Systemic studies on the effects of mitogen-activated protein kinase （MAPK） signal transduction pathway on the growth and development of Setosphaeria turcica is helpful not only in understanding the molecular mechani...Systemic studies on the effects of mitogen-activated protein kinase （MAPK） signal transduction pathway on the growth and development of Setosphaeria turcica is helpful not only in understanding the molecular mechanism of pathogenhost interaction but also in the effective control of the diseases caused by S. turcica. U0126, the specific MEK inhibitor, is used to treat S. turcica before the observation of the conidial germination, appressorium production, and pathogenicity of the pathogen. There is no significant effect of U0126 on the colony morphology and mycelium growth of the pathogen. After treatment with U0126, the growth of mycelium and conidia are normal, but the conidial germination, appressorium production, and pathogenicity of S. turcica on susceptible corn leaves are significantly inhibited. Under the definite concentration scope, an increase in U0126 concentration increases the inhibition degree of conidial germination and appressorium production, but the inhibition degree decreases with elongation of treatment time. The conidial germination, appressorium production, and pathogenicity of S. turcica on susceptible corn leaves are regulated by the MAPK pathway inhibited by U0126.展开更多
A mature appressorium cDNA library of rice blast fungus, Magnaporthe grisea, was constructed in a λTriplEx2 vector by SMART?cDNA library containing 2.37×106 independent clones about 100% of which harbor foreign ...A mature appressorium cDNA library of rice blast fungus, Magnaporthe grisea, was constructed in a λTriplEx2 vector by SMART?cDNA library containing 2.37×106 independent clones about 100% of which harbor foreign cDNA inserts with average size of 660 bp. Of 9 randomly selected clones, 2 expressed sequence tags (ESTs) sequences did not have homologous EST sequences of M grisea in GenBank. The appressorium cDNA library is suitable for gene expression analysis and function analysis of the late stages of appressorium formation and the early stages of penetration of M grisea.展开更多
Magnaporthe oryzae has been used as a primary model organism for investigating fungus-plant interaction. Many researches focused on molecular mechanisms of appressorium formation to restrain this fungal pathogen. Auto...Magnaporthe oryzae has been used as a primary model organism for investigating fungus-plant interaction. Many researches focused on molecular mechanisms of appressorium formation to restrain this fungal pathogen. Autophagy is a very high conserved process in eukaryotic cells. Recently, autophagy has been considered as a key process in development and differentia-tion in M. oryzae. In this report, we present and discuss the current state of our knowledge on gene expression in appressorium formation and the progress in autophagy of rice blast fungi.展开更多
Setosphaeria turcica(syn.Exserohilum turcicum)is the pathogenic fungus of maize(Zea mays)that causes northern leaf blight,which is a major maize disease worldwide.Melanized appressoria are highly specialized infection...Setosphaeria turcica(syn.Exserohilum turcicum)is the pathogenic fungus of maize(Zea mays)that causes northern leaf blight,which is a major maize disease worldwide.Melanized appressoria are highly specialized infection structures formed by germinated conidia of S.turcica that infect maize leaves.The appressorium penetrates the plant cuticle by generating turgor,and glycerol is known to be the main source of the turgor.Here,the infection position penetrated by the appressorium on maize leaves was investigated,most of the germinated conidia entered the leaf interior by directly penetrating the epidermal cells,and the appressorium structure was necessary for the infection,whether it occurred through epidermal cells or stomata.Then,to investigate the effects of key factors in the development of the appressorium,we studied the effects of three inhibitors,including a melanin inhibitor(tricyclazole,TCZ),a DNA replication inhibitor(hydroxyurea,HU),and an autophagy inhibitor(3-methyladenine,3-MA),on appressorium turgor and glycerol content.As results,appressorium turgor pressure and glycerol concentration in the appressorium reached their highest levels at the mature stage of the appressorium under the control and inhibitor treatments.The three inhibitors had the greatest effects on appressorium turgor pressure at this stage.Glycogen and liposomes are the main substances producing glycerol.It was also found inhibitors affected the distribution of glycogen and liposomes,which were detected in the conidia,the germ tube,and the appressorium during appressorium development.This study provides profound insight into the relationship between appressorium turgor pressure and glycerol content,which was affected by the synthesis of melanin,DNA replication,and autophagy in the developing appressorium during a S.turcica infection.展开更多
