Arbuscular mycorrhizal fungi in the Brazilian Atlantic forest: A gradient of environmental restoration

Arbuscular mycorrhizal fungi (AMF) are of great importance for the successful regeneration of degraded natural areas. The objective of this study was to examine how the time of environmental recuperation is affecting the occurrence and diversity of AMF species in riparian areas belonging to the Atlantic Forest biome in the State of São Paulo, Brazil. The study involved a native forest area (NT) and a gradient of environmental restoration: five (R05), ten (R10), and twenty (R20) years after reforestation. Soil samples were collected in the rainy (January) and dry season (June). Chemical, physical and microbiological analyses were performed including the amount of glomalin and quantification of AMF spores. The frequency of occurrence of genera and ecological indices, as richness (R), Shannon's diversity (H) and Simpson's dominance index (Is) were calculated. The largest spore number was found in R05 and the highest richness and diversity indices of AMF species in NT. Considering the two sampling periods and the four areas studied, we found 22 AMF species, and the genera Glomus and Acaulospora were the most frequent. A Canonical Discriminant Analysis showed that Glomus viscosum, Acaulospora scrobiculata, Acaulospora mellea and Scutellospora heterogama were the species that contributed the most to distinguishing the areas. Moisture, density and glomalin were positively correlated with the number of spores, however, soil nitrate showed a negative correlation. This work gives a better understanding of the interactions between AMF and forest soils and allows to know the distribution of AMF species according to environmental recovery time.     

Arbuscular mycorrhizal fungal dynamics under Mitragyna parvifolia (Roxb.) Korth. in Thar Desert

The temporal and spatial dynamics of arbuscular mycorrhizal fungi (AMF) were investigated in Indian Thar Desert. Soil samples under Mitragyna parvifolia were collected from July 2003 to June 2004. AMF colonization and spore density were used to compare the responses of AMF to different abiotic parameters. The mean percent colonization and spore density of AMF reached maximal values in rainy and summer seasons, respectively. Vesicular and hyphal colonizations were positively correlated with soil organic carbon content. AMF spore density was positively correlated with soil pH and negatively correlated with Olsen P content. A high Shannon–Weiner diversity index of AMF was observed in Thar Desert. A total of fifteen AMF species were associated with M. parvifolia. Percent spore density and species richness suggest that the genus Glomus was the predominant AMF under Thar Desert environment. The reasons for the observed variations are discussed.     

Biodiversity of arbuscular mycorrhizas in three vegetational types from the semiarid of Ceará State,Brazil

Semiarid lands are the object of a limited number of studies, very few among them aimed at characterizing root-associated fungal communities. The diverse vegetation occurring in the tropical dry forest from the Ceará State, Brazil, core area of the Brazilian tropical semiarid, has been attributed to its soil, topography and climatic variation. However, the arbuscular mycorrhizal (AM) symbiosis may have an important role in the function of these ecosystems. We examined AM association in 29 semiarid Brazilian species from three different locations: thorny dry woody savanna vegetation, known as caatinga; non-thorny dry forest and closed, non thorny dry tall-shrubby vegetation, known as carrasco. AM fungal diversity was also compared among the different sites. Twenty of the 22 trees and two of the seven herbs examined had AM association. Arum-type AM morphology was the dominant association occurring in 19 trees and in 3 hemicryptophyte plants. AM morphology is reported for the first time in 21 trees and two herbaceous species. Over the different sites, spore densities in the soil ranged from 5 to 32 per 100 g air-dried soil. Spores of 32 AM fungal taxa were isolated from the soil samples of trees of which twelve belonged to Acaulospora, two to Scutellospora, three to Gigaspora, four to Racocetra, three to Glomus, one to Clareoideoglomus, one to Ambispora, one to Pacispora, one to Sclerocystis, one to Dentiscutata, one to Orbispora, one to Quatunica and one to Entrophospora. Species richness was high in woody caatinga and Glomus macrocarpum, Gigaspora gigantea and Cetraspora pellucida were the most frequent species at different sites. Species diversity (Shannon–Weaver index) did not differ significantly among sites. Water content and phosphorus availability was found to influence the AMF species composition at the plant community level, providing information about the caatinga dominium biodiversity, mainly for its conservation.     

