Covered smut, which is caused by Ustilago hordei（Pers.） Lagerh., is one of the most damaging diseases of highland barley（Hordeum vulgare Linn. var. nudum Hook. f） in Tibetan areas of China. To understand the molec...Covered smut, which is caused by Ustilago hordei（Pers.） Lagerh., is one of the most damaging diseases of highland barley（Hordeum vulgare Linn. var. nudum Hook. f） in Tibetan areas of China. To understand the molecular diversity of U. hordei, a total of 27 isolates, which were collected from highland barley plants from Tibet, Sichuan, Qinghai, and Gansu provinces/autonomous region, were analyzed using random amplified polymorphic DNA（RAPD） and simple sequence repeat（SSR） markers. Among the 100 RAPD primers used, 24 primers exhibited polymorphism. A total of 111 fragments were amplified, of which 103 were polymorphic with a polymorphic rate of 92.79%. The average observed number of alleles（Na）, effective number of alleles（Ne）, Nei＇s genetic diversity（H）, Shannon＇s information index（I） and polymorphism information content（PIC） value in the RAPD markers were 1.9279, 1.5016, 0.2974, 0.4503 and 0.6428, respectively. For the SSR markers, 40 of the 111 primer pairs exhibited polymorphism and provided a total of 119 bands, of which 109 were polymorphic and accounted for 91.60% of the total bands. The Na, Ne, H, I and PIC values of the SSR markers were 1.9160, 1.4639, 0.2757, 0.4211 and 0.4340, respectively. The similarity coefficients ranged from 0.4957 to 0.9261 with an average of 0.7028 among all the 27 isolates used. The dendrogram, which was developed based on the RAPD and SSR combined marker dataset showed that the 27 U. hordei isolates were divided into 3 clusters at similarity coefficient of 0.7314. We determined that RAPD and SSR markers can be successfully used to assess the genetic variation among U. hordei isolates. The RAPD markers revealed higher levels of genetic polymorphism than did the SSR markers in this study. There existed a moderate genetic difference among isolates. The molecular variation and differentiation was somewhat associated with geographical origin but not for all of the isolates.展开更多
The Central region of Kenya which is the second largest market oriented dairy zone, faces a threat in milk production. The challenge is a disease known as the napier head smut caused by Ustilago kamerunensis. This fun...The Central region of Kenya which is the second largest market oriented dairy zone, faces a threat in milk production. The challenge is a disease known as the napier head smut caused by Ustilago kamerunensis. This fungal microorganism is a facultative pathogen which has been reported to cause yield losses in napier grass (Pennisetum purpureum) ranging from 25% to 46% across the affected areas. Additionally, there are reports of the continual spread of the disease into neighbouring county of Nakuru in Rift-Valley region which is the leading milk producing zone in the country. This scenario of spread is worrying combined with observation of variations in damage levels of napier grass clones across the five counties of Central Kenya. These observations led to the hypothesis that possible differences might be existing among the Ustilago kamerunensis variants in Kenya. Further, the differences in biomass yield losses that are within a certain percentage range mentioned-above, seemed to support the existence of possible differences. Therefore, to inform effective integrated management strategies of the pathogen in case it’s co-evolving, this study sought to determine the molecular differences of Ustilago kamerunensis isolates in affected counties using ITS 1 and 2 regions which are spanned by 5.8S ribosomal RNA gene. The Ustilago kamerunensis propagules were systematically collected from affected counties’ hot spot areas for sequencing and phylogenetic analysis. The study revealed the most affected areas to be within the mean altitude level of 1988.17 ± 71.97 metres above sea level. Further, differences in the growth in vitro and molecular characteristics of the seemingly altitude restricted isolates were observed. The Kiambu, Nyandarau and Nakuru counties isolates clustered together, whereas those of Murang’a, Nyeri and Kirinyaga formed another clade. The sequences of sixteen Ustilago kamerunensis isolates were deposited in GenBank with accession numbers ranging from MG722754 to MG722769. The results suggest the existence of possible genetic divergence of the isolates which might be reflected in their pathogenic potential too. Effective integration of management strategies is vital towards slowing the phenomenon for an optimal mitigation of the disease in Kenya.展开更多