We investigated the possibility to reduce the usage of Blasin^Flowable （BF）, a disinfectant inhibiting the germination and appressorium formation of Pyricularia oryzae Cavara conidia, by using carbon dioxide microbu...We investigated the possibility to reduce the usage of Blasin^Flowable （BF）, a disinfectant inhibiting the germination and appressorium formation of Pyricularia oryzae Cavara conidia, by using carbon dioxide microbubbles （CO2MB）. Germination was significantly inhibited by 10 000-fold diluted BF solution containing CO2MB generated by the decompression-type generator compared to CO2 millibubbles （CO2MMB） and CO2MB generated by the gas-water circulating-type generator. Appressodum formation in the 10 000-fold diluted BF solution containing both CO2MBs was less than that in CO2MMB. Scanning electron microscopy showed wrinkles and dents on the surface of conidia treated with 5 000-fold diluted BF solution containing both CO2MBs. Via transmission electron microscopy, we observed the expansion of the vacuole and the intracellular space and bloated or absent lipid granules in the conidia treated with BF solution containing both CO2MBs. Our results show that inhibition of the conidium germination and appressorium formation of P. oryzae Cavara by 10 000-fold diluted BF solution could be achieved by using the decompression-type CO2MB.展开更多
The application of fungicides is an effective strategy for controlling plant diseases.Among these agents,plant-derived antifungal metabolites are particularly promising due to their eco-friendly and sustainable nature...The application of fungicides is an effective strategy for controlling plant diseases.Among these agents,plant-derived antifungal metabolites are particularly promising due to their eco-friendly and sustainable nature.Plant secondary metabolites typically exhibit broad-spectrum antifungal activity without selective toxicity against pathogens.However,only a small fraction of antifungal metabolites have been identified from the tens of thousands of known plant secondary metabolites.In this study,we conducted a metabolomic analysis on both blast-resistant(Digu)and-susceptible(Lijiangxintuanheigu)rice varieties to uncover novel metabolites that enhance blast resistance.We found that 24 and 48 h post-inoculation with Magnaporthe oryzae were critical time points for metabolomic profiling,based on the infected status of M.oryzae in rice and the observed differences in shikimate accumulation between the two varieties.Following metabolomic analysis,we identified nine flavonoids that were differentially accumulated and are considered potential candidates for disease control.Among these,apigenin-7-glucoside,rhamnetin,and spireoside were found to be effective in controlling blast disease,with spireoside demonstrating the most pronounced efficacy.We discovered that spireoside controlled blast disease by inhibiting both spore germination and appressorium formation in M.oryzae,primarily through disrupting cell membrane integrity.However,spireoside did not induce rice immunity.Furthermore,spireoside was also effective in controlling sheath blight disease.Thus,spireoside shows considerable promise as a candidate for the development of a fungicide for controlling plant diseases.展开更多
