产β-甘露聚糖酶内生菌

植物内生菌研究已经成为微生物研究的热点[1],最初主要集中于拮抗菌的筛选,近几年更关注于生物活性物质的分离.最近有报道,将从植物内生菌作为一种开发工业用酶资源的新角度去研究[2],这为继续开发其它工业用酶或生物活性物质的内生菌的研究提供了理论依据,从而拓宽了植物内生菌的应用研究范围.     

植物内生菌的开发与研究进展

植物的内生菌是巨大的资源宝库,具有重大的研究和开发价值。对近年来植物内生菌的开发与研究进展进行了综述,包括内生菌的起源、分布特点、分离方法,内生菌在医药、生物防治、对污染物的降解等开发与应用方面的研究进展。     

植物内生菌生物抗菌活性物质研究进展

植物内生菌作为一种新型的微生物资源,分离和确定其代谢产物是一条寻找新型天然活性物质的重要途径。目前为止,许多研究者从不同的植物内生菌中分离到大量具有抗菌活性的新化合物,这些新的化合物被认为是解决日益严重的微生物多重耐药性的希望之一。本文从植物内生菌的多样性、抗菌活性物质多样性及国内内生菌研究进展等多个角度概述了当前有关植物内生菌研究的主要成果和最新进展,以期为植物内生菌相关研究提供借鉴。     

植物内生菌研究进展

植物内生菌是指生活史中某一阶段生活在植物组织内,对植物没有明显病害症状的一类微生物,研究发现其主要包括内生细菌、内生真菌和内生放线菌。内生菌能够产生与宿主植物相同或相似的活性物质,从而拓宽了药用资源并且具有巨大的应用价值。从植物内生菌的分布规律及其生长特点,与宿主植物的关系,研究领域以及发展现状与存在问题等方面进行了综述,并对植物内生菌在药用资源开发中的前景进行了展望。     

植物内生菌群落组成及其功能研究进展

植物内生菌是栖居在植物组织内部、以宿主植物代谢物为营养物质的一类微生物。植物内生菌种类丰富,并通过不同的方式定殖在植物体内,与宿主植物互利共生。植物内生菌促进植物的生长发育,通过增强营养物质吸收、与病原菌竞争生态位、在代谢过程中产生抗菌物质以及诱导宿主植物产生抗性等机制,提高宿主植物的抗逆性,并且其群落的组成因生态环境、寄主植物不同部位、生长周期的不同发育阶段而显著不同。人们利用传统组织分离法、高通量测序法以及人工重组生物群落等研究方法对植物与内生菌相互作用进行了深入的研究。本文对植物内生菌群落的组成、内生菌对宿主植物影响的功能研究以及人工内生菌群的构建进行重点阐述,以期为植物内生菌的开发和利用奠定坚实基础。     

盾叶薯蓣内生菌研究进展

植物内生菌是与植物协同进化的一大类微生物种群,具有抵抗病原微生物、促进宿主生长、产与宿主相似的次生代谢物等多种有益特性,是宝贵的生物资源库。盾叶薯蓣具有很高的药用价值,也是多种激素类药物合成前体的主要植物来源。从盾叶薯蓣植物分离具有有益特性的内生菌成为近年内生菌研究的热点。本文从盾叶薯蓣内生菌的分离鉴定方法和盾叶薯蓣内生菌的特性两个方面概述了近年来盾叶薯蓣内生菌的研究现状,以期为盾叶薯蓣内生菌的进一步研究开发提供参考。     

分子生物学技术在植物内生菌分类鉴定中的应用

植物内生菌作为微生物中的一个研究领域,近年来一直备受关注。不仅是因为内生菌在农牧业生产和环境净化方面应用的良好表现,而且还为新药研制提供了新的途径。与此同时,植物内生菌分类鉴定的研究也有一定的进展,特别是在分子生物学技术应用到其中后。基于这点,就最近10年来有关植物内生菌分类鉴定的文献所使用的技术进行了分析和讨论。     

植物内生菌研究进展

内生菌由于生长于植物体内且不引起植物病害所以不易被发现,它是一类具有高实用价值的植物内生微生物。经过人们的不断研究,越来越多的植物内生菌被发现,其活性代谢产物的优势也得到了更多研究者的认可。综述了国内外有关植物内生菌研究的主要成果和进展,并从植物内生菌的发现、研究历史、多样性、生理生化特性以及植物内生菌与宿主植物间的作用关系等多个层次进行了概述,以期为植物内生菌相关研究提供参考。     

植物内生菌的研究进展

植物内生菌是存在于植物内部与植物密不可分的一类微生物,包括内生真菌和内生细菌两大类。随着研究的不断深入,发现内生菌不仅产生多种有益的生物学作用,如防病、促生、固氮等,还能对寄主植物的生长发育产生不利影响。近年来,植物内生菌已成为我国微生物学领域研究的热点问题之一。本文综述了植物内生真菌和内生细菌的研究概况,以期更好地研究和了解植物内生菌。     

植物内生细菌对植物健康的作用

植物内生菌是一个多样性十分丰富的微生物类群,存在于没有外在感染症状的健康植物组织内,并与宿主植物协同进化.随着研究领域的不断拓宽和研究方法的不断更新,植物内生菌与植物健康的关系以及应用逐渐成为研究热点.本文主要综述了内生细菌的多样性、进入植物组织内的机制以及内生细菌的主要功能及应用,提出了现阶段内生菌研究存在的问题,并展望了内生菌研究的前景.     

