罗汉果内生真菌多样性研究

该文采用传统形态学方法结合r DNA-ITS序列分析,对我国重要药用植物罗汉果中的内生真菌进行了鉴定并研究其多样性。结果表明:采用组织培养法从罗汉果健康植株中共分离得到150株内生真菌,包括罗汉果中雌株的内生真菌96株、雄株的内生真菌54株。122株内生真菌经形态学结合r DNA-ITS序列分析鉴定为9个属,均归属为子囊菌门,包含座囊菌纲(Dothideomycetes)和子囊菌纲(Sordariomycetes)。其中,座囊菌纲(Dothideomycetes)真菌包含3科、3属;子囊菌纲(Sordariomycetes)真菌包含6科、6属。优势属为刺盘孢属(Colletotrichum)和镰刀菌属(Fusarium)。罗汉果雌、雄植株不同组织中内生真菌的定殖率及分离率的变化规律均不相同,雌株中以根中内生真菌的定殖率和分离率最高,叶片中的最低;在雄株中以叶片中的定殖率和分离率最高,根中的最低。不同菌株在雌、雄两种植株的不同组织中的分布均不同,结合内生真菌群落组成的相似性比较结果,表明部分内生真菌对罗汉果雌株和雄株,以及同一植株中的不同组织均具有偏好性。不同组织中内生真菌的多样性指数在0.11~0.69的范围,其中雌株根部的内生真菌多样性指数最高。以上研究结果为后期探究内生真菌与罗汉果互作关系奠定了基础。     

内生真菌感染对宿主羊草抗病性的影响

以感染内生真菌的天然禾草羊草为实验材料,通过体外纯培养条件下的内生真菌、感染内生真菌的离体叶片和在体叶片对3种病原菌的抑菌实验,以探讨内生真菌对宿主植物羊草在抗病性方面的贡献。结果表明:体外纯培养条件下,分离自羊草的内生真菌Epichlobromicola对新月弯孢(Curvularia lunata)、根腐离蠕孢(Bipolaris sorokiniana)和枝孢霉(Cladosporium sp.)这3种病原菌都具有抑制作用,抑菌率分别达56.22%,46.93%和45.15%,且内生真菌培养滤液可以有效抑制这3种病原菌的孢子萌发,平均萌发率分别为30.4%,15.7%和16.4%;宿主植物叶片在离体条件下,内生真菌感染可以有效降低羊草叶片受C.lunata和C.sp.侵染后的病斑数或病斑长度,但对B.sorokiniana不起作用,甚至提高了叶片的病斑数及病斑长度,而离体叶片提取液对不同病原菌均有不同程度的抑制作用;在体条件下,内生真菌均可以通过降低叶片病斑数来增强羊草植株对这3种病原菌的抗性。由此看来,内生真菌E.bromicola对宿主植物羊草在抗病原菌侵染方面有一定的增益作用。     

钾矿区海金沙内生真菌多样性及生态分布研究

为探明不同钾矿区同种植物内生真菌的物种多样性、群落组成以及生态分布规律, 运用传统组织分离方法与分子生物学方法相结合, 对3 个不同钾矿区(龙南安基山、南京小龙山、黎川龙安)的海金沙居群地采样, 进行了海金沙内生真菌的分离频率、种类组成、多样性和生态分布分析, 同时与非钾矿区(庐山莲花洞)海金沙内生真菌进行对比分析。结果表明: 从海金沙1200 个组织块中分离出477 株内生真菌, 其中产孢菌株229 株, 占总数48 %, 不产孢菌248 株, 占52%。根据形态学特征和形态型菌株的rDNA 的18S 基因和ITS 序列的相似性比较和分子系统发育分析确定477 菌株中438 菌株鉴定隶属于Alternaria、Colletotrichum、Fusarium、Peniccillium 等75 个分类单元, 还有39 株不产孢类群无法鉴定。在真菌属的水平, 以Colletotrichum (20.96%)、Fusarium (11.32%)和Alternaria (8.81%)为优势菌群。从分离频率来看, 不同钾矿区内生真菌出现频率存在差异, 各矿区内生真菌菌群之间的相似性低, 相似性系数(Cs)在0.07-0.30 之间。钾矿区海金沙内生真菌出现频率高于非钾矿区, 非钾矿区(莲花洞)菌株分离频率为19.08%, 而在钾矿区中南京分离频率最高(33.33%)。在宿主组织中, 海金沙叶片、叶柄和根状茎等不同组织部位内生真菌在数量、种群分布以及优势种群等方面存在较大差异, 叶柄(44.44%)>叶片(39.41%)>根状茎(16.15%), 在各个组织部位的优势类群分布也存在一定的差异。形成内生真菌分布差异性与不同地理位置、气候因素、土壤理化性质和宿主植物组织的生理状况以及化学组成变化等密切相关。     