Fungal G-protein coupled receptors(GPCRs)play essential roles in sensing environmental cues including host signals.The study of GPCR in mediating fungus-insect interactions is still limited.Here we report the evolutio...Fungal G-protein coupled receptors(GPCRs)play essential roles in sensing environmental cues including host signals.The study of GPCR in mediating fungus-insect interactions is still limited.Here we report the evolution of GPCR genes encoded in the entomopathogenic Metarhizium species and found the expansion of Pth11-like GPCRs in the generalist species with a wide host range.By deletion of ten candidate genes MrGpr1–MrGpr10 selected from the six obtained subfamilies in the generalist M.robertsii,we found that each of them played a varied level of roles in mediating appressorium formation.In particular,deletion of MrGpr8 resulted in the failure of appressorium formation on different substrates and the loss of virulence during topical infection of insects but not during injection assays when compared with the wild-type(WT)strain.Further analysis revealed that disruption of MrGpr8 substantially impaired the nucleus translocation of the mitogen-activated protein kinase(MAPK)Mero-Fus3 but not the MAPK Mero-Slt2 during appressorium formation.We also found that the defect ofΔMrGpr8 could not be rescued with the addition of cyclic AMP for appressorium formation.Relative to the WT,differential expression of the selected genes have also been detected inΔMrGpr8.The results of this study may benefit the understanding of fungus-interactions mediated by GPCRs.展开更多
Lipid droplets are important storages in fungal conidia and can be used by plant pathogenic fungi for infection.However,the regulatory mechanism of lipid droplets formation and the utilization during fungal developmen...Lipid droplets are important storages in fungal conidia and can be used by plant pathogenic fungi for infection.However,the regulatory mechanism of lipid droplets formation and the utilization during fungal development and infection are largely unknown.Here,in Magnaporthe oryzae,we identified a lipid droplet-associated protein Nem1 that played a key role in lipid droplets biogenesis and utilization.Nem1 was highly expressed in conidia,but lowly expressed in appressoria,and its encoded protein was localized to lipid droplets.Deletion of NEM1 resulted in reduced numbers of lipid droplets and decreased content of diacylglycerol(DAG)or triacylglycerol(TAG).NEM1 was required for asexual development especially conidia production.TheΔnem1 mutant was nearly loss of virulence to host plants due to defects in appressorial penetration and invasive growth.Remarkably,Nem1 was regulated by the TOR signaling pathway and involved in the autophagy process.The Ser303 residue of Nem1 could be phosphorylated by the cAMP-PKA signaling pathway and was important for biological function of Nem1.Together,our study revealed a regulatory mechanism of lipid biogenesis and metabolism during the conidium and appressorium formation of the rice blast fungus.展开更多
基金supported by the National Natural Science Foundation of China(30471126)Doctoral Foundation Project of Hebei Province,China(05547007D-2).
文摘Systemic studies on the effects of mitogen-activated protein kinase （MAPK） signal transduction pathway on the growth and development of Setosphaeria turcica is helpful not only in understanding the molecular mechanism of pathogenhost interaction but also in the effective control of the diseases caused by S. turcica. U0126, the specific MEK inhibitor, is used to treat S. turcica before the observation of the conidial germination, appressorium production, and pathogenicity of the pathogen. There is no significant effect of U0126 on the colony morphology and mycelium growth of the pathogen. After treatment with U0126, the growth of mycelium and conidia are normal, but the conidial germination, appressorium production, and pathogenicity of S. turcica on susceptible corn leaves are significantly inhibited. Under the definite concentration scope, an increase in U0126 concentration increases the inhibition degree of conidial germination and appressorium production, but the inhibition degree decreases with elongation of treatment time. The conidial germination, appressorium production, and pathogenicity of S. turcica on susceptible corn leaves are regulated by the MAPK pathway inhibited by U0126.
文摘A mature appressorium cDNA library of rice blast fungus, Magnaporthe grisea, was constructed in a λTriplEx2 vector by SMART?cDNA library containing 2.37×106 independent clones about 100% of which harbor foreign cDNA inserts with average size of 660 bp. Of 9 randomly selected clones, 2 expressed sequence tags (ESTs) sequences did not have homologous EST sequences of M grisea in GenBank. The appressorium cDNA library is suitable for gene expression analysis and function analysis of the late stages of appressorium formation and the early stages of penetration of M grisea.
