Trichoderma Biocontrol of Colletotrichum acutatum and Botrytis cinerea and Survival in Strawberry

Trichoderma isolates are known for their ability to control plant pathogens. It has been shown that various isolates of Trichoderma, including T. harzianum isolate T-39 from the commercial biological control product TRICHODEX, were effective in controlling anthracnose (Colletotrichum acutatum) and grey mould (Botrytis cinerea) in strawberry, under controlled and greenhouse conditions. Three selected Trichoderma strains, namely T-39, T-161 and T-166, were evaluated in large-scale experiments using different timing application and dosage rates for reduction of strawberry anthracnose and grey mould. All possible combinations of single, double or triple mixtures of Trichoderma strains, applied at 0.4% and 0.8% concentrations, and at 7 or 10 day intervals, resulted in reduction of anthracnose severity; the higher concentration (0.8%) was superior in control whether used with single isolates or as a result of combined application of two isolates, each at 0.4%. Only a few treatments resulted in significant control of grey mould. Isolates T-39 applied at 0.4% at 2 day intervals, T-166 at 0.4%, or T-161 combined with T-39 at 0.4% were as effective as the chemical fungicide fenhexamide. The survival dynamics of populations of the Trichoderma isolates (T-39, T-105, T-161 and T-166) applied separately was determined by dilution plating and isolates in the mixtures calculated according to the polymerase chain reaction (PCR) using repeat motif primers. The biocontrol isolates were identified to the respective species T. harzianum (T-39), T. hamatum (T-105), T. atroviride (T-161) and T. longibrachiatum (T-166), according to internal transcribed spacer sequence analysis.     

Bacterial community analysis of purulent material from liver abscesses of crossbred cattle and Holstein steers fed finishing diets with or without tylosin

Liver abscesses in feedlot cattle are polymicrobial infections. Culture-based studies have identified Fusobacterium necrophorum as the primary causative agent, but a number of other bacterial species are frequently isolated. The incidence of liver abscesses is highly variable and is affected by a number of factors, including cattle type. Holstein steers raised for beef production have a higher incidence than crossbred feedlot cattle. Tylosin is the commonly used antimicrobial feed additive to reduce the incidence of liver abscesses. The objective of this study was to utilize 16S ribosomal RNA amplicon sequence analyses to analyze the bacterial community composition of purulent material of liver abscesses of crossbred cattle (n = 24) and Holstein steers (n = 24), each fed finishing diet with or without tylosin. DNA was extracted and the V3 and V4 regions of the 16S rRNA gene were amplified, sequenced, and analyzed. The minimum, mean, and maximum sequence reads per sample were 996, 177,070, and 877,770, respectively, across all the liver abscess samples. Sequence analyses identified 5 phyla, 14 families, 98 genera, and 102 amplicon sequence variants (ASV) in the 4 treatment groups. The dominant phyla identified were Fusobacteria (52% of total reads) and Proteobacteria (33%). Of the top 25 genera identified, 17 genera were Gram negative and 8 were Gram positive. The top 3 genera, which accounted for 75% of the total reads, in the order of abundance, were Fusobacterium, Pseudomonas, and Bacteroides. The relative abundance, expressed as percent of total reads, of phyla, family, and genera did not differ (P > 0.05) between the 4 treatment groups. Generic richness and evenness, determined by Shannon–Weiner and Simpson’s diversity indices, respectively, did not differ between the groups. The UniFrac distance matrices data revealed no clustering of the ASV indicating variance between the samples within each treatment group. Co-occurrence network analysis at the genus level indicated a strong association of Fusobacterium with 15 other genera, and not all of them have been previously isolated from liver abscesses. In conclusion, the culture-independent method identified the bacterial composition of liver abscesses as predominantly Gram negative and Fusobacterium as the dominant genus, followed by Pseudomonas. The bacterial community composition did not differ between crossbred and Holstein steers fed finishing diets with or without tylosin.     

不同处理对蛭石栽培的微型薯疮痂病防控效果及其微生态效应分析

通过田间小区试验评价了6个不同处理对蛭石栽培的微型马铃薯疮痂病的防效,并采用16S核糖体基因高通量测序技术研究了蛭石中细菌群落结构的变化.试验结果显示,棉隆+青霉菌34107处理对疮痂病防效最好(93.43％),显著高于对照药剂中生菌素处理(65.10％);而且商品薯的数量和经济效益也最高,分别达到348.3万个/hm...     

