The necrotrophic fungus, Sclerotinia sclerotiorum, employs an array of cell wall-degrading enzymes(CWDEs), including cellulase, to dismantle host cell walls. However, the molecular mechanisms through which S. scleroti...The necrotrophic fungus, Sclerotinia sclerotiorum, employs an array of cell wall-degrading enzymes(CWDEs), including cellulase, to dismantle host cell walls. However, the molecular mechanisms through which S. sclerotiorum degrades cellulose remain elusive. Here, we unveil a novel secretory cellobiohydrolase, SsdchA, characterized by a signal peptide and a Glyco_hydro_7(GH7) domain. SsdchA exhibits a robust expression of during early infection stages. Interestingly, colony morphology and growth rates remain unaffected across the wild-type, SsdchA deletion strains and SsdchA overexpression strains on potato dextrose agar(PDA) medium. Nevertheless, the pathogenicity and cellobiohydrolase activity decreased in the SsdchA deletion strains, but enhanced in the SsdchA overexpression strains. Moreover,the heterologous expression of SsdchA in Arabidopsis thaliana leads to reduced cellulose content and heightened susceptibility to S. sclerotiorum. Collectively, our data underscore the pivotal role of the novel cellobiohydrolase SsdchA in the pathogenicity of S. sclerotiorum.展开更多
With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotioru...With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotiorum.Identification of important genes in the defense responses is critical for molecular breeding,which is an important strategy for controlling the disease.In this study,we isolated a B.napus WRKY transcription factor gene,BnaWRKY75.BnaWRKY75 was found to encode a nucleus-localized protein and exhibited relatively high expression in the stems.Arabidopsis thaliana transgenic plants expressing BnaWRKY75 showed enhanced resistance to S.sclerotiorum,and both ProBnaWRKY75:GUS and gene expression analyses showed that BnaWRKY75 was highly responsive to S.sclerotiorum infection,indicating the involvement of BnaWRKY75 in response to this infection.Furthermore,overexpression(OE)of BnaWRKY75 in B.napus significantly enhanced the resistance to S.sclerotiorum,whereas the resistance was reduced in RNAi transgenic B.napus plants.Moreover,the BnaWRKY75-OE B.napus plants exhibited constitutive activation of salicylic acid-,jasmonic acid-,and ethylene-mediated defense responses and the inhibition of both H_(2)O_(2)and O_(2)·^(-)accumulation in response to this pathogen.By contrast,BnaWRKY75-RNAi plants showed a reverse pattern,suggesting that BnaWRKY75 is involved in hormonal signaling pathways and in the control of reactive oxygen species accumulation.In conclusion,these data indicate that BnaWRKY75,a regulator of multiple defense responses,positively regulates resistance against S.sclerotiorum,which may guide the improvement of resistance in rapeseed.展开更多
Laboratory mutants of Sclerotinia sclerotiorum(Lib)de Bary,resistant to boscalid,have been extensively characterized.However,the resistance situation in the lettuce field remains largely elusive.In this study,among th...Laboratory mutants of Sclerotinia sclerotiorum(Lib)de Bary,resistant to boscalid,have been extensively characterized.However,the resistance situation in the lettuce field remains largely elusive.In this study,among the 172 S.sclerotiorum isolates collected from asparagus lettuce field in Jiangsu Province,China,132 isolates(76.74%)exhibited low-level resistance to boscalid(Bos^(LR)),with a discriminatory dose of 5μg mL-1.In comparison to the boscalid-sensitive(BosS)isolates,most Bos^(LR)isolates demonstrated a slightly superior biological fitness,as evidenced by data on mycelial growth,sclerotium production and pathogenicity.Moreover,most Bos^(LR)isolates showed comparable levels of oxalic acid(OA)accumulation,increased exopolysaccharide(EPS)content and reduced membrane permeability when compared to the BosS isolates.Nevertheless,their responses to distinct stress factors diverged significantly.Furthermore,the effectiveness of boscalid in controlling