水稻新病害——水稻褐变穗

依据柯赫氏法则，对水稻的一种新病害-水稻褐变穗进行分离培养及病原菌鉴定；按照Ainsworth分类系统进行鉴定，确定分离得到的菌种是链格孢（Altemaria altentaat（Fr．）Keissl），通过回接证明了水稻褐变穗确实是由链格孢引起的。其水稻褐变穗的症状是水稻出穗后不久遇强风易发生，粒上出现褐色斑点，严重时变浓褐或黑褐色，病斑不规则形，但水稻叶鞘几乎没有褐变。     

蓖麻种芽腐烂病害的病原鉴定

为明确引起蓖麻种芽腐烂病害的病原菌种类,本研究采用常规组织分离法分离获得病原菌,根据柯赫氏法则对病原菌进行致病性测定,并结合形态学特征观察和分子生物学技术确定病原菌分类。结果表明,从蓖麻种芽病样组织中分离得到RFR1-4菌株为致病菌。形态学鉴定该菌为茄腐镰孢菌(Fusarium solani)。对致病菌株进行ITS、β-tubulin和TEF-1α基因分析,结果显示与Fusarium-ID数据库中的茄腐镰孢复合种(F. solani species complex)有100%的相似性。因此结合形态学鉴定结果,确定引起蓖麻种芽腐烂病害的病原菌为茄腐镰孢复合种。该病原鉴定对蓖麻种芽腐烂病害的防控有重要的指导作用。     

三种热作细菌性病害的病原菌鉴定

分别对叶子花、咖啡和蝴Ｂａ兰３种热带作物细菌性病害进行症状描述，并测定其病原菌的致病性、细菌学性状，寄主范围以及血清学反应。其病原菌分别鉴定为须芒草假单细胞、丁香假单胞菌咖啡致病变种和菊疫欧氏菌。     

海南桑树青枯病病原菌鉴定及其分子鉴定

桑树青枯病是由青枯雷尔氏菌引起的细菌性病害,热带、亚热带地区发病严重,严重影响蚕桑产业的可持续发展。雷尔氏菌不同种间致病力和宿主各不相同,其防治策略也相应不同,准确地分离鉴定病原菌是青枯病有效防控的先决条件。本研究采集、分离了海南省琼中县桑青枯病发病桑园（‘桂桑优62’）桑树根部、茎部病原菌,并通过致病性、生理小种、生化变种测定,结合16S rDNA、特异性引物、复合PCR检测体系、序列变种等分子鉴定方法初步确定了病原菌的种类和分类地位。结果表明,引发海南省琼中县桑青枯病的病原菌属于青枯雷尔氏菌（Ralstonia solanacearum）、生理小种5（race 5）、生化变种Ⅴ（biovar Ⅴ）,病原菌遗传进化分析结果显示病原菌属演化型Ⅰ（phylotype Ⅰ）即亚洲分支菌株,序列变种12（sequevar 12）。这些结果将为海南桑青枯病的有效防控奠定基础。     

作物青枯病研究进展

综述了作物青枯病病原菌的分类、分子生物学和致病机制;从抗性鉴定、抗病机制和抗性遗传三方面概述了目前作物青枯病抗性研究情况;并介绍了化学防治、生物防治和抗病品种培育三种青枯病防治的主要措施。     

水稻新病害——水稻褐变穗

依据柯赫氏法则,对水稻的一种新病害—水稻褐变穗进行分离培养及病原菌鉴定,按照Ainsworth分类系统进行鉴定,确定分离得到的菌种是链格孢(Alternariaalternata(Fr.)Keissl),通过回接证明了水稻褐变穗确实是由链格孢引起的。其水稻褐变穗的症状是水稻出穗后不久遇强风易发生,粒上出现褐色斑点,严重时变浓褐或黑褐色,病斑不规则形,但水稻叶鞘几乎没有褐变。     

我国大豆根腐病研究概况及存在的问题

对我国大豆根腐病的症状、病原菌种类、主要病原菌的寄主范围、主要病原菌在大豆上的致病力分化、传播途径、消长规律、影响发病的因素、大豆抗根腐病鉴定方法等作了介绍，并提出需要进一步研究的问题。     

玉米丝黑穗病及病菌生理分化研究进展

玉米丝黑穗病是玉米生产上的一种主要病害,从玉米丝黑穗病的发生与危害、病原菌生物学、抗病性鉴定与育种、防治、病原菌生理分化以及植物病原菌生理分化鉴定技术等方面进行了综述。     

