The necrotrophic fungus Rhizoctonia cerealis is the causal agent of devastating diseases of cereal crops including wheat(Triticum aestivum).We present a high-quality genome assembly of R.cerealis Rc207,a virulent stra...The necrotrophic fungus Rhizoctonia cerealis is the causal agent of devastating diseases of cereal crops including wheat(Triticum aestivum).We present a high-quality genome assembly of R.cerealis Rc207,a virulent strain causing wheat sharp eyespot.The assembly(56.36 Mb)is composed of 17.87%repeat sequences and 14,433 predicted protein-encoding genes.The Rc207 genome encodes a large and diverse set of genes involved in pathogenicity,especially rich in those encoding secreted proteins,carbohydrateactive enzymes(CAZymes),peptidases,nucleases,cytochrome P450,and secondary metabolismassociated enzymes.Most secretory protein-encoding genes,including CAZymes,peroxygenases,dehydrogenases,and cytochrome P450,were up-regulated during fungal infection of wheat.We identified 831 candidate secretory effectors and validated the functions of 10 up-regulated candidate effector proteins.Of them,nine were confirmed as necrotrophic pathogen’s effectors promoting fungal infection.Abundant potential mobile or plastic genomic regions rich in repeat sequences suggest their roles in fungal adaption and virulence-associated genomic evolution.This study provides valuable resources for further comparative and functional genomics on important fungal pathogens,and provides essential tools for development of effective disease control strategies.展开更多
Receptor-like cytoplasmic kinases(RLCKs)represent a large family of proteins in plants.In Arabidopsis and rice,several RLCKs in subfamily VII(RLCKs-VII)have been implicated in pathogen-associated molecular pattern-tri...Receptor-like cytoplasmic kinases(RLCKs)represent a large family of proteins in plants.In Arabidopsis and rice,several RLCKs in subfamily VII(RLCKs-VII)have been implicated in pathogen-associated molecular pattern-triggered immunity and basal resistance against bacterial and fungal pathogens.However,little is known about roles of RLCKs-VII of the important crop common wheat(Triticum aestivum)in immune responses.Here,we isolated a RLCK-VII-encoding gene from wheat,designated as TaRLCK1B,and investigated its role in host immune response to infection of a necrotrophic fungus Rhizoctonia cerealis that is a major pathogen of sharp eyespot,a destructive disease of wheat.RNA-sequencing and RT-qPCR analyses showed that transcriptional level of TaRLCK1B was significantly higher in sharp eyespot-resistant wheat cultivars than in susceptible wheat cultivars.The gene transcription was rapidly and markedly elevated in the resistant wheat cultivars by R.cerealis infection.The TaRLCK1B protein was closely related to OsRLCK176,a rice resistance-related RLCKs-VII,with 84.03%identity.Virus-induced gene silencing plus wheat response to R.cerealis assay results indicated that silencing of TaRLCK1 impaired resistance to R.cerealis.Meantime,silencing of TaRLCK1 significantly elevated both the content of H2 O2(a major kind of reactive oxygen species,ROS)and the transcriptional level of the ROS-generating enzyme-encoding gene RBOH,but repressed the expression of the ROS-scavenging enzyme-encoding gene CAT1 at 18 hours after inoculation(hai)with R.cerealis.Taken together,these data suggested that TaRLCK1B was required for the early immune response of wheat to R.cerealis through modulating ROS signaling in wheat.展开更多