烟草内生真菌多样性和种群结构

从云南“世界烟草品种园”10种烟草的根、茎、叶中分离得到199株内生真菌,根据rDNA-ITS系统发育分析鉴定为17属25种,其中格孢腔菌目Pleosporales内生真菌的种类和数量最多;茎点霉属Phoma、链格孢属Alternaria和镰孢菌属Fusarium为主要优势属,相对频率分别为25.1%、24.6%和11.6%,优势度Y值分别为0.251、0.172和0.104。烟草不同组织内生真菌的种群结构存在显著差异,分离自根的内生真菌的主要优势属为Fusarium和Phoma,Y值分别为0.235和0.123;分离自茎的内生真菌的主要优势属为Phoma和Alternaria,Y值分别为0.186和0.155;分离自叶片的内生真菌的主要优势属为Alternaria,Y值为0.286。Phoma从烟草根茎叶中均可分离得到,而Alternaria只分布在地上部茎叶中,Fusarium只分布在根茎中,表明这3个优势属真菌对根茎叶组织的专化性不同。     

内生真菌对羽茅抗病性的影响

为探讨不同种类内生真菌对宿主植物羽茅(Achnatherum sibiricum)抗病性的影响, 以感染不同内生真菌的天然禾草羽茅为实验材料, 进行了体外纯培养的内生真菌、感染内生真菌的离体叶片和在体叶片对3种植物病原真菌的抑菌实验。结果表明: 体外纯培养条件下, 分离自羽茅的内生真菌Neotyphodium sibiricum、Neotyphodium gansuensis和Epichloë gansuensis对新月弯孢霉(Curvularia lunata)、根腐离蠕孢(Bipolaris sorokiniana)和枝孢霉(Cladosporium sp.)等3种病原真菌都具有抑制作用, 其中N. sibiricum的抑制作用最强, 对新月弯孢霉、根腐离蠕孢和枝孢霉的抑菌率分别为47.8%、40.1%、39.4%; 内生真菌培养滤液也可以有效抑制这3种病原真菌的孢子萌发, 其中N. gansuensis的抑制作用最强, 新月弯孢、根腐离蠕孢和枝孢霉的孢子萌发率分别为9.8%、8.7%、8.5%。对于离体叶片, N. sibiricum和N. gansuensis感染可以有效降低叶片受3种病原真菌侵染后的病斑数和孢子浓度, 其中N. sibiricum对根腐离蠕孢的抑制作用显著高于N. gansuensis, 而E. gansuensis只降低新月弯孢和枝孢霉侵染的病斑数以及枝孢霉侵染的孢子浓度。在体条件下, 内生真菌均可以显著降低病原真菌侵染羽茅后的病斑数、病斑长度和孢子浓度, 其中E. gansuensis的抑菌作用趋于最弱, 而N. sibiricum的抑菌作用趋于最强。     

