Wetland dicots and monocots differ in colonization by arbuscular mycorrhizal fungi and dark septate endophytes

As an initial step towards evaluating whether mycorrhizas influence composition and diversity in calcareous fen plant communities, we surveyed root colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytic fungi (DSE) in 67 plant species in three different fens in central New York State (USA). We found colonization by AMF and DSE in most plant species at all three sites, with the type and extent of colonization differing between monocots and dicots. On average, AMF colonization was higher in dicots (58±3%, mean±SE) than in monocots (13±4%) but DSE colonization followed the opposite trend (24±3% in monocots and 9±1% in dicots). In sedges and cattails, two monocot families that are often abundant in fens and other wetlands, AMF colonization was usually very low (<10%) in five species and completely absent in seven others. However, DSE colonization in these species was frequently observed. Responses of wetland plants to AMF and DSE are poorly understood, but in the fen communities surveyed, dicots appear to be in a better position to respond to AMF than many of these more abundant monocots (e.g., sedges and cattails). In contrast, these monocots may be more likely to respond to DSE. Future work directed towards understanding the response of these wetland plants to AMF and DSE should provide insight into the roles these fungal symbionts play in influencing diversity in fen plant communities.     

Red list plants: colonization by arbuscular mycorrhizal fungi and dark septate endophytes

Since information concerning the mycorrhization of endangered plants is of major importance for their potential re-establishment, we determined the mycorrhizal status of Serratula tinctoria (Asteraceae), Betonica officinalis (Lamiaceae), Drosera intermedia (Droseraceae) and Lycopodiella inundata (Lycopodiaceae), occurring at one of two wetland sites (fen meadow and peat bog), which differed in soil pH and available P levels. Root colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) was quantified. Colonization by AMF appeared to be more frequent in the fen meadow than in the peat bog, and depended on the host plant. Roots of S. tinctoria and B. officinalis were well colonized by AMF in the fen meadow (35–55% root length) and both arbuscules and vesicles were observed to occur in spring as well as in autumn. In the peat bog, L. inundata showed a low level of root colonization in spring, when vesicles were found frequently but no arbuscules. In roots of D. intermedia from the peat bog, arbuscules and vesicles were observed, but AMF colonization was lower than in L. inundata. In contrast, the amount of AMF spores extracted from soil at the peat bog site was higher than from the fen meadow soil. Spore numbers did not differ between spring and autumn in the fen meadow, but they were higher in spring than in autumn in the peat bog. Acaulospora laevis or A. colossica and Glomus etunicatum were identified amongst the AMF spores extracted from soil at the two sites. S. tinctoria and B. officinalis roots were also regularly colonized by DSE (18–40% root length), while L. inundata was only rarely colonized and D. intermedia did not seem to be colonized by DSE at all.     

丛枝菌根真菌与深色有隔内生真菌生态修复功能与作用

生态修复是目前全球关注的热点问题,如何增加植被的覆盖度及生态修复效率是目前研究的重点。丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)和深色有隔内生真菌(dark septate endophyte,DSE)均是自然界植物根际分布广泛的一类内生真菌,均能与植物形成菌根共生体,具有一定的促进植物生长、抵抗逆境及修复污染土壤等功能与作用,在生态修复中具有广泛的应用潜力。本文综述了AMF及DSE两种微生物的功能、作用及其在生态修复应用中的研究进展,并进一步对AMF和DSE在生态修复中存在的问题和前景进行展望。     

Occurrence and coexistence of arbuscular mycorrhizal fungi and dark septate fungi in aquatic macrophytes in a tropical river-floodplain system

In this study, carried out in four water bodies in the Upper Paraná River floodplain, we assessed the occurrence of root colonization by arbuscular mycorrhizal fungi (AMF) and dark septate fungi (DSF), as well as the AMF species richness associated with 24 species of aquatic macrophytes belonging to different life forms. AMF were found in nine species of macrophytes and DSF in 16 species among the 24 investigated. AM colonization occurred mainly in eudicotiledons (five of the six species evaluated) and the Paris morphology was the most common type. Co-occurrence of AMF and DSF was observed in seven species of macrophytes (Commelinaceae sp. 1, Limnobium laevigatum (H.B.K. ex Willd) Heine, Hygrophila cf. costata, Myriophyllum brasiliense (Camb), Polygonum acuminatum Kunth, P. ferrugineum Wedd and P. stelligerum Cham). Four species of macrophytes (Pistia stratiotes L., Eichhornia crassipes (Mart.) Solms, Egeria najas Planch and Nymphaea amazonum Mart. & Zucc) were not colonized by any type of fungi. In total, 27 morphotypes of AMF were recorded, and spores occurred both in the rhizosphere of macrophytes whose roots were internally colonized by AMF and in non-colonized macrophytes. Acaulospora delicata, Acaulospora aff. laevis, Acaulospora longula, Glomus lamellosum, Glomus luteum and NID 1 (a non-identified species) were the most frequent species. Samples collected close to the roots of N. amazonum had the highest AMF richness (20 species), but this plant was not colonized by fungi. A species richness curve indicated that more root-associated fungi than reported here are likely present in this floodplain.     