Arbuscular mycorrhizal fungal communities in changing environments: The effects of seasonality and anthropogenic disturbance in a seasonal dry forest

The landscape of Mexican seasonal dry forests is affected by various periodic (long and drastic drought) and random (elimination of the forest coverage for agricultural purposes) disturbance events. The community of arbuscular mycorrhizal fungi (AMF) responds to these changes, sporulating and reducing its activity during the dry season, and slowly reestablishing itself following abandonment of cultivated fields. To determine the dynamics of the AMF community in response to natural phenomena and anthropogenic disturbances, we collected soil samples during the wet and dry seasons from plots with different time periods since abandonment of agricultural activity, categorized as early (less than 5 years), middle (11–23 years), and late (over 30 years) age plots. From each plot, AMF spores were isolated and identified in order to estimate abundance, richness and diversity. In addition, the number of infective propagules and value of mycorrhizal inoculum potential were calculated for each plot. Twenty-three species were recorded, for which Glomeraceae and Acaulosporaceae were the most commonly represented families. Significant differences were found in AMF species richness among plots and seasons and the diversity index of AMF was higher than 1.0 in most cases. There were no significant differences in spore abundance. Viable propagules were observed in all soil samples, with fluctuations relating mainly to time since abandonment. Overall, seasonality has a strong influence on AMF diversity but not on AMF infectivity, while time since abandonment had a more important impact.     

Community structure of arbuscular mycorrhizal fungi associated with Robinia pseudoacacia in uncontaminated and heavy metal contaminated soils

The significance of arbuscular mycorrhizal fungi (AMF) in soil remediation has been widely recognized because of their ability to promote plant growth and increase phytoremediation efficiency in heavy metal (HM) polluted soils by improving plant nutrient absorption and by influencing the fate of the metals in the plant and soil. However, the symbiotic functions of AMF in remediation of polluted soils depend on plant–fungus–soil combinations and are greatly influenced by environmental conditions. To better understand the adaptation of plants and the related mycorrhizae to extreme environmental conditions, AMF colonization, spore density and community structure were analyzed in roots or rhizosphere soils of Robinia pseudoacacia. Mycorrhization was compared between uncontaminated soil and heavy metal contaminated soil from a lead–zinc mining region of northwest China. Samples were analyzed by restriction fragment length polymorphism (RFLP) screening with AMF-specific primers (NS31 and AM1), and sequencing of rRNA small subunit (SSU). The phylogenetic analysis revealed 28 AMF group types, including six AMF families: Glomeraceae, Claroideoglomeraceae, Diversisporaceae, Acaulosporaceae, Pacisporaceae, and Gigasporaceae. Of all AMF group types, six (21%) were detected based on spore samples alone, four (14%) based on root samples alone, and five (18%) based on samples from root, soil and spore. Glo9 (Rhizophagus intraradices), Glo17 (Funneliformis mosseae) and Acau3 (Acaulospora sp.) were the three most abundant AMF group types in the current study. Soil Pb and Zn concentrations, pH, organic matter content, and phosphorus levels all showed significant correlations with the AMF species compositions in root and soil samples. Overall, the uncontaminated sites had higher species diversity than sites with heavy metal contamination. The study highlights the effects of different soil chemical parameters on AMF colonization, spore density and community structure in contaminated and uncontaminated sites. The tolerant AMF species isolated and identified from this study have potential for application in phytoremediation of heavy metal contaminated areas.     

