Rice blast caused by <em>Magnaporthe oryzae</em> (<em>M. oryzae</em>) is one of the most destructive diseases, which causes significant rice yield losses and affects global food security. To be...Rice blast caused by <em>Magnaporthe oryzae</em> (<em>M. oryzae</em>) is one of the most destructive diseases, which causes significant rice yield losses and affects global food security. To better understand genetic variations among different isolates of <em>M. oryzae</em> in the nature field, we re-sequenced and analyzed the genomes of three field isolates, QJ08-2006, QJ10-10, and QJ10-3001, which showed distinct pathogenicity on Xin-Yin-Zhan, an elite variety in South China. Genome annotation indicated that these three isolates assemblies have similar genome sizes with 38.4 Mb, 38.3 Mb, and 38.4 Mb, respectively. The QJ08-2006 assembly has 2082 contigs with an N50 of 127.4 kb, the QJ10-10 assembly has 2239 contigs with an N50 of 105.13 kb, the QJ10-3001 assembly has 2025 contigs with an N50 of 133.16 kb. A total of 10,432 genes including 1408 putative secreted protein genes were identified from the annotated isolate QJ08-2006 genome, 10,418 genes including 1410 putative secreted protein genes were identified in QJ10-10, and 10,401 genes including 1420 putative secreted protein genes were identified in QJ10-3001. There are as many as 11,076 identical genes in these three isolates and contained only a few unique genes among three isolates, of which 277 unique genes in QJ08-2006 and 264 unique genes in QJ10-10, and 213 unique genes in QJ10-3001. Most of the predicted secreted protein genes had been identified, and the three re-sequenced strains contained 371, 369, and 387 small Indel, respectively. <em>Avr </em>genes were analyzed in several sequenced <em>Magnaporthe</em> strains, the results revealed that <em>Avr-Pi9</em> and <em>Avr-Piz-t </em>were present in all the sequenced isolates. The isolates QJ08-2006 contained <em>AvrPib</em>, QJ10-10, and QJ10-3001 had an insertion of a Pot3 element in the promoter of the <em>AvrPib</em> gene. Our results showed that, the rapid dominancy of virulence mutant isolates via clonal propagation displayed in the field after the release of the elite variety Xin-Yin-Zhan.展开更多
Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major dise...Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.展开更多
The fungus U. virens is the causal agent of rice false smut disease. The green fluorescent protein (GFP) was used to mark this fungus in order to visualize and analyze the colonization and infection processes in vivo....The fungus U. virens is the causal agent of rice false smut disease. The green fluorescent protein (GFP) was used to mark this fungus in order to visualize and analyze the colonization and infection processes in vivo. Using epifluorescence microscopy colonization and infection on rice roots were visualized in vivo. After inoculation for 2 to 15 d, it was observed that the conidia and their germ-tubes had penetrated into epidermis of young roots. The hyphae were found inside the root xylem 18 d after inoculation. Generally, the transformed fungus colonized the rhizosphere, the cortex as well as the vascular tissues with symptoms of root necrosis observed. The results of this work show that U. virens colonize not only rice panicles but also the roots.展开更多
Pathogenic isolates were collected from different rice-cropping regions in southern China to dissect the pathogenic disintegration and variation of Xanthornonas oryzae pv. oryzae （Xoo）. Two sets of rice-Xoo differen...Pathogenic isolates were collected from different rice-cropping regions in southern China to dissect the pathogenic disintegration and variation of Xanthornonas oryzae pv. oryzae （Xoo）. Two sets of rice-Xoo differential hosts, including Chinese system with such five euhivars as IR26, Java14, Nangeng15, Tetep and Jingang 30 and international system with a series of nearisogenic lines （NILs） including IRBB5, IRBB13, IRBB3, IRBB14, IRBB2 and IR24 carrying different known resistance genes,were used to detect pathogenic disintegration for the reaction between host and pathogen with leaf-clippingmethod at the rice booting stage. The results showed the type of the pathogen were divided intosix