辽宁省9种兰科植物根内与根际土壤中真菌群落结构的差异

兰科植物的生存及生长高度依赖其根中的共生真菌,其中的菌根真菌更是对兰科植物的种子萌发与后续生长有着非常重要的作用,研究兰科植物根中的真菌,尤其是菌根真菌,对兰科植物的保护有重要作用。该研究利用第二代测序技术,对中国辽宁省境内的9种属于极小种群的兰科植物的根、根际土和根围土中的真菌群落和菌根真菌组成进行了研究。结果显示,兰科植物根中的真菌群落和根际土、根围土中的真菌群落具有显著差异。兰科植物根中的总操作分类单元(OTU)数目远小于根际土和根围土中的总OTU数目。同时,兰科植物根中菌根真菌的种类和丰度与根际土、根围土中菌根真菌的种类与丰度没有明显联系。FunGuild分析结果显示,丛枝菌根真菌在根际土与根围土中的丰度非常高,但在兰科植物的根中却数量极少。这些结果表明,兰科植物根中的真菌群落与土壤中的真菌群落在一定程度上是相互独立的。     

濒危药用植物掌裂兰根部内生真菌和根际土真菌多样性分析

【背景】植物内生真菌对宿主植物促生长、抗旱和增强抗病能力等方面有着重大的研究和利用价值,尤其对兰科植物的生长起到重要的作用。【目的】通过对掌裂兰根部内生真菌和根际土真菌多样性进行系统分析,掌握掌裂兰根部内生真菌与根际土真菌群落结构,为进一步探究掌裂兰植物与真菌共生规律提供参考。【方法】采用Illumina MiSeq高通量测序技术分析掌裂兰根部内生真菌和根际土真菌多样性。【结果】掌裂兰根部内生真菌隶属于7门89属,优势菌属为瘤菌根菌属(Epulorhiza)(16.93%)、头梗霉属(Cephaliophora)(10.41%)、酵母属(Saccharomyces)(5.73%)、角担菌属(Ceratobasidium)(5.32%)和镰刀菌属(Fusarium)(5.12%),其中Epulorhiza和Ceratobasidium为兰科植物菌根真菌;根际土真菌隶属于11门269属,优势菌属为镰刀菌属(Fusarium)(8.09%)、丛赤壳属(Neonectria)(6.79%)、Plectosphaerella (3.39%)和被孢霉属(Mortierella)(3.01%)。通过...     

辽宁省八种兰科植物根内生真菌多样性

兰科植物的生存强烈依赖菌根真菌,研究兰科菌根真菌对兰科植物的保护有重要作用。本研究以辽宁省的无柱兰(Amitostigma gracile)、二叶舌唇兰(Platanthera chlorantha)、小斑叶兰(Goodyera repens)、蜻蜓兰(Tulotis fuscescens)、山兰(Oreorchis patens)、羊耳蒜(Liparis japonica)、长苞头蕊兰(Cephalanthera longibracteata)和绶草(Spiranthes sinensis) 8种属于极小种群的野生兰科植物为例,利用第二代测序技术对其根内生真菌多样性进行了研究。结果表明:无柱兰、二叶舌唇兰、小斑叶兰和山兰都偏好与角担菌科(Ceratobasidiaceae)真菌共生,羊耳蒜偏好与胶膜菌科(Tulasnellaceae)真菌共生;长苞头蕊兰主要与革菌科(Thelephoraceae)和蜡壳耳科(Sebacinaceae)真菌共生;绶草不仅能与丝核菌属(Rhizoctonia)真菌共生,还能与蜡壳耳科真菌共生;同种兰科植物的不同植株在同一生境下所选择的菌根真菌有差异,而同一地点的不同兰科植物的菌根真菌群落各不相同。由此可见,兰科植物根中菌根真菌的组成并非完全受植物自身控制,但主要菌根真菌仍取决于兰科植物的选择;这8种兰科植物根中的真菌绝大多数为非菌根真菌,而菌根真菌的丰度通常很低,这可能是辽宁地区兰科植物稀少的原因之一。     

