中国特有的三种榆科植物枝条内生真菌菌群多样性

为了解我国特有的3种古老的野生榆科植物内生真菌菌群多样性及探讨同一生境条件下内生真菌菌群在不同植物之间的组成特征,以安徽琅琊山国家森林公园内的野生青檀、琅琊榆和醉翁榆的当年生健康枝条为研究对象,采用组织分离法和形态分类学方法对其内生真菌进行了分离和鉴定。结果表明,从3种榆科植物的1 778个组织块中,分离内生真菌1 938株,隶属于10目16科22属,未产孢的一类暂归为无孢菌群,占10.2%。3种榆科植物均是以子囊菌类所占比例最高(80.72%–89.71%),目级水平以肉座菌目Hypocreales的相对多度最高,科级水平以间座菌科Diaporthaceae的相对多度最高,属级水平以拟茎点霉属Phomopsis的相对多度最高。琅琊榆枝条中分离的内生真菌菌群最多(14属),醉翁榆菌群最少(10属)。内生真菌菌群组成在3种榆科植物之间存在宿主特异性。Shannon指数(H′)从高到低的顺序为:青檀琅琊榆醉翁榆,Margalef指数(R)从高到低的顺序为:琅琊榆青檀醉翁榆,均匀度指数(E)从高到低的顺序为:青檀醉翁榆琅琊榆。琅琊榆和醉翁榆之间的内生真菌菌群组成相似度最高,相似性系数达0.62,青檀和琅琊榆的相似性系数最低(C_S=0.44)。费舍尔检验(Fisher’s exact test)表明,3种榆科植物在内生真菌菌群组成上无明显差异(P=0.26‐0.500.05)。     

Assessment of root endophytic aquatic hyphomycetous fungi on plant growth

The role of root endophytic aquatic hyphomycetous fungi in plant health was studied by employing pot experiments. Three aquatic hyphomycetous fungi Heliscus lugdunensis, Tetrachaetum elegans and Tetracladium nainitalense isolated as root endophytes of riparian plants were artificially inoculated into two test plants viz., Solanum melongena and Hibiscus esculentus. T. elegans and H. lugdunensis showed significant effects (fresh weight, dry weight and length of shoots and roots) on both test plants, whereas T. nainitalense had no effect.     

Psychrophilic endophytic fungi with biological activity inhabit Cupressaceae plant family

Psychrophilic microorganisms are cold-adapted organisms that have an optimum growth temperature below 15 °C, and often below 5 °C. Endophytic microorganisms live inside healthy plants and biosynthesize an array of secondary metabolites which confer major ecological benefits to their host. We provide information, for the first time, on an endophytic association between bioactive psychrophilic fungi and trees in Cupressaceae plant family living in temperate to cold, semi-arid habitats. We have recovered psychrophilic endophytic fungi (PEF) from healthy foliar tissues of Cupressus arizonica, Cupressus sempervirens and Thuja orientalis (Cupressaceae, Coniferales). In total, 23 such fungi were found out of 110 endophytic fungal isolates. They were identified as ascomycetous fungi, more specifically Phoma herbarum, Phoma sp. and Dothideomycetes spp., all from Dothideomycetes. The optimal growth temperature for all these 23 fungal isolates was 4 °C, and the PEF isolates were able to biosynthesize secondary metabolite at this temperature. Extracted metabolites from PEF showed significant antiproliferative/cytotoxic, antifungal and antibacterial effects against phytopathogenic fungi and bacteria. Of special interest was their antibacterial activity against the ice-nucleation active bacterium Pseudomonas syringae. Accordingly, we suggest that evergreen Cupressaceae plants may benefit from their psychrophilic endophytic fungi during cold stress. Whether such endosymbionts confer any ecological and evolutionary benefits to their host plants remains to be investigated in vivo.     

