孑遗植物桫椤内生真菌的多样性与群落组成

桫椤为木本蕨类,在世界范围内属于濒危的孑遗植物,关于桫椤内生真菌的研究还未见报道。本文基于形态学特征和DNA序列分析技术,探讨了桫椤内生真菌多样性和群落组成。研究发现,桫椤组织中蕴藏着丰富的真菌资源,内生真菌定殖率达到87.6%;从桫椤的234个生活组织块中,分离到内生真菌291株,被鉴定为64个分类单元;桫椤组织中常见真菌种类大约占内生真菌的60%,其中铺散内曼菌Nemania diffusa表现出明显的分布优势;内生真菌总体多样性指数达到3.53的较高水平,并且表现出叶轴>根部>羽片>叶柄>茎皮的分布规律;分析不同组织中内生真菌的相似性系数和聚类结果,发现桫椤的组织性质影响内生真菌的组成和分布;根据物种累积曲线,现有的研究样本中超过80%的内生真菌已经被分离到,研究结果能够反映桫椤内生真菌的多样性和群落组成。通过分析桫椤的叶柄凋落物中真菌定殖率、丰度、多样性、相似性和真菌种类等特征性数值,表明凋落的桫椤组织中真菌的分布特征已经发生了明显改变。     

Endophytic fungi from medicinal plants: a treasure hunt for bioactive metabolites

Endophytic fungi are ubiquitous organisms found in the plants, residing intercellular or intracellular, at least for a portion of their lives without causing apparent symptoms of infection. Almost all plants are known to harbor endophytes. The choice of the plant to be used for exploring endophytes for bioactives is important. Therefore, medicinal plants which are known to be used since centuries as an alternative source of medicine, are a valuable source for bioprospecting endophytes. Nevertheless, due to many reasons there is a dire need for novel resources for novel drugs which can be an answer to many deadly diseases. It is in this context that the present review was envisaged. The review reveals the importance of endophytic fungi from medicinal plants as a source of bioactive and chemically novel compounds. The bioactive metabolites produced by endophytic fungi originate from different biosynthetic pathways and belong to diverse structural groups such as terpenoids, steroids, quinones, phenols, coumarins etc. Endophytes therefore, represent a chemical reservoir for new compounds such as, anticancer, immunomodulatory, antioxidant, antiparasitic, antiviral, antitubercular, insecticidal etc. for use in the pharmaceutical and agrochemical industries. Although, efforts have been made to accommodate as many examples as possible but the depth of the subject is so vast that it cannot be covered in one single review. This in itself speaks of the fact that endophytic fungi from medicinal plants is indeed a treasure worth searching. In the present review only some selected examples have been covered.     

三种红树林植物健康与非健康叶片中真菌的比较

红树林叶片感染真菌后可能会向非健康状态变化,为了比较三种红树林植物海漆、秋茄和桐花树健康与非健康叶片真菌类群,明确其中真菌类群的差异,该研究从广西茅尾海红树林自然保护区采集海漆、秋茄和桐花树健康与非健康叶片,对叶片中真菌分离纯化并进行形态学鉴定,提取真菌的DNA,采用RAPD多样性、ITS序列对真菌进行分子鉴定。经过初步分析,从海漆、秋茄和桐花树中共分离到157株真菌,经过形态学和RAPD分析,可能为19种不同的真菌。采用真菌ITS序列对19种真菌代表性菌株进行分析,结果表明:19种真菌都属于子囊菌门,有15株与已有的真菌ITS序列相似性在97%以上;有4株相似性低于95%,可能为新种。海漆健康和非健康叶片分别分离到真菌7种和5种,健康叶片含了非健康叶片中所有真菌;秋茄健康和非健康叶片分离到真菌1种和9种,且健康叶片中分离到的内生真菌Dothiorella aegiceri也包含于非健康叶片分离的真菌中;桐花树健康和非健康叶片分离到真菌1种和3种,且桐花树分离的内生真菌也是Dothiorella aegiceri,其包含于非健康叶片中分离到的真菌。该研究证明,海漆内生真菌同时也可能是植物病原菌,内生真菌与植物病原菌没有明显界限;另一方面,该研究发现秋茄和桐花树叶片的病变是由外部的病原真菌感染引起,感染的原因可能是昆虫叮咬红树林植物后留下了创口,这些创口有利于真菌的感染。     