荒漠北沙柳根系丛枝菌根真菌和黑隔内生真菌定殖状况

为利用土壤共生真菌资源促进荒漠植被恢复和生态重建, 分别于2013年6月、8月和10月, 从内蒙古元上都地区采集北沙柳(Salix psammophila)根围0-10、10-20、20-30、30-40和40-50 cm共5个土层的土壤样品, 系统研究了丛枝菌根真菌(AMF)和黑隔内生真菌(DSE)的时空分布及其与土壤因子的相关性。结果表明: AMF和DSE的平均定殖率分别为77%和84%, 说明北沙柳根系能与这两类真菌形成良好的共生关系。AMF和DSE的分布和定殖具有明显的时空异质性, 并与土壤因子密切相关。AMF和DSE的平均定殖率均表现为10月> 8月> 6月。土壤深度对AMF和DSE的定殖率有显著影响, AMF和DSE定殖率的最大值分别在0-20 cm和0-10 cm土层。双因子方差分析表明, 月份和土层对AMF和DSE的定殖率以及土壤因子具有显著的交互效应。主成分分析表明, 土壤湿度、pH值、碱性磷酸酶、易提取球囊霉素是内蒙古荒漠环境中AMF和DSE定殖的主要影响因子。     

丛枝菌根真菌与深色有隔内生真菌对姜瘟病的防效及抗病机理初探

【背景】青枯劳尔氏菌(Ralstonia solanacearum,R.S)引发的姜瘟病是生姜产业发展的瓶颈问题。丛枝菌根真菌(arbuscular mycorrhiza fungi, AMF)与深色有隔内生真菌(dark septate endophytes,DSE)是两类重要的共生微生物。【目的】前期研究发现,AMF与DSE可提高生姜对姜瘟病的抗性,但其抗病机制尚不清楚,极大地限制了利用这两类共生真菌对该病的防治。【方法】在温室条件下做盆栽试验,以生姜组培苗为材料,设立接种AMF、DSE和不接种AMF、DSE的对照(CK)处理,并在上述处理下的植物生长4周后淋入病原菌液,病原菌接种1周后,通过测定菌根侵染率、发病率、叶绿素含量、光合指标、磷(P)含量、防御性酶活性及丙二醛(malondialdehyde, MDA)含量,研究AMF和DSE互作对病原菌侵染后生姜生长和生理生化指标的影响。【结果】AMF和DSE分别使姜瘟病发病率降低了45.27%和52.04%(P<0.05)。AMF+DSE组合处理抑病效果更好,发病率较对照降低60.87%(P<0.05)。AMF、DSE及...     

Impact of dark septate endophytes on tomato growth and nutrient uptake

ABSTRACT

Background

Dark septate endophytes (DSEs) represent a form-group of ascomycetous fungi that inhabit the roots of a wide range of plant species, but our knowledge on their interaction with the host plants is still limited.     

设施栽培黄瓜根内AMF与DSE结构发育特征

本研究旨在观察和测定设施栽培黄瓜根系丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)与暗隔内生真菌(dark septate endophytic fungi,DSE)形态结构,明确其发育特征,为进一步探索AMF与DSE相互作用奠定基础。自山东莱阳、寿光和莱西等设施蔬菜主产区选择黄瓜Cucumis sativus样地,从不同连作年限、黄瓜生育期和土层深度分别采集黄瓜根系和根区土壤;观察根内AMF与DSE形态特征、测定AMF和DSE侵染数量、分析AMF或DSE侵染发育数量与黄瓜根结线虫Meloidogyne incognita病害的相关性。从黄瓜根系中可观察到典型的AMF泡囊、疆南星型(Arum,A)与重楼型(Paris,P)丛枝结构、DSE菌丝和微菌核。以黄瓜结果中期根系AMF和DSE侵染率最高,分别为57%和28%,苗期最低,分别为18%和8%;初花期的丛枝为P型,苗期和结果中期则为A型+P型。连作7年和7–10年的黄瓜根内丛枝为A型+P型,AMF和DSE的侵染率均分别显著高于连作10年的侵染率,连作10年的丛枝为A型。黄瓜根系以0–15cm土层中AMF侵染率最高(29%),丛枝为P型;以30cm的侵染率最低(12%),丛枝为A型;15–30cm土层的为A型+P型。AMF P型着生率、P/A比率和DSE侵染率分别与根结线虫病的为害程度具有相关性。研究结果还表明黄瓜根系AMF侵染率与DSE侵染率呈显著正相关关系。     