The diversity of endophytic fungi in the above-ground tissue of two Lycopodium species in Poland

Endophytes are a large and diverse group of fungi that colonize healthy plant tissues without causing any symptoms. The majority of studies have focused on angiosperm and conifer hosts and few have examined the endophytes of lycophytes. In the present study, we characterized culturable endophytic fungi in two closely related Lycopodium species (L. annotinum and L. clavatum) from pine, beech, oak and spruce forests across Poland. More than 400 strains were isolated but only 18 Ascomycete species were identified. Members of the Dothideomycetes dominated the fungal endophyte communities in Lycopodium. The most abundant taxa cultured were Phoma brasiliensis (from L. clavatum) and Paraconiothyrium lycopodinum (from L. annotinum). Five taxa were isolated exclusively from L. annotinum, but only two of them (Paraconiothyrium lycopodinum and Mycosphaerella sp.) were relatively abundant. Two taxa were only found in L. clavatum, namely: Stagonospora pseudovitensis and an unidentified Dothideomycete. The taxon assigned as Ascomycota 2 (SH219457.06FU) was isolated only from strobili of both host species. Direct PCR and cloning from L. annotinum shoots revealed a substantially greater endophyte richness compared with the results from culturing.     

Genotypic diversity of an invasive plant species promotes litter decomposition and associated processes

Following studies that showed negative effects of species loss on ecosystem functioning, newer studies have started to investigate if similar consequences could result from reductions of genetic diversity within species. We tested the influence of genotypic richness and dissimilarity (plots containing one, three, six or 12 genotypes) in stands of the invasive plant Solidago canadensis in China on the decomposition of its leaf litter and associated soil animals over five monthly time intervals. We found that the logarithm of genotypic richness was positively linearly related to mass loss of C, N and P from the litter and to richness and abundance of soil animals on the litter samples. The mixing proportion of litter from two sites, but not genotypic dissimilarity of mixtures, had additional effects on measured variables. The litter diversity effects on soil animals were particularly strong under the most stressful conditions of hot weather in July: at this time richness and abundance of soil animals were higher in 12-genotype litter mixtures than even in the highest corresponding one-genotype litter. The litter diversity effects on decomposition were in part mediated by soil animals: the abundance of Acarina, when used as covariate in the analysis, fully explained the litter diversity effects on mass loss of N and P. Overall, our study shows that high genotypic richness of S. canadensis leaf litter positively affects richness and abundance of soil animals, which in turn accelerate litter decomposition and P release from litter.     

Understanding the diversity of foliar endophytic fungi: progress,challenges, and frontiers

Fungal endophytes, a diverse group of primarily ascomycetous fungi defined functionally by their occurrence within asymptomatic photosynthetic tissues of plants, occur in all major lineages of land plants and in natural and anthropogenic communities ranging from the arctic to the tropics. Because of the tremendous diversity they encompass, ecological questions regarding the interactions of endophytes with the plants in which they live - and with other organisms that in turn interact with endophyte-plants symbiota – are difficalt to address. The goals of this review are to highlight progress, challenges, and frontiers in the study of foliar endophyte diversity, with the ultimate goal of encouraging research that both bridges the gap between, and advances, research in alpha taxonomy and ecology. I focus on four themes that are reflected in the recent and rapidly expanding literature regarding endophyte biology: (1) the taxonomic and ecological distinctiveness of endophytes relative to other nonpathogenic plant-associated fungi; (2) the insights that can be gained from studies that consider genotypes as the relevant unit of biological organization, especially in the context of traditional species-level taxonomy and robust phylogenetic methods that tie these genotypes and species together in an explicit evolutionary context; (3) the context-dependency of endophyte communities, highlighting the importance of both the identify of host plants and the geographic location in which plants occur; and (4) the complexity of the endophyte-pathogen-saprotroph continuum, and the challeges and exciting frontiers that lie in understanding the evolutionary relationships and ecological lability of fungi that exhibit these ecological modes. I argue that never before has the study of endophytic fungi been more exciting or more tractable, and that the potential for endophyte researchers to inform diverse areas of biology has never been greater.     