小黄花茶内生真菌的多样性分析及抑菌活性初筛

为探究小黄花茶内生真菌种类和种群分布规律以及对植物病原真菌的抑制作用,该研究采用组织分离法对小黄花茶内生真菌进行分离纯化,基于形态学和分子生物学进行鉴定并结合统计学分析评价其多样性,再通过平板对峙法筛选出具有抑菌活性的菌株。结果表明：(1)从小黄花茶324份组织块中分离得到内生真菌261株,隶属1门5纲9目22属,其中优势属包括炭疽菌属(Colletotrichum)、间座壳属(Diaporthe)、拟盘多毛孢属(Pestalotiopsis),分离频率分别为21.84%、16.86%、10.34%。(2)研究发现小黄花茶内生真菌在不同季节分布不同,冬季分离出的菌株数量最多,为72株(占27.59%,隶属16个属),春季62株(隶属13个属),夏季59株(隶属15个属),秋季68株(隶属13个属),冬季的香农-维纳指数(H′)、辛普森指数(D)、Pielou’s均匀度指数(E)和Margalef’s丰富度指数(M)最高,春季与冬季内生真菌种类相似性较高,夏季与秋季内生真菌种类相似性较高。(3)小黄花茶内生真菌不同部位分布不同,茎中内生真菌的分布最多,有102株(占39.08%,隶属15...     

量天尺根部内生真菌的多样性

为了解不同量天尺（火龙果）品种根部内生真菌菌群组成及多样性,采集GHL-1、GHL-2、GHL-3、ML-1和DL 5个量天尺品种健康根部样品,进行内生真菌分离,采用形态观察和ITS序列分析相结合的方法进行鉴定、归类。共分离得到内生真菌菌株117株,总体分离率为25.71%,分别隶属于13个属,其中Trichoderma、Fusarium、Chaetomium和Phoma为量天尺内生真菌的优势种群,分别占总菌株数的24.79%、35.04%、10.26%和10.26%;不同量天尺品种内生真菌的结构和组成存在一定差异,GHL-2、GHL-3和DL 3个品种中分离频率最高的内生真菌类群为Fusarium,GHL-1和ML-1分离频率最高的类群为Trichoderma;多样性分析结果反映出不同量天尺品种内生真菌菌群的多样性指数、丰富度指数和均匀度指数水平存在差异,其中GHL-2的3项指数均为最高。表明品种差异对内生真菌的组成和多样性均有影响。     

云南大理烟区烟叶内生真菌多样性及分布特征

【目的】研究大理烟区烟叶内生真菌的多样性及分布特征。【方法】通过形态特征和ITS-rDNA序列分析对获得的菌株进行分类。【结果】从烟草叶片中共分离得到内生真菌1 568株,分别归于31个属,在属水平上的优势菌群为链格孢属(Alternaria)和镰孢属(Fusarium),分别占真菌总数的40.79%和18.73%。【结论】烟草内生真菌的数量、种类、多样性和分布分别在不同部位叶片间和不同地区间存在差异,在下部叶数量较多,而上部叶的种类较多,多样性更丰富。随着烟草的发育成熟,内生真菌数量、种类和多样性增加,在现蕾期和成熟期最大。     

氮素水平对不同品种茶树光合及叶绿素荧光特性的影响

为探明氮素水平对不同品种茶树的光合系统的影响机制,以‘福鼎大白茶’、‘保靖黄金茶1号’、‘白毫早’两年生茶苗为材料,设置不施氮N_0(0g)、低氮N_1(11g)、中氮N_2(22g)和高氮N_3(33g)4个氮素[(NH_4)_2SO_4]水平的盆栽实验,研究了铵态氮对3个品种茶树的生长势、叶片叶绿素含量、光合参数与叶绿素荧光参数的影响。结果表明:(1)施氮处理能够显著促进茶树的生长,提高茶树叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),降低胞间CO_2浓度(Ci),并以N_2处理最好,但水分利用率(WUE)在3个品种茶树间表现不同。(2)在N_2处理下,3个茶树品种的叶片光系统Ⅱ(PSⅡ)暗适应下的最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、PSⅡ的相对电子传递速率(rETR)亦增加最大,非光化学淬灭系数(NPQ)降低。(3)茶树叶片叶绿素含量与光合参数间存在着一定的联系,并且具有品种特异性。研究发现,适量施氮能够显著增加茶树叶绿素含量、气孔导度、光合活性,从而使得各品种茶树净光合速率增加;氮素水平对各茶树品种的光合及荧光特性影响存在差异,水分利用率亦具有品种特异性;生产中应综合叶绿素含量、光合作用参数、叶绿素荧光参数,可快速、直观地评价不同品种茶树对氮素营养的内在需求,为茶园施肥管理提供指导。     

