocytosis and autophagy. In this study, we characterized MoSnf7 in Magnaporthe oryzae, a homolog of yeast Snf7, the core protein of ESCRT-III subcomplex. Like Snf7, MoSnf7 also localizes next to the vacuoles. Deletion of MoSNF7 resulted in significant decrease in vegetative growth and pathogenicity. Further analyses of ΔMosnf7 mutants showed that they were defective in endocytosis, sexual and asexual development, turgor pressure maintenance of appressorium at hyphal tips, and cell wall integrity. Additional assays for the localization and degradation of GFP-MoAtg8 in ΔMosnf7 mutants showed that they were defective in autophagy pathway. Based on the roles of yeast Snf7 in endocytosis and autophagy, we propose that the decreased vegetative growth and pathogenicity of ΔMosnf7 rice blast fungus M. oryzae, was partly due to the conservative roles of MoSnf7 in vesicle trafficking and autophagy pathway.