In this study, the changes in activities of peroxidase （POD）, glutathione S-transferase （GST）, catalase （CAT）, and superoxide distmuase （SOD） in leaves of four wheat cultivars, including resistant cultivars Sh...In this study, the changes in activities of peroxidase （POD）, glutathione S-transferase （GST）, catalase （CAT）, and superoxide distmuase （SOD） in leaves of four wheat cultivars, including resistant cultivars Shannong 0431 and Shanhongmai, a mildsusceptible cultivar Lumai 21, and a susceptible cultivar Wenmai 6, were investigated to explore if these antioxidantrelated enzymes were involved in wheat defense response to Rhizoctonia cerealis attack. Results showed that the activities of these enzymes in different wheat cultivars varied greatly after challenging with R. cerealis. The POD activities in resistant cultivars Shannong 0431 and Shanhongmai increased much quicker after the inoculation and displayed much higher activity than that in susceptible cultivar Wenmai 6. In contrast, POD activity showed a slow accumulation and a delayed peak time. The activities of GST and CAT in Shannong 0431 and Lumai 21 increased obviously within 48 h post inoculation （hpi）, whereas SOD activity decreased dramatically within 24 hpi in Shannong 0431 and 24-48 hpi in Lumai 21. In susceptible cultivar Wenmai 6, the SOD and CAT activities didn’t change obviously, whereas the activity of GST was decreased. The activities of CAT and GST in Shanhongmai did not show significant difference compared with those in Wenmai 6. Results suggested that POD activity may be positively associated with wheat defense to R. cerealis.展开更多
Wheat(Triticum aestivum L.)is an important staple crop for global human.The necrotrophic fungus Rhizoctonia cerealis is the causal pathogen of sharp eyespot,a devastating disease of wheat.Herein,we identified RcMEP1,a...Wheat(Triticum aestivum L.)is an important staple crop for global human.The necrotrophic fungus Rhizoctonia cerealis is the causal pathogen of sharp eyespot,a devastating disease of wheat.Herein,we identified RcMEP1,a zinc metalloproteaseencoding gene from R.cerealis genomic sequences,and characterized its pathogenesis function.RcMEP1 expressed at markedly-high levels during R.cerealis infection process to wheat.The predicted protein RcMEP1 comprises of 287 amino acid residues and contains a signal peptide and a M43 metalloprotease domain harboring the active site motif(HEVGHWLGLYH).The assays of Agrobacterium tumefaciens-mediated transient expression in Nicotiana benthamiana leaves indicated that RcMEP1 is an apoplastic elicitor of cell death,and that the predicted signal peptide functions and is required for secretion and cell death-induction.The purified RcMEP1 protein and its M43 domain peptide were individually able to induce plant cell death and H2 O2 accumulation,and to inhibit expression of host chitinases when infiltrated into wheat and N.benthamiana leaves,while the M43 domain-deleting peptide and negative control lacked the capacity.Moreover,compared with the control pretreatment,the purified RcMEP1 protein or its M43-domain peptide resulted in enhanced pathogenesis in the inoculated wheat,whereas the M43 domain-deleting peptide failed.These results suggest that RcMEP1 acted as an important pathogenicity factor during R.cerealis infection to wheat and that its signal peptide and M43 domain are required for the secretion and pathogenesis of RcMEP1.This study provides insights into pathogenesis role of M43 domain-containing metalloproteases during R.cerealis infection to wheat.展开更多
Wheat sharp eyespot, a stem disease caused by the soilborne fungus Rhizoctonia cerealis van der Hoeven,has become a threat to wheat production worldwide. Exploiting resistance resources from wild relatives of wheat is...Wheat sharp eyespot, a stem disease caused by the soilborne fungus Rhizoctonia cerealis van der Hoeven,has become a threat to wheat production worldwide. Exploiting resistance resources from wild relatives of wheat is a promising strategy for controlling this disease. In this study, a new wheat–Dasypyrum villosum T2DS·2V#4L translocation line in the background of Chinese Spring(CS) showed stable resistance to R. cerealis. Introgression of the T2DS·2V#4L chromosome into wheat cultivar Aikang 58 by backcrossing produced a