Bos^(LR)isolates on radish was diminished compared to its efficacy on BosS isolates.Genetic mutations were identified in the SDH genes of Bos^(LR)isolates,revealing the existence of three resistant genotypes:I(^(A11V)at SDHB,SDHB^(A11V)),II(^(Q38R)at SDHC,SDHC^(Q38R))and III(SDHB^(A11V)+SDHC^(Q38R)).Importantly,no cross-resistance was observed between boscalid and other fungicides such as thifluzamide,pydiflumetofen,fluazinam,or tebuconazole.Our molecular docking analysis indicated that the docking total score(DTS)of the type I resistant isolates(1.3993)was lower than that of the sensitive isolates(1.7499),implying a reduced affinity between SDHB and boscalid as a potential mechanism underlying the boscalid resistance in S.sclerotiorum.These findings contribute to an enhanced comprehension of boscalid’s mode of action and furnish valuable insights into the management of boscalid resistance.展开更多
The present work was aimed to the study of the antifungal activity of essential oils of two aromatic plants against three strains of Sclerotinia sclerotiorum responsible for white rot of bean. The two essential oils (...The present work was aimed to the study of the antifungal activity of essential oils of two aromatic plants against three strains of Sclerotinia sclerotiorum responsible for white rot of bean. The two essential oils (EO) of the studied plants: Thymus vulgaris (HET) and Cymbopogon citratrus (HEC), used at different concentrations: C1 (0.75 ml/ml), C2 (1.5 ml/ml) and C3 (3 ml/ml) presented significant inhibitory activities on the three tested fungal strains namely Bia 1, Bia 2, and Njo 2. Two control treatments (T-: containing no antifungal substance and T+: synthetic fungicide) were also used. The antifungal activity here is related to the inhibition of mycelial growth especially with high concentrations of essential oils. Thus, against S. sclerotiorum, HET showed the highest activity comparable to that of T+ (100% inhibition) at all concentrations on the Bia 1 and Bia 2 strains and at concentration C3 on the Njo 2 strain compared to that of HEC, which certainly inhibited the mycelial growth of the different strains considerably (with a maximum of 78.15% on the Njo 2 strain) but not completely. According to their sensitivity, the Bia 2 strain showed a higher sensitivity to essential oils than the others while the Njo 2 strain was more aggressive. On the basis of MIC<sub>50</sub> and MIC<sub>90</sub> obtained on the Njo 2 strain, the HET turns out to be the most efficient with respective lower values of (1.73 and 23.34 ml/ml) against (4.76 and 26.03 ml/ml) for the HEC. These EO could thus be exploited as biodegradable antifungal substances, likely to control white rot of bean.展开更多
[Objective] The study was to investigate roles of Brassica napus EINB in （ BnEIN3 ） resistance to Sclerotinia sclerotiorum. [ Methods] Genomic PCR and RT-PCR were carded out to isolate genomic DNA and cDNA sequences...[Objective] The study was to investigate roles of Brassica napus EINB in （ BnEIN3 ） resistance to Sclerotinia sclerotiorum. [ Methods] Genomic PCR and RT-PCR were carded out to isolate genomic DNA and cDNA sequences of BnEIN3 from oilseed rape, based on the highly conserved region of EIN3 gene from Arabidopsis thaliana and the homologous sequences of oilseed rape ESTs. Expression levels of BnEIN3 were detected in three varieties of oilseed rape inoculated with S. sclerotiorum by real-time quantitative PCR.[Results] A 1 947 bp DNA fragment was obtained from oilseed rape. The fragment shared 82% identity to A. thaliana EIIV3, encoded 614 amino acids containing an EIN3 domain, and was named as BnEIN3. Real-time PCR results showed that expression patterns of BnEIN3 were drastically different in different varieties. In highly resistant oilseed rape variety D083, BnEIN3 expression level was significantly increased 72 h after S. sclerotiorum inoculation whereas in middle resistant and susceptible varieties Zhongshuang 9 and 84039, BnEIN3 expression was suppressed. [ Conclusion ] BnEIIV3 may play an important role in oilseed rape resistance to S. sclerotiorum.展开更多