Anti-Candida metabolites from endophytic fungi

Submerged cultures of some 1500 Ascomycota and Basidiomycota isolated from their fruit-bodies or as soil-borne, coprophilous or endophytic fungi were screened for activity against Candida albicans and a range of other pathogenic and saprotrophic fungi. Considerably more Ascomycota (11-16%) than Basidiomycota (3.5%) produced metabolites with activity against C. albicans. From five species of endophytes, six bioactive compounds were isolated and identified, viz. cerulenin (1), arundifungin (2), sphaeropsidin A (3), 5-(1,3-butadiene-1-yl)-3-(propene-1-yl)-2-(5H)-furanone (4), ascosteroside A (formerly called ascosteroside; 5) and a derivative of 5, ascosteroside B (6). 1, 3 and 5 were isolated from fungi belonging to different orders than previously described producers. Antifungal activities of 2 and 4-6 in the agar diffusion test were comparable with those of amphotericin B. Compound 6 exhibited a similar antifungal activity as 5 but its cytotoxicity towards Hep G2 cells was considerably lower. This study points to endophytic fungi related to hemibiotrophic or latent plant pathogens as an important source of bio- and chemodiversity.     

Assessing the diversity of AM fungi in arid gypsophilous plant communities

In the present study, we used PCR-Single-Stranded Conformation Polymorphism (SSCP) techniques to analyse arbuscular mycorrhizal fungi (AMF) communities in four sites within a 10 km² gypsum area in Southern Spain. Four common plant species from these ecosystems were selected. The AM fungal small-subunit (SSU) rRNA genes were subjected to PCR, cloning, SSCP analysis, sequencing and phylogenetic analyses. A total of 1443 SSU rRNA sequences were analysed, for 21 AM fungal types: 19 belonged to the genus Glomus , 1 to the genus Diversispora and 1 to the Scutellospora. Four sequence groups were identified, which showed high similarity to sequences of known glomalean species or isolates: Glo G18 to Glomus constrictum , Glo G1 to Glomus intraradices , Glo G16 to Glomus clarum , Scut to Scutellospora dipurpurescens and Div to one new genus in the family Diversisporaceae identified recently as Otospora bareai . There were three sequence groups that received strong support in the phylogenetic analysis, and did not seem to be related to any sequences of AM fungi in culture or previously found in the database; thus, they could be novel taxa within the genus Glomus : Glo G4, Glo G2 and Glo G14. We have detected the presence of both generalist and potential specialist AMF in gypsum ecosystems. The AMF communities were different in the plant studied suggesting some degree of preference in the interactions between these symbionts.     

天目山山胡椒不同部位内生真菌组成及多样性分析

采用表面消毒法,从浙江天目山野生山胡椒[ Lindera glauca( Sieb.et Zucc.) Blume]的茎、叶和树皮中分离出内生真菌,基于ITS序列分析进行分类鉴定;并以内生真菌的分离率、定殖率、分离频率、多样性指数(H')及相似性系数为指标,分析了山胡椒内生真菌的菌群组成及多样性.结果显示:在26株山胡椒样株的728块组织块中共分离得到328株内生真菌(茎、叶和树皮中分别有161、40和127株);共鉴定出44个分类单元(茎、叶和树皮中各有19、18和28个),其中25个分类单元鉴定到种、17个鉴定到属、2个鉴定到科,ITS序列的GenBank登录号从JF502420至JF502462.在44个分类单元中,有40个分类单元属于子囊菌(310株),存在于山胡椒的各个部位;仅有4个分类单元属于担子菌(18株),且仅存在于茎和树皮中.山胡椒茎、树皮和叶中内生真菌的定殖率分别为65％、60％和15％,分离率分别为0.77、0.61和0.19;叶和树皮中内生真菌的多样性指数均为2.63,远大于茎(H’=1.83).山胡椒内生真菌的优势属为Phomopsis、Paraconiothyrium、Phoma和Colletotrichum,大量存在于叶、茎和树皮中.山胡椒茎与树皮、茎与叶及叶与树皮间内生真菌的相似性系数分别为0.27、0.19和0.18,显示树皮和叶之间以及树皮和茎之间内生真菌的组成极不相似.研究结果表明:山胡椒体内存在大量的内生真菌,其茎、叶和树皮的内生真菌菌群组成具有一定程度的多样性和差异性,且内生真菌的分布具有组织特异性.     