再接种内生真菌对葡萄叶内生真菌群落结构的影响

【目的】探讨回接内生真菌对葡萄叶内生真菌群落结构的影响。【方法】将葡萄叶中分离到的8株内生真菌回接到健康生长的玫瑰蜜葡萄叶片上,同时设置管理上喷施农药与未喷施农药两组处理,3个月后分析不同真菌菌剂处理后葡萄叶片内生真菌的分离率、优势度和多样性指数。【结果】5种菌剂的处理(Xylaria sp.、Nigrospora sp.、Alternaria sp.1、Alternaria sp.2和Colletotrichum sp.)在处理后的叶片中分离到了较多数量的接种菌。不同菌剂处理后葡萄叶片菌群结构差异显著。【结论】与对照处理的葡萄相比,菌剂的处理增加了叶内生真菌的分离率,但显著降低了内生真菌的多样性指数;发现喷施农药组叶片内生真菌的分离率较低,但多样性相对较高。     

Endophytic and epiphytic phyllosphere fungi of Camellia japonica: seasonal and leaf age-dependent variations

Seasonal and leaf age-dependent variations in the endophytic and epiphytic phyllosphere fungal assemblages of Camellia japonica were examined and compared. Live leaves of C. japonica were collected in four seasons (May, Aug, Nov, Feb), and fungi were isolated from healthy-looking leaves of 0, 1, 2 and 3 y old. The infection rate and total number of endophytic fungi increased May-Feb, and species richness of endophytes increased as leaves aged. In contrast the infection rate of epiphytic fungi was 100% for all leaf ages at every sampling date. The total number of epiphytic fungi isolated was greatest in May and lowest in Aug. The species richness of epiphytes did not differ significantly by season or leaf age. Eight fungal species were recorded as major phyllosphere fungi of C. japonica. Seasonal variations were detected for the frequencies of Colletotrichum gloeosporioides, C. acutatum, and epiphytes Pestalotiopsis sp.1, Aureobasidium pullulans, Phoma sp.1 and Ramichloridium sp., whereas the frequency of the endophyte Geniculosporium sp.1 varied with leaf age. The frequency of the epiphyte Cladosporium cladosporioides varied with both season and leaf age.     

Endophytic fungal diversity of 2 sand dune wild legumes from the southwest coast of India

Endophytic fungi of 3 age classes (seeds, seedlings, and mature plants) and 5 tissue classes (cotyledons, seed coats, roots, stems, and leaves) of coastal sand dune legumes Canavalia cathartica and Canavalia maritima were assessed by plating surface-sterilized segments on malt extract agar. Forty-six fungal taxa comprising 6 ascomycetes, 33 mitosporic fungi, 2 zygomycetes, and 5 sterile morphospecies were recovered. There was no significant difference in the colonization frequency of endophytes between plant species (p = 0.4098, Student's t test). Among the age classes, endophytic fungi colonized over 90% of seedlings and mature plants. Similarly, among tissue classes, endophytic fungi colonized over 90% of root, stem, and leaf segments. Diversity and richness of endophytic fungi were higher in C. cathartica than in C. maritima. Rarefaction curves revealed a "higher expected number of species" in mature plants of C. cathartica and seedlings of C. maritima, whereas it was highest in leaves of both plant species. The most dominant endophyte, Chaetomium globosum, colonized over 50% of the root, stem, and leaf segments of C. maritima and over 50% of the root segments of C. cathartica. The colonization frequency of C. globosum was found to be 5%-12.5% in seeds and increased up to 40%-64.4% in seedlings or mature plants. Halosarpheia sp. was the only marine fungus recovered among the endophytes.     

