Mycoviruses are viruses that infect fungi,and hypovirulence-associated mycoviruses have the potential to control fungal diseases.However,it is unclear how mycovirus-mediated hypovirulent strains live and survive in th...Mycoviruses are viruses that infect fungi,and hypovirulence-associated mycoviruses have the potential to control fungal diseases.However,it is unclear how mycovirus-mediated hypovirulent strains live and survive in the field,and no mycovirus has been applied for field crop protection.In this study,we found that a previously identified small DNA mycovirus(SsHADV-1)can convert its host,Sclerotinia sclerotiorum,from a typical necrotrophic pathogen to a beneficial endophytic fungus.SsHADV-1 downregulates the expression of key pathogenicity factor genes in S.sclerotiorum during infection.When growing in rapeseed,the SsHADV-1-infected strain DT-8 significantly regulates the expression of rapeseed genes involved in defense,hormone signaling,and circadian rhythm pathways.As a result,plant growth is promoted and disease resistance is enhanced.Field experiments showed that spraying DT-8 at the early flowering stage can reduce the disease severity of rapeseed stem rot by 67.6%and improve yield by 14.9%.Moreover,we discovered that SsHADV-1 could also infect other S.sclerotiorum strains on DT-8-inoculated plants and that DT-8 could be recovered from dead plants.These findings suggest that the mycoviruses may have the ability to shape the origin of endophytism.Our discoveries suggest that mycoviruses may influence the origin of endophytism and may also offer a novel strategy for disease control in which mycovirus-infected strains are used to improve crop health and release mycoviruses into the field.展开更多
Rice sheath blight pathogen,Rhizoctonia solani,produces numerous sclerotia to overwinter.As a rich source of nutrients in the soil,sclerotia may lead to the change of soil microbiota.For this purpose,we amended the sc...Rice sheath blight pathogen,Rhizoctonia solani,produces numerous sclerotia to overwinter.As a rich source of nutrients in the soil,sclerotia may lead to the change of soil microbiota.For this purpose,we amended the sclerotia of R.solani in soil and analyzed the changes in bacterial microbiota within the soil at different time points.At the phyla level,Proteobacteria,Acidobacteria,Bacteroidetes,Actinobacteria,Chloroflexi and Firmicutes showed varied abundance in the amended soil samples compared to those in the control.An increased abundance of ammonia-oxidizing bacterium(AOB)Nitrosospira and Nitrite oxidizing bacteria(NOB)i.e.,Nitrospira was observed,where the latter is reportedly involved in the nitrifier denitrification.Moreover,Thiobacillus,Gemmatimonas,Anaeromyxobacter and Geobacter,the vital players in denitrification,N2O reduction and reductive nitrogen transformation,respectively,depicted enhanced abundance in R.solani sclerotia-amended samples.Furthermore,asymbiotic nitrogen-fixing bacteria,notably,Azotobacter as well as Microvirga and Phenylobacterium with nitrogen-fixing potential also enriched in the amended samples compared to the control.Plant growth promoting bacteria,such as Kribbella,Chitinophaga and Flavisolibacter also enriched in the sclerotia-amended soil.As per our knowledge,this study is of its kind where pathogenic fungal sclerotia activated microbes with a potential role in N transformation and provided clues about the ecological functions of R.solani sclerotia on the stimulation of bacterial genera involved in different processes of N-cycle within the soil in the absence of host plants.展开更多
Plants recognize microbe-associated molecular patterns(MAMPs)to activate immune responses and defense priming to defend against pathogen infections.Transcriptional regulation of gene expression is crucial for plant im...Plants recognize microbe-associated molecular patterns(MAMPs)to activate immune responses and defense priming to defend against pathogen infections.Transcriptional regulation of gene expression is crucial for plant immunity and is mediated by multiple factors,including DNA methylation.However,it remains unknown whether and how DNA demethylation contributes to immune responses in MAMPtriggered immunity.Here,we report that active DNA demethylation is required for MAMP-triggered immunity to bacterial pathogens.The rdd-2 triple mutant carrying mutations in ROS1,DML2,and DML3 that encode DNA glycosylases,which are key DNA demethylation enzymes,exhibits compromised immune responses triggered by the MAMPs fig22 and elf18.Genome-wide methylome analysis reveals that fig22 induces rapid and specific DNA demethylation in an RDD-dependent manner.The expression levels of salicylic acid signaling-related and phytoalexin biosynthesis-related genes are tightly associated with the fig22-induced promoter demethylation.The compromised accumulation of priming compounds and antimicrobial metabolites ultimately leads to a defense priming defect in the rdd-2 mutant.Our results reveal the critical role of active DNA demethylation in the MAMP-triggered immune response and provide unique insight into the molecular mechanism of fig22-modulated DNA demethylation.展开更多
