Gene Flow Analysis of Phytophthora porri Reveals a New Species: Phytophthora brassicae Sp. Nov.

Isozyme analysis and sequence analysis of the internal transcribed spacer regions (ITS-1 and ITS-2) and the 5.8S subunit of the ribosomal DNA gene repeat were used to examine whether isolates of Phytophthora porri from Allium and Brassica represent a single homogeneous species. Twenty-six strains of P. porri, 16 strains isolated from the genus Allium, and 10 strains isolated from the genus Brassica, were analyzed using malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH) and lactate dehydrogenase (LDH), represented altogether by four putative loci (Mdh-2, Idh-1, Idh-2, and Ldh-2). Isozyme analysis revealed that strains isolated from Allium contained five private alleles at three isozyme loci (Ldh-2 ⁸³, Ldh-2 ¹⁰⁴, Idh-1 ¹⁰⁸, Idh-1 ¹¹², and Idh-2 ⁹⁸), whereas six different alleles were observed at four isozyme loci (Ldh-2 ⁸⁵, Ldh-2 ¹⁰⁰, Ldh-2 ¹¹⁴, Idh-1 ¹⁰⁰, Idh-2 ¹⁰⁰, and Mdh-2 ¹¹¹) in strains obtained from Brassica. The heterozygosity at the Ldh-2 locus, differing in allele composition, however, between strains from Allium and Brassica, was present in all strains, indicating that it is probably fixed. Sequence analysis of the ITS regions and the 5.8S subunit showed consistent differences between isolates from Allium and isolates from Brassica. Based on isozyme data, ITS sequence analysis and formerly published differences in restriction enzyme patterns of mitochondrial DNA, morphology and pathogenicity, it was concluded that the isolates of P. porri Foister did not represent a homogeneous species. Isolates from Brassica constitute a distinct species which is described here as P. brassicae sp. nov. It was inferred from isozyme patterns, which were in no case intermediate between the two species, that P. porri and P. brassicae do not hybridize and are reproductively isolated by barriers to gene flow.     

七叶树溃疡病病原真菌的分离与鉴别

【目的】分离和鉴别引起七叶树溃疡病的病原菌,为制定合理的防治技术提供依据。【方法】采用组织分离培养、人工接种、形态观察及核糖体转录间隔区序列(ITS-rDNA)分析,对引起七叶树溃疡病的水渍型溃疡病病原菌NW397和干腐型溃疡病病原菌NW3362种真菌进行鉴别与比较。【结果】引起七叶树溃疡病的病原为2种不同的真菌,并表现出不同的危害特征。水渍型溃疡病菌NW397 ITS-rDNA序列与多主葡萄座腔菌(Botryosphaeria dothidea Sacc.)等的序列同源性高达99%;干腐型溃疡病菌NW336ITS-rDNA序列与乌饭树拟茎点菌(Phomopsisvaccinii)等的同源性高达95%以上。【结论】七叶树水渍型溃疡病菌定名为多主葡萄座腔菌(Botryosphaeria do-thidea Sacc.),干腐型溃疡病菌定名为梨干枯拟茎点菌(Phompsis fukushii Tanaka et Mill)。     

两种沙漠微藻的形态学和分子生物学鉴定

文中从古尔班通古特沙漠采集的沙样中,运用96孔板有限稀释法分离出两种形态各异的微藻物种GTD8A1和GTD9C2,形态学初步鉴定分别为绿藻门小球藻目和环藻目。利用GenBank中绿藻门不同科属种类序列的18S核糖体RNA基因保守区和28S核糖体RNA基因保守区分别设计18S rDNA特异性引物和5.8S rDNA-ITS区特异性引物。以自行设计的18S rDNA特异性引物与5.8S rDNA-ITS区特异性引物分别对以上两个物种进行PCR和测序后,经blastn比对,系统发育树及遗传距离分析,结果表明GTD8A1可能与Chlo-rella sp.MBIC10595为同一个物种,GTD9C2可能为Desmodesmus multivariabilis种内的一个变种。     

石榴采后腐烂病病原菌的分子鉴定

按照柯赫氏法则对石榴采后腐烂病病原菌进行了分离, 应用PCR技术对分离菌rDNA的内转录间隔区( ITS区) 基因克隆后测序, 并将所测序列提交到欧洲分子生物学实验室核酸数据库( EuropeanMolecular Biology Laboratory Genbank) , 通过Blast程序将该序列与数据库已有的序列进行分析比较, 发现与葡萄座腔菌(Botryosphaeria dothidea) 的同源性达到了99%以上, 因此认为石榴腐烂的病原菌是葡萄座腔菌。该菌引起的石榴腐烂病害特征与以往报道的石榴干腐病相似。对葡萄座腔菌的部分生物学特性和侵染循环规律进行了描述。     

Morphological and molecular characterization of Phytophthora species associated with root and crown rot of pomegranate in Iran