Two fungal symbioses collide: endophytic fungi are not welcome in leaf-cutting ant gardens

Interactions among the component members of different symbioses are not well studied. For example, leaf-cutting ants maintain an obligate symbiosis with their fungal garden, while the leaf material they provide to their garden is usually filled with endophytic fungi. The ants and their cultivar may interact with hundreds of endophytic fungal species, yet little is known about these interactions. Experimental manipulations showed that (i) ants spend more time cutting leaves from a tropical vine, Merremia umbellata, with high versus low endophyte densities, (ii) ants reduce the amount of endophytic fungi in leaves before planting them in their gardens, (iii) the ants'' fungal cultivar inhibits the growth of most endophytes tested. Moreover, the inhibition by the ants'' cultivar was relatively greater for more rapidly growing endophyte strains that could potentially out-compete or overtake the garden. Our results suggest that endophytes are not welcome in the garden, and that the ants and their cultivar combine ant hygiene behaviour with fungal inhibition to reduce endophyte activity in the nest.     

Impact of environmental variables on the isolation,diversity and antibacterial activity of endophytic fungal communities from Madhuca indica Gmel. at different locations in India

A total of 1,897 isolates of endophytic fungi from Madhuca indica Gmel., representing 40 morphologically distinct fungal taxa were obtained from 2,700 segments of stem, bark and leaf from three different locations (Loc 1, Loc 2 and Loc 3) in Uttar Pradesh, India. Out of 40 taxa, 28 were identified microscopically and the remaining 12 by molecular methods. Coelomycetes (62.41 %) were the most prevalent fungal group followed by hyphomycetes (28.89 %) and ascomycetes (8.70 %). Colonisation frequency (CF) was greater in stem (82.55 %) than in leaf (65.00 %) and bark (63.22 %). Due to the dominance of a few taxa, species richness and Shannon and Simpson diversity indices were lower in stem than in leaf and bark at each location. Interestingly, less rainfall and lower temperatures disfavoured the overall colonisation of fungal endophytes at Loc 2. The stem samples from all locations were very similar in their endophytic composition, whereas bark and leaf samples showed differences. The dominant endophytic fungi isolated were Phomopsis sp. 1 (9.185 %), and Colletotrichum gloeosporioides (7.00 %). Principal component analysis showed 55 % tissue specificity with 51.08 % maximum variance. Antibacterial activity revealed that 58.33 % endophytic fungi were active against at least one or more bacterial pathogens, whereas the crude extract of five endophytic fungi inhibited the growth of five or more than five (50 %) of the pathogens tested. This report illustrates the value of having an adequate sample size from different tissues and different locations for species and chemical diversity in search of novel natural products.     

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...     