The smut Ustilago esculenta is an endophytic fungus that invades Zizania latifolia(Jiaobai)and plays an important role in inducing the host stem to form a swollen gall.The aims of this study were to investigate isolat...The smut Ustilago esculenta is an endophytic fungus that invades Zizania latifolia(Jiaobai)and plays an important role in inducing the host stem to form a swollen gall.The aims of this study were to investigate isolation,identification and inoculation methods of U.esculenta from Jiaobai.The spore suspension culturing method was the best method of isolating U.esculenta,and yeast-like fungal strains and septate hyphal strains were obtained.The universal primers ITS1 and ITS4 amplified a ribosomal DNA spacer element from all tested strains,while specific primers for Lam16A gene generated a 442 bp product only with septate hyphae strains.De novo transcriptome assembly results showed that the yeast-like fungal strains did not match Ustilago,and genomic analysis suggested the septate hyphae strains were highly similar to known smut fungi.Therefore,the septate hyphae strains were identified as U.esculenta,which indicated that the ITS primers were not species-specific but that Lam16A-specific primers can distinguish U.esculenta accurately and easily.In vitro,U.esculenta grew quickly on PDA medium at 28°C in darkness.Furthermore,an inoculation method was established to produce swollen stems by injecting a spore suspension of U.esculenta at OD600=2.5 into the basal culm internode of male Jiaobai.展开更多
Ustilago maydis is the causal agent of the disease known as corn smut or Huitlacohe;their natural hosts are maize (Zea mays L.) and its putative ancestor teocintle (Zea mays ssp. parviglumis and ssp. mexicana). In M&#...Ustilago maydis is the causal agent of the disease known as corn smut or Huitlacohe;their natural hosts are maize (Zea mays L.) and its putative ancestor teocintle (Zea mays ssp. parviglumis and ssp. mexicana). In México there is an evidence of its use as human food since pre-hispanic times. Huitlacoche is a typical Mexican food with interesting nutritional properties and distinctive flavor. Its use in cuisine is considered as a culinary delicacy in Mexico and several parts of the world and the current consumption is increasing markedly, mainly due to its exclusive flavor different from any other known food. Huitlacoche contains proteins, carbohydrates, fats, minerals and vitamins that contribute to its nutritional value, also it has been reported that it contains proteins with balanced levels of essential amino acids, something which does not occur in corn having a deficiency mostly in lysine. The fungus also contains compounds with antioxidant properties, consequently it can be included in what are now known as nutraceutical foods. Besides its use in the food, this fungus has been used in different kinds of basic investigation, such as DNA recombination, signaling, cell biology, biotrophic plant-pathogen interactions and others. Its characteristics of dimorphism, and the detailed knowledge we have on its pathogenic development, that we describe in detail, make it an ideal subject for the analysis of fungal differentiation, and for the knowledge of the behavior of the highly aggressive plant pathogens that are members of its taxonomic group, the Ustilaginales. In the present communication we make a thorough review of the nutritional characteristics of U. maydis, its life cycle, and the molecular bases of its differentiation, morpohogenesis and pathogenicity.展开更多
基金sponsored by the National Millet Crops Research and Development System, China (CARS-0712.5-A9)the National Key Technology R&D Program of China, (2014BAD07B03)the National Natural Science Foundation of China (313 71529)
文摘Covered smut, which is caused by Ustilago hordei（Pers.） Lagerh., is one of the most damaging diseases of highland barley（Hordeum vulgare Linn. var. nudum Hook. f） in Tibetan areas of China. To understand the molecular diversity of U. hordei, a total of 27 isolates, which were collected from highland barley plants from Tibet, Sichuan, Qinghai, and Gansu provinces/autonomous region, were analyzed using random amplified polymorphic DNA（RAPD） and simple sequence repeat（SSR） markers. Among the 100 RAPD primers used, 24 primers exhibited polymorphism. A total of 111 fragments were amplified, of which 103 were polymorphic with a polymorphic rate of 92.79%. The average observed number of alleles（Na）, effective number of alleles（Ne）, Nei＇s genetic diversity（H）, Shannon＇s information index（I） and polymorphism information content（PIC） value in the RAPD markers were 1.9279, 1.5016, 0.2974, 0.4503 and 0.6428, respectively. For the SSR markers, 40 of the 111 primer pairs exhibited polymorphism and provided a total of 119 bands, of which 109 were polymorphic and accounted for 91.60% of the total bands. The Na, Ne, H, I and PIC values of the SSR markers were 1.9160, 1.4639, 0.2757, 0.4211 and 0.4340, respectively. The similarity coefficients ranged from 0.4957 to 0.9261 with an average of 0.7028 among all the 27 isolates used. The dendrogram, which was developed based on the RAPD and SSR combined marker dataset showed that the 27 U. hordei isolates were divided into 3 clusters at similarity coefficient of 0.7314. We determined that RAPD and SSR markers can be successfully used to assess the genetic variation among U. hordei isolates. The RAPD markers revealed higher levels of genetic polymorphism than did the SSR markers in this study. There existed a moderate genetic difference among isolates. The molecular variation and differentiation was somewhat associated with geographical origin but not for all of the isolates.
