单端孢菌素对几种作物病原菌的室内毒力及田间防效

为明确单端孢菌素对主要作物病原菌的抑菌活性和田间防效,采用孢子萌发抑制测定法、菌丝生长速率法和田间药效常规试验方法,测定了单端孢菌素在不同质量浓度下对作物病原菌的室内毒力及田间药效。结果表明:单端孢菌素对供试16个病原菌的MIC为1.9~15.5mg/L,对辣椒炭疽病菌、番茄早疫病菌、水稻恶苗病菌、水稻稻瘟病菌、番茄灰霉病菌、玉米小斑病菌和马铃薯晚疫病菌等7个病原菌的EC50分别为5.93、7.90、9.27、10.78、13.34、14.95和16.50mg/L,500mg/L质量浓度对番茄灰霉病、番茄早疫病、辣椒炭疽病、马铃薯晚疫病、玉米小斑病和水稻稻瘟病的防治效果分别为78.98%、81.29%、85.28%、72.42%、78.99%和72.74%。单端孢菌素具有较强的抑菌活性和较广的抑菌谱,对几种主要作物真菌和卵菌病害具有较好的田间防治效果,应用前景广。     

产多酚氧化酶茶树内生真菌的筛选及产酶条件优化

以愈创木酚、α-萘酚、没食子酸、L-酪氨酸和单宁酸等5种酚类物质为底物,采用鉴别培养基筛选法从14株茶树内生真菌中初筛获得4株产多酚氧化酶的真菌。根据变色圈的大小、颜色深浅和摇瓶发酵的结果复筛获得产多酚氧化酶能力较强的菌株CSN-13。对菌株CSN-13产酶营养条件进行初步分析,结果表明,在供试的6种碳源物质中,以麸皮对菌株CSN-13产多酚氧化酶的促进作用最为明显;供试的5种氮源物质中,以硝酸铵的促进作用最为明显;在发酵培养基中添加茶水,对产酶有明显的促进作用。采用正交设计对CSN-13产酶发酵培养基进行初步优化,优化后的培养基配方为：麸皮（40βg·L^-1）、硝酸铵（15βg·L^-1）、茶水（4βg·L^-1）、KH₂PO₄（2βg·L^-1）、MgSO₄·7H₂O（0.5βg·L^-1）、无水CaCl₂（0.075βg·L^-1）、CuSO₄·5H₂O（0.01βg·L^-1）。采用优化后的培养基,菌株CSN-13在28℃下培养5βd,酶活力达到241βU·mL^-1·min^-1,比优化前提高8.5倍。茶树内生真菌菌株CSN-13及其发酵产酶培养基的研究为多酚氧化酶的进一步开发打下了基础。     

石斛内生细菌DEB-2对5种辣椒病原真菌的抑制作用

为了探明石斛内生细菌DEB-2菌株对贵州辣椒病原真菌的抑制作用,采用生长速率法测定了菌株DEB-2发酵液对辣椒黑斑病病原菌Alternaria alternate、辣椒疫病病原菌Phytophthora capsici、辣椒黑点炭疽病病原菌Colletotrichum capsici、辣椒红色炭疽病病原菌Colletotrichum gloesporioide和辣椒早疫病病原菌Alternaria solani的毒力。结果显示,内生菌DEB-2菌株能显著抑制5种辣椒病原真菌菌丝生长和孢子萌发,菌丝尖端均有不同程度变粗、膨大、崩解或者菌丝分枝增多的现象;分生孢子及芽管产生畸形。DEB-2菌株发酵液对5种病原菌菌丝生长的抑制中浓度EC₅₀值分别是28.5、76.2、80.7、79.9、72.0 μL/mL;对辣椒疫病病原菌和早疫病病原菌分生孢子萌发的EC₅₀分别为73.5 μL/mL和68.7 μL/mL。研究表明,DEB-2菌株能有效地同时抑制5种辣椒病原真菌菌丝生长和孢子萌发,对该5种辣椒真菌病原菌具有一定的生防潜力,可作为生防菌进行开发和应用。     

First report of ophidiomycosis in Asia caused by Ophidiomyces ophiodiicola in captive snakes in Japan

Ophidiomycosis is an emerging infectious disease caused by the fungus Ophidiomyces ophiodiicola, which has been affecting wild and captive snakes in North America, Europe, and Australia. We report 12 cases of suspected ophidiomycosis in captive colubrid snakes in Japan. Pathological and microbiological examinations were performed, and the results confirmed the diagnosis of ophidiomycosis in two snakes, which indicated that the remaining sympatrically raised snakes also had ophidiomycosis since they exhibited similar lesions. This is the first report of ophidiomycosis in Asia caused by O. ophiodiicola. To prevent the expansion of ophidiomycosis in the natural environment in Japan, there is a need to evaluate the ophidiomycosis carrier status of imported snakes, the pathogenicity of the infection in native snakes, and the prevalence and distribution of O. ophiodiicola in wild and captive snakes. Measures also must be taken to prevent endemicity globally.     