基金the National Natural Science Foundation of China (Nos. 30671351 and 30870101)the Hi-Tech Research and Development Program (863) of China (No. 2002AA245041)
文摘Magnaporthe oryzae has been used as a primary model organism for investigating fungus-plant interaction. Many researches focused on molecular mechanisms of appressorium formation to restrain this fungal pathogen. Autophagy is a very high conserved process in eukaryotic cells. Recently, autophagy has been considered as a key process in development and differentia-tion in M. oryzae. In this report, we present and discuss the current state of our knowledge on gene expression in appressorium formation and the progress in autophagy of rice blast fungi.
基金supported by the grants from the National Natural Science Foundation of China(32072370 and 31901827)the China Agriculture Research System of MOF and MARA(CARS-02-25)+1 种基金the Natural Science Foundation of Hebei Province,China(C2020204039 and C2018204059)the Projects of Overseas Foundation,Hebei Province,China(C20190508)。
文摘Setosphaeria turcica(syn.Exserohilum turcicum)is the pathogenic fungus of maize(Zea mays)that causes northern leaf blight,which is a major maize disease worldwide.Melanized appressoria are highly specialized infection structures formed by germinated conidia of S.turcica that infect maize leaves.The appressorium penetrates the plant cuticle by generating turgor,and glycerol is known to be the main source of the turgor.Here,the infection position penetrated by the appressorium on maize leaves was investigated,most of the germinated conidia entered the leaf interior by directly penetrating the epidermal cells,and the appressorium structure was necessary for the infection,whether it occurred through epidermal cells or stomata.Then,to investigate the effects of key factors in the development of the appressorium,we studied the effects of three inhibitors,including a melanin inhibitor(tricyclazole,TCZ),a DNA replication inhibitor(hydroxyurea,HU),and an autophagy inhibitor(3-methyladenine,3-MA),on appressorium turgor and glycerol content.As results,appressorium turgor pressure and glycerol concentration in the appressorium reached their highest levels at the mature stage of the appressorium under the control and inhibitor treatments.The three inhibitors had the greatest effects on appressorium turgor pressure at this stage.Glycogen and liposomes are the main substances producing glycerol.It was also found inhibitors affected the distribution of glycogen and liposomes,which were detected in the conidia,the germ tube,and the appressorium during appressorium development.This study provides profound insight into the relationship between appressorium turgor pressure and glycerol content,which was affected by the synthesis of melanin,DNA replication,and autophagy in the developing appressorium during a S.turcica infection.
文摘We investigated the possibility to reduce the usage of Blasin^Flowable （BF）, a disinfectant inhibiting the germination and appressorium formation of Pyricularia oryzae Cavara conidia, by using carbon dioxide microbubbles （CO2MB）. Germination was significantly inhibited by 10 000-fold diluted BF solution containing CO2MB generated by the decompression-type generator compared to CO2 millibubbles （CO2MMB） and CO2MB generated by the gas-water circulating-type generator. Appressodum formation in the 10 000-fold diluted BF solution containing both CO2MBs was less than that in CO2MMB. Scanning electron microscopy showed wrinkles and dents on the surface of conidia treated with 5 000-fold diluted BF solution containing both CO2MBs. Via transmission electron microscopy, we observed the expansion of the vacuole and the intracellular space and bloated or absent lipid granules in the conidia treated with BF solution containing both CO2MBs. Our results show that inhibition of the conidium germination and appressorium formation of P. oryzae Cavara by 10 000-fold diluted BF solution could be achieved by using the decompression-type CO2MB.
基金supported by the National Natural Science Foundation of China(Grant Nos.32172419,32372555,32121003,32425005,32072407,and 32272033)the National Key Research and Development Program of China(Grant No.2021YFA1300702)the Sichuan Science and Technology Program,China(Grant Nos.2023NSFSC0005,2023NSFSC1996,2024NSFSC0322,2024YFNH0014,2022NSFSC1755,2022-NSFSC1650,2022NSFSC0156,and 2022NSFSC0166).