The purpose of this research was to identify the pathogens causing root and crown rot in major pomegranate-growing areas of Iran. Infected tissue samples were collected from trees with symptoms from 49 pomegranate orchards in four provinces of Iran: Fars, Markazi, Isfahan, and Kohgiluyeh va Boyer-Ahmad. In total, 23 Phytophthora spp. isolates were obtained, which were identified as P. cryptogea species complex (12 isolates) and P. cinnamomi (11 isolates) based on morphological characters. Molecular confirmation of identification was performed by inference of phylogeny of ITS-rDNA regions, β-tubulin gene, and the mitochondrial gene cytochrome c oxidase subunit 1. The results of our phylogenetic analysis confirmed the morphological identification of P. cinnamomi isolates and placed them in Clade 7c of Phytophthora. In addition, the P. cryptogea species complex isolates, despite morphological similarities, were in fact four distinct species including P. cryptogea sensu stricto (two isolates), P. pseudocryptogea (one isolate), P. sp. kelmania (one isolate), and P. erythroseptica (six isolates). This is the first report of pomegranate root and crown rot caused by P. cinnamomi and P. cryptogea species complex.     

海南粗榧内生真菌多样性分析

以海南五指山自然保护区海南粗榧为研究对象,从423个表面消毒的组织块中,分离获得416个内生真菌菌株。通过形态学观察和ITS-rDNA 序列分析对分离得到的真菌进行鉴定,分别归入12个属,10属为半知菌,2属为子囊菌。结果表明,在海南粗榧不同组织中,刺盘孢属（Colletotrichum）、拟茎点霉（Phomopsis）均为优势类群,其中,刺盘孢属在叶中最多,拟茎点霉属在树干皮、根皮中最多。此外,镰孢霉属（Fusarium）为树干皮的优势类群,球二孢属（Lasiodiplodia）为根皮的优势类群,双胞束梗霉属（Didymostilbe）为叶的优势类群;Shannon-Wiener多样性指数（H忆）为0.97~1.83,不同组织之间的相似性系数（CS）为0.63~1.00曰分离得到的菌株中,WZS7165、WZS7240及WZS7277与已报道基因序列的相似性分别只有97%、92豫、88豫,具有进一步研究的价值,以确定其是否为微生物新种资源。     

杨树溃疡病、苹果轮纹病等病原菌的ITS-rDNA-RFLP解析

该文从ITS-rDNA—PCR—RFLP方面揭示了杨树溃疡病菌与苹果干腐病菌、轮纹病菌、流胶病菌之间的划分分子依据，干腐病菌和轮纹病菌形成特征性带谱，干腐病菌和轮纹病菌均具有120bp的特征性谱带，且轮纹病菌具有210bp的特征性谱带；流胶病菌具有210bp的特征性谱带而无100bp的特征性谱带，杨树溃疡病菌既无120bp，也无210bp的特征性带谱。     

瑞典常春藤漆斑病病原鉴定

 通过病原菌的形态特征、培养性状和致病性测定的方法对引起瑞典常春藤漆斑病的病原菌进行了分离鉴定, 采用PCR技术扩增病菌rDNA2ITS基因, 获得一长度为523 bp的DNA片段, 序列测定结果表明该片段序列与GenBank已有的露湿漆斑菌序列的同源性达到了99%。综合两种方法鉴定结果, 露湿漆斑菌是引起瑞典常春藤漆斑病的致病菌, 露湿漆斑菌为该寄主上的真菌新病害。     

Host range and phytotoxicity of <Emphasis Type="Italic">Stemphylium solani</Emphasis>, causing leaf blight of garlic (<Emphasis Type="Italic">Allium sativum</Emphasis>) in China

Since 2004, a new leaf blight disease on garlic of high severity has been observed in Dangyang County, Hubei province, China. Initial symptoms consisted of multiple, small, irregular to oval, white leaf spots, which enlarge to produce sunken purple lesions, sometimes surrounded by a bright yellow margin. As the disease progressed, lesions expanded and merged, resulting in withering of leaf tips. After isolation and pathogenicity testing, the causal agent of leaf blight of garlic was identified as Stemphylium solani from cultural and morphological characteristics, and subsequent analysis of the internal transcribed spacer region of ribosomal DNA. When fungal plugs of two S. solani isolates were inoculated onto 11 garlic cultivars and 20 other crop species, leaf spots appeared on all inoculated plants, but two garlic cultivars (Qingganruanye and Ruanruanye) and three crop species (Capsicum annuum, Brassica napus and Amaranthus mangostanus) showed the smallest leaf spots. In cross-inoculation experiments, no indications of host specificity were observed, but S. solani isolated from garlic was generally the most virulent on five plant species, while the isolate from leek (Allium odorum) was generally the least virulent. Toxicity testing of the crude culture filtrates indicated that garlic isolates produced toxin(s) that were not heat-labile and induced different levels of phytotoxicity toward various garlic cultivars and crops.     

苹果汁中棒曲霉素主要产生菌的ITS序列分析鉴定

从浓缩苹果汁生产原料中分离出多种棒曲霉素产生菌,形态学初步鉴定表明其均为青霉属和曲霉属真菌。为确定其分类地位,又用ITS-DNA测序鉴定进行了验证。将ITS-rDNA提取后进行PCR扩增,测序后提交到EuropeanMolecularBiologyLaboratory(EMBL)核酸数据库,通过Blast程序,将ITS-rDNA序列与Genebank中的核酸序列进行对照,结果确定其确为青霉属与曲霉属菌株。