Zhongshuang9, a new semi-winter Brassica napus variety with high resistance to Sclerotinia sclerotiorum and lodging, high-yield, double-low quality and extensive adaptability, was bred by multiple crossing and microsp...Zhongshuang9, a new semi-winter Brassica napus variety with high resistance to Sclerotinia sclerotiorum and lodging, high-yield, double-low quality and extensive adaptability, was bred by multiple crossing and microspore culture technique. It was registered and released in China in 2002. In regional trial of Hubei Province in China, Zhongshuang9 yielded 2 482. 2 kg ha-1 averagely in 2000 - 2002, 15. 33% higher than the control variety Zhongyou821. Erucic acid, glucosinolates and oil contents of Zhongshuang9 were 0.23%, 22.69 μmol g-1(in meal)and 42%, respectively. In field assessment of resistance to S. Sclerotiorum , the disease incidence and disease index of Zhongshuang9 averaged 13.31 % and 6.47, respectively, which were lower than those of Zhongyou821 by 28% and 36%, respectively. After inoculation of detached leaves with mycelia, the lesion size of Zhongshuang9 was 4. 709 cm2, which was significantly smaller than that of the mid-resistant variety Zhongyou821(5. 933 cm2). The stem lesion length of Zhongshuang9 after match-stick inoculation was 1.275 cm, which was significantly lower than that of Zhongyou821(1.943 cm). The possible mechanism of resistance to S. sclerotiorum was studied through comparing the activities of phenylalanine ammonia lyase(PAL), exo-chitinase, β-1, 3-glucanase, peroxidase(POD)and polyphenoloxidase(PPO)in Zhongshuang9 with those in other resistant, mid-resistant and susceptible cultivars.展开更多
Sclerotinia sclerotiorum is one of the most devastating necrotrophic phytopathogens. Virulence of the hyphae of this fungus at different ages varies significantly. Molecular mechanisms underlying this functional disti...Sclerotinia sclerotiorum is one of the most devastating necrotrophic phytopathogens. Virulence of the hyphae of this fungus at different ages varies significantly. Molecular mechanisms underlying this functional distinction are largely unknown. In this study, we confirmed the effect of mycelial culture time/age on virulence in two host plants and elucidated its molecular and morphological basis. The virulence of the S. sclerotiorum mycelia in plants dramatically decreases along with the increase of the mycelial age. Three-day-old mycelia lost the virulence in plants. Comparative proteomics analyses revealed that metabolism pathways were comprehensively reprogrammed to suppress the oxalic acid（OA） accumulation in old mycelia. The oxaloacetate acetylhydrolase（OAH）, which catalyzes OA biosynthesis, was identified in the S. sclerotiorum genome. Both gene expression and protein accumulation of OAH in old mycelia were strongly repressed. Moreover, in planta OA accumulation was strikingly reduced in old mycelia-inoculated plants compared with young vegetative mycelia-inoculated plants. Furthermore, supply with 10 mmol L^（-1） OA enabled the old mycelia infect the host plants, demonstrating that loss of virulence of old mycelia is mainly caused by being unable to accumulate OA. Additionally, aerial mycelia started to develop from 0.5-day-old vegetative mycelia and dominated over 1-day-old mycelia grown on potato dextrose agar plates. They were much smaller in hypha diameter and grew significantly slower than young vegetative mycelia when subcultured, which did not maintain to progenies. Collectively, our results reveal that S. sclerotiorum aerial hyphae-dominant old mycelia fail to accumulate OA and thereby lose the virulence in host plants.展开更多