狐尾椰子炭疽病病原菌的初步鉴定

通过对狐尾椰子炭疽病症状及其病原菌形态进行观察,按照柯赫氏法则对该病原菌进行分离培养鉴定,初步鉴定结果认为该病原菌为胶孢炭疽菌属（Colletotrichum sp）,并根据发病规律提出防治建议。     

大麦纹枯病病原菌的初步研究

本文报道了大麦纹枯病在江苏省的发生危害情况，症状特点，病原菌形态学和生物学的某些特性，大麦纹秸病的病原菌鉴定表明，以禾谷丝核菌(Rhigoctoniacevel is)的CAG-1菌丝融合群为主。     

小麦-玉米轮作体系中土壤细菌菌群结构及多样性分析

合理的轮作可以改善土壤微生物群落结构,提高土壤肥力,减少病虫害的发生。为了探讨小麦和玉米轮作对土壤细菌的影响,采用传统PCR克隆文库构建、克隆测序并结合EzBioCloud细菌分类鉴定,对河南小麦-玉米轮作体系下农田土壤细菌的菌群结构变化及多样性特征进行了分析。结果表明,变形菌门（33.73%）和拟杆菌门（31.50%）细菌是小麦-玉米轮作体系土壤中最主要的优势菌群,其次为酸杆菌门、芽单胞菌门、放线菌门和疣微菌门等。在小麦和玉米生长期内细菌的丰度和多样性明显高于二者的间隔期;玉米生长期间细菌菌群丰度和物种多样性更高。不同的微生物群落在土壤中担负不同的生态功能。     

1株广谱抗真菌芽孢杆菌TR21的鉴定

利用API50CH鉴定系统、16S rDNA、gyrA和gyrB基因序列分析法,对1株分离自石斛兰叶片的广谱抗真菌芽孢杆菌TR21进行生化和分子鉴定。通过API50CH系统测试,TR21菌株与枯草芽孢杆菌相似性为90.3%,被鉴定为枯草芽孢杆菌。利用16SrDNA序列分析发现TR21菌株与枯草芽孢杆菌(Bacillus subtilis)、B.subtilis subsp.subtilis、B.subtilis subsp.spizizenii和B.velezensis的相应核苷酸序列具有很高的同源性,其序列相似性皆为99%,而基于gyrA和gyrB基因序列构建的系统发育树显示,该菌株与枯草芽孢杆菌的相似性分别为96%和91%。结合16SrDNA、gyrA和gyrB基因序列分析,也确定该菌为枯草芽孢杆菌。比较API鉴定和基于不同基因的鉴定发现,分子鉴定更加快速、灵敏。     

琯溪蜜柚炭疽病拮抗放线菌的筛选和鉴定

为筛选出对琯溪蜜柚炭疽病有防治效果的生防菌,以琯溪蜜柚炭疽病菌（Colletotrichum gloeosporioides）为靶标菌,采用平板对峙法进行初筛,用生长速率法和人工接种法对抑菌效果较好的菌株FX28进行抑菌谱及防治效果测定;通过形态学、生理生化特征,结合16S rDNA序列分析等方法研究其分类地位。结果表明：从25份土样中共分离到放线菌105株,对琯溪蜜柚炭疽病菌有较好拮抗作用的放线菌有16株,其中菌株FX28抑菌活性最高,其抑菌带宽度为15.3 mm,抑制率达86.4%,抑菌谱广,对琯溪蜜柚炭疽病菌、琯溪蜜柚黑点病菌、琯溪蜜柚黑斑病菌等14种供试植物病原菌均有抑制作用;其作用机制表现为菌丝分枝增多、变粗、顶端膨大等,对琯溪蜜柚炭疽病的预防效果和治疗效果分别为83.8%和71.1%。根据形态、生理生化特性及16S rDNA序列分析,初步确定菌株FX28为深红紫链霉菌（Streptomyces violaceorubidus）。     

Actinomycetes from Red Sea Sponges: Sources for Chemical and Phylogenetic Diversity