Effects of mowing on fungal endophytes and arbuscular mycorrhizal fungi in subalpine grasslands

In French subalpine grasslands, cessation of mowing promotes dominance of Festuca paniculata, which alters plant diversity and ecosystem functioning. One of the mechanisms underpinning such effects may be linked to simultaneous changes in the abundance of fungal symbionts such as endophytes and arbuscular mycorrhizal fungi. In field conditions, mowing reduced the abundance of the endophyte Neotyphodium sp. in leaves of F. paniculata by a factor of 6, and increased mycorrhizal densities by a factor of 15 in the soil. In greenhouse experiments, the mycorrhizal colonization of Trifolium pratense and Allium porrum increased 3- fold and 3.8- fold respectively in mown vs unmown grassland soil. Significantly reduced growth of the two host plants was also observed on soil from the unmown grassland. Such opposite effects of mowing on the two functional groups of fungal symbionts could suggest interactions between these two groups, which in turn could contribute to structuring plant communities in subalpine grasslands.     

Dark septate endophyte and arbuscular mycorrhizal status of vegetation colonizing a bottomland hardwood forest after a 100 year flood

Levels of arbuscular mycorrhizal (AM) colonization and dark septate endophyte (DSE) colonization were assessed in the vegetation recolonizing a remnant bottomland hardwood forest in north central Texas following a 100 year flood. Thirty seven plant species representing 21 dicotyledonous and 2 montocotyledonous families established following floodwater recession. AM and/or DSE were found in all species. AM colonization was found in 31 out of the 37 species assessed including both monocotyledonous families (Poaceae and Cyperaceae) and 17 out of 21 dicotyledonous families (Acanthaceae, Asteraceae, Boraginaceae, Cucurbitaceae, Euphorbiaceae, Lamiaceae, Loganiaceae, Lythraceae, Malvaceae, Onagraceae, Pedaliaceae, Ranunculaceae, Sapindaceae, Scrophulariaceae, Solanaceae, Verbanaceae and Violaceae). DSE were found in 31 out of 37 species assessed including both monocotyledonous families and 15 out of 21 dicotyledonous families (Amaranthaceae, Asteraceae, Boraginaceae, Brassicaceae, Cucurbitaceae, Euphorbiaceae, Lamiaceae, Lythraceae, Malvaceae, Pedaliaceae, Phytolaccaceae, Polygonaceae, Ranunculaceae, Sapindaceae, Scrophulariaceae and Violaceae). There were no detectable differences in AM or DSE colonization levels among wetland indicator groups (p > 0.05). Levels of DSE colonization were negatively correlated with vesicular colonization and hyphal colonization for the obligate wetland species. There were no other significant relationships between AM and DSE colonization detected. Spearman rank order correlation coefficients did not differ significantly among wetland indicatory category for any level of AM or DSE colonization.     

宁夏枸杞深色有隔内生真菌的侵染特征及多样性

【背景】枸杞是享誉中外的名贵药材,深色有隔内生真菌(Dark septate endophytes,DSE)是枸杞内生真菌的重要组成部分。【目的】从宁夏枸杞栽培品种和野生品种的根系分离获得DSE菌株,研究枸杞DSE的群落组成、物种多样性及在宿主植物内的侵染定殖情况。【方法】从宁夏枸杞栽培园采集栽培品种宁杞1号、宁杞3号、宁杞5号、宁杞6号、宁杞7号、宁杞8号以及野生品种黄果枸杞和黑果枸杞共8个枸杞品种的根系,分离DSE菌株,运用形态学特征、r DNA-ITS序列分析进行菌株鉴定,采用回接试验方法确定DSE真菌。【结果】DSE在枸杞根系能形成大量"微菌核"典型结构。从8个枸杞品种根系中共分离获得DSE菌株279株,分属于18个属,具有丰富的物种多样性。镰刀菌属(Fusarium)为各品种的共有属和优势属,相对频率最高达85%。Monosporascus、蓝状菌属(Talaromyces)和俄氏孔菌属(Earliella)为枸杞内首次报道的DSE。枸杞不同品种中DSE群落物种多样性指数、均匀度指数和Simpson指数差异显著。【结论】DSE在枸杞栽培品种及野生品种中具有丰富的生物多样性,能够与枸杞根系形成良好的共生关系,增强了枸杞对生态环境的适应性。     