Changes of arbuscular mycorrhizal traits and community structure with respect to soil salinity in a coastal reclamation land

A comprehensive knowledge on the relationship between soil salinity and arbuscular mycorrhizal fungi (AMF) is vital for a deeper understanding of ecosystem functioning under salt stress conditions. The objective of this study was to determine the effects of soil salinity on AMF root colonization, spore count, glomalin related soil protein (GRSP) and community structure in Saemangeum reclaimed land, South Korea. Soil samples were collected and grouped into five distinct salt classes based on the electrical conductivity of soil saturation extracts (EC_se). Mycorrhizal root colonization, spore count and GRSP were measured under different salinity levels. AMF community structure was studied through three complementary methods; spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Results revealed that root colonization (P < 0.01), spore count (P < 0.01) and GRSP (P < 0.01) were affected negatively by soil salinity. Spore morphology and T-RFLP data showed predominance of AMF genus Glomus in Saemangeum reclaimed land. T-RFLP and DGGE analysis revealed significant changes in diversity indices between non (EC_se < 2 dS/m) and extremely (EC_se > 16 dS/m) saline soil and confirmed dominance of Glomus caledonium only in soils with EC_se < 8 dS/m. However, ribotypes of Glomus mosseae and Glomus proliferum were ubiquitous in all salt classes. Combining spore morphology, T-RFLP and DGGE analysis, we could show a pronounced effect in AMF community across salt classes. The result of this study improve our understanding on AMF activity and dominant species present in different salt classes and will substantially expand our knowledge on AMF diversity in reclaimed lands.     

长期保护性耕作对丛枝菌根真菌多样性的影响

为了明确我国北方干旱地区长期保护性耕作以及深松对丛枝菌根真菌(AMF)多样性的影响,笔者于2014年在山西省临汾市连续22年实施保护性耕作的长期定位试验基地,针对免耕覆盖(NTS)、深松免耕覆盖(SNTS)及传统耕作(TT)3种处理方式,进行了不同耕作条件下土壤AMF物种丰度、孢子密度、Shannon多样性指数以及AMF侵染率等因素的比较研究。结果显示,长期保护性耕作(NTS和SNTS)共分离鉴定出AMF 7属9种,其中根孢囊霉属(Rhizophagus)和斗管囊霉属(Funneliformis)各2种,球囊霉属(Glomus)、近明球囊霉属(Claroideoglomus)、无梗囊霉属(Acaulospora)、硬囊霉属(Sclerocystis)和隔球囊霉属(Septoglomus)各1种;而传统耕作(TT)共分离鉴定出AMF 6属8种,没有检测到无梗囊霉属。NTS、SNTS和TT处理在不同土层的AMF优势种基本一致,0~40 cm土层为摩西斗管囊霉(Fu.mosseae)和变形球囊霉(G.versiforme),40~80 cm土层为摩西斗管囊霉、变形球囊霉和聚丛根孢囊霉(Rh.aggregatum),80~120 cm土层为聚丛根孢囊霉,120 cm土层以下只有NTS和SNTS处理中存在聚丛根孢囊霉,说明保护性耕作措施促进了AMF向土壤深层发展。NTS和SNTS处理在同一土层的AMF物种丰度、孢子密度和Shannon多样性指数均高于TT处理,SNTS处理高于NTS处理。同一耕作措施不同土层的AMF物种丰度、孢子密度和Shannon多样性指数均随土层加深而逐渐降低;NTS和SNTS处理在小麦各生育期的丛枝侵染率和孢子密度均高于TT处理;各处理在小麦拔节期的AMF侵染率最高,分别为14.9%、16.1%和10.6%,而在收获期的土壤孢子密度最高,分别为111.7个·(100g)~(-1)、125.0个·(100g)~(-1)和90.3个·(100g)~(-1)。研究认为,长期免耕覆盖、尤其深松免耕覆盖,提高了AMF多样性。该研究结果可为中国北方旱作农田生态系统中AMF自然潜力的充分发挥,以及保护性耕作技术的合理应用提供科学依据。     