The diversity of actinomycetes associated with marine sponges collected off Fsar Reef (Saudi Arabia) was investigated in the present study. Forty-seven actinomycetes were cultivated and phylogenetically identified based on 16S rRNA gene sequencing and were assigned to 10 different actinomycete genera. Eight putatively novel species belonging to genera Kocuria, Mycobacterium, Nocardia, and Rhodococcus were identified based on sequence similarity values below 98.2% to other 16S rRNA gene sequences available in the NCBI database. PCR-based screening for biosynthetic genes including type I and type II polyketide synthases (PKS-I, PKS-II) as well as nonribosomal peptide synthetases (NRPS) showed that 20 actinomycete isolates encoded each at least one type of biosynthetic gene. The organic extracts of nine isolates displayed bioactivity against at least one of the test pathogens, which were Gram-positive and Gram-negative bacteria, fungi, human parasites, as well as in a West Nile Virus protease enzymatic assay. These results emphasize that marine sponges are a prolific resource for novel bioactive actinomycetes with potential for drug discovery.     

Marine myxobacteria as a source of antibiotics--comparison of physiology, polyketide-type genes and antibiotic production of three new isolates of Enhygromyxa salina

Three myxobacterial strains, designated SWB004, SWB005 and SWB006, were obtained from beach sand samples from the Pacific Ocean and the North Sea. The strains were cultivated in salt water containing media and subjected to studies to determine their taxonomic status, the presence of genes for the biosynthesis of polyketides and antibiotic production. 16S rDNA sequence analysis revealed the type strain Enhygromyxa salina SHK-1(T) as their closest homolog, displaying between 98% (SWB005) and 99% (SWB004 and SWB006) sequence similarity. All isolates were rod-shaped cells showing gliding motility and fruiting body formation as is known for myxobacteria. They required NaCl for growth, with an optimum concentration of around 2% [w/v]. The G + C-content of genomic DNA ranged from 63.0 to 67.3 mol%. Further, the strains were analyzed for their potential to produce polyketide-type structures. PCR amplified ketosynthase-like gene fragments from all three isolates enhances the assumption that these bacteria produce polyketides. SWB005 was shown to produce metabolites with prominent antibacterial activity, including activity towards methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE).     

克隆文库分析红树林土壤中放线菌的多样性

直接提取8个红树林土壤的总DNA,用放线菌门的特异性PCR引物进行扩增,通过构建16S rRNA文库,测序及系统发育分析,获取新颖放线菌菌株.结果发现,有酸微菌亚纲(Acidimicrobidae) (30.2％)、放线菌亚纲(Actinobacteridae) (68.0％)、红蝽菌亚纲(Coriobacteridae)(1.1％)和去腈基菌亚纲(Nitriliruptoridae)( 0.7％)成员,没有红色杆菌亚纲( Rubrobacteridae)成员.仙农指数和Chao1物种多样性指数(Schao1)表明,红树林土壤样品中含有丰富的放线菌多样性.以16S rDNA基因的相似率≥97％作为临界点,45.1％可能代表新候选种(candidate species)(未培养、分离).本研究为进一步获取新颖的红树林放线菌资源提供了基础.     

Morphological identification of foodborne pathogens colonizing rice grains in south Asia

The aim of this study was to identify the foodborne pathogens mainly, Aspergillus sp. colonizing rice grains using cultural and microscopic methods. Four differential media (Czapek Dox Agar (CZA), Czapek Yeast Agar (CYA), Malt Extract Agar (MEA) and Czapek yeast 20% sucrose agar (CYA20S)) were used for differentiation of five Aspergillus sp., colonizing rice grains comparing with standard cultures. We studied macroscopic (colony color and diameter, conidia color, exudates, sclerotia and colony texture) and microscopic (conidiophore color, length and breadth, conidia size, shape and surface texture, vesicle diameter and phialides length and breadth) characteristics for identification of 110 isolates of Aspergillus sp. isolated from 65 rice grain samples collected from various countries in South Asia (Cambodia, India, Indonesia, Malaysia and Thailand). According to morphological characters, all these isolates were belonging to Aspergillus flavus (45), A. fumigatus (8), A. ochraceus (7), A. niger (42) and A. tamarii (8). This is the first report on identification of large number of Aspergillus strains isolated from rice grains in South Asia.     