Sclerotinia sclerotiorum is generally considered one of the most economically damaging pathogens in oilseed rape(Brassica napus).Breeding for Sclerotinia resistance is challenging,as no immune germplasm available in B...Sclerotinia sclerotiorum is generally considered one of the most economically damaging pathogens in oilseed rape(Brassica napus).Breeding for Sclerotinia resistance is challenging,as no immune germplasm available in B.napus.It is desirable to develop new breeding strategies.In the present study,hostinduced gene silencing(HIGS),developed based on RNA interference(RNAi),was applied to protect B.napus from S.sclerotiorum infection.Three pathogenicity genes,the endo-polygalacturonase gene(Ss PG1),cellobiohydrolase gene(Ss CBH),and oxaloacetate acetylhydrolase gene(Ss OAH1),were chosen as HIGS targets.Co-incubation of synthesized double-stranded RNAs(ds RNAs)with S.sclerotiorum in liquid medium significantly reduced the transcript levels of the target genes.Application to plant surfaces of ds RNA targeting the three genes conferred effective protection against S.sclerotiorum.Stable transgenic B.napus plants expressing small interfering RNAs with sequence identity to Ss PG1,Ss CBH,and Ss OAH1 were generated.HIGS transgenic B.napus prevented the expression of S.sclerotiorum target genes,slowed pathogenicity-factor accumulation,impeded fungal growth,and suppressed appressorium formation,thereby conferring resistance to S.sclerotiorum.Simultaneous silencing of Ss PG1,Ss CBH,and Ss OAH1 by stable expression of a chimeric hairpin RNAi construct in B.napus led to enhanced protection phenotypes(with disease lesion size reduced by 36.8%–43.7%).We conclude that HIGS of pathogenic-factor genes of S.sclerotiorum is a promising strategy for controlling Sclerotinia rot in oilseed rape.展开更多
The antifungal activity of chitosan on a common fungal phytopathogen, Sclerotinia sclerotiorum, and the control effect on sclerotinia rot of carrot were investigated. Mycelial growth and fungal biomass were strongly i...The antifungal activity of chitosan on a common fungal phytopathogen, Sclerotinia sclerotiorum, and the control effect on sclerotinia rot of carrot were investigated. Mycelial growth and fungal biomass were strongly inhibited by chitosan. Using propidium iodide stain combined with fluorescent microscopy, the plasma membrane of chitosan-treated S. sclerotiorum mycelia was observed to be markedly damaged. Concomitantly, protein leakage and lipid peroxidation was also found to be significantly higher in chitosan-treated mycelia compared to the control. Chitosan provided an effective control of sclerotinia rot of carrot, with induction of activity of defense-related enzymes including polyphenoloxidase and peroxidase. These data suggest that the effects of chitosan on sclerotinia rot of carrot may be associated with the direct damage to the plasma membrane and lipid peroxidation of S. sclerotiorum, and the elicitation of defense response in carrot.展开更多
基金financially supported by the National Nature Science Foundation of China (32372077)the Project of Chongqing Science and Technology Commission (CSTB2023NSCQ-MSX0355)the Fundamental Research Funds for the Central Universities (SWU120075)。
文摘The necrotrophic fungus, Sclerotinia sclerotiorum, employs an array of cell wall-degrading enzymes(CWDEs), including cellulase, to dismantle host cell walls. However, the molecular mechanisms through which S. sclerotiorum degrades cellulose remain elusive. Here, we unveil a novel secretory cellobiohydrolase, SsdchA, characterized by a signal peptide and a Glyco_hydro_7(GH7) domain. SsdchA exhibits a robust expression of during early infection stages. Interestingly, colony morphology and growth rates remain unaffected across the wild-type, SsdchA deletion strains and SsdchA overexpression strains on potato dextrose agar(PDA) medium. Nevertheless, the pathogenicity and cellobiohydrolase activity decreased in the SsdchA deletion strains, but enhanced in the SsdchA overexpression strains. Moreover,the heterologous expression of SsdchA in Arabidopsis thaliana leads to reduced cellulose content and heightened susceptibility to S. sclerotiorum. Collectively, our data underscore the pivotal role of the novel cellobiohydrolase SsdchA in the pathogenicity of S. sclerotiorum.
基金supported by the National Natural Science Foundation of China(Grant No.31771836)the National Key Research and Development Program of China(Grant No.2018YFD0201003).