华北特有腐生型兰科植物北京无喙兰根际土壤微生物多样性研究

北京无喙兰(Holopogon pekinensis X. Y. Mu & Bing Liu)为华北地区特有珍稀腐生型兰科植物,分布在海拔约1100 m的杂木林内,生境与本区域内其他腐生型兰科植物(常在1600 m以上桦木林中生长)显著不同。本研究针对北京玉渡山和百花山两个北京无喙兰种群的根际土壤样品开展基于高通量测序技术的根际土壤微生物多样性分析,解析北京无喙兰根际土壤微生物群落组成及多样性。测序分析结果显示,共得到4973个细菌OTU(Operational taxonomic unit),发现北京无喙兰根际土壤的优势细菌类群为变形菌门、放线菌门、拟杆菌门等7个门,优势属有MND1、硝化螺菌属(Nitrospira)和Haliangium等。1914个真菌OTU的分析结果表明,根际土壤优势真菌类群为子囊菌门、担子菌门、结合菌门等;优势属有Archaeorhizomyces、蜡壳耳属(Sebacina)和被孢霉属(Mortierella)等;优势真菌多为外生菌根真菌,可能是北京无喙兰潜在的菌根真菌。多样性指数分析显示,北京无喙兰玉渡山种群根际土壤中的真菌和细菌群落的丰富度和均匀度均高于百花山种群,各种群土壤微生物多样性与北京无喙兰所在种群的乔木种类多样性具有一定的相关性。     

黄精根际及药用部位内生真菌群落组成和生态功能分析

为寻找促进药用植物活性代谢产物合成的微生物,该文以黄精为研究对象,利用高通量测序技术和生态功能预测平台,测定根际土真菌、根茎和根内生真菌的ITS序列,分析其真菌多样性和群落组成,并预测根茎内生真菌的生态功能。结果表明:(1)测序得到1 023个可操作分类单元(OTUs),根际、根茎和根真菌OTU数分别为703、128和141,三种部位真菌群落组成差异显著,根际土存在特有的真菌类群,即壶菌门。(2)根际土、根茎及根共有OTU 41个,子囊菌门占共有真菌的58.15%,丰度最大。(3)根茎内生真菌被划分6个生态功能群,包括未定义腐生菌、菌寄生真菌、动物病原菌、植物病原菌、丛枝菌根真菌和地衣共生真菌,37个undefined种类(34.91%)在FUNGuild数据库中没有参考信息。研究认为根茎中优势菌属Setophoma、新赤壳属等内生真菌可能与活性代谢产物密切相关,可为黄精药用功能菌群的发掘提供数据参考。     

黑老虎内生真菌及根际土壤真菌的群落结构与生态功能分析

为探讨黑老虎(Kadsura coccinea)根际土壤和组织内生真菌菌群的组成及其生态功能，该研究采用ITS高通量测序技术对成熟黑老虎(根、茎、叶)内生真菌及根际土壤真菌群落结构、多样性和生态功能进行了分析。结果表明：(1)从12个样品中共获得2 241个可操作分类单元(OTU),涉及10门、41纲、95目、212科、367属，内生真菌(根、茎、叶)和根际土壤真菌OTU数分别为386、536、258、1 435个，其中共有的OTU为18个。在门水平上，黑老虎内生真菌及根际土壤真菌优势群落均为子囊菌门和担子菌门，其中子囊菌门在叶和茎中占比分别高达96.99%和95.37%;在属水平上，黑老虎根际土壤真菌中腐生真菌被孢霉属占比较高(为13.5%),叶和茎等生长旺盛的组织中子囊菌门未分类属和痂囊腔菌属占比较高。(2)α多样性分析结果显示，黑老虎根际土壤真菌群落的丰度和多样性明显高于内生真菌，茎中内生真菌丰度显著高于根和叶，而根、茎和叶组织间内生真菌多样性差异不显著；PCoA分析结果显示，叶和茎的真菌群落结构相似性更高。(3)利用FUNGuild数据库进行的功能预测分析结果显示，黑老虎根际土...     