pathotypes, i.e. , Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅸ based on the Chinese differential system, and seven pathogenicraces including RI, R2, R3, R4, R5, R8 and R10 based on the international differential system. The pathogenicity frequency of Xoo pathotypes V and IV and pathogenic races R8 and R5 were 27.40% , 19.30% and 44.67% , 15.34%, which were considered to be the prevailing races in southern China. Pathogenic rates of pathotypes Ⅳ, Ⅴ, Ⅸ and races R8, R5 against 500 varieties derived from southernChina were 96.40% , 95.00% , 50.40% , 62.00% , and 42.60%, respectively. Among which pathotype Ⅸ was the most virulent pathotype. The pathotype Ⅴ became preponderant pathotype and the new pathotype Ⅸ grew up quickly.展开更多
Specific molecular markers for detecting the alleles of Pi2/Pi9/Piz-t,designated as Pi2 SNP,Pi9 SNP and Pizt-PA,respectively,have been successfully developed through sequence comparison method.These three specific mar...Specific molecular markers for detecting the alleles of Pi2/Pi9/Piz-t,designated as Pi2 SNP,Pi9 SNP and Pizt-PA,respectively,have been successfully developed through sequence comparison method.These three specific markers can distinctly distinguish target genes from others mapped on Pi2/9 locus,which facilitates the molecular marker-assistant selection and the development of pyramiding cultivars combined with other allele R genes.Additionally,101 main cultivars and breeding parents collected from different rice-planting areas have been diagnosed with these three specific markers,and the results showed that only 2 out of the 101 cultivars carried Piz-t,but neither Pi2 nor Pi9 band had been detected.It indicates that most of the main cultivars and breeding parents in China do not carry Pi2/Pi9/Piz-t.These results provide important information for the application of Pi2/Pi9/Piz-t in the blast resistance breeding programs.展开更多
[Objectives]This study was conducted to screen out rice resources resistant to rice blast(Magnaporthe oryzae).[Methods]The qualitative and quantitative resistance of 1659 rice resources from 45 countries and regions t...[Objectives]This study was conducted to screen out rice resources resistant to rice blast(Magnaporthe oryzae).[Methods]The qualitative and quantitative resistance of 1659 rice resources from 45 countries and regions to rice blast were evaluated by disease nursery in upland condition and the test of the spectrum to rice blast isolates.[Results]There were 292 entries which accounted for 17.6%showed high blast resistance(0 and 1 disease scale),68 entries(counted for 4.1%)showed resistance to blast(3 disease scale);and the number of the entries showed intermediate resistance,intermediate susceptible and susceptible were 208(with the corresponding percentage of 12.5%),471(28.4%),620(37.4%)respectively.Among the tested entries,27 entries including BG1222,BL122,BTX,IR37704-131-2-3-2,and LEBONNET had showed broad-spectrum blast resistance with the resistance frequency of higher than 90%,Quantitative resistance evaluation was conducted on some key resources,and 14 entries,of which are BR27,DRAGO,IR100,QINLIUAI、SERIBU GANTANG,YUEXIANGZHAN and so on,showed good quantitative resistances,and 8 entries had higher quantitative resistances than IR36.[Conclusions]This study provides important blast resistance resources for the local rice breeding program and has a significant value for the discovery of new blast resistance genes and its application in the blast resistance breeding.展开更多
[Objectives]The paper was to identify the characteristics and the potency of new fungicides to rice blast disease,and study their preventive and therapeutic effects on the disease.[Methods]Six new and conventional fun...[Objectives]The paper was to identify the characteristics and the potency of new fungicides to rice blast disease,and study their preventive and therapeutic effects on the disease.[Methods]Six new and conventional fungicides with different mechanisms of action were selected to compare their preventive and therapeutic effects on rice seedling blast in greenhouse.[Results]The agents which showed to be highly efficacious in blast prevention(greater than 90%)were 25%pyraclostrobin EC,20%fenoxanil SC,75%tricyclazole WP and 50%prochloraz-manganese WP sprayed at the dosages of 112.5-150,180-360,270-450 and 450-600 g/ha,respectively.The therapeutic effect of new fungicides 25%pyraclostrobin EC and 50%prochloraz-manganese WP on rice blast were above 90%when the dosages were 90-150 and 360-600 g/ha,respectively.The therapeutic effect of the conventional fungicide 40%isoprothiolane EC on rice blast was 69.04%when the dosage was 480 g/ha,while those of other fungicides were worse.[Conclusions]Both 25%pyraclostrobin EC and 50%prochloraz-manganese WP have good preventive and therapeutic effects on rice blast,which will provide a reference for the use of these fungicides in the field.展开更多