ARBUSCULAR MYCORRHIZAL FUNGI IN REVEGETATED MINED DUNES

This study aimed to thoroughly investigate communities of arbuscular mycorrhizal fungi (AMF) in six coastal, mined, reconstituted and revegetated dune areas in Northeast Brazil. AMF spore density and species richness as well as the numbers of infective AMF propagules and glomalin‐related soil protein (GRSP) were analyzed. Four areas had been restored for 16, 12, 8 and 4 years, and after being mined, reconstituted and re‐vegetated, the fifth was mined and reconstituted but not yet re‐vegetated, and the sixth had a native and undisturbed coastal forest vegetation. The soil samples were sampled in the dry and wet seasons of 2005. The number of infective propagules was significantly higher in the dry than in wet season, except in the un‐vegetated dune area, which had less than 0·2 propagules cm⁻³ soil. AMF spore density and especially GRSP contents changed little between the seasons. GRSP contents were positively correlated to Al and Fe soil levels and were highest in the restinga forest. In total, 29 AMF species were identified, and glomoid and gigasporoid species predominated in all areas. AMF species richness and viable propagules of AMF were lowest in the un‐vegetated dune area. Remarkably, higher species richness (28) was found in the re‐vegetated areas, compared with the forest area that had only 10 species. The numbers of infective propagules tended to be also lower in the forest than in the re‐vegetated sites. In conclusion, re‐vegetation appears to favour the AMF communities in terms of infective propagule numbers and AMF species richness. Copyright © 2011 John Wiley & Sons, Ltd.     

不同土壤类型下AM 真菌分布多样性及与土壤因子的关系

以禾本科植物群落为研究对象, 研究了宁夏六盘山林地、银川农耕地、暖泉农耕地、固原农耕地、盐池沙地、灵武沙地6 个采样地点5 种土壤类型(黑垆土、灌淤土、黄绵土、灰钙土、风沙土)下AM 真菌物种多样性及其与土壤因子的关系。结果表明: 5 种土壤类型采样点的植被根际土壤中共鉴定出5 属48 种AM真菌, 其中, 无梗囊霉属(Acaulospora)1 种, 巨孢囊霉属(Gigaspora)3 种, 球囊霉属(Glomus)37 种, 类球囊霉属(Paraglomus)1 种, 盾巨孢囊霉属(Scutellospora)6 种, 各采样点土壤均以球囊霉属为优势属。地球囊霉(G.geosporum)和木薯球囊霉(G. manihotis)是6 个采样地点中的优势种。不同土壤类型各采样点AM 真菌各属的频度存在明显差异, 球囊霉属在各点均有出现, 频度值最高。具有较高植被多样性的暖泉样点, AM 真菌的种属数量较多。土壤环境因子对AM 真菌孢子密度的影响因所处土壤、植被类型不同而异。pH、全盐、速效钾、速效磷等土壤肥力因子, 在PCA 轴上能最大程度地解释AM 真菌孢子密度与土壤环境因子之间相互关系的大部分信息。宁夏不同土壤类型区域中AM 真菌种类及分布一定程度上与该采样点的植被类型、植物多样性和土壤肥力特征相对应。     

Diversity patterns of indigenous arbuscular mycorrhizal fungi associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in Benin,West Africa

Assessment of diversity and understanding factors underlying species distribution are fundamental themes in ecology. However, the diversity of native arbuscular mycorrhizal fungi (AMF) species in African tropical agro-ecosystems remains weakly known. This research was carried out to assess the morphological diversity of indigenous AMF species associated with rhizosphere of cowpea (Vigna unguiculata (L.) Walp.) in different agro-ecological zones (AEZ) of Benin and to examine the effects of soil chemical properties, climatic factors and agricultural practices on this diversity. Results showed that, in Benin, cowpea was grown by farmers in very exhausted soils, where available phosphorus and potassium were deficient. The indigenous AMF spore density was on average 202 spores per 100 g dry soil and there was no difference in the density among the agro-ecological zones (P = 0.56). Fifteen AMF morphospecies belonging to eight genera (Gigaspora, Scutellospora, Racocetra, Acaulospora, Funneliformis, Rhizophagus, Glomus and Claroideoglomus) were detected. The computed species richness estimators indicated that a limited number of additional undetected morphospecies are probably present in cowpea fields. According to analysis of similarity (ANOSIM), the arbuscular mycorrhizas community composition of the Sudanian zone and Guinean zone were not significantly different (r = −0.01; P = 0.517). The diversity of AMF morphospecies in the fields was weak with prevalence of Glomeraceae (92%). Furthermore, AMF diversity and evenness indices were negatively correlated with annual rainfall (P < 0.01) and with available phosphorus (P < 0.05). However, no significant correlation was observed between AMF diversity indices and soil organic carbon. Ultimately, this study tends to confirm that soil management practices (tillage, soil disturbance) have negative effect on AMF diversity.     