红树植物对根域真菌生态的影响

植物根系具有丰富的微生物种类和生物量,为了掌握红树植物根系真菌的生态状况,在广东湛江红树林国家级自然保护区内6种红树植物群落中采集样品分离根际与非根际真菌,分析红树植物对根域真菌生态的影响以及根域真菌与环境因子的关系。从分离培养的6种红树植物的根域样本中,鉴定出5属11种真菌。桐花树、木榄、无瓣海桑和秋茄根际真菌的丰度与种类均高于非根际真菌,说明这4种红树植物对根际真菌生长有促进作用,而红海榄与白骨壤则相反,说明其对根际真菌有抑制作用。总体上,红树林林内真菌种类数远高于林外,表明红树植物覆盖对促进真菌物种多样性有积极作用。根际真菌丰度与总有机碳(TOC)呈显著负性相关关系,非根际真菌种类数与硝态氮(NO3-N)呈显著正相关关关系,说明根际TOC中可能含有抑制真菌生长作用的物质,而在非根际,红树植物根系分泌物影响较小。红树植物根系分泌物对根际微生物数量和种类数有一定的影响。     

重度火烧迹地兴安落叶松(Larix gmelinii)根际土壤真菌群落研究

为探究内蒙古根河大兴安岭林区重度火烧迹地不同生长状态的兴安落叶松根际土壤真菌群落特征,选取火烧枯立木（BDW）、火烧存活木（BSW）、未火烧对照木（CK）,通过磷脂脂肪酸方法分析根际土壤真菌群落生物量变化,利用高通量测序技术对根际土壤真菌群落组成与功能进行分析,探讨影响根际土壤真菌群落的主要环境因子。结果表明：（1）相较于未火烧对照木,火烧枯立木与火烧存活木根际土壤真菌群落磷脂脂肪酸含量显著降低,真菌群落α多样性显著降低。β多样性分析与群落相似性分析结果显示,火烧枯立木、火烧存活木、未火烧对照木根际土壤真菌群落组成存在显著差异。（2）相较于未火烧对照木,火烧枯立木与火烧存活木根际土壤中担子菌门（Basidiomycota）真菌相对丰度显著下降,子囊菌门（Ascomycota）真菌相对丰度显著升高。子囊菌门（Ascomycota）内,火烧枯立木根际土壤中内生真菌相对丰度显著高于火烧存活木与未火烧对照木,而火烧存活木根际土壤中腐生-外生菌根复合型真菌相对丰度显著高于火烧枯立木与未火烧对照木。（3）根际土壤总磷、总钾含量是影响重度火烧迹地兴安落叶松根际土壤真菌群落优势菌门由担子菌门（Basidiomycota）转变为子囊菌门（Ascomycota）的主要环境因子,而根际土壤总碳、总氮、总磷含量则是造成火烧枯立木与火烧存活木根际土壤真菌群落组成与功能差异的主要环境因子。本研究有助于了解大兴安岭林区土壤真菌群落结构,对真菌群落多样性的维持与管理具有参考价值。     

兰科菌根的生态学研究进展

兰科植物(Orchidaceae)是典型的菌根植物,自然条件下其种子的成功萌发和生长的早期阶段对菌根真菌有绝对的依赖性,在有些成年兰科植物中菌根真菌仍起着重要的作用。目前大部分兰科植物已为濒危物种,鉴于兰科植物天然的菌根共生关系,开展兰科植物和菌根真菌互作的生态学研究不仅具有极高的科研价值,更有助于兰科植物的物种保护和野生种群的生态恢复。近年研究表明,兰科植物对真菌的选择和二者共生关系的建立与菌根真菌的空间分布和丰度密切相关,然而当前对自然环境中兰科菌根真菌的实际分布还了解甚少,因此文章从生态学角度系统分析兰科植物与菌根真菌的关系,探讨该领域的研究热点,旨在为兰科菌根的生态学研究提供参考。     