基于rDNA ITS序列研究蚌科6种类的系统发生关系

通过测定核糖体转录间隔区ITS1以及ITS2序列研究了江苏地区蚌科(Unionidae)6种常见贝类——褶纹冠蚌(Cristaria plicata)、三角帆蚌(Hyriopsis cumingii)、背角无齿蚌(Anodneta woodiana woodiana)、扭蚌(Arconaialanceolata)、圆顶珠蚌(Unio douglasiae)以及背瘤丽蚌(Lamprotula leai)的系统发生关系。结果显示:6种蚌的ITS1序列长度介于354~439 bp之间,平均G+C百分含量为52.7%;ITS2序列长度介于287~354 bp之间,平均G+C百分含量为51.2%。对6种贝类的相关序列进行比对,ITS1的比对长度包括501个位点,其中有364个变异位点和99个简约信息位点;ITS2的比对长度包括381个位点,其中有259个变异位点和66个简约信息位点。以虾夷扇贝(Mizuhopecten yessoensis)为外群,采用邻接法(NJ)分析6种贝类的系统发生关系,贝类明显聚合为3个类群:类群Ⅰ包括三角帆蚌(H.culingii)和背瘤丽蚌(L.leai),类群Ⅱ包括扭蚌(A.lanceolata)和圆顶珠蚌(U.douglasiae),类群Ⅲ由背角无齿蚌(A.woodiana woodiana)和褶纹冠蚌(C.plicata)组成。     

中华绒螯蟹核糖体DNA全序列分析

核糖体DNA通常被选作系统发育研究的分子标记,核糖体DNA中IGS部分序列的变异在一定程度上影响着生物的生长。报道了中华绒螯蟹核糖体DNA全序列的分离和序列特征。中华绒螯蟹核糖体DNA全长11660bp,包括18S(1873bp),ITS1(317bp),5.8S(163bp),ITS2(614bp),28S(4461bp)和IGS(4240bp);不同部分AT含量在40.1%～48.6%之间,低于果蝇(55.8%～80.0%),高于鲤(22.0%～43.7%)。平均100个核苷酸含简单重复序列(SSR)数由高到低依次为ITS2(0.98%),IGS(0.49%),28S(0.38%),ITS1(0.32%),18S(0.21%),5.8S(0%)。个体内差异分析结果表明,中华绒螯蟹个体内存在两类ITS2序列,其中一类在405nt处有一12bp(CGCAGGACCACC)插入序列。中华绒螯蟹rDNA的IGS部分长4240bp,AT含量为42.6%。IGS部分包含一个有约7个连续136～139bp单元组成的重复序列区,重复序列单元中存在XhoⅠ内切酶位点,为河蟹特有的重复序列;重复序列区后有一个由182个碱基对...     

胨冻样芽孢杆菌(Bacillus mucilaginosus YNUCC0001)絮凝剂生产、絮凝特性及其系统发育学分析

对BacillusmucilaginosusYNUCC000116SrDNA的1481bp片段与GenBank中最相似的16个分类单位进行了比较。UPGMA,NJ,ME和MP方法构建的系统发育树显示B.mucilaginosusYNUCC0001与B.mucilaginosusHSCC1605T、B.mucilaginosus1480D及Paenibacillussp.NBT形成一个单系群分支。在50L全自动发酵罐中30℃发酵52h后,菌株YNUCC0001产生的胞外生物多聚絮凝剂(EBF)达到最大产率(粘度:3420C.P.)。在pH4.0、用量为0.25mlL-1的条件下,这种EBF对高岭土悬浊液的絮凝活性最大(99.8%);121℃高压灭菌60min后絮凝活性维持在98.6%。Hg2+,Ca2+,Mg2+,K+,Zn2+对其絮凝活性有促进作用,而Fe3+、Al3+、EDTA和Cu2+则有强烈抑制。     