茶轮斑病对茶树叶片内生真菌群落结构的影响

[目的] 茶树叶片内生真菌长期与茶树协同进化,互利共生,在生物和非生物胁迫的生态系统中对茶树起着重要的保护作用,其群落结构组成相对稳定,但在外界因素的影响下,也会发生一定的变化。然而,关于生物胁迫对茶树叶片内生真菌群落结构的影响还缺乏系统的研究。因此,对生物胁迫下叶片内生真菌群落结构的多样性研究具有重要意义。[方法] 本研究采用高通量测序技术,测序了茶轮斑病发病茶树叶片和健康茶树叶片的内生真菌ITS rRNA基因的ITS1区序列,对比分析了内生真菌的多样性和群落结构组成。[结果] 结果表明,发病组叶片的内生真菌多样性和物种丰度均低于健康组。在门分类水平上,2组样本的优势菌群均为子囊菌门（Ascomycota）,在属分类水平上,发病组的优势菌群为炭疽菌属（Colletotrichum）和假拟盘多毛孢属（Pseudopestalotiopsis）,而健康组的优势菌为枝孢属（Cladosporium）。此外,2组样本内生真菌在群落结构组成上也有显著差异,发病组中假拟盘多毛孢属（Pseudopestalotiopsis）、炭疽菌属（Colletotrichum）和节菱孢属（Arthrinium）的相对丰度显著高于健康组,健康组中被孢霉属（Mortierella）、曲霉属（Aspergillus）、织球壳菌属（Plectosphaerella）、Lectera、葡孢霉属（Botryotrichum）、青霉菌属（Penicillium）、赤霉属（Gibberella）、毛壳菌属（Chaetomium）、Lulwoana和轮枝孢属（Verticillium）的相对丰度显著高于发病组。[结论] 综上,茶轮斑病的发生改变了茶树叶片内生真菌的群落结构,使少数物种优势生长。通过研究,明确了真菌病害对茶叶内生真菌群落结构的影响,为病菌的致病机理研究奠定基础,为茶树病害防治提供理论依据。     

A comparative study of endophytic and epiphytic fungal association with leaf of <Emphasis Type="Italic">Eucalyptus citriodora</Emphasis> Hook., and their antimicrobial activity

Eucalyptus citriodora Hook, is frequently cultivated tree in India for its wood and medicinal usages. The endophytic and epiphytic fungi were estimated from healthy leaves of E. citriodora growing in the premise of Banaras Hindu University, Varanasi, India. A total of 33 fungal species were isolated from leaf segments. Of 33 taxa, 20 were recorded as endophytes, while 22 as epiphytes. Nine, out of 33 species were found to be common in leaf tissues and surfaces (Alternaria alternata, Aspergillus fumigatus, A. terreus, Cladosporium cladosporioides, Drechslera rostrata, Humicola grisea, Nigrospora oryzae, Penicillium cristata, and Pestalotia sp.). Out of 478 fungal isolates, 279 were epiphytic while only 199 were endophytic. Most isolates were anamorphic filamentous fungi which often don’t produce sexual spores. The Sorensen’s index of similarity between endophytes and epiphytes (leaf surface colonizers) was found to be at 0.300. Diversity index of fungal species was higher in endophytes than epiphytes. The frequency of colonization differs greatly in both myco-populations. Cladosporium cladosporioides (26%) was dominant species on leaf surfaces while Botrytis cinerea (10.5%) was dominant in leaf tissues. Out of 16 endophytic isolates evaluated for antagonistic test, 8 (50%) gave the antagonistic activity against variety of fungi representing pathogens to both humans and plants.     

健康与患病刺梨植株可培养叶际真菌菌群差异比较

本研究比较了健康与患叶斑病刺梨植株叶际真菌群落特征差异,以期探索病原菌的潜在来源,为人工构建具拮抗功能群落和刺梨叶斑病的生物防控提供参考。通过可培养方法对不同健康状况的刺梨叶际真菌进行分离培养,结合形态学和分子系统学对菌株进行综合鉴定;利用FUNGuild平台对真菌进行功能注释;结合根际、根部真菌作拆分网络分析探索病原菌的潜在来源。本研究结果表明：1）刺梨叶际真菌具有丰富的多样性。从刺梨叶际8个样品中共分离到真菌266株,其隶属于3门、6纲、13目、30科、46属中的61个种。其中,健康植株叶际内生真菌（LHE）包括8属10种27株,附生真菌（LHS）包括33属37种77株。患病叶际内生真菌（LDE）分离到7属10种38株;附生真菌（LDS）分离到31属35种124株。2）不同样品的真菌优势属和特有类群有差异。不同健康状况下叶际附生真菌的优势属均为拟盘多毛孢属Pestalotiopsis,但二者的相对多度存在差异,LHS为11.49%,LDS为32.26%;内生真菌优势属二者均为链格孢属Alternaria,但相对多度各异,LHE为33.33%,LDE为63.16%。其中,LHE特有类群为盘长孢状刺盘孢 Colletotrichum gloeosporioides和果生刺盘孢Colletotrichum fructicola等8种;LDE特有类群为茄链格孢 Alternaria solani和Didymella sinensis 等8种;LHS特有类群是草酸青霉Penicillium oxalicum和Peniophora crassitunicata等21种;LDS特有类群是尖孢镰刀菌Fusarium oxysporum、赭绿青霉Penicillium ochrochloron和易脆毛霉Mucor fragilis等19种。3）不同样品叶际真菌功能不同。经FUNGuild解析表明,LHS、LHE和LDE的叶际真菌功能群主要以腐生型为主,LDS则主要以植物病原菌群为主。本研究结果初步揭示刺梨植株健康与患叶斑病叶际间真菌多样性、群落组成及营养功能群存在差异,植株健康状况与其真菌群落特征密切相关;叶斑病病原菌主要源于刺梨叶际的附生微生物群。     