文摘With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotiorum.Identification of important genes in the defense responses is critical for molecular breeding,which is an important strategy for controlling the disease.In this study,we isolated a B.napus WRKY transcription factor gene,BnaWRKY75.BnaWRKY75 was found to encode a nucleus-localized protein and exhibited relatively high expression in the stems.Arabidopsis thaliana transgenic plants expressing BnaWRKY75 showed enhanced resistance to S.sclerotiorum,and both ProBnaWRKY75:GUS and gene expression analyses showed that BnaWRKY75 was highly responsive to S.sclerotiorum infection,indicating the involvement of BnaWRKY75 in response to this infection.Furthermore,overexpression(OE)of BnaWRKY75 in B.napus significantly enhanced the resistance to S.sclerotiorum,whereas the resistance was reduced in RNAi transgenic B.napus plants.Moreover,the BnaWRKY75-OE B.napus plants exhibited constitutive activation of salicylic acid-,jasmonic acid-,and ethylene-mediated defense responses and the inhibition of both H_(2)O_(2)and O_(2)·^(-)accumulation in response to this pathogen.By contrast,BnaWRKY75-RNAi plants showed a reverse pattern,suggesting that BnaWRKY75 is involved in hormonal signaling pathways and in the control of reactive oxygen species accumulation.In conclusion,these data indicate that BnaWRKY75,a regulator of multiple defense responses,positively regulates resistance against S.sclerotiorum,which may guide the improvement of resistance in rapeseed.
基金supported by the Jiangsu Provincial Key Research and Development, China (BE2021361)the Jiangsu Agriculture Science and Technology Innovation Fund ((CX(21)2037 and CX(22)3072))the National Natural Science Foundation of China (31672065)。
文摘Laboratory mutants of Sclerotinia sclerotiorum(Lib)de Bary,resistant to boscalid,have been extensively characterized.However,the resistance situation in the lettuce field remains largely elusive.In this study,among the 172 S.sclerotiorum isolates collected from asparagus lettuce field in Jiangsu Province,China,132 isolates(76.74%)exhibited low-level resistance to boscalid(Bos^(LR)),with a discriminatory dose of 5μg mL-1.In comparison to the boscalid-sensitive(BosS)isolates,most Bos^(LR)isolates demonstrated a slightly superior biological fitness,as evidenced by data on mycelial growth,sclerotium production and pathogenicity.Moreover,most Bos^(LR)isolates showed comparable levels of oxalic acid(OA)accumulation,increased exopolysaccharide(EPS)content and reduced membrane permeability when compared to the BosS isolates.Nevertheless,their responses to distinct stress factors diverged significantly.Furthermore,the effectiveness of boscalid in controlling Bos^(LR)isolates on radish was diminished compared to its efficacy on BosS isolates.Genetic mutations were identified in the SDH genes of Bos^(LR)isolates,revealing the existence of three resistant genotypes:I(^(A11V)at SDHB,SDHB^(A11V)),II(^(Q38R)at SDHC,SDHC^(Q38R))and III(SDHB^(A11V)+SDHC^(Q38R)).Importantly,no cross-resistance was observed between boscalid and other fungicides such as thifluzamide,pydiflumetofen,fluazinam,or tebuconazole.Our molecular docking analysis indicated that the docking total score(DTS)of the type I resistant isolates(1.3993)was lower than that of the sensitive isolates(1.7499),implying a reduced affinity between SDHB and boscalid as a potential mechanism underlying the boscalid resistance in S.sclerotiorum.These findings contribute to an enhanced comprehension of boscalid’s mode of action and furnish valuable insights into the management of boscalid resistance.
文摘The present work was aimed to the study of the antifungal activity of essential oils of two aromatic plants against three strains of Sclerotinia sclerotiorum responsible for white rot of bean. The two essential oils (EO) of the studied plants: Thymus vulgaris (HET) and Cymbopogon citratrus (HEC), used at different concentrations: C1 (0.75 ml/ml), C2 (1.5 ml/ml) and C3 (3 ml/ml) presented significant inhibitory activities on the three tested fungal strains namely Bia 1, Bia 2, and Njo 2. Two control treatments (T-: containing no antifungal substance and T+: synthetic fungicide) were also used. The antifungal activity here is related to the inhibition of mycelial growth especially with high concentrations of essential oils. Thus, against S. sclerotiorum, HET showed the highest activity comparable to that of T+ (100% inhibition) at all concentrations on the Bia 1 and Bia 2 strains and at concentration C3 on the Njo 2 strain compared to that of HEC, which certainly inhibited the mycelial growth of the different strains considerably (with a maximum of 78.15% on the Njo 2 strain) but not completely. According to their sensitivity, the Bia 2 strain showed a higher sensitivity to essential oils than the others while the Njo 2 strain was more aggressive. On the basis of MIC<sub>50</sub> and MIC<sub>90</sub> obtained on the Njo 2 strain, the HET turns out to be the most efficient with respective lower values of (1.73 and 23.34 ml/ml) against (4.76 and 26.03 ml/ml) for the HEC. These EO could thus be exploited as biodegradable antifungal substances, likely to control white rot of bean.