常见瓜类植物的内生真菌多样性

为认识和掌握常见瓜类植物内生真菌多样性及其变化规律,对从4个地点采集的9种70株健康瓜类植物进行了内生真菌的分离,共获得534个菌株,总体分离率为20.9%。结合形态学和ITS序列分析,鉴定了分属于55个属的455个菌株,有8个属的真菌属于优势类群,相对多度最高的3个属依次为Colletotrichum、Fusarium和Rhizopycnis。Colletotrichum主要存在于植株地上部,Fusarium主要存在于根部和下部茎,Rhizopycnis主要存在于根部,表现出明显的部位差异。河南原阳不同瓜类植物样品中主要内生真菌类群的相对多度和内生真菌的多样性存在明显差异,蛇瓜中Colletotrichum的相对多度达44.7%,显著高于丝瓜中Colletotrichum的相对多度8.0%;黄瓜中Fusarium的相对多度达32.4%,远高于在其他瓜类植物中的相对多度,而在南瓜中Fusarium的相对多度最低,仅为3.0%。江苏无锡和河南原阳的丝瓜植株样品中内生真菌的类群组成有很大不同,表明植株生长的地理环境可能对内生真菌的组成和多样性具有显著影响。     

Arbuscular mycorrhizal fungi enhance P uptake and alter plant morphology in the invasive plant Microstegium vimineum

Invasive plant species can interact with native soil microbes in ways that change how they use nutrients and allocate biomass. To examine whether Microstegium vimineum form symbiotic associations with arbuscular mycorrhizal fungi (AMF) and whether AMF mediate nutrient acquisition and growth of the plant, we conducted a field survey in Raleigh, NC and Hangzhou, China and two experiments in growth chambers. This is the first report that M. vimineum is mycorrhizal, with colonization rates of 47 and 21 % in its native and invaded range, respectively. In the growth chamber, addition of an AMF inoculum mixture significantly promoted M. vimineum biomass accumulation in both field and sterilized soils, particularly after 64 days of growth. Arbuscular mycorrhizal fungi also increased plant phosphorous (P) uptake but did not consistently affect total plant nitrogen (N) acquisition, leading to decreases in plant N:P ratios. More interestingly, AMF significantly altered plant morphology, increasing the number of stolons and aerial roots per individual (59 and 723 %), aerial roots per gram aboveground biomass (374 %) and aerial roots per stolon (404 %). Our results suggest that mycorrhizal enhancement of plant growth by stimulating tillering may serve as another mechanism by which M. vimineum can quickly take over new territory. Future studies on invasive plant-microbial interactions are needed to understand the mechanisms through which microbes contribute to the competitive ability of invasive plants.     

植物内生真菌化感作用的研究现状

植物内生真菌能产生酚类、萜类和生物碱类等多种类型的化感物质,它们在植物的生长发育、抗生物胁迫和非生物胁迫方面发挥重要作用。对植物内生真菌的化感作用及其所产生的化感物质进行了综述,并展望了其化感作用的应用前景。     

入侵植物粗毛牛膝菊种群遗传多样性及遗传分化

利用ISSR分子标记技术,分析粗毛牛膝菊(Galinsoga quadriradiata)在中国分布的18个地理种群遗传多样性和遗传结构特点,为粗毛牛膝菊的防控奠定基础。结果表明:筛选的10条引物共扩增出349个位点,经Popgene软件分析,粗毛牛膝菊种群多态位点百分比(P)为8.88%~29.51%,Nei基因多样性指数(H)为0.0248~0.1023;种群遗传分化系数(Gst)为0.4663,种群间基因流(Nm)为0.5723;遗传相似度平均为0.9404,遗传距离平均为0.0621,UPGMA聚类分析将18个粗毛牛膝菊地理种群分为5大类;经Mantel检验,不同地理种群遗传距离与地理距离相关性不显著。研究表明,粗毛牛膝菊种群的遗传多样性较低;各地理种群间产生了一定程度的遗传分化;粗毛牛膝菊的入侵及扩散途径以人为多次反复传播为主。     