Human papillomaviruses prevalence and genital co-infections in HIV-seropositive women in Ouagadougou (Burkina Faso)

The vaginal swabs among HIV-positive women in Africa often revealed opportunistic infections such as human Papillomavirus (HPV) and Mycoplasma that induce respectively cervix cancer and diseases such as vaginosis, abortions, infertility in through salpingitis. The purposes of this study were to: (1) seek for, the prevalence of pathogens such as HPV and Mycoplasma; (2) characterize the strains of HPV and estimate their prevalence; (3) identify among these women, those who were co-infected by these pathogens in order to cure them. From February 2009 to January 2010, 156 HIV-positive women attending our medical centers and aged from 19-45 years (mean age 33.65 +/- 5.75 years) had voluntarily accepted vaginal specimen's tests. PCR, ELISA and molecular hybridization were used for the identification and characterization of these pathogens. The results revealed the presence of Mycoplasma and HPV in 25.64 and 58.33% cases, respectively. The following HPV genotypes and the following prevalence were recorded: HPV-50'S (24.11%), HPV-18 (21.28%), HPV-30'S (18.44%) and HPV-16 (5.67%). The study also enable the identification of co-infections such as HPV-18 strains with HPV-30'S (5.67%) and HPV-30'S with HPV-50'S (3.55%). Other germs infecting the female genital tract including Candida albicans (20.51%), Escherichia coli (12.18%), Treponema pallidum (3.85%), Streptococcus agalactiae (3.21%) and Staphylococcus aureus (1.92%) were isolated. This preliminary research work showed the incidence of several genital pathogens, this could be a springboard for nationwide epidemiological study on HPV strains circulating in Burkina Faso.     

Identification and molecular characterization of phytoplasmas and rickettsia pathogens associated with ‘Bunchy Top Symptom’ (BTS) and ‘Papaya Bunchy Top’ (PBT) of papaya in Cuba

Two different papaya diseases have been previously reported in Cuba, Bunchy Top Symptom (BTS) associated with a phytoplasma of group 16SrII ‘Candidatus Phytoplasma aurantifolia’ and Papaya Bunchy Top (PBT), associated with a rickettsia. Regarding the regional phytosanitary impact of both diseases for the papaya crop, the present study investigated the occurrence of BTS and PBT in papaya fields in Cuba, and the possible mixed infection of phytoplasma and rickettsia pathogens associated. Papaya plants showing symptoms of BTS or PBT or both, were collected in Las Tunas and Havana provinces from January 2009 to February 2010, and evaluated for phytoplasma and rickettsia by PCR with primers targeting the 16S ribosomal RNA and the rickettsial succinate deshydrogenase (sdhA) genes, respectively. Phytoplasmas and rickettsia were individually detected in 76/86 BTS-symptomatic and 22/22 PBT-symptomatic papaya plants, and simultaneously detected in 5/86 (5.81%) of the BTS-symptomatic and 17/22 (77.27%) of the PBT-symptomatic plants. Conventional and virtual RFLP analyses of the 16S rDNA sequences revealed the presence of phytoplasmas of group 16SrI ‘Candidatus Phytoplasma asteris’ and 16SrII in papaya plants affected by BTS and PBT, and identified two new phytoplasma subgroups, 16SrI-X and 16SrII-N in papayas fields of Las Tunas, which was confirmed by phylogenetic analysis. The partial rickettsia sdhA gene sequences were 100% identical to that of the rickettsia associated with PBT in Puerto Rico. Results confirm that phytoplasmas are consistently associated with both BTS and PBT symptoms, and that mixed infections of phytoplasma and rickettsia pathogens can occur in either BTS or PBT-affected papaya fields, which implies new epidemiological constraints for the disease control.     

A universal protocol for identification of cereals

Plant fingerprinting and identification has increasingly become a focus in commerce and manufacturing with an emphasis on fast, reliable and cost effective high throughput techniques. GBSS1 is a well conserved single copy nuclear gene in the grass family with potential for generating a universal approach to grass fingerprinting. Alignment of DNA sequences from Poaceae members identified five well conserved regions. PCR primers designed to these regions amplified single DNA fragments on all grasses tested. DNA sequencing revealed polymorphism within these DNA fragments allowing identification at the species level. A universal sequencing primer for Poaceae enabled pyrosequencing through a 28 base pair highly polymorphic region generating unique pyrograms for rice, wheat, barley and maize. Analysis of exon/intron composition including intron length and number, of GBSS1 provided another distinct fingerprinting method for grasses. Phylogenetic utility of these fragments was demonstrated by production of phylograms consistent with previously described taxonomic relationships for the Poaceae family. The sequence polymorphism of the GBSS1 gene provides the basis for universal primer design for identification of members of the Poaceae family. The protocols developed may prove more generally useful in the distinction of plant species in other plant families.