矿区土壤丛枝菌根真菌对采陷时间序列的响应

煤炭井工开釆造成大面积的地表塌陷,破坏了原有地表植被、土壤结构和地貌,影响土壤微生物群落结构和组成.为了研究井工矿开釆沉陷区丛枝菌根真菌(AMF)多样性与开采时间序列的相关性,本文以补连塔矿区不同开采年份的采煤沉陷区作为样地,以AMF和土壤因子为研究对象,探索随着采煤沉陷时间的延续,AMF物种多样性、种群结构变化规律及...     

滇中高原不同植被恢复条件下土壤肥力和水分特征研究

在干湿不同季节分析滇中高原不同恢复措施下群落的土壤肥力条件和土壤水分条件,结果表明,无论干湿季节,土壤养分含量在不同类型的植被中由优到劣依次为次生常绿阔叶林、针阔混交林、云南松林、桉树林、荒坡灌草丛;各种植被对0～30cm的剖面层次的土壤肥力影响最大,自然恢复更新的植物群落对0～30cm土层的肥力影响显著优于人工林,其变化幅度也高于人工林;自然恢复更新的植物群落在30～60cm、60～90cm土层中,营养物质含量较低,尤其在雨季这些深层土壤营养物质的含量更小。次生常绿阔叶林的持水能力最强,桉树林的持水保水能力最低。次生常绿阔叶林和针阔混交林土壤养分和水分在干湿季节间变化幅度较小,而桉树林和云南松林变化幅度较大。讨论认为雨季补充营养可以显著提高植被恢复的速度,生态建设中尽可能以自然演替恢复更新为主。     

Mesofaunal arthropod diversity in shrub mangrove litter of Cozumel Island,Quintana Roo,México

We studied the mesofaunal arthropod diversity in a shrub mangrove in the Punta Sur area within the National Park Reefs of Cozumel Island in the South of Mexico. Two mangrove areas were selected for sampling, dominated by Rhizophora mangle and Avicennia nitida, respectively. Four sampling periods, two during the dry season and two during the rainy season, and 25 random litter samples of litter (225 cm²) per site and date led to a total of 200 samples. Spatial and temporal variation of arthropod diversity was analyzed at the order/suborder level. A total of 90,680 arthropods belonging to 30 taxa were recorded during the study, Oribatida being most abundant with 61.8%, followed by springtails (14%). Densities of arthropods were higher in the rainy season than in the dry season, showing a strong positive correlation with humidity. Highest abundance was found in the R. mangle mangrove in the rainy season, and highest diversity was found in the A. nitida mangrove in the dry season. Seasonal distribution of litter fauna in two mangroves are related with the particular characteristics shown in each one.     

Ants (Hymenoptera: Formicidae) diversity in agricultural ecosystems at Mezquital Valley,Hidalgo, Mexico

We studied the changes in ant communities within agricultural ecosystems according with their seasonal variation and type of irrigation (well water and wastewater) in five plots. Plots were located in the Mezquital Valley, in the central Mexico. Collects were carried out in 2003, from February to March (dry season) and August (rainy season) using Pitfall traps. A total of 1638 organisms were collected (477 and 1161, dry and rainy season, respectively), corresponding to 16 genera, Pheidole (42.38%) and Monomorium (26.67%) were the most frequently collected. The capture frequency of ants was 0.58 throughout the whole study (0.45 and 0.71, dry and rainy season, respectively). An ANOVA two-ways analysis shows a significant season, plot and interaction effect on the ant capture frequency. A high diversity was observed during the rainy season (14 species). The plots with low disturbances show more species richness and abundance, indicating that the quality of the water is a determining factor for the community structure. The genera Tapinoma and Odontomachus could be indicators of low disturbance levels.     