文摘[Objective] The study was to investigate roles of Brassica napus EINB in （ BnEIN3 ） resistance to Sclerotinia sclerotiorum. [ Methods] Genomic PCR and RT-PCR were carded out to isolate genomic DNA and cDNA sequences of BnEIN3 from oilseed rape, based on the highly conserved region of EIN3 gene from Arabidopsis thaliana and the homologous sequences of oilseed rape ESTs. Expression levels of BnEIN3 were detected in three varieties of oilseed rape inoculated with S. sclerotiorum by real-time quantitative PCR.[Results] A 1 947 bp DNA fragment was obtained from oilseed rape. The fragment shared 82% identity to A. thaliana EIIV3, encoded 614 amino acids containing an EIN3 domain, and was named as BnEIN3. Real-time PCR results showed that expression patterns of BnEIN3 were drastically different in different varieties. In highly resistant oilseed rape variety D083, BnEIN3 expression level was significantly increased 72 h after S. sclerotiorum inoculation whereas in middle resistant and susceptible varieties Zhongshuang 9 and 84039, BnEIN3 expression was suppressed. [ Conclusion ] BnEIIV3 may play an important role in oilseed rape resistance to S. sclerotiorum.
文摘Zhongshuang9, a new semi-winter Brassica napus variety with high resistance to Sclerotinia sclerotiorum and lodging, high-yield, double-low quality and extensive adaptability, was bred by multiple crossing and microspore culture technique. It was registered and released in China in 2002. In regional trial of Hubei Province in China, Zhongshuang9 yielded 2 482. 2 kg ha-1 averagely in 2000 - 2002, 15. 33% higher than the control variety Zhongyou821. Erucic acid, glucosinolates and oil contents of Zhongshuang9 were 0.23%, 22.69 μmol g-1(in meal)and 42%, respectively. In field assessment of resistance to S. Sclerotiorum , the disease incidence and disease index of Zhongshuang9 averaged 13.31 % and 6.47, respectively, which were lower than those of Zhongyou821 by 28% and 36%, respectively. After inoculation of detached leaves with mycelia, the lesion size of Zhongshuang9 was 4. 709 cm2, which was significantly smaller than that of the mid-resistant variety Zhongyou821(5. 933 cm2). The stem lesion length of Zhongshuang9 after match-stick inoculation was 1.275 cm, which was significantly lower than that of Zhongyou821(1.943 cm). The possible mechanism of resistance to S. sclerotiorum was studied through comparing the activities of phenylalanine ammonia lyase(PAL), exo-chitinase, β-1, 3-glucanase, peroxidase(POD)and polyphenoloxidase(PPO)in Zhongshuang9 with those in other resistant, mid-resistant and susceptible cultivars.