Hidden diversity of endophytic fungi in an invasive plant

Fungal endophytes are important in plant ecology and common in plants. We attempted to test cointroduction and host-jumping hypotheses on a community basis by comparing endophytes isolated from invasive spotted knapweed (Centaurea stoebe, Asteraceae) in its native and invaded ranges. Of 92 combined, sequence-based haplotypes representing eight classes of Fungi, 78 occurred in only one of the two ranges. In the native range of C. stoebe, one haplotype of Alternaria alternata was clearly dominant, whereas in the invaded range, no haplotype was dominant. Many haplotypes were closely related to one another and novel. For example, six putative, new species of Botrytis were discovered as endophytes of C. stoebe, which has never been reported to have Botrytis spp.. Apparent differences between the two communities of endophytes were significant according to an analysis of similarity, but phylogenetic community structure did not differ significantly between the ranges. Both host-jumping and cointroduction of fungal endophytes likely took place during the spotted knapweed invasion.     

Genetic diversity in epichloid endophytes of Hordelymus europaeus suggests repeated host jumps and interspecific hybridizations

Epichloid fungal endophytes (Epichloë and Neotyphodium spp.) are excellent model systems for studying speciation processes because of their variable life history traits that are linked to host grass fitness. Presumed jumps to new hosts and subsequent somatic hybridizations appear to be common among epichloid endophytes resulting in increased genetic variation upon which selection can act and speciation be initiated. In this study, we explored the endophyte diversity of a rare European native woodland grass species, Hordelymus europaeus, along a latitudinal transect covering the entire distribution range of H. europaeus. From 28 populations in six countries, isolates were sampled and molecularly characterized. Based on the sequences of tubB and tefA, six distinct epichloid taxa (interspecific hybrid or cryptic haploid species) were found, of which four were novel and two have been previously reported from this host. Of the novel endophytes, two were presumed to be interspecific hybrids and two of nonhybrid origin. While previously known endophytes of H. europaeus are seed‐born and strictly asexual, one of the novel nonhybrid endophytes found in the glacial refugium of the Apennine peninsula reproduced sexually in cultured plants. This is the first case of a seed‐borne, but sexually reproducing endophyte of this host. We discuss the origin, and possible ancestral species, of the six epichloid taxa using phylogenetic analyses. Repeated host jumps and somatic hybridizations characterize the diversity of the endophytes. To date, no other grass species is known to host a larger diversity of endophytes than H. europaeus.     

Isolation,molecular characterization and virome analysis of culturable wood fungal endophytes in esca symptomatic and asymptomatic grapevine plants

Europe is the world largest grape producer, but in recent years, the report of diseases due to infection by grapevine trunk pathogens (GTPs) is becoming one of the main constraints for viticulture. Among grapevine trunk diseases (GTDs), esca syndrome is one of the most complex, characterized by simultaneous infection of several fungi, which leads to important reduction in yield and quality. Previous characterization of fungal isolates associated with esca syndrome leads to the recognition of at least three important players: Phaeocremonium minimum, Phaemoniella chlamydospora and Fomitiporia mediterranea. Here we isolated and characterized molecularly fungal endophytes directly from field wood tissues of plants showing or not esca symptoms. In addition, to better characterize such collection, a deep RNA sequencing (100 M reads in paired-end) to screen for mycovirus presence was performed. Thirty-nine viral genomes were detected, 38 of which were putative new viral species; some of these viruses infected GTPs, including P. minimum and F. mediterranea. In this work, we reported for the first time a curated collection of grapevine fungal endophytes identifying the associated mycoviruses some of which could be employed in future biotechnological exploitation as biological control agents for sustainable plant protection.     

Endophyte or parasite--what decides?

Symbiosis between a fungus and a plant is a widespread phenomenon in nature. The outcome of such an interaction can vary in a seamless manner from mutualism to parasitism. In most cases, the host plant does not suffer, in fact it often gains an advantage from colonization by a fungus. This benefit is based on a fine-tuned balance between the demands of the invader and the plant response. If the interaction becomes unbalanced, disease symptoms appear or the fungus is excluded by induced host defence reactions. Symbioses of plants with beneficial or neutral endophytes share many common attributes with plant interactions with pathogens. Recent findings emerging from studies of compatible host-fungus interactions have enhanced our understanding of what determines whether the fungus behaves as an endophyte or a parasite and of how plants avoid exploitation by detrimental parasites but benefit from mutualistic endophytes.     