江苏省小麦禾谷孢囊线虫群体核糖体DNA-ITS区序列分析

对采集自江苏省徐州、宿迁、连云港和盐城4个地区的15个小麦禾谷孢囊线虫群体进行核糖体DNA-ITS区的RFLP分析。结果表明:测定的所有群体均具有相同的酶切图谱,既具有与国外B型群体(印度群体)相同的AluⅠ和RsaⅠ酶切图谱,同时也具有中国群体独特的HinfⅠ和Tru9Ⅰ酶切图谱(C型)。采用Neighbor-Joining法(MEGA4.0)构建的ITS序列系统进化树显示:所有15个江苏群体均聚在小麦禾谷孢囊线虫组(Heterodera avenae group)下的小麦禾谷孢囊线虫复合种群(H.avenae complex)分支内,且多数江苏群体与草地孢囊线虫(H.pratensis)德国和俄罗斯群体的遗传距离相对较近。通过江苏群体与其他近源群体的ITS序列分析比较,河南郑州群体与澳州孢囊线虫(H.australis)的遗传距离较近,青海群体和河南郑州群体在分子遗传水平上具有明显的地域性,而江苏省和我国其他省份的小麦孢囊线虫群体具有丰富的遗传多样性。     

10株白僵菌菌株形态学与分子鉴定

对10株白僵菌属菌株的菌落形态、产孢结构和分生孢子形状、大小作了观察与测量,形态学鉴定为球孢白僵菌。同时对此10株球孢白僵菌核糖体DNA-ITS进行了测序分析,与NCBI数据库中的球孢白僵菌(Beauveria bassiana)多个菌株的同源性达99.10%～99.64%。依此,10株白僵菌菌株分子鉴定结果为球孢白僵菌(Beauveria bassiana)。     

华南主要树木丛枝菌根真菌物种多样性调查研究

为调查华南地区丛枝菌根（arbuscular mycorrhiza,AM）真菌的物种多样性与资源分布状况,本研究对该区域红花羊蹄甲（Bauhinia blakeana）、黄梁木（Neolamarckia cadamba）、构树（Broussonetia papyrifera）、尾叶桉（Eucalyptus urophylla）和杧果（Mangifera indica）5种主要树木AM真菌侵染状况进行研究,通过形态学特征及核糖体18S rRNA基因序列分析鉴定AM真菌种类。结果表明:1）5种树木均能形成丛枝菌根,红花羊蹄甲和尾叶桉为疆南星型（Arum-type）,杧果、构树和黄梁木为重楼型（Paris-type）。红花羊蹄甲和杧果的菌根侵染率高、孢子密度大,构树、黄梁木和尾叶桉的AM真菌侵染率和孢子密度相对较低。2）鉴定出AM真菌5属8种,分别为无梗囊霉属（Acaulospora）的浅窝无梗囊霉（Acaulospora lacunosa）和刺无梗囊霉（Acaulospora spinosa）,斗管囊霉属（Funneliformis）的摩西斗管囊霉（Funneliformis mosseae）,根孢囊霉属（Rhizophagus）的根内根孢囊霉（Rhizophagus intraradices）,以及球囊霉属（Glomus）的3种Glomus spp.和硬囊霉属（Sclerocystis）1种Sclerocystis sp.。3）球囊霉属的AM真菌广泛分布在红花羊蹄甲、杧果和构树根际,刺无梗囊霉分布在杧果和尾叶桉根际,摩西斗管囊霉为优势种,分布在构树和黄梁木根际;而浅窝无梗囊霉和硬囊霉只分布在1种树根际,表明其宿主专一性相对较强。结果显示华南树木根际土壤中AM真菌物种多样性较高,同时本研究为深入研究该地区林木根际AM真菌功能多样性提供了初步科学依据。     

基于18S rRNA的鸡组织滴虫病PCR诊断方法的建立

河南某鸡场约4周龄鸡疑似发生鸡组织滴虫病.根据鸡组织滴虫18 S rRNA序列设计引物,提取肝脏、盲肠内客物寄生虫DNA,采用PCR方法检测.结果表明,PCR扩增到与预期大小一致的产物,经测序比对,证实为鸡组织滴虫感染.所建立的PCR方法具有灵敏、特异、快速等优点,不仅能用于鸡组织滴虫病临床诊断,还能用于开展流行病学研...