真菌DNA条形码研究进展

DNA条形码（DNA barcode）是通过一段短的标准DNA片段实现物种的快速、准确和标准化鉴定。线粒体细胞色素C氧化酶亚基I（COI）基因作为动物的DNA条形码已广泛应用于物种鉴定中,在植物上已选定叶绿体rbcL和matK基因作为基本的DNA条形码。目前世界各国真菌学家正对不同的真菌类群进行不同基因片段的筛选与评价,并在第四届国际生命条形码大会上正式推荐了ITS作为真菌的首选DNA条形码。对国内外真菌DNA条形码的研究进展进行总结与分析,并展望真菌DNA条形码的应用前景。     

不同扩增引物对高通量测序分析盐角草内生真菌多样性的影响

【背景】高通量测序分析作为深入了解环境微生物群落组成的重要方法,已成为植物内生真菌多样性研究的有效手段,然而由于引物的扩增差异,采用不同引物可对实验结果分析造成影响。同时,盐角草作为世界上最耐盐的植物之一,存在着多种功能性的内生真菌,而较为全面介绍其内生真菌组成和多样性的报道鲜见。【目的】为了揭示盐角草内生真菌的多样性,解析不同扩增引物对内生菌多样性分析的影响。【方法】分别采用真菌高通量测序常用引物对ITS1-5F、ITS1-1F、ITS2对采自乌鲁木齐达坂城盐湖的盐角草内生真菌进行扩增,开展其内生真菌OTU的分析。【结果】通过不同引物对扩增并测序共获得102个盐角草内生真菌OTU,涉及真菌界8个门和未分类菌群,其中子囊菌门(Ascomycota)占绝对优势,其次为担子菌门(Basidiomycota);在属层次上,盐角草内生真菌共涉及64个属及20个未分类属,其中Alternaria、Cladosporium、Podospora等3个属为盐角草内生真菌优势菌群。对不同引物对扩增测序结果分析表明,不同引物对扩增对分析内生真菌OTU数量和种类具有明显的影响,在全部所得的102个OTU中,...     

鬼臼类植物内生真菌的分离及其抗癌活性研究

通过对三属四种鬼臼类植物地下茎内生真菌的分离,发现鬼臼类植物地下茎中内生真菌的物种类型极其丰富,主要分布在地下茎的表皮层和维管组织中,来源于外界环境.通过对包括鬼臼类植物在内的7种植物内生真菌的抗癌活性测定,发现内生真菌的抗癌活性与宿主有密切有关系,鬼臼类植物地下茎内生真菌含有较高比例的抗癌活性菌株.宿主种类、地理位置都会影响内生真菌的分布,进而影响活性菌株出现的频率.通过对所有鬼臼类植物地下茎内生真菌次生代谢产物的深入分析,并没有发现产生鬼臼毒素的内生真菌,鬼臼类植物地下茎内生真菌的抗癌活性成分是独立产生的.     

云南三个地区马铃薯内生真菌多样性研究

为研究云南马铃薯(Solanum tuberosum)内生真菌的多样性,该文以采自云南省德宏芒市、大理喜洲和临沧双江3个地区的马铃薯植株为研究对象,采用组织块分离法、尖端菌丝挑取法对马铃薯根、茎及块茎中的内生真菌进行分离纯化,并采用形态学鉴定方法和ITS序列分析法对分离得到的内生真菌进行鉴定,对内生真菌的定殖率、分离率及多样性指数进行计算和分析。结果表明:(1)共分离得到内生真菌98株,其中从德宏芒市的样品中获得40株,从大理喜洲的样品中获得27株,从临沧双江的样品中获得31株。(2)经鉴定,分离得到的马铃薯内生真菌共涵盖10目10科13属,大多为子囊菌门和担子菌门,优势菌为镰刀菌属(Fusarium)和青霉属(Penicillium),褶皱裸孢壳(Emericella rugulosa)、接骨木镰刀菌(Fusarium sambucinum)、毛韧革菌(Stereum hirsutum)、Psathyrella sulcatotuberculosa和Epicoccum catenisporum 5种真菌均为首次从马铃薯植株中分离得到。(3)马铃薯块茎内生真菌的定殖率最高,根部内生真菌定殖率最低; 内生真菌的分离率以马铃薯根部为最高,而茎部最低; 不同组织中内生真菌的多样性指数趋势均为根>块茎>茎。从综合来看,云南马铃薯植株中的内生真菌具有较高的多样性,不同地区的马铃薯样品中内生真菌优势菌不同,马铃薯根部具有最丰富的内生真菌种群和最高的分离率,是最适合进行内生真菌分离的材料。该研究结果为后期探究马铃薯内生真菌对病原菌的拮抗作用奠定了基础,也为马铃薯内生真菌多样性研究提供了参考数据。     