Cumulative effects of tree-based intercropping on arbuscular mycorrhizal fungi

In tree-based intercropping system (agroforestry), the role of perennial trees in maintaining active populations and mycelial networks of arbuscular mycorrhizal fungi (AMF) is well documented. Agroforestry positively influences the AMF community, but complete studies regarding mycorrhization in such systems are scarce. The present study was conducted to assess the effect of tree introduction in agriculture fields on mycorrhization. In particular, we investigated the effect of trees on AMF colonization of intercrops and vice versa, the effect of canopy management of trees on their root colonization, and the cross-infectivity of AMF isolated from tree rhizosphere in intercrops and vice versa. The results of the field study suggest that in agroforestry systems, trees acted as AMF inoculum reservoir for intercrops, especially during the rainy season. Intercropping (Phaseolus mungo and Triticum aestivum in the rainy and winter seasons, respectively) increased mycorrhization, i.e., root colonization and spore population in the rhizosphere of Albizia procera and Eucalyptus tereticornis. Canopy management, i.e., shoot pruning, reduces root colonization in A. procera, Anogeissus pendula, Dalbergia sissoo, Hardwickia binata, and Tectona grandis, especially in April 2005 (late spring), but during subsequent periods, differences among the treatments were at par. Results from greenhouse suggest that AMF are nonspecific in their selection of host since species isolated from tree rhizosphere could colonize the roots of crops and vice versa.     

Plant type differently promote the arbuscular mycorrhizal fungi biodiversity in the rhizosphere after revegetation of a degraded, semiarid land

It is suggested that the diversity of arbuscular mycorrhizal fungi (AMF) and their association with distinct plants species are crucial in the early stages of revegetation procedures since the AMF roots colonisation plays an important role improving plant establishment and growth. We carried out a study where we analyse the AMF community composition in the roots of Ephedra fragilis, Rhamnus lycioides, Pistacia lentiscus and Retama sphaerocarpa fourteen months after revegetation in a Mediterranean semiarid degraded area of southeast Spain in order to verify whether different plant species can variably promote the diversity of AM fungi in their rhizospheres after planted. We analysed a portion of approximately 795 bases pairs of the small-subunit ribosomal DNA by means of nested PCR, cloning, sequencing and phylogenetic analyses. Eight fungal sequence types belonging to Glomus group A and B and to the genus Paraglomus were identified. The different plant species had different AM fungal community composition. Thus, R. lycioides harboured the highest number of four fungal sequence types while from E. fragilis only two types could be characterized that were specific for this plant species. P. lentiscus and R. sphaerocarpa harboured each one three sequence types and two of them were shared. All AMF sequence types were found in the natural soil. These results show that one effective way of restoring degraded lands is to increase the number of plant species used, which would increase the AMF diversity in the soil and thus the below-ground, positive interactions.     

The effect of turf cutting on plant and arbuscular mycorrhizal spore recolonisation: Implications for heathland restoration

In two natural heathland vegetations, we analysed the effect of turf cutting on spore numbers of arbuscular mycorrhizal fungi (AMF). Next to this, we performed a controlled factorial experiment to examine the role of AMF for germination and establishment of Arnica montana in both turf cut and non-turf cut situations. AMF spore numbers decreased with soil depth, and, along with the topsoil, almost all AMF spores were removed with the removal of the acidified and/or eutrophied organic layer. Recolonisation of AMF spore numbers after turf cutting was slow: spore numbers of approximately 60-95 spores g⁻¹ dry soil were found two and a half years after turf cutting, corresponding with 55-70% of AMF spore numbers found in natural field populations of A. montana. Since AMF colonisation increased establishment and biomass, and decreased mortality of A. montana, it was suggested that lack of AMF after turf removal might complicate the establishment of this herbaceous species. Removal of organic material as a management measure should therefore carefully be applied, taking in consideration the low recolonisation rates of AMF as this can markedly effect the success of restoration.     