marked increase in sharp eyespot resistance in NIL-T2DS·2V#4L in comparison with NILT2DS·2DL, and no detrimental effects of 2V#4L on agronomic traits were observed in the BC2F2, BC2F2:3,and BC2F2:4generations. Flow-sorted sequencing of 2V#4L yielded 384.3 Mb of assembled sequence, and8836 genes were predicted of which 6154 had orthologs in at least one of the 2AL, 2BL, and 2DL arms of CS, whereas 1549 genes were unique to 2V#4L. About 100,000 SNPs were detected in genes of 2V#4L and2DL in 10 sequenced bread wheat cultivars. A Kompetitive Allele Specific Polymerase chain reaction and30 conserved ortholog sequence markers were developed to trace the 2V#4L chromatin in wheat backgrounds. T2DS·2V#4L compensating translocation lines represent novel germplasm with sharp eyespot resistance and the markers will allow rapid detection in breeding programs.展开更多
To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with ri...To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with rice straw for two or three years. Bacterial and fungal populations were evaluated in the cultures prepared from the wheat rhizosphere and bulk soils. Rice straw mulching increased the number of pseudomonas colony forming units in wheat rhizosphere and bulk soils. The proportion of total bacteria that were fluorescent pseudomonads was higher in mulched than in unmulched soil. Bacterial isolates antagonistic to Rhizoctonia cerealis were identified using an inhibition zone test. A series of these isolates were typed by partial sequencing of the 16S rRNA gene. Pseudomonads had higher antagonistic activity against R. cerealis than other species, and more than 80% of rhizosphere fluorescent pseudomonads were antagonistic to R. eerealis. The disease indices were lower in the mulched plots than in the unmulched control. These results suggest that rice straw mulching in a rice-wheat rotation increases the number of fluorescent pseudomonads. Additionally, these fluorescent pseudomonads may contribute to the control of wheat sharp eyespot.展开更多
基金funded by the National Key Project for Research on Transgenic Biology,China(2016ZX08002001 to Zengyan Zhang)。
文摘The necrotrophic fungus Rhizoctonia cerealis is the causal agent of devastating diseases of cereal crops including wheat(Triticum aestivum).We present a high-quality genome assembly of R.cerealis Rc207,a virulent strain causing wheat sharp eyespot.The assembly(56.36 Mb)is composed of 17.87%repeat sequences and 14,433 predicted protein-encoding genes.The Rc207 genome encodes a large and diverse set of genes involved in pathogenicity,especially rich in those encoding secreted proteins,carbohydrateactive enzymes(CAZymes),peptidases,nucleases,cytochrome P450,and secondary metabolismassociated enzymes.Most secretory protein-encoding genes,including CAZymes,peroxygenases,dehydrogenases,and cytochrome P450,were up-regulated during fungal infection of wheat.We identified 831 candidate secretory effectors and validated the functions of 10 up-regulated candidate effector proteins.Of them,nine were confirmed as necrotrophic pathogen’s effectors promoting fungal infection.Abundant potential mobile or plastic genomic regions rich in repeat sequences suggest their roles in fungal adaption and virulence-associated genomic evolution.This study provides valuable resources for further comparative and functional genomics on important fungal pathogens,and provides essential tools for development of effective disease control strategies.
基金This study was funded by the Natural Science Foundation of China(31771789)the National Key Project for Research on Transgenic Biology,China(2016ZX08002-001-004)+1 种基金Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2018QNRC001)The authors are very grateful to Prof.Jia Jizeng(ICS,CAAS)for providing the RIL population and Prof.Yu Jinfeng(Shandong Agricultural University,Shandong)for providing R.cerealis strain WK207.