广西北部湾红树植物内生真菌多样性

【目的】研究广西北部湾地区红树植物内生真菌多样性,建立北部湾红树植物内生真菌种质资源库,为利用内生真菌生物技术促进农业可持续发展提供理论依据。【方法】从广西北部湾地区采集红树植物组织样本,采用表面消毒法分离真菌,通过测定分离菌株对宿主植物是否具有致病性来筛选内生真菌,结合形态学特征和分子生物学分析对内生真菌进行分类与鉴定。【结果】从60个红树植物样本中分离得到1 764个菌株,经过致病性测定筛选获得41株内生真菌,分离率为2.3%。其中从宿主植物红海榄分离得到15株内生真菌,占总菌株数的36.6%,比例最高。通过分析,发现这些内生真菌在ITS-NJ、NS-NJ两个系统发育树上各聚为7个大分支,分属8个科(目)。其中球腔菌属Mycosphaerella、德福里斯孢属Devriesia、假尾孢属Pseudocercospora、枝孢霉属Cladosporium、Pleosporales等属(科)真菌是广西红树林的优势菌。【结论】广西北部湾地区红树植物内生真菌菌种资源丰富。     

Culturable endophytic filamentous fungi from leaves of transgenic imidazolinone-tolerant sugarcane and its non-transgenic isolines

The diversity of endophytic filamentous fungi from leaves of transgenic imidazolinone-tolerant sugarcane plants and its isoline was evaluated by cultivation followed by amplified rDNA restriction analysis (ARDRA) of randomly selected strains. Transgenic and non-transgenic cultivars and their crop management (herbicide application or manual weed control) were used to assess the possible non-target effects of genetically modified sugarcane on the fungal endophytic community. A total of 14 ARDRA haplotypes were identified in the endophytic community of sugarcane. Internal transcribed spacer (ITS) sequencing revealed a rich community represented by 12 different families from the Ascomycota phylum. Some isolates had a high sequence similarity with genera that are common endophytes in tropical climates, such as Cladosporium, Epicoccum, Fusarium, Guignardia, Pestalotiopsis and Xylaria. Analysis of molecular variance indicated that fluctuations in fungal population were related to both transgenic plants and herbicide application. While herbicide applications quickly induced transient changes in the fungal community, transgenic plants induced slower changes that were maintained over time. These results represent the first draft on composition of endophytic filamentous fungi associated with sugarcane plants. They are an important step in understanding the possible effects of transgenic plants and their crop management on the fungal endophytic community.     

盐生植物翅碱蓬的内生真菌多样性分析

【目的】对辽宁省盘锦市双台子河口国家自然保护区的盐生植物翅碱蓬(Suaedaheteroptera Kitag.)的内生真菌进行研究。【方法】利用传统分离方法对翅碱蓬的根、茎、叶组织进行分离和纯化,根据形态学和理化特征,并结合rDNA-ITS序列分析对菌种进行鉴定。【结果】共分离得到内生真菌49株,这些内生真菌分属于13个属,其中小丛壳菌属(Glomerella)、链格孢属(Alternaria)、毛盘孢属(Colletotrichum)和枝孢属(Cladosporium)为优势菌属。翅碱蓬的内生真菌分布具有一定的组织特异性,两种不同生境中的翅碱蓬内生真菌群落丰富度差异较小,相似度较高,但在某些种属上存在特异性。【结论】翅碱蓬体内含有丰富的内生真菌资源,其内生真菌具有很高的宿主特异性,而且其分布受生境影响。     

植物内生真菌抗肿瘤活性代谢产物研究进展

癌症已成为全球头号杀手,迫切需要从自然界寻找更新、更有效的抗肿瘤药物。植物内生真菌是指生活在宿主植物体内,不会对宿主植物组织引起明显病害症状的一类真菌。众多研究表明,植物内生真菌在寻找抗肿瘤药物中起着至关重要的作用。随着植物内生真菌研究的深入,从植物内生真菌中寻找新的抗肿瘤活性成分已成为研究的热点。大量的抗肿瘤活性成分从植物内生真菌中分离出来,并表现出良好的抗肿瘤活性。目前,植物内生真菌抗肿瘤活性代谢产物主要有紫杉醇、喜树碱、长春新碱,鬼臼毒素等等,本文主要对近年来植物内生真菌抗肿瘤活性成分的研究进展进行了综述。     