The incidence of arbuscular mycorrhiza in two submerged Isoëtes species

We investigated the occurrence of arbuscular mycorrhizal fungi in the roots of Isoëtes lacustris and I. echinospora. These submerged lycopsids are the only macrophyte species inhabiting the bottom of two acidified glacial lakes in the Czech Republic. Arbuscular mycorrhizal (AM) fungi were detected in the roots of both species but the percentage of root colonization was both low and variable. Nevertheless, planting Littorella uniflora in the sediments from Isoëtes rhizosphere revealed high levels of viable AM propagules in both lakes. While AM colonization of Isoëtes roots did not exceed 25%, the average colonization of Littorella roots amounted to more than 80%. Although colonization of quillwort roots by AM fungi is evident, the taxonomic identity and role of these AM fungi in plant growth remain unclear. In addition to AM fungi, root-colonizing dark septate endophytic fungi were observed in both Isoëtes species.     

Molecular and cell biology of arbuscular mycorrhizal symbiosis

The roots of most extant plants are able to become engaged in an interaction with a small group of fungi of the fungal order Glomales (Glomeromycota). This interaction—arbuscular mycorrhizal (AM) symbiosis—is the evolutionary precursor of most other mutualistic root-microbe associations. The molecular analysis of this interaction can elucidate basic principles regarding such associations. This review summarizes our present knowledge about cellular and molecular aspects of AM. Emphasis is placed on morphological changes in colonized cells, transfer of nutrients between both interacting partners, and plant defence responses. Similarities to and differences from other associations of plant and microorganisms are highlighted regarding defence reactions and signal perception.     

中国大陆地区丛枝菌根真菌菌种资源的分离鉴定与形态学特征

【目的】分离收集保藏中国大陆各个地区不同生态环境的丛枝菌根真菌菌种资源,为丛枝菌根的研究提供资源、奠定基础。【方法】以高粱为宿主植物,采用诱导培养、单孢培养和扩繁培养分离土壤样品中的丛枝菌根真菌菌种并鉴定。【结果】从我国大陆的45个地区50余种宿主植物根区土壤中分离到丛枝菌根真菌135株,隶属于23个种;对各个菌株的形态特征进行了描述。【结论】我国蕴藏着丰富的丛枝菌根真菌菌种资源,文中描述的菌种资源是目前从我国大陆地区获得的种类和数量最多、覆盖范围最广的AM真菌菌种资源。     

Dark septate endophytes: a review of facultative biotrophic root-colonizing fungi

Dark septate root endophytes (DSE) are conidial or sterile fungi (Deuteromycotina, Fungi Imperfecti) likely to be ascomycetous and colonizing plant roots. They have been reported for nearly 600 plant species representing about 320 genera and 100 families. DSE fungi occur from the tropics to arctic and alpine habitats and comprise a heterogeneous group that functionally and ecologically overlaps with soil fungi, saprotrophic rhizoplane-inhabiting fungi, obligately and facultatively pathogenic fungi and mycorrhizal fungi. Numerous species of undescribed sterile and anamorphic taxa may also await discovery. Although DSE are abundant in washed root and soil samples from various habitats, and are easily isolated from surface-sterilized roots of ecto-, ectendo-, endo- and non-mycorrhizal host species, their ecological functions are little understood. Studies of DSE thus far have yielded inconsistent results and only poorly illustrate the role of DSE in their natural habitats. These inconsistencies are largely due to the uncertain taxonomic affinities of the strains of DSE used. In addition, because different strains of a single anamorph taxon seem to vary greatly in function, no clear generalizations on their ecological role have been drawn. This paper reviews the current literature on DSE and the ecology and discusses the need for and direction of future research.     