文摘The Central region of Kenya which is the second largest market oriented dairy zone, faces a threat in milk production. The challenge is a disease known as the napier head smut caused by Ustilago kamerunensis. This fungal microorganism is a facultative pathogen which has been reported to cause yield losses in napier grass (Pennisetum purpureum) ranging from 25% to 46% across the affected areas. Additionally, there are reports of the continual spread of the disease into neighbouring county of Nakuru in Rift-Valley region which is the leading milk producing zone in the country. This scenario of spread is worrying combined with observation of variations in damage levels of napier grass clones across the five counties of Central Kenya. These observations led to the hypothesis that possible differences might be existing among the Ustilago kamerunensis variants in Kenya. Further, the differences in biomass yield losses that are within a certain percentage range mentioned-above, seemed to support the existence of possible differences. Therefore, to inform effective integrated management strategies of the pathogen in case it’s co-evolving, this study sought to determine the molecular differences of Ustilago kamerunensis isolates in affected counties using ITS 1 and 2 regions which are spanned by 5.8S ribosomal RNA gene. The Ustilago kamerunensis propagules were systematically collected from affected counties’ hot spot areas for sequencing and phylogenetic analysis. The study revealed the most affected areas to be within the mean altitude level of 1988.17 ± 71.97 metres above sea level. Further, differences in the growth in vitro and molecular characteristics of the seemingly altitude restricted isolates were observed. The Kiambu, Nyandarau and Nakuru counties isolates clustered together, whereas those of Murang’a, Nyeri and Kirinyaga formed another clade. The sequences of sixteen Ustilago kamerunensis isolates were deposited in GenBank with accession numbers ranging from MG722754 to MG722769. The results suggest the existence of possible genetic divergence of the isolates which might be reflected in their pathogenic potential too. Effective integration of management strategies is vital towards slowing the phenomenon for an optimal mitigation of the disease in Kenya.
基金This study was financially supported by the 58th batch of the China Postdoctoral Science Foundation,Jiangsu Agricul-ture Science and Technology Innovation Fund(CX(20)3104)Natural Science Fund Project of Colleges in Jiangsu Province(15KJB210006).
文摘The smut Ustilago esculenta is an endophytic fungus that invades Zizania latifolia(Jiaobai)and plays an important role in inducing the host stem to form a swollen gall.The aims of this study were to investigate isolation,identification and inoculation methods of U.esculenta from Jiaobai.The spore suspension culturing method was the best method of isolating U.esculenta,and yeast-like fungal strains and septate hyphal strains were obtained.The universal primers ITS1 and ITS4 amplified a ribosomal DNA spacer element from all tested strains,while specific primers for Lam16A gene generated a 442 bp product only with septate hyphae strains.De novo transcriptome assembly results showed that the yeast-like fungal strains did not match Ustilago,and genomic analysis suggested the septate hyphae strains were highly similar to known smut fungi.Therefore,the septate hyphae strains were identified as U.esculenta,which indicated that the ITS primers were not species-specific but that Lam16A-specific primers can distinguish U.esculenta accurately and easily.In vitro,U.esculenta grew quickly on PDA medium at 28°C in darkness.Furthermore,an inoculation method was established to produce swollen stems by injecting a spore suspension of U.esculenta at OD600=2.5 into the basal culm internode of male Jiaobai.
文摘Ustilago maydis is the causal agent of the disease known as corn smut or Huitlacohe;their natural hosts are maize (Zea mays L.) and its putative ancestor teocintle (Zea mays ssp. parviglumis and ssp. mexicana). In México there is an evidence of its use as human food since pre-hispanic times. Huitlacoche is a typical Mexican food with interesting nutritional properties and distinctive flavor. Its use in cuisine is considered as a culinary delicacy in Mexico and several parts of the world and the current consumption is increasing markedly, mainly due to its exclusive flavor different from any other known food. Huitlacoche contains proteins, carbohydrates, fats, minerals and vitamins that contribute to its nutritional value, also it has been reported that it contains proteins with balanced levels of essential amino acids, something which does not occur in corn having a deficiency mostly in lysine. The fungus also contains compounds with antioxidant properties, consequently it can be included in what are now known as nutraceutical foods. Besides its use in the food, this fungus has been used in different kinds of basic investigation, such as DNA recombination, signaling, cell biology, biotrophic plant-pathogen interactions and others. Its characteristics of dimorphism, and the detailed knowledge we have on its pathogenic development, that we describe in detail, make it an ideal subject for the analysis of fungal differentiation, and for the knowledge of the behavior of the highly aggressive plant pathogens that are members of its taxonomic group, the Ustilaginales. In the present communication we make a thorough review of the nutritional characteristics of U. maydis, its life cycle, and the molecular bases of its differentiation, morpohogenesis and pathogenicity.