药用植物内生真菌及活性物质多样性研究进展

药用植物具有丰富的物种多样性,是人类生存与发展的重要自然资源。内生真菌广泛存在于健康植物组织内部,是植物微生态系统的重要组成部分,各种药用植物中蕴藏着非常丰富的内生真菌。通过与药用植物的“协同进化”,某些内生真菌具有了产生与宿主植物相同或相似的生物活性物质的能力。内生真菌产生的各种活性物质,在生物制药、农业生产、工业发酵等方面都表现出美好的应用前景,受到世界各国专家的广泛关注。利用内生真菌发酵实现生物活性物质的工业化生产,可以提高产量、降低产品成本,满足人们日益增长的需求;同时有利于珍稀、濒危药用植物资源的保护,对减少野生药用植物多样性的破坏具有重要意义。本文从药用植物内生真菌物种多样性与产生生物活性物质多样性等方面总结近年最新的研究进展,提出了内生真菌及活性物质研究的未来发展方向。     

Effects of endophytic Fusarium oxysporum towards Radopholus similis activity in absence of banana

Four endophytic fungi (Fusarium spp.) isolated from the cortical tissue of surface-sterilised banana as well as from tomato roots were tested for their capacity of biological control towards the burrowing nematode Radopholus similis on banana. The pathogenic and parasitic capacities of endophytic fungi towards R. similis were tested in in vitro experiments. No parasitism of fungi on R. similis was observed. However, nematode activity decreased significantly in the presence of all endophytic fungi in vitro when compared to nematodes in the absence of fungi. The effects of fungi on R. similis activities in the soil were tested in the absence of plants. Nematode activities were reduced significantly by 16-30% by endophytic fungi when compared to untreated soil.     

Antitumor and antifungal activities in endophytic fungi isolated from pharmaceutical plants Taxus mairei, Cephalataxus fortunei and Torreya grandis

The purpose of this work was to screen the endophytic fungi having antitumor or antifungal activity, which were isolated from the inner barks of three kinds of pharmaceutical plants, Taxus mairei, Cephalataxus fortunei and Torreya grandis, collected from Fujian province, China. Antitumor activity was studied by the MTT assay and antifungal activity was determined by observing fungal growth inhibition. 13.4% of endophytic fungi fermentation broths displayed cytotoxic activity on HL-60 cells at and below a dilution of 1:50, and 6.4% on KB cells. 52.3% of endophytic fungi fermentation broths displayed growth inhibition on at least one pathogenic fungi, such as Neurospora sp., Trichoderma sp. and Fusarium sp. Among all endophytic fungi isolated, the genus Paecilomyces sp. has the highest positive rate of antitumor and antifungal activity. These results indicate that endophytic fungi could be a promising source for antitumor and antifungal bioactive agents.     

Genetically modified crops: environmental and human health concerns

About 10,000 years ago subsistence farmers started to domesticate plants and it was only much later, after the discovery of the fundaments of genetics, those organisms were submitted to rational genetic improvement mainly by selecting of traits of interest. Breeders used appropriate gene combinations to produce new animal races, plant varieties and hybrids, as well as improved microorganisms such as yeasts. After the introduction of recombinant DNA techniques, the transfer of DNA between species belonging to different genera, families or kingdoms became possible. The release of transgenic plants has aroused debates about several aspects of the environmental and human risks that could result from the introduction of genetically modified crops. Less effort has been dedicated to evaluate the impact of transgenic plants on their associated microorganisms, some of which (e.g. nitrogen-fixing bacteria, mycorrhizal fungi and endophytic microbiota) are extremely important for the survival of the plant. Investigations have been made regarding the horizontal transfer of genetic material between transgenic plants and microorganisms and on the disturbance of useful symbiotic associations between plants and endophytic, epiphytic and rhizosphere communities. In most cases the results do no show any adverse effect of transgenic plants on autochthonous plant-associated microorganisms. Results from our laboratory show small changes caused by genetically modified endophytic bacteria on the indigenous endophytic population of the sweet orange Citrus sinensis. In tests using appropriated fungal strains preliminary results using extracts from transgenic plants indicate that these plants do not affect haploidization, mitotic crossing-over, mutation rate or chromosomal alterations.     