羊肚菌白霉病发生对土壤真菌群落结构的影响

【目的】了解羊肚菌白霉病发生对土壤真菌群落结构的影响。【方法】采用Illumina Mi Seq高通量测序技术,对未栽培羊肚菌土壤、正常生长羊肚菌和染白霉病羊肚菌根际土真菌群落结构进行研究。【结果】9个样品共得到393 347条有效序列。未栽培羊肚菌土壤真菌多样性指数和丰度显著大于羊肚菌根际土,染病羊肚菌根际真菌丰度和多样性大于正常生长的羊肚菌,各样品的群落组成和优势类群有较大差异。【结论】羊肚菌栽培后真菌多样性降低,白霉病发生后根际真菌种类增多,土壤真菌群落结构发生变化,优势真菌类群也产生了较大变化。     

High specificity of a rare terrestrial orchid toward a rare fungus within the North American tallgrass prairie

The Orchidaceae are globally distributed and represent a diverse lineage of obligate mycotrophic plants. Given their dependence on symbiotic fungi for germination and/or plant development, fungal community structure in substrates is expected to influence the distribution and persistence of orchid species. Yet, simultaneous characterization of orchid mycorrhizal fungal (OMF) communities in roots and in soil is rarely reported. To explain the co-distributions of OMF in roots, orchid-occupied, and bulk soil, we characterized mycorrhizal fungi associated with Platanthera praeclara over multiple years across its entire natural distribution within the North American tallgrass prairie. Root derived OMF communities included 24 Ceratobasidiaceae and 7 Tulasnellaceae operational taxonomic units (OTUs) though the orchid exhibited high spatio-temporal specificity toward a single Ceratobasidiaceae OTU, which was strongly stable across population sizes and phenological stages of the sampled individuals. The preferred OMF OTUs were primarily restricted to orchid-occupied locations while infrequent or absent in bulk soil. Variation in soil OMF assemblies was explained most by soil moisture, magnesium, manganese, and clay. In this first study of coupled root and soil OMF communities across a threatened grassland ecosystem, we report a strong relationship, further nuanced by soil chemistry, between a rare fungus and a rare orchid.     

菌根真菌与兰科植物氮营养关系的研究进展

兰科植物是典型的菌根植物。兰菌根是兰科植物根与真菌形成的菌根共生体。兰菌根真菌的营养来源影响宿主植物的生活方式和营养水平。氮是植物生长的主要限制因子。兰科植物具有富集氮的特征, 其组织和器官的氮含量通常高于同生境中的其他植物。该文综述了兰菌根真菌类别、兰科植物氮营养特征和兰菌根的氮转移机制等的研究进展, 以期为兰科植物资源的保护、再生及可持续利用的相关研究提供参考和借鉴。     

A rare temperate terrestrial orchid selects similar Tulasnella taxa in ex situ and in situ environments

Mycorrhizal symbiosis in orchids is unique in that fungal presence is considered a requirement for germination as well as for further development. Additionally, orchid fungal associations can exhibit high specificity in nature. Yet, an important ecological question remains unanswered: ‘With which orchid mycorrhizal fungi (OMF) do un-inoculated orchid seedlings form symbiosis when cultured ex situ?’ Simultaneously, it is asserted that orchid conservation efforts involving ex situ plant culture should exclusively utilize natural symbionts of the respective orchid taxa. We present a first comparison of OMF communities within the roots of asymbiotically cultured plants of the rare orchid Platanthera chapmanii grown ex situ (ES), and those occurring naturally in situ (IS). Nuclear ribosomal internal transcribed spacer (nrITS) barcoding region was used to identify peloton forming OMF from roots collected between 2012 and 2014 from both growing environments. Our 114 sequences clustered into 11 operational taxonomic units (OTUs) belonging to four closely related clades of the fungal family Tulasnellaceae. Shannon–Wiener (H) and Simpson diversity (D) indices were similar (p = 0.81 for both) for ES and IS OMF communities. Beta diversity comparisons also showed similarity between ES and IS treatments based on weighted (p = 0.10) and unweighted (p = 0.20) Bray–Curtis dissimilarity matrices. Bayesian and Maximum Likelihood (ML) phylograms clustered ES and IS derived fungal OTUs into the same clades. Our data suggest that P. chapmanii: (1) forms symbiosis with taxonomically similar fungi in ex situ culture and in its native soil, and (2) exhibits a narrow phylogenetic breadth of mycorrhizal fungal OTUs within the Tulasnellaceae.     