文摘Receptor-like cytoplasmic kinases(RLCKs)represent a large family of proteins in plants.In Arabidopsis and rice,several RLCKs in subfamily VII(RLCKs-VII)have been implicated in pathogen-associated molecular pattern-triggered immunity and basal resistance against bacterial and fungal pathogens.However,little is known about roles of RLCKs-VII of the important crop common wheat(Triticum aestivum)in immune responses.Here,we isolated a RLCK-VII-encoding gene from wheat,designated as TaRLCK1B,and investigated its role in host immune response to infection of a necrotrophic fungus Rhizoctonia cerealis that is a major pathogen of sharp eyespot,a destructive disease of wheat.RNA-sequencing and RT-qPCR analyses showed that transcriptional level of TaRLCK1B was significantly higher in sharp eyespot-resistant wheat cultivars than in susceptible wheat cultivars.The gene transcription was rapidly and markedly elevated in the resistant wheat cultivars by R.cerealis infection.The TaRLCK1B protein was closely related to OsRLCK176,a rice resistance-related RLCKs-VII,with 84.03%identity.Virus-induced gene silencing plus wheat response to R.cerealis assay results indicated that silencing of TaRLCK1 impaired resistance to R.cerealis.Meantime,silencing of TaRLCK1 significantly elevated both the content of H2 O2(a major kind of reactive oxygen species,ROS)and the transcriptional level of the ROS-generating enzyme-encoding gene RBOH,but repressed the expression of the ROS-scavenging enzyme-encoding gene CAT1 at 18 hours after inoculation(hai)with R.cerealis.Taken together,these data suggested that TaRLCK1B was required for the early immune response of wheat to R.cerealis through modulating ROS signaling in wheat.
基金supported by the National High-Tech R&D Program of China (2006AA10A104)the CoreResearch Budget of the Nonprofit Governmental Re-search Institution (the Public Welfare Project of CAAS,China, 2060302-2-09)
文摘In this study, the changes in activities of peroxidase （POD）, glutathione S-transferase （GST）, catalase （CAT）, and superoxide distmuase （SOD） in leaves of four wheat cultivars, including resistant cultivars Shannong 0431 and Shanhongmai, a mildsusceptible cultivar Lumai 21, and a susceptible cultivar Wenmai 6, were investigated to explore if these antioxidantrelated enzymes were involved in wheat defense response to Rhizoctonia cerealis attack. Results showed that the activities of these enzymes in different wheat cultivars varied greatly after challenging with R. cerealis. The POD activities in resistant cultivars Shannong 0431 and Shanhongmai increased much quicker after the inoculation and displayed much higher activity than that in susceptible cultivar Wenmai 6. In contrast, POD activity showed a slow accumulation and a delayed peak time. The activities of GST and CAT in Shannong 0431 and Lumai 21 increased obviously within 48 h post inoculation （hpi）, whereas SOD activity decreased dramatically within 24 hpi in Shannong 0431 and 24-48 hpi in Lumai 21. In susceptible cultivar Wenmai 6, the SOD and CAT activities didn’t change obviously, whereas the activity of GST was decreased. The activities of CAT and GST in Shanhongmai did not show significant difference compared with those in Wenmai 6. Results suggested that POD activity may be positively associated with wheat defense to R. cerealis.
基金funded by the Key Sci-Tech Program of China(2016ZX08002-001-004)。
文摘Wheat(Triticum aestivum L.)is an important staple crop for global human.The necrotrophic fungus Rhizoctonia cerealis is the causal pathogen of sharp eyespot,a devastating disease of wheat.Herein,we identified RcMEP1,a zinc metalloproteaseencoding gene from R.cerealis genomic sequences,and characterized its pathogenesis function.RcMEP1 expressed at markedly-high levels during R.cerealis infection process to wheat.The predicted protein RcMEP1 comprises of 287 amino acid residues and contains a signal peptide and a M43 metalloprotease domain harboring the active site motif(HEVGHWLGLYH).The assays of Agrobacterium tumefaciens-mediated transient expression in Nicotiana benthamiana leaves indicated that RcMEP1 is an apoplastic elicitor of cell death,and that the predicted signal peptide functions and is required for secretion and cell death-induction.The purified RcMEP1 protein and its M43 domain peptide were individually able to induce plant cell death and H2 O2 accumulation,and to inhibit expression of host chitinases when infiltrated into wheat and N.benthamiana leaves,while the M43 domain-deleting peptide and negative control lacked the capacity.Moreover,compared with the control pretreatment,the purified RcMEP1 protein or its M43-domain peptide resulted in enhanced pathogenesis in the inoculated wheat,whereas the M43 domain-deleting peptide failed.These results suggest that RcMEP1 acted as an important pathogenicity factor during R.cerealis infection to wheat and that its signal peptide and M43 domain are required for the secretion and pathogenesis of RcMEP1.This study provides insights into pathogenesis role of M43 domain-containing metalloproteases during R.cerealis infection to wheat.