广藿香内生真菌多样性及其对青枯菌的拮抗活性

【目的】对广藿香各部位内生真菌的类群结构及多样性进行系统分析,筛选出对青枯菌具拮抗活性的菌株。【方法】采用组织块分离法从广藿香健康植株的根、茎、叶中分离内生真菌,结合形态学和基于ITS-r DNA序列分析鉴定方法分析广藿香内生真菌的类群结构及多样性,并利用双层平板拮抗法筛选对青枯菌具有抑制活性的菌株。【结果】从广藿香中共分离获得313株内生真菌,隶属于30个属,其中链格孢属(占28.75%)、拟茎点霉属(占23.00%)和炭疽菌属(11.82%)为优势类群,此外还分离到炭皮菌属、弯孢聚壳属、Gibellulopsis、新萨托菌属、葡萄座腔菌属、篮状菌属等较为少见的类群。茎、叶内生真菌的定殖率和分离率明显高于根,而根部多样性指数为2.64,要高于茎(2.00)和叶(1.97);广藿香茎与叶、根与茎、根与叶之间的内生真菌相似性指数分别为0.35、0.20、0.19,均小于0.5,显示各部位之间的内生真菌组成不相似程度高。从313株广藿香内生真菌中通过拮抗实验筛选到16株对青枯菌有拮抗活性的菌株,其中GHXR07、GHXR27和GHXR29的拮抗活性尤为显著,分别被鉴定为Talaromyces sp.、Myrothecium roridum Tode和Talaromyces wortmannii(Kl?cker)Benjamin。【结论】广藿香内生真菌具有丰富的物种多样性且其类群分布具有一定的组织特异性,其中部分菌株对青枯菌具有明显的拮抗活性。     

Measuring diversity of endophytic fungi in leaf fragments: does size matter?

Endophytic fungi inhabit living plant tissues without causing disease symptoms. Although abundant, the extent of their contribution to fungal biodiversity remains unclear. Since endophytic fungi are poorly known, especially in the tropics, current estimates of fungal species are probably conservative. Here we tested strategies for sampling endophytic fungi in tropical plants. We compared the number of fungi isolated from 400 mm2 leaf pieces that were divided into increasingly small fragments. Leaf pieces were surface-sterilized, cut into fragments and plated on culture media. For a given area, cutting leaf pieces into smaller fragments significantly increased the number of fungal morphospecies recovered. There was a strong linear relationship between size of fragments and number of fungi isolated. By extrapolation, an estimated 16 +/- 3 fungi could be recovered from a 2 x 2 cm leaf piece, using infinitely small fragments. This represents a large part of the fungal diversity estimated to exist in leaf endophytes in a population. We conclude that reducing the size and increasing the number of leaf fragments will increase the number of fungal species isolated. This strategy will help to estimate real values of endophytic fungal diversity.