Rice blast is the most devastating disease in rice,and it seriously threatens the safety of rice production.Improving the ability of integrated prevention and control of rice blast has always been an important part of...Rice blast is the most devastating disease in rice,and it seriously threatens the safety of rice production.Improving the ability of integrated prevention and control of rice blast has always been an important part of ensuring food production safety.In the past decade,scientists have made great progress in the prevention and control techniques of rice blast,which paves the way for the green controlling of rice diseases.In this article,the advances in the intelligentization of rice blast field monitoring techniques,the optimization of prediction and forecast modeling system,the research and development of low-toxic and high-efficiency chemical pesticides,biogenic pesticides and inducers and the regulation of multiple ecological factors including variety and cultivation are reviewed,and the new strategies for green controlling of rice blast based on these techniques are summarized.Further,the problems such as high pesticide prices and pesticide residue faced by rice blast prevention and control and the challenge of slow research and development of low-toxic and economical biogenic pesticides are discussed.Finally,the development direction of green controlling of rice blast based on molecular targets,small interfering RNA(siRNA)and CRISPR/Cas9 technologies is predicted,with a view to guaranteeing the safety of rice production.展开更多
文摘Rice blast caused by <em>Magnaporthe oryzae</em> (<em>M. oryzae</em>) is one of the most destructive diseases, which causes significant rice yield losses and affects global food security. To better understand genetic variations among different isolates of <em>M. oryzae</em> in the nature field, we re-sequenced and analyzed the genomes of three field isolates, QJ08-2006, QJ10-10, and QJ10-3001, which showed distinct pathogenicity on Xin-Yin-Zhan, an elite variety in South China. Genome annotation indicated that these three isolates assemblies have similar genome sizes with 38.4 Mb, 38.3 Mb, and 38.4 Mb, respectively. The QJ08-2006 assembly has 2082 contigs with an N50 of 127.4 kb, the QJ10-10 assembly has 2239 contigs with an N50 of 105.13 kb, the QJ10-3001 assembly has 2025 contigs with an N50 of 133.16 kb. A total of 10,432 genes including 1408 putative secreted protein genes were identified from the annotated isolate QJ08-2006 genome, 10,418 genes including 1410 putative secreted protein genes were identified in QJ10-10, and 10,401 genes including 1420 putative secreted protein genes were identified in QJ10-3001. There are as many as 11,076 identical genes in these three isolates and contained only a few unique genes among three isolates, of which 277 unique genes in QJ08-2006 and 264 unique genes in QJ10-10, and 213 unique genes in QJ10-3001. Most of the predicted secreted protein genes had been identified, and the three re-sequenced strains contained 371, 369, and 387 small Indel, respectively. <em>Avr </em>genes were analyzed in several sequenced <em>Magnaporthe</em> strains, the results revealed that <em>Avr-Pi9</em> and <em>Avr-Piz-t </em>were present in all the sequenced isolates. The isolates QJ08-2006 contained <em>AvrPib</em>, QJ10-10, and QJ10-3001 had an insertion of a Pot3 element in the promoter of the <em>AvrPib</em> gene. Our results showed that, the rapid dominancy of virulence mutant isolates via clonal propagation displayed in the field after the release of the elite variety Xin-Yin-Zhan.
文摘Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.