Phylogenetic constrains on mycorrhizal specificity in eight Dendrobium(Orchidaceae) species

Plant phylogeny constrains orchid mycorrhizal(OrM) fungal community composition in some orchids. Here, we investigated the structures of the OrM fungal communities of eight Dendrobium species in one niche to determine whether similarities in the OrM fungal communities correlated with the phylogeny of the host plants and whether the Dendrobium-OrM fungal interactions are phylogenetically conserved. A phylogeny based on DNA data was constructed for the eight coexisting Dendrobium species,and the OrM fungal communities were characterized by their roots. There were 31 different fungal lineages associated with the eight Dendrobium species. In total, 82.98% of the identified associations belonging to Tulasnellaceae, and a smaller proportion involved members of the unknown Basidiomycota(9.67%). Community analyses revealed that phylogenetically related Dendrobium tended to interact with a similar set of Tulasnellaceae fungi. The interactions between Dendrobium and Tulasnellaceae fungi were significantly influenced by the phylogenetic relationships among the Dendrobium species. Our results provide evidence that the mycorrhizal specificity in the eight coexisting Dendrobium species was phylogenetically conserved.     

摩西斗管囊霉改善连作花生根际土壤的微环境

花生(Arachis hypogaea)长期连作导致土壤环境恶化, 严重影响产量和品质。丛枝菌根真菌(AMF)作为有益真菌能够与80%的陆生植物根系形成共生关系, 这种共生体能够改善植物根系微环境, 提高植物对营养物质的吸收和对逆境胁迫的抗性。为了探究AMF对花生连作土壤微环境的影响, 该研究通过对花生连作土壤接种和未接种摩西斗管囊霉(Funneliformis mosseae)试验, 在花生不同生长期检测根际土壤的酶活性、土壤矿物质含量、土壤微生物群落结构和多度的变化情况, 以及对连作花生产量和品质的影响。研究结果表明: 1)摩西斗管囊霉能够显著提高花生根际土壤蔗糖酶、脲酶、碱性磷酸酶和硝酸还原酶的活性; 2)摩西斗管囊霉显著增加花生连作土壤中全氮、全磷、全钾、速效磷和速效钾的含量; 3)摩西斗管囊霉显著降低土壤中有害真菌曲霉菌属(Aspergillus)的多度, 减少镰刀菌属(Fusarium)和赤霉菌属(Gibberella)的多度, 但是没有达到显著水平, 显著增加有益细菌放线菌Gaiella属的多度; 4)摩西斗管囊霉显著提高连作花生的产量, 增加籽仁中蛋白质、油酸和亚油酸的含量。因此, 摩西斗管囊霉能够改善连作花生根际土壤微生态环境, 增强连作土壤对致病菌的抵抗能力, 从而缓解连作障碍对花生根系的危害。     

Continental-scale distribution and diversity of Ceratobasidium orchid mycorrhizal fungi in Australia

Background and AimsMycorrhizal fungi are a critical component of the ecological niche of most plants and can potentially constrain their geographical range. Unlike other types of mycorrhizal fungi, the distributions of orchid mycorrhizal fungi (OMF) at large spatial scales are not well understood. Here, we investigate the distribution and diversity of Ceratobasidium OMF in orchids and soils across the Australian continent.MethodsWe sampled 217 Ceratobasidium isolates from 111 orchid species across southern Australia and combined these with 311 Ceratobasidium sequences from GenBank. To estimate the taxonomic diversity of Ceratobasidium associating with orchids, phylogenetic analysis of the ITS sequence locus was undertaken. Sequence data from the continent-wide Australian Microbiome Initiative were used to determine the geographical range of operational taxonomic units (OTUs) detected in orchids, with the distribution and climatic correlates of the two most frequently detected OTUs modelled using MaxEnt.Key ResultsWe identified 23 Ceratobasidium OTUs associating with Australian orchids, primarily from the orchid genera Pterostylis, Prasophyllum, Rhizanthella and Sarcochilus. OTUs isolated from orchids were closely related to, but distinct from, known pathogenic fungi. Data from soils and orchids revealed that ten of these OTUs occur on both east and west sides of the continent, while 13 OTUs were recorded at three locations or fewer. MaxEnt models suggested that the distributions of two widespread OTUs are correlated with temperature and soil moisture of the wettest quarter and far exceeded the distributions of their host orchid species.ConclusionsCeratobasidium OMF with cross-continental distributions are common in Australian soils and frequently have geographical ranges that exceed that of their host orchid species, suggesting these fungi are not limiting the distributions of their host orchids at large spatial scales. Most OTUs were distributed within southern Australia, although several OTUs had distributions extending into central and northern parts of the continent, illustrating their tolerance of an extraordinarily wide range of environmental conditions.     