A significant number of mycoviruses have been identified that are related to plant viruses,but their evolutionary relationships are largely unexplored.A fusarivirus,Rhizoctonia solani fusarivirus 4(RsFV4),was identifi...A significant number of mycoviruses have been identified that are related to plant viruses,but their evolutionary relationships are largely unexplored.A fusarivirus,Rhizoctonia solani fusarivirus 4(RsFV4),was identified in phytopathogenic fungus Rhizoctonia solani(R.solani)strain XY74 co-infected by an alphaendornavirus.RsFV4 had a genome of 10,833 nt(excluding the poly-A tail),and consisted of four non-overlapping open reading frames(ORFs).ORF1 encodes an 825 aa protein containing a conserved helicase domain(Hel1).ORF3 encodes 1550 aa protein with two conserved domains,namely an RNA-dependent RNA polymerase(RdRp)and another helicase(Hel2).The ORF2 and ORF4 likely encode two hypothetical proteins(520 and 542 aa)with unknown functions.The phylogenetic analysis based on Hel2 and RdRp suggest that RsFV4 was positioned within the fusarivirus group,but formed an independent branch with three previously reported fusariviruses of R.solani.Notably,the Hel1 and its relatives were phylogenetically closer to helicases of potyviruses and hypoviruses than fusariviruses,suggesting fusarivirus Hel1 formed an evolutionary link between these three virus groups.This finding provides evidence of the occurrence of a horizontal gene transfer or recombination event between mycoviruses and plant viruses or between mycoviruses.Our findings are likely to enhance the understanding of virus evolution and diversity.展开更多
The cause of virulence decline of hypovirulent isolate Ep-1PN of Sclerotinia sclerotiorum (Lib.) de Bary has been studied through transmitting test and analysing its offsprings derived from single ascospore. When the ...The cause of virulence decline of hypovirulent isolate Ep-1PN of Sclerotinia sclerotiorum (Lib.) de Bary has been studied through transmitting test and analysing its offsprings derived from single ascospore. When the colony of a normal strain Ep-1PNA 183 intermingled with the colony of Ep-1PN, its margin became abnormal, just like Ep-1PN. Cultures isolated from top-tip of the colony of Ep-1PNA 183 showed the hypovirulence and its associated properties of Ep-1PN. Moreover, a series of cultures which have characteristics between Ep-1PN and normal strain could be isolated from stipes of Ep-1PN. More than 200 offsprings derived from single ascospore of Ep-1PN were normal strains. According to those results, there exists a transmissible cytoplasmic hypovirulent element in hypovirulent isolate Ep-1PN of S. sclerotiorum.展开更多
基金the National Science Foundation of China(31430070)the National Key R&D Program(2017YFD0200602)the China Agriculture Research System(CARS-12).
文摘Mycoviruses are viruses that infect fungi,and hypovirulence-associated mycoviruses have the potential to control fungal diseases.However,it is unclear how mycovirus-mediated hypovirulent strains live and survive in the field,and no mycovirus has been applied for field crop protection.In this study,we found that a previously identified small DNA mycovirus(SsHADV-1)can convert its host,Sclerotinia sclerotiorum,from a typical necrotrophic pathogen to a beneficial endophytic fungus.SsHADV-1 downregulates the expression of key pathogenicity factor genes in S.sclerotiorum during infection.When growing in rapeseed,the SsHADV-1-infected strain DT-8 significantly regulates the expression of rapeseed genes involved in defense,hormone signaling,and circadian rhythm pathways.As a result,plant growth is promoted and disease resistance is enhanced.Field experiments showed that spraying DT-8 at the early flowering stage can reduce the disease severity of rapeseed stem rot by 67.6%and improve yield by 14.9%.Moreover,we discovered that SsHADV-1 could also infect other S.sclerotiorum strains on DT-8-inoculated plants and that DT-8 could be recovered from dead plants.These findings suggest that the mycoviruses may have the ability to shape the origin of endophytism.Our discoveries suggest that mycoviruses may influence the origin of endophytism and may also offer a novel strategy for disease control in which mycovirus-infected strains are used to improve crop health and release mycoviruses into the field.
基金funded by the National Key R&D Program(grant number No.2017YFD0200600)and the earmarked fund for CARS-12.