Relative abundance and activity of melanized hyphae in different soil ecosystems

Here we report on the frequency of melanized fungal hyphae in 323 soils, covering different land use types. The proportion of total hyphae that was melanized averaged 61%. Arable fields with loamy sand, heathlands and city parks on sandy soils had the highest percentage of melanized hyphae. In addition to the frequency determinations, a microcosm study was performed on the role of melanized hyphae in two different ecosystems: an ex-arable field and a forest. Melanized hyphae appeared to be part of the active hyphae in the forest soil but not in the ex-arable soil. In conclusion, our results indicate that (1) melanized hyphae represent a large proportion of the total fungal biomass in soils and that (2) their function might differ between ecosystems.     

In vitro susceptibility patterns of Aspergillus and Fusarium species isolated from equine ulcerative keratomycosis cases in the midwestern and southern United States with inclusion of the new antifungal agent voriconazole

Objective  To evaluate and compare the in vitro susceptibility of Aspergillus and Fusarium spp. isolated from horses with ulcerative keratomycosis, address regional differences in equine keratomycosis isolates, and provide susceptibility data to update prior studies.
Animal studied  Fourteen horses with ulcerative keratomycosis.
Procedures  Banked fungal isolates from equine corneal ulcers (eight Aspergillus spp. and six Fusarium spp.) were identified at The University of Texas Health Science Center at San Antonio. In vitro minimum inhibitory concentration and susceptibility to natamycin, fluconazole, itraconazole, voriconazole, ketoconazole, and miconazole were determined for each isolate.
Results  Fungi were significantly more susceptible to voriconazole than to natamycin, itraconazole, fluconazole, and ketoconazole, but miconazole susceptibility did not differ significantly from voriconazole. Aspergillus spp. were most susceptible to voriconazole, miconazole, and itraconazole, which were significantly better to fluconazole and ketoconazole. Fusarium spp. susceptibility was greatest to natamycin and voriconazole and lowest to itraconazole and ketoconazole. Fusarium spp. were significantly less susceptible to itraconazole and ketoconazole compared to natamycin. No significant differences in susceptibility were found when isolates from Florida were compared with isolates from other states.
Conclusions and clinical relevance  Based on in vitro evidence, voriconazole appears to be the most effective antifungal for initial treatment of equine keratomycosis in the midwestern and southern United States. Results are comparable with previous studies in that isolated fungi from equine keratomycosis cases showed consistently poor susceptibility to fluconazole. Organisms isolated in different geographic locations of the midwestern and southern United States appeared to have similar patterns of antifungal susceptibility.     

ISSR标记技术在植物病原真菌研究中的应用

本文对ISSR在植物病原真菌研究中的应用现状进行综述。在植物病原真菌研究中,ISSR主要应用在遗传多样性研究,种间及种内关系及病菌检测,种群遗传分化以及在抗病基因标记及定位中的应用等方面。ISSR技术具操作简单、重复性、多态性丰富和耗资少等优点,并且能鉴定到病原真菌小种,这将使其在新物种鉴定、病菌检测、遗传分化等研究中发挥积极作用,也会被越来越多地应用在更多领域中。     

无机铜试剂对棉花苯丙氨酸解氨酶活性的影响

利用无机铜试剂（CIE）在新陆早17和新陆中26两棉花品种的3叶期和蕾期进行叶面喷施,检测棉株叶片内的苯丙氨酸解氨酶（PAL）的活性变化。结果表明,两品种在3叶期和蕾期均表现为PAL活性显著增高,第2天后即开始产生对PAL活性诱导作用,第10天后PAL的活性开始回落至对照组水平;两品种蕾期PAL的诱导活性均明显高于3叶期,且PAL高活性水平持续天数较3叶期长;棉花不同生育期使用CIE,均可增强棉叶PAL的活性;两品种在不同生育期的PAL活性出现峰值的时间、强度不一,显示出品种抗性的差异性。试验表明,CIE可诱导增强棉叶中PAL的活性。     

微生物蛋白激发子PeaT1的获得及诱导水稻抗旱性的初步研究

PeaT1是来源于极细链格胞菌（Alternaria tenuissima）的一种蛋白激发子,具有促进植物生长和提高抗逆性的功能。为了进一步研究该激发子的功能,构建了表达该蛋白质的原核表达载体pET28a-peaT1,诱导表达获得大量目的蛋白质。利用AKTA蛋白质纯化系统,通过亲和层析、离子交换层析和分子筛等纯化技术,获得高纯度的PeaT1蛋白。用不同浓度的纯化蛋白处理水稻,进行抗旱性检测,结果表明PeaT1可明显提高水稻的抗旱性。     

贵州花江峡谷木豆主要真菌病害调查

为了解真菌病害在木豆上的发生情况,采用实地调查、随机抽样调查并结合访问调查方法对贵州花江峡谷地区木豆主要真菌病害进行了研究.结果表明.木豆白粉病(Oidium sp.)、木豆褐斑病(Alternaria sp.)、木豆灰霉病(Botrytissp.)、木豆斑点病(Phyllosticta sp.)和木豆根腐病(Fusarium oxysporum)是木豆上发生的主要真菌病害,并对5种病害的发病症状和病原进行了描述.