Mycorrhizal fungal community composition in seven orchid species inhabiting Song Mountain,Beijing, China

Mycorrhizal fungi play an important role in the germination and growth of orchids essentially influencing their survival,abundance, and spatial distribution. In this study, we investigated the composition of the mycorrhizal fungal community in seven terrestrial orchid species inhabiting Song Mountain, Beijing, China, using Illumina MiSeq high-throughput sequencing. The mycorrhizal communities in the seven orchids were mainly composed of members of the Ceratobasidiaceae, Sebacinales, and Tulasnellaceae, while a number of ectomycorrhizal fungi belonging to the Russulaceae, Tricholomataceae, Thelephoraceae, and Cortinariaceae were occasionally observed. However, the dominant fungal associates and mycorrhizal community differed significantly among the orchid species as well as subhabitats. These findings confirm the previous observation that sympatric orchid species show different preferences for mycorrhizal fungi, which may drive niche partitioning and contribute to their cooccurrence.     

Can orchid mycorrhizal fungi be persistently harbored by the plant host?

The environmental distribution of non-obligate orchid mycorrhizal (OM) symbionts belonging to the ‘rhizoctonia’ complex remains elusive. Some of these fungi, indeed, are undetectable in soil outside the host rhizosphere. A manipulation experiment was performed to assess the importance of neighbouring non-orchid plants and soil as possible reservoirs of OM fungi for Spiranthes spiralis, a widespread photosynthetic European terrestrial orchid species. Fungi of S. spiralis roots were identified by DNA metabarcoding before and 4 months after the removal of the surrounding vegetation and soil. Although such a treatment significantly affected fungal colonization of newly-formed orchid roots, most OM fungi were consistently associated with the host roots. Frequency patterns in differently aged roots suggest that these fungi colonize new orchid roots from either older roots or other parts of the same plant, which may thus represent an environmental source for the subsequent establishment of the OM symbiosis.     

A narrowly endemic photosynthetic orchid is non‐specific in its mycorrhizal associations

Mycorrhizal association is a common characteristic in a majority of land plants, and the survival and distribution of a species can depend on the distribution of suitable fungi in its habitat. Orchidaceae is one of the most species‐rich angiosperm families, and all orchids are fully dependent on fungi for their seed germination and some also for subsequent growth and survival. Given this obligate dependence, at least in the early growth stages, elucidating the patterns of orchid–mycorrhizal relationships is critical to orchid biology, ecology and conservation. To assess whether rarity of an orchid is determined by its specificity towards its fungal hosts, we studied the spatial and temporal variability in the host fungi associated with one of the rarest North American terrestrial orchids, Piperia yadonii. The fungal internal transcribed spacer region was amplified and sequenced by sampling roots from eight populations of P. yadonii distributed across two habitats, Pinus radiata forest and maritime chaparral, in California. Across populations and sampling years, 26 operational taxonomic units representing three fungal families, the Ceratobasidiaceae, Sebacinaceae and Tulasnellaceae, were identified. Fungi belonging to the Sebacinaceae were documented in orchid roots only at P. radiata forest sites, while those from the Ceratobasidiaceae and Tulasnellaceae occurred in both habitats. Our results indicate that orchid rarity can be unrelated to the breadth of mycorrhizal associations. Our data also show that the dominance of various fungal families in mycorrhizal plants can be influenced by habitat preferences of mycorrhizal partners.