文摘The fungus U. virens is the causal agent of rice false smut disease. The green fluorescent protein (GFP) was used to mark this fungus in order to visualize and analyze the colonization and infection processes in vivo. Using epifluorescence microscopy colonization and infection on rice roots were visualized in vivo. After inoculation for 2 to 15 d, it was observed that the conidia and their germ-tubes had penetrated into epidermis of young roots. The hyphae were found inside the root xylem 18 d after inoculation. Generally, the transformed fungus colonized the rhizosphere, the cortex as well as the vascular tissues with symptoms of root necrosis observed. The results of this work show that U. virens colonize not only rice panicles but also the roots.
基金Supported by Special Fund of Agro-scientific Research in Public Interest(201303015)Earmarked Fund for China Agriculture Research System(CARS-01-24)Natural Science Foundation of China(31272010)
文摘Pathogenic isolates were collected from different rice-cropping regions in southern China to dissect the pathogenic disintegration and variation of Xanthornonas oryzae pv. oryzae （Xoo）. Two sets of rice-Xoo differential hosts, including Chinese system with such five euhivars as IR26, Java14, Nangeng15, Tetep and Jingang 30 and international system with a series of nearisogenic lines （NILs） including IRBB5, IRBB13, IRBB3, IRBB14, IRBB2 and IR24 carrying different known resistance genes,were used to detect pathogenic disintegration for the reaction between host and pathogen with leaf-clippingmethod at the rice booting stage. The results showed the type of the pathogen were divided intosix pathotypes, i.e. , Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅸ based on the Chinese differential system, and seven pathogenicraces including RI, R2, R3, R4, R5, R8 and R10 based on the international differential system. The pathogenicity frequency of Xoo pathotypes V and IV and pathogenic races R8 and R5 were 27.40% , 19.30% and 44.67% , 15.34%, which were considered to be the prevailing races in southern China. Pathogenic rates of pathotypes Ⅳ, Ⅴ, Ⅸ and races R8, R5 against 500 varieties derived from southernChina were 96.40% , 95.00% , 50.40% , 62.00% , and 42.60%, respectively. Among which pathotype Ⅸ was the most virulent pathotype. The pathotype Ⅴ became preponderant pathotype and the new pathotype Ⅸ grew up quickly.
基金National Key R&D Program of China(2017YFD0100100)Natural Science Foundation of Guangdong Province(2018B030311035)+2 种基金Project of Guangzhou Science Plan(No.202002030001)Rice Industry System(CARS-01-322019KJ105)。
文摘Specific molecular markers for detecting the alleles of Pi2/Pi9/Piz-t,designated as Pi2 SNP,Pi9 SNP and Pizt-PA,respectively,have been successfully developed through sequence comparison method.These three specific markers can distinctly distinguish target genes from others mapped on Pi2/9 locus,which facilitates the molecular marker-assistant selection and the development of pyramiding cultivars combined with other allele R genes.Additionally,101 main cultivars and breeding parents collected from different rice-planting areas have been diagnosed with these three specific markers,and the results showed that only 2 out of the 101 cultivars carried Piz-t,but neither Pi2 nor Pi9 band had been detected.It indicates that most of the main cultivars and breeding parents in China do not carry Pi2/Pi9/Piz-t.These results provide important information for the application of Pi2/Pi9/Piz-t in the blast resistance breeding programs.