基金supported by the National Key Research and Develpment Program of China (2021YFD1200600)the National Natural Science Foundation of China (31871619, 32101703, and 32101800)+4 种基金the Natural Science Foundation of Jiangsu Province (BK20210152)the Jiangsu Seed Industry Revitalization Project (JBGS (2021) 013)the Key Research and Development Program of Jiangsu Province(BE2022346)Jiangsu Agricultural Science and Technology Innovation Fund of China (CX (20) 3029)supported by the European Regional Development Fund (CZ.02.1.01/0.0/0.0/16_019/0000827)。
文摘Wheat sharp eyespot, a stem disease caused by the soilborne fungus Rhizoctonia cerealis van der Hoeven,has become a threat to wheat production worldwide. Exploiting resistance resources from wild relatives of wheat is a promising strategy for controlling this disease. In this study, a new wheat–Dasypyrum villosum T2DS·2V#4L translocation line in the background of Chinese Spring(CS) showed stable resistance to R. cerealis. Introgression of the T2DS·2V#4L chromosome into wheat cultivar Aikang 58 by backcrossing produced a marked increase in sharp eyespot resistance in NIL-T2DS·2V#4L in comparison with NILT2DS·2DL, and no detrimental effects of 2V#4L on agronomic traits were observed in the BC2F2, BC2F2:3,and BC2F2:4generations. Flow-sorted sequencing of 2V#4L yielded 384.3 Mb of assembled sequence, and8836 genes were predicted of which 6154 had orthologs in at least one of the 2AL, 2BL, and 2DL arms of CS, whereas 1549 genes were unique to 2V#4L. About 100,000 SNPs were detected in genes of 2V#4L and2DL in 10 sequenced bread wheat cultivars. A Kompetitive Allele Specific Polymerase chain reaction and30 conserved ortholog sequence markers were developed to trace the 2V#4L chromatin in wheat backgrounds. T2DS·2V#4L compensating translocation lines represent novel germplasm with sharp eyespot resistance and the markers will allow rapid detection in breeding programs.
基金Supported by the National Key Technology R&D Program of China (No. 2006BAD08A05)the National Special Research Programs for Non-Profit Trades of China (No. nyhyzx3-16)
文摘To assess the effect of rice straw mulching on changes of antagonistic bacteria and the incidence of wheat sharp eyespot, a multi-year field study was performed to compare unmulched plots and the plots mulched with rice straw for two or three years. Bacterial and fungal populations were evaluated in the cultures prepared from the wheat rhizosphere and bulk soils. Rice straw mulching increased the number of pseudomonas colony forming units in wheat rhizosphere and bulk soils. The proportion of total bacteria that were fluorescent pseudomonads was higher in mulched than in unmulched soil. Bacterial isolates antagonistic to Rhizoctonia cerealis were identified using an inhibition zone test. A series of these isolates were typed by partial sequencing of the 16S rRNA gene. Pseudomonads had higher antagonistic activity against R. cerealis than other species, and more than 80% of rhizosphere fluorescent pseudomonads were antagonistic to R. eerealis. The disease indices were lower in the mulched plots than in the unmulched control. These results suggest that rice straw mulching in a rice-wheat rotation increases the number of fluorescent pseudomonads. Additionally, these fluorescent pseudomonads may contribute to the control of wheat sharp eyespot.