文摘Rice sheath blight pathogen,Rhizoctonia solani,produces numerous sclerotia to overwinter.As a rich source of nutrients in the soil,sclerotia may lead to the change of soil microbiota.For this purpose,we amended the sclerotia of R.solani in soil and analyzed the changes in bacterial microbiota within the soil at different time points.At the phyla level,Proteobacteria,Acidobacteria,Bacteroidetes,Actinobacteria,Chloroflexi and Firmicutes showed varied abundance in the amended soil samples compared to those in the control.An increased abundance of ammonia-oxidizing bacterium(AOB)Nitrosospira and Nitrite oxidizing bacteria(NOB)i.e.,Nitrospira was observed,where the latter is reportedly involved in the nitrifier denitrification.Moreover,Thiobacillus,Gemmatimonas,Anaeromyxobacter and Geobacter,the vital players in denitrification,N2O reduction and reductive nitrogen transformation,respectively,depicted enhanced abundance in R.solani sclerotia-amended samples.Furthermore,asymbiotic nitrogen-fixing bacteria,notably,Azotobacter as well as Microvirga and Phenylobacterium with nitrogen-fixing potential also enriched in the amended samples compared to the control.Plant growth promoting bacteria,such as Kribbella,Chitinophaga and Flavisolibacter also enriched in the sclerotia-amended soil.As per our knowledge,this study is of its kind where pathogenic fungal sclerotia activated microbes with a potential role in N transformation and provided clues about the ecological functions of R.solani sclerotia on the stimulation of bacterial genera involved in different processes of N-cycle within the soil in the absence of host plants.
基金supported by the National Natural Science Foundation of China (31770278, 31970125 to B.L.)Fundamental Research Funds for the Central Universities, Huazhong Agricultural University Scientific & Technological Self-innovation Foundation (2021ZKPY011, 2017RC001 to B.L.)
文摘Plants recognize microbe-associated molecular patterns(MAMPs)to activate immune responses and defense priming to defend against pathogen infections.Transcriptional regulation of gene expression is crucial for plant immunity and is mediated by multiple factors,including DNA methylation.However,it remains unknown whether and how DNA demethylation contributes to immune responses in MAMPtriggered immunity.Here,we report that active DNA demethylation is required for MAMP-triggered immunity to bacterial pathogens.The rdd-2 triple mutant carrying mutations in ROS1,DML2,and DML3 that encode DNA glycosylases,which are key DNA demethylation enzymes,exhibits compromised immune responses triggered by the MAMPs fig22 and elf18.Genome-wide methylome analysis reveals that fig22 induces rapid and specific DNA demethylation in an RDD-dependent manner.The expression levels of salicylic acid signaling-related and phytoalexin biosynthesis-related genes are tightly associated with the fig22-induced promoter demethylation.The compromised accumulation of priming compounds and antimicrobial metabolites ultimately leads to a defense priming defect in the rdd-2 mutant.Our results reveal the critical role of active DNA demethylation in the MAMP-triggered immune response and provide unique insight into the molecular mechanism of fig22-modulated DNA demethylation.
基金financially supported by the Fundamental Research Funds for the Central Universities(2662018PY041)the Natural Science Foundation of China(31772111)the National Key Research and Development Program of China(2017YFD0201100)。
文摘A significant number of mycoviruses have been identified that are related to plant viruses,but their evolutionary relationships are largely unexplored.A fusarivirus,Rhizoctonia solani fusarivirus 4(RsFV4),was identified in phytopathogenic fungus Rhizoctonia solani(R.solani)strain XY74 co-infected by an alphaendornavirus.RsFV4 had a genome of 10,833 nt(excluding the poly-A tail),and consisted of four non-overlapping open reading frames(ORFs).ORF1 encodes an 825 aa protein containing a conserved helicase domain(Hel1).ORF3 encodes 1550 aa protein with two conserved domains,namely an RNA-dependent RNA polymerase(RdRp)and another helicase(Hel2).The ORF2 and ORF4 likely encode two hypothetical proteins(520 and 542 aa)with unknown functions.The phylogenetic analysis based on Hel2 and RdRp suggest that RsFV4 was positioned within the fusarivirus group,but formed an independent branch with three previously reported fusariviruses of R.solani.Notably,the Hel1 and its relatives were phylogenetically closer to helicases of potyviruses and hypoviruses than fusariviruses,suggesting fusarivirus Hel1 formed an evolutionary link between these three virus groups.This finding provides evidence of the occurrence of a horizontal gene transfer or recombination event between mycoviruses and plant viruses or between mycoviruses.Our findings are likely to enhance the understanding of virus evolution and diversity.
文摘The cause of virulence decline of hypovirulent isolate Ep-1PN of Sclerotinia sclerotiorum (Lib.) de Bary has been studied through transmitting test and analysing its offsprings derived from single ascospore. When the colony of a normal strain Ep-1PNA 183 intermingled with the colony of Ep-1PN, its margin became abnormal, just like Ep-1PN. Cultures isolated from top-tip of the colony of Ep-1PNA 183 showed the hypovirulence and its associated properties of Ep-1PN. Moreover, a series of cultures which have characteristics between Ep-1PN and normal strain could be isolated from stipes of Ep-1PN. More than 200 offsprings derived from single ascospore of Ep-1PN were normal strains. According to those results, there exists a transmissible cytoplasmic hypovirulent element in hypovirulent isolate Ep-1PN of S. sclerotiorum.