基金Supported by Science and Technology Plan Project of Shaoguan(210804164531395)Special Fund for Modern Agricultural Industry Technology System(CARS-01-32,2022KJ105)"14thFive-Year Plan"New Discipline Team Building Project of Guangdong Academy of Agricultural Sciences(202116TD)。
文摘[Objectives]This study was conducted to screen out rice resources resistant to rice blast(Magnaporthe oryzae).[Methods]The qualitative and quantitative resistance of 1659 rice resources from 45 countries and regions to rice blast were evaluated by disease nursery in upland condition and the test of the spectrum to rice blast isolates.[Results]There were 292 entries which accounted for 17.6%showed high blast resistance(0 and 1 disease scale),68 entries(counted for 4.1%)showed resistance to blast(3 disease scale);and the number of the entries showed intermediate resistance,intermediate susceptible and susceptible were 208(with the corresponding percentage of 12.5%),471(28.4%),620(37.4%)respectively.Among the tested entries,27 entries including BG1222,BL122,BTX,IR37704-131-2-3-2,and LEBONNET had showed broad-spectrum blast resistance with the resistance frequency of higher than 90%,Quantitative resistance evaluation was conducted on some key resources,and 14 entries,of which are BR27,DRAGO,IR100,QINLIUAI、SERIBU GANTANG,YUEXIANGZHAN and so on,showed good quantitative resistances,and 8 entries had higher quantitative resistances than IR36.[Conclusions]This study provides important blast resistance resources for the local rice breeding program and has a significant value for the discovery of new blast resistance genes and its application in the blast resistance breeding.
基金Agricultural Science and Technology Development and Resource and Environmental Protection Management Fund of Guangdong Provincial Rural Revitalization Strategy Project(2022KJ153-06)Special Fund for China Agricultural Industry Research System(CARS-01-32,2022KJ105)+1 种基金"The 14 th Five-Year Plan"New Discipline Team Building Project of Guangdong Academy of Agricultural Sciences(202116TD)Science and Technology Plan Project of Shaoguan(210804164531395).
文摘[Objectives]The paper was to identify the characteristics and the potency of new fungicides to rice blast disease,and study their preventive and therapeutic effects on the disease.[Methods]Six new and conventional fungicides with different mechanisms of action were selected to compare their preventive and therapeutic effects on rice seedling blast in greenhouse.[Results]The agents which showed to be highly efficacious in blast prevention(greater than 90%)were 25%pyraclostrobin EC,20%fenoxanil SC,75%tricyclazole WP and 50%prochloraz-manganese WP sprayed at the dosages of 112.5-150,180-360,270-450 and 450-600 g/ha,respectively.The therapeutic effect of new fungicides 25%pyraclostrobin EC and 50%prochloraz-manganese WP on rice blast were above 90%when the dosages were 90-150 and 360-600 g/ha,respectively.The therapeutic effect of the conventional fungicide 40%isoprothiolane EC on rice blast was 69.04%when the dosage was 480 g/ha,while those of other fungicides were worse.[Conclusions]Both 25%pyraclostrobin EC and 50%prochloraz-manganese WP have good preventive and therapeutic effects on rice blast,which will provide a reference for the use of these fungicides in the field.
基金Key R&D Project of Guangdong(2019B020217003)Science and Technology Plan Project of Guangzhou(202002030001)+2 种基金Fund for Modern Agro-Industry Technology Research System(CARS-01-32,2020KJ105)Natural Science Foundation of Guangdong(2020A1515011213)New Discipline Team Building Project of Guangdong Academy of Agricultural Sciences(202116TD).
文摘Rice blast is the most devastating disease in rice,and it seriously threatens the safety of rice production.Improving the ability of integrated prevention and control of rice blast has always been an important part of ensuring food production safety.In the past decade,scientists have made great progress in the prevention and control techniques of rice blast,which paves the way for the green controlling of rice diseases.In this article,the advances in the intelligentization of rice blast field monitoring techniques,the optimization of prediction and forecast modeling system,the research and development of low-toxic and high-efficiency chemical pesticides,biogenic pesticides and inducers and the regulation of multiple ecological factors including variety and cultivation are reviewed,and the new strategies for green controlling of rice blast based on these techniques are summarized.Further,the problems such as high pesticide prices and pesticide residue faced by rice blast prevention and control and the challenge of slow research and development of low-toxic and economical biogenic pesticides are discussed.Finally,the development direction of green controlling of rice blast based on molecular targets,small interfering RNA(siRNA)and CRISPR/Cas9 technologies is predicted,with a view to guaranteeing the safety of rice production.