Diversity and plant growth-promoting ability of endophytic fungi from the five flower plant species collected from Yunnan,Southwest China

The diversity and plant growth-promoting ability of endophytic fungi associated with the five flower plant species growing in Yunnan, Southwest China, were investigated. A total of 357 culturable endophytic fungi were isolated from 1000 segments of healthy leaves and stems of the five plant species. Based on the morphological characteristics and the rDNA internal transcribed spacer (ITS) analysis, the isolates were identified to 24 taxa, of which Alternaria, Phomopsis, Cladosporium, and Colletotrichum were the dominant genera. The Sorenson's coefficient similarity indices of the endophytic fungi from the five flower plant species ranged from 0.36 to 0.80. It was found that the similarity index between two cultivated flowers (0.8) or the similarity index between two wild flowers (0.71–0.76) was higher than the similarity index between one cultivated flower and one wild flower (0.36–0.48). The Shannon indices (H) of the endophytic fungi from the five plant species ranged from 1.73 to 2.45, and the diversity indices of the wild flowers were higher than those of the cultivated flowers. The plant growth-promoting tests indicated that some isolates could improve the host plants' growth more efficiently when compared with the control (p < 0.05, least significant difference test).     

Contrasting effects of an invasive ant on a native and an invasive plant

When invasive species establish in new environments, they may disrupt existing or create new interactions with resident species. Understanding of the functioning of invaded ecosystems will benefit from careful investigation of resulting species-level interactions. We manipulated ant visitation to compare how invasive ant mutualisms affect two common plants, one native and one invasive, on a sub-tropical Indian Ocean island. Technomyrmex albipes, an introduced species, was the most common and abundant ant visitor to the plants. T. albipes were attracted to extrafloral nectaries on the invasive tree (Leucaena leucocephala) and deterred the plant’s primary herbivore, the Leucaena psyllid (Heteropsylla cubana). Ant exclusion from L. leucocephala resulted in decreased plant growth and seed production by 22% and 35%, respectively. In contrast, on the native shrub (Scaevola taccada), T. albipes frequently tended sap-sucking hemipterans, and ant exclusion resulted in 30% and 23% increases in growth and fruit production, respectively. Stable isotope analysis confirmed the more predacious and herbivorous diets of T. albipes on the invasive and native plants, respectively. Thus the ants’ interactions protect the invasive plant from its main herbivore while also exacerbating the effects of herbivores on the native plant. Ultimately, the negative effects on the native plant and positive effects on the invasive plant may work in concert to facilitate invasion by the invasive plant. Our findings underscore the importance of investigating facilitative interactions in a community context and the multiple and diverse interactions shaping novel ecosystems.     

The dark side is not fastidious--dark septate endophytic fungi of native and invasive plants of semiarid sandy areas

Dark septate endophytic (DSE) fungi represent a frequent root-colonizing fungal group common in environments with strong abiotic stress, such as (semi)arid ecosystems. This work aimed to study the DSE fungi colonizing the plants of semiarid sandy grasslands with wood steppe patches on the Great Hungarian Plain. As we may assume that fungi colonizing both invasive and native species are generalists, root associated fungi (RAF) were isolated from eight native and three invasive plant species. The nrDNA sequences of the isolates were used for identification. To confirm that the fungi were endophytes an artificial inoculation system was used to test the isolates: we considered a fungus as DSE if it colonized the roots without causing a negative effect on the plant and formed microsclerotia in the roots. According to the analyses of the ITS sequence of nrDNA the 296 isolates clustered into 41 groups. We found that 14 of these 41 groups were DSE, representing approximately 60% of the isolates. The main DSE groups were generalist and showed no specificity to area or season and colonized both native and invasive species, demonstrating that exotic plants are capable of using the root endophytic fungi of the invaded areas. The DSE community of the region shows high similarity to those found in arid grasslands of North America. Taking into account a previous hypothesis about the common root colonizers of those grasslands and our results reported here, we hypothesize that plants of (semi)arid grasslands share common dominant members of the DSE fungal community on a global scale.