Arbuscular mycorrhizal morphology and dark septate fungal associations in medicinal and aromatic plants of Western Ghats, Southern India

We investigated roots of 107 medicinal and aromatic plants (MAPs) in the Western Ghats region of Southern India for arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) associations. Of the 107 MAPs belonging to 98 genera in 52 families examined, 79 were AM and 38 harbored a DSE association. Typical Arum- and Paris-type mycorrhizas are first reported in the presumed nonmycorrhizal family Amaranthaceae. Similarly, DSE associations are recorded for the first time in nine plant families and 37 plant species. Thirty MAPs had both AM and DSE associations. The number of MAPs having Arum-type mycorrhiza was greater than those having Paris-type. This was more prominent among herbaceous plants than in trees where the Paris-type was predominant. Similarly, the Arum-type was more prevalent in annuals than in perennials. DSE associations were more frequent in herbs and perennials compared to other MAPs.     

丛枝菌根真菌-豆科植物-根瘤菌共生体系的研究进展

丛枝菌根真菌（Arbuscular Mycorrhizal Fungi,AMF）-豆科植物-根瘤菌（Rhizobia）三者形成的共生体。是植物与微生物共生中的一种特殊类型。本文对这种共生体中微生物与植物之间的营养关系;AMF和根瘤菌双接种豆科植物的效应以及影响双接种效应的因素;AMF和根瘤菌在与豆科植物形成共生过程中的分子互作机制等进行了综述。同时对这种共生体还需进一步研究的问题及其在基础研究和实践应用方面的前景进行了讨论。     

接种AMF和DSE对蛋白桑提质增产效应的影响

【目的】探究丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)和深色有隔内生真菌(dark septate endophyte,DSE)对蛋白桑(Morus alba)产量及品质的影响。【方法】采用盆栽试验,以丛枝菌根真菌和深色有隔内生真菌为微生物处理菌剂,通过设置单接种DSE、单接种AMF和联合接种DSE+AMF 3种不同微生物组合研究对蛋白桑生长、产量和品质等影响,探索微生物菌剂对生态饲料作物蛋白桑的经济潜力。【结果】与未接菌处理(CK)相比,3种接菌处理均能显著促进蛋白桑地上部生长,提高地上部生物量,增加幅度为156.4%‒196.6%;接菌微生物提高了蛋白桑的光合速率,增加了植物叶片氮、磷、钾的累积,提高蛋白桑的产量。接种微生物会使蛋白桑叶粗蛋白含量提升,降低饲料纤维营养价值,从而综合改善蛋白桑品质。微生物处理能够显著增加蛋白桑的叶茎比,提升了蛋白桑叶片的比例,优化生长结构,不同微生物处理对蛋白桑叶片各饲用品质指标的影响较其相应茎部更为明显,可以根据桑叶和茎秆的蛋白含量进行合理搭配获得饲料不同品级,从整体水平上提升蛋白桑地上部植株的饲用品质。接种微生物均对蛋白桑饲用品质等级得到极大提升,显著降低了酸性洗涤纤维和中性洗涤纤维含量,降低幅度分别为18.4%‒34.6%和41.0%‒45.4%;接菌处理各蛋白桑的相对饲用价值范围在220.0‒241.5,显著提高0.8‒1.0倍,且维生素C含量、含糖量和生物碱含量等均有增加。【结论】采用主成分分析方法,按照对蛋白桑产量和品质的综合影响大小的贡献排序,依次为:AMF+DSE>DSE>AMF>CK,DSE可作为采煤沉陷区生物修复中经济作物蛋白桑的优选微生物菌剂,能促进蛋白桑的产量并提升品质。     

The arbuscular mycorrhizal symbiosis links N mineralization to plant demand

Arbuscular mycorrhizal (AM) fungi facilitate inorganic N (NH₄ ⁺ or NO₃ ⁻) uptake by plants, but their role in N mobilization from organic sources is unclear. We hypothesized that arbuscular mycorrhizae enhance the ability of a plant to use organic residues (ORs) as a source of N. This was tested under controlled glasshouse conditions by burying a patch of OR in soil separated by 20-μm nylon mesh so that only fungal hyphae can pass through it. The fate of the N contained in the OR patch, as influenced by Glomus claroideum, Glomus clarum, or Glomus intraradices over 24 weeks, was determined using ¹⁵N as a tracer. AM fungal species enhanced N mineralization from OR to different levels. N recovery and translocation to Russian wild rye by hyphae reached 25% of mineralized N in G. clarum, which was most effective despite its smaller extraradical development in soil. Mobilization of N by G. clarum relieved plant N deficiency and enhanced plant growth. We show that AM hyphae modify soil functioning by linking plant growth to N mineralization from OR. AM species enhance N mineralization differentially leading to species-specific changes in the quality of the soil environment (soil C-to-N ratio) and structure of the soil microbial community.