铁皮石斛内生真菌分布

本研究从铁皮石斛(Dendrobium officinale)根、茎和叶中分离得到内生真菌67株,经形态学和分子生物学鉴定分别归属于16个属,Fusarium和Alternaria为铁皮石斛内生真菌的优势种群。研究发现,铁皮石斛根、茎、叶中内生真菌分布存在较大差别,具有一定的组织差异性,不同石斛植物中内生真菌的存在情况差别较大,具有一定的宿主差异性。本研究丰富了真菌资源,为石斛属药用植物内生真菌资源的开发利用提供了基础理论依据。     

野生五唇兰根部内生真菌多样性研究

兰科植物根部的内生真菌在兰科植物的整个生活史中起着重要的作用, 为了解不同生境不同类型的兰科植物内生真菌菌群的多样性, 作者于2004年7月至2005年10月, 以海南岛霸王岭自然保护区内的野生五唇兰(Doritis pulcherrima)作为实验材料, 对不同生境、不同形态的五唇兰植株根部的内生真菌群落多样性进行了研究。从附生于石上及生于杂木林或灌丛中、叶背绿色及叶背紫红色的五唇兰植株新鲜营养根段中共分离出83株内生真菌, 鉴定为19个属, 其中包括培养基筛选实验中分离出的30株14属。镰刀菌属(Fusarium)(24.1%)和丝核菌属 (Rhizocto-nia)(14.5%)为优势属。两种叶色的五唇兰内生真菌群落丰富度较为一致; 而两种不同生境中的五唇兰内生真菌群落丰富度则表现出较大的差异: 附生于灌木的五唇兰内生真菌群落Shannon多样性指数远高于附生岩石的。研究结果表明五唇兰内生真菌多样性更多地受生境的影响而不是受植株形态类型的影响。     

广东肉桂内生真菌多样性及其抗肉桂枝枯病菌初步研究

本研究从广东省罗定市20年生和1年生肉桂的叶、枝、根和皮等不同器官共分离得到90株内生真菌,通过菌落特征、显微观察和ITS序列分析鉴定为2门3纲10目14科22属,其中拟盘多毛孢属Pestalotiopsis、黑孢霉属Nigrospora和间座壳属Diaporthe为优势属;肉桂内生真菌的分布存在明显的组织特异性和偏好...     

红树林内生真菌研究进展

红树林作为一种特殊的植物群落具有丰富的内生真菌资源,目前已分离鉴定的红树林真菌超过200种,成为海洋真菌的第二大类群,已报道的红树林内生真菌主要类群是链格孢霉(Alternaria)、曲霉(Aspergillus)、芽枝霉(Cladosporium)、炭疽菌(Colletotrichum)、镰孢霉(Fusarium)、拟青霉(Paecilomyces)、拟盘多毛孢(Pestalotiopsis)、青霉(Penicillium)、茎点霉(Phoma)、拟茎点霉(Phomopsis)、叶点霉(Phyllosticta)和木霉(Trichoderma)等.大部分红树林内生真菌具有较宽的宿主范围,极少数只有单一的宿主,不同红树林植物的内生真菌区系及优势种群有很大差异.红树林内生真菌的定殖因宿主植物不同部位、植株的年龄及季节和环境的变化明显不同.红树林内生真菌能产生多种代谢产物,具有抗菌、抗肿瘤等药用价值.红树林植物内生真菌的研究和开发具有重要意义.本文综述了红树林内生真菌的生物多样性及其分布、生物学功能和次生代谢产物等方面的研究进展.     

基于rDNA ITS序列的油茶叶片内生真菌多样性研究(英文)

油茶是我国热带和亚热带地区广泛栽培的一类重要的经济树种,其种子可生产优质食用油(茶油)。为了比较全面地了解油茶的内生真菌多样性,采用基于rDNA ITS的免培养法从油茶叶片中提取了总DNA,再从总DNA样本中直接扩增了内生真菌核糖体RNA基因内转录间隔区序列(ITS),进而构建了ITS克隆文库。共计从50个克隆子中获得了22种不同的克隆序列,其中3个为嵌合体,7个归属为植物,其余克隆序列根据序列相似性和系统发育分析归为12个不同的分类操作单元(OTUs),全部为子囊菌,分属于4纲4目,其中Aspergillus属2种,Mycosphaerellaceae科1种,Sordariales目4种,Helotiales目5种,Aspergillus属真菌是优势菌。结果表明油茶叶片内生真菌的种类分布较广。