Geographic locality greatly influences fungal endophyte communities in Cephalotaxus harringtonia

Although endophytes of conifers have been extensively studied, few data are available on Cephalotaxaceae. We examined foliar and stem endophytes of Cephalotaxus harringtonia, within its natural range in Japan and outside its natural range in France to study the effect of geography on endophyte community composition. In Japan, rapidly growing endophytes were dominant and may have masked the real diversity, in comparison to France where most endophytes were growing slowly. Analyses of ITS rDNA revealed 104 different Blast Groups among 554 isolates. Almost no overlap between endophyte assemblages of C. harringtonia from the two countries was observed. It seems that Japanese C. harringtonia trees, which should be well adapted to their native site, would host a specific, endemic endophyte community, while trees that have been introduced recently to a foreign site, in France, should have captured existing cosmopolitan and more generalist taxa. In Japan the majority of xylariaceous taxa, which dominated the communities, were unknown and, although closely related to Asian taxa, may be new to science. Dothideomycetes were more prevalent in France. Locally, urban environment, particularly in Japan, may have introduced some perturbations in the native endophyte community of C. harringtonia, with an abundance of generalist fungi such as Nigrospora and Colletotrichum.     

Bioactive secondary metabolites produced by microorganisms associated with plants

In the past few decades groups of scientists have focused their study on relatively new microorganisms called endophytes. By definition these microorganisms, mostly fungi and bacteria, colonise the intercellular spaces of the plant tissues. The mutual relationship between endophytic microorganisms and their host plants, taxanomy and ecology of endophytes are being studied. Some of these microorganisms produce bioactive secondary metabolites that may be involved in a host-endophyte relationship. Recently, many endophytic bioactive metabolites, known as well as new substances, possesing a wide variety of biological activities as antibiotic, antitumor, antiinflammatory, antioxidant, etc. have been identified. The microorganisms such as endophytes may be very interesting for biotechnological production of bioactive substances as medicinally important agents. Therefore the aim of this review is to briefly characterize endophytes and summarize the structuraly different bioactive secondary metabolites produced by endophytic microorganisms as well as microbial sources of these metabolites and their host plants.     

禾草-内生真菌共生体在草地农业系统中的作用

综述了国内外近年对禾草 -内生真菌 (N eotyphodium)的研究进展。全世界现已报道 14种禾草内生真菌 ,与 2 3个属的禾草形成共生体 ,我国已在 13属 2 5种天然草地禾草中发现内生真菌 ,其中发草属 (Descampsia)、大麦属 (H ord eum)和赖草属(L eymus)以往在国际文献中未曾报道。内生真菌在禾草体内产生的生物碱 ,致使采食带菌禾草的马、牛、羊、鹿等家畜产生中毒症状 ,每年给美国、新西兰等国造成的经济损失达 6.4亿美元之多 ,对其毒理研究取得了进展。已发现我国醉马草 (Achnatheruminebrians)对家畜的毒性与内生真菌的侵染有关。内生真菌侵染增加可使禾草对 42种害虫的抗性 ,并可增加对某些线虫和病害的抗性。与不带菌禾草相比 ,带菌禾草的另一特点是抗逆性强 ,牧草产量高。国际在该领域的研究主要集中在多年生黑麦草(L olium p erenne)和高羊茅 (Festuca arundinacea)。我国的研究发现 ,带菌布顿大麦草 (H ordeum bodg anii)和圆柱披碱草(Elymus cylind ricus)的牧草产量分别增加 3 3 .3 %和 2 78.8% ,分孽数分别增加 13 6.8%和 84.5%。目前 ,国际研究的重点包括大规模开展内生真菌生物学与生态学特性的研究 ,创造不含对家畜有害毒素的有益禾草 -内生真菌共生体 ,培育带内生真菌的草坪草品种 ,培育抗毒     

内生真菌对草坪植物病原真菌抑制作用的比较

分别从野生牧草羽茅(Achnatherum sibiricum (L.) Keng)、栽培种高羊茅(Festuca arundinacea Schreb.)(品种Millennium)、栽培种黑麦草(Lolium perenne L.) (品种Justus)中分离出内生真菌Neotyphodium sp.、N. coenophialum和N. lolli,通过体外培养法比较了这3种内生真菌对草坪植物病原真菌的抑制作用.结果表明,从羽茅中分离的内生真菌Neotyphodium sp.在两菌相交前对所有供试的病原真菌都有一定的抑制作用,其中对枝孢霉属(Cladosporium sp.)、弯孢霉属(Curvularia sp.)和拟茎点属(Phomopsis sp.)病原真菌的抑制效果尤为显著,对峙培养3d后的抑菌率分别达70.1%、52.3%和30.9%,营养竞争作用、重寄生作用是其主要的拮抗机制;从高羊茅中分离的内生真菌N. coenophialum对枝孢霉属病原真菌存在一定的抑制作用;而从黑麦草中分离的内生真菌N. lolli与病原真菌对峙培养时,病原真菌菌落慢慢侵占整个营养空间,内生真菌停止生长并逐渐褐变死亡.体外培养结果说明Neotyphodium sp.对供试病原真菌的拮抗效果优于N. coenophialum和N. lolli,由此推测Neotyphodium sp.与宿主植物羽茅的共生可能有利于宿主植物抵抗病原真菌的侵扰.