Shrubs influence arbuscular mycorrhizal fungi communities in a semi-arid environment

Interactions between arbuscular mycorrhizal fungi (AMF) and plants are essential components of ecosystem functioning; however, they remain poorly known in dry ecosystems. We examined the relationship between seven shrub species and their associated AMF community in a semi-arid plant community in southern Spain. Soil characteristics and plant physiological status were measured and related to AMF community composition and genetic diversity by multivariate statistics. We found differences in AMF communities in soils under shrubs and in gaps among them, whereas no differences were detected among AMF communities colonizing roots. Soil nutrients content drove most of the spatial variations in the AMF community and genetic diversity. AMF communities were more heterogeneous in fertile islands with low nitrogen-to-phosphorus ratio and vice versa. AMF genetic diversity increased in soils limited by phosphorus and with high soil organic matter content, while AMF genetic diversity increased in roots growing in soil not limited by phosphorus. Overall, we could not find a clear link between plant performance and the associated AMF community. Our findings show that different shrub species generate islands of fertility which differ in nutrient content and, therefore, support different AMF communities, increasing AMF diversity at the landscape level.     

Variation in community structure of arbuscular mycorrhizal fungi associated with a Cu tolerant plant—Elsholtzia splendens

Little is known about the characteristics of arbuscular mycorrhizal fungi (AMF) community in the roots of host plants growing on heavy metal contaminated sites. The objectives of this study were to examine the community structure of AMF associated with the roots of a copper (Cu) tolerant plant—Elsholtzia splendens in a Cu mining area in southeastern Anhui Province, China. Molecular techniques were used to analyze AMF community composition and phylogenetic relationship in E. splendens roots sampled from three Cu mine spoils and two adjacent reference areas. Results obtained showed that root colonization and AMF diversity were very low and negatively correlated with total and extractable Cu concentrations. All the DNA sequences recovered belonged to the genus of Glomus. The principal component analysis (PCA) revealed that the AMF community composition varied remarkably among different sites and was related closely to soil properties, especially Cu concentrations. The distribution pattern of AMF species in various sites suggested the degree of AMF tolerance to Cu contamination. The unique AMF species that presented exclusively in heavily contaminated sites need to be further examined for potential application in phytoremediation of metal contaminated soils.     

Perennial plant species from semiarid gypsum soils support higher AMF diversity in roots than the annual Bromus rubens

The arbuscular mycorrhizal fungi (AMF) communities composition regulate plant interactions and determine the structure of plant communities. In this study we analysed the diversity of AMF in the roots of two perennial gypsophyte plant species, Herniaria fruticosa and Senecio auricula, and an annual herbaceous species, Bromus rubens, growing in a gypsum soil from a semiarid area. The objective was to determine whether perennial and annual host plants support different AMF communities in their roots. The roots were analysed by nested PCR, cloning, sequencing of the ribosomal DNA small subunit region and phylogenetic analysis. Twenty AMF sequence types, belonging to the Glomus group A, Glomus group B, Diversisporaceae, Acaulosporaceae, Archaeosporaceae and Paraglomeraceae, were identified. Both gypsophyte perennial species, H. fruticosa and S. auricula had different compositions of the AMF community and higher diversity than B. rubens. This annual plant species shared the full composition of its AMF community with both perennial plant species. Seasonal variations in the colonisation of AM fungi could explain the observed differences in AMF community composition, but this is still a working hypothesis that requires the analysis of further data obtained from a higher number of both annual and perennial plant species in order to be fully tested.