基金supported by grants from the Special Fund for Agro-Scientific Research in the Public Interest, China (201103016)the Specialized Research Fund for the Doctoral Program of Higher Education, China (SRFDP) (20110101110092)+2 种基金the National Natural Science Foundation of China (31371892)the Program for New Century Excellent Talents in University (NCET-08-0485)the Program for New Century 151 Talents of Zhejiang Province, China
文摘Sclerotinia sclerotiorum is one of the most devastating necrotrophic phytopathogens. Virulence of the hyphae of this fungus at different ages varies significantly. Molecular mechanisms underlying this functional distinction are largely unknown. In this study, we confirmed the effect of mycelial culture time/age on virulence in two host plants and elucidated its molecular and morphological basis. The virulence of the S. sclerotiorum mycelia in plants dramatically decreases along with the increase of the mycelial age. Three-day-old mycelia lost the virulence in plants. Comparative proteomics analyses revealed that metabolism pathways were comprehensively reprogrammed to suppress the oxalic acid（OA） accumulation in old mycelia. The oxaloacetate acetylhydrolase（OAH）, which catalyzes OA biosynthesis, was identified in the S. sclerotiorum genome. Both gene expression and protein accumulation of OAH in old mycelia were strongly repressed. Moreover, in planta OA accumulation was strikingly reduced in old mycelia-inoculated plants compared with young vegetative mycelia-inoculated plants. Furthermore, supply with 10 mmol L^（-1） OA enabled the old mycelia infect the host plants, demonstrating that loss of virulence of old mycelia is mainly caused by being unable to accumulate OA. Additionally, aerial mycelia started to develop from 0.5-day-old vegetative mycelia and dominated over 1-day-old mycelia grown on potato dextrose agar plates. They were much smaller in hypha diameter and grew significantly slower than young vegetative mycelia when subcultured, which did not maintain to progenies. Collectively, our results reveal that S. sclerotiorum aerial hyphae-dominant old mycelia fail to accumulate OA and thereby lose the virulence in host plants.
基金the National Natural Science Foundation of China(32072020,U20A2028,and 31901504)the Jiangsu Agricultural Science and Technology Innovation Fund(CX(20)3120)+1 种基金the Project of Special Funding for Crop Science Discipline Development(yzuxk202006)the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Qinglan Project of Yangzhou University。
文摘Sclerotinia sclerotiorum is generally considered one of the most economically damaging pathogens in oilseed rape(Brassica napus).Breeding for Sclerotinia resistance is challenging,as no immune germplasm available in B.napus.It is desirable to develop new breeding strategies.In the present study,hostinduced gene silencing(HIGS),developed based on RNA interference(RNAi),was applied to protect B.napus from S.sclerotiorum infection.Three pathogenicity genes,the endo-polygalacturonase gene(Ss PG1),cellobiohydrolase gene(Ss CBH),and oxaloacetate acetylhydrolase gene(Ss OAH1),were chosen as HIGS targets.Co-incubation of synthesized double-stranded RNAs(ds RNAs)with S.sclerotiorum in liquid medium significantly reduced the transcript levels of the target genes.Application to plant surfaces of ds RNA targeting the three genes conferred effective protection against S.sclerotiorum.Stable transgenic B.napus plants expressing small interfering RNAs with sequence identity to Ss PG1,Ss CBH,and Ss OAH1 were generated.HIGS transgenic B.napus prevented the expression of S.sclerotiorum target genes,slowed pathogenicity-factor accumulation,impeded fungal growth,and suppressed appressorium formation,thereby conferring resistance to S.sclerotiorum.Simultaneous silencing of Ss PG1,Ss CBH,and Ss OAH1 by stable expression of a chimeric hairpin RNAi construct in B.napus led to enhanced protection phenotypes(with disease lesion size reduced by 36.8%–43.7%).We conclude that HIGS of pathogenic-factor genes of S.sclerotiorum is a promising strategy for controlling Sclerotinia rot in oilseed rape.
基金supported by grants from the National Natural Science Foundation of China (31101364)the Ministry of Agriculture of China (CARS-25-E-01 and 201203095)the Beijing Academy of Agriculture and Forestry Sciences,China (CXJJ201304)
文摘The antifungal activity of chitosan on a common fungal phytopathogen, Sclerotinia sclerotiorum, and the control effect on sclerotinia rot of carrot were investigated. Mycelial growth and fungal biomass were strongly inhibited by chitosan. Using propidium iodide stain combined with fluorescent microscopy, the plasma membrane of chitosan-treated S. sclerotiorum mycelia was observed to be markedly damaged. Concomitantly, protein leakage and lipid peroxidation was also found to be significantly higher in chitosan-treated mycelia compared to the control. Chitosan provided an effective control of sclerotinia rot of carrot, with induction of activity of defense-related enzymes including polyphenoloxidase and peroxidase. These data suggest that the effects of chitosan on sclerotinia rot of carrot may be associated with the direct damage to the plasma membrane and lipid peroxidation of S. sclerotiorum, and the elicitation of defense response in carrot.