文摘The application of fungicides is an effective strategy for controlling plant diseases.Among these agents,plant-derived antifungal metabolites are particularly promising due to their eco-friendly and sustainable nature.Plant secondary metabolites typically exhibit broad-spectrum antifungal activity without selective toxicity against pathogens.However,only a small fraction of antifungal metabolites have been identified from the tens of thousands of known plant secondary metabolites.In this study,we conducted a metabolomic analysis on both blast-resistant(Digu)and-susceptible(Lijiangxintuanheigu)rice varieties to uncover novel metabolites that enhance blast resistance.We found that 24 and 48 h post-inoculation with Magnaporthe oryzae were critical time points for metabolomic profiling,based on the infected status of M.oryzae in rice and the observed differences in shikimate accumulation between the two varieties.Following metabolomic analysis,we identified nine flavonoids that were differentially accumulated and are considered potential candidates for disease control.Among these,apigenin-7-glucoside,rhamnetin,and spireoside were found to be effective in controlling blast disease,with spireoside demonstrating the most pronounced efficacy.We discovered that spireoside controlled blast disease by inhibiting both spore germination and appressorium formation in M.oryzae,primarily through disrupting cell membrane integrity.However,spireoside did not induce rice immunity.Furthermore,spireoside was also effective in controlling sheath blight disease.Thus,spireoside shows considerable promise as a candidate for the development of a fungicide for controlling plant diseases.
基金the National Key Research and Development Programs of China(2017YFD0200400 and 2017YFD0201202)the National Natural Science Foundation of China(31501699).
文摘Fungal G-protein coupled receptors(GPCRs)play essential roles in sensing environmental cues including host signals.The study of GPCR in mediating fungus-insect interactions is still limited.Here we report the evolution of GPCR genes encoded in the entomopathogenic Metarhizium species and found the expansion of Pth11-like GPCRs in the generalist species with a wide host range.By deletion of ten candidate genes MrGpr1–MrGpr10 selected from the six obtained subfamilies in the generalist M.robertsii,we found that each of them played a varied level of roles in mediating appressorium formation.In particular,deletion of MrGpr8 resulted in the failure of appressorium formation on different substrates and the loss of virulence during topical infection of insects but not during injection assays when compared with the wild-type(WT)strain.Further analysis revealed that disruption of MrGpr8 substantially impaired the nucleus translocation of the mitogen-activated protein kinase(MAPK)Mero-Fus3 but not the MAPK Mero-Slt2 during appressorium formation.We also found that the defect ofΔMrGpr8 could not be rescued with the addition of cyclic AMP for appressorium formation.Relative to the WT,differential expression of the selected genes have also been detected inΔMrGpr8.The results of this study may benefit the understanding of fungus-interactions mediated by GPCRs.
基金supported by the National Natural Science Foundation of China(Grants 32072365 and 32272476)the Open Research Fund of the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China(SKL-KF202216).
文摘Lipid droplets are important storages in fungal conidia and can be used by plant pathogenic fungi for infection.However,the regulatory mechanism of lipid droplets formation and the utilization during fungal development and infection are largely unknown.Here,in Magnaporthe oryzae,we identified a lipid droplet-associated protein Nem1 that played a key role in lipid droplets biogenesis and utilization.Nem1 was highly expressed in conidia,but lowly expressed in appressoria,and its encoded protein was localized to lipid droplets.Deletion of NEM1 resulted in reduced numbers of lipid droplets and decreased content of diacylglycerol(DAG)or triacylglycerol(TAG).NEM1 was required for asexual development especially conidia production.TheΔnem1 mutant was nearly loss of virulence to host plants due to defects in appressorial penetration and invasive growth.Remarkably,Nem1 was regulated by the TOR signaling pathway and involved in the autophagy process.The Ser303 residue of Nem1 could be phosphorylated by the cAMP-PKA signaling pathway and was important for biological function of Nem1.Together,our study revealed a regulatory mechanism of lipid biogenesis and metabolism during the conidium and appressorium formation of the rice blast fungus.
