贵州务川汞矿区土壤丛枝菌根真菌多样性研究

对贵州务川汞矿区不同水平汞污染植物根际土壤丛枝菌根(Arbuscular Mycorrhizal,AM)真菌资源分布及多样性进行分析，结果发现：本研究选取的务川汞矿区3个样地土壤汞含量在94.1～268.0 mg/kg，远高于国家规定的土壤汞含量，汞污染极其严重。随着汞含量增加，AM真菌侵染率、孢子密度显著降低，AM真菌群落丰富度、多样性及均匀度均有所降低，但差异未达显著水平，而仍有部分对汞污染耐受性较强的AM真菌有较高的分布。另外，管柄囊霉属AM真菌在5个样品中均有较高丰度，球囊霉属AM真菌在火棘根际的相对丰度随着汞含量升高而升高，因此，火棘–管柄囊霉属AM真菌或火棘–球囊霉属AM真菌联合进行汞污染修复，有一定的应用价值。     

丛枝菌根真菌根内菌丝碱性磷酸酶活性与菌根共生效应的研究

试验研究 3种丛枝菌根真菌根内菌丝碱性磷酸酶活性与菌根共生效应的结果表明 ,3种丛枝菌根真菌对宿主植物的效应不同 ,与接种G .spp处理和未接种对照相比 ,接种G .m和G .i处理显著增加玉米地上部和根系干物质量、P浓度和吸P量 ,但后两者间无显著差异 ;而接种G .spp处理与对照无显著差异。播种后 35d时接种G .m和G .i处理根内菌丝碱性磷酸酶活性显著高于接种G .spp处理 ,而前二者间无显著差异 ,且随生长时间的变化趋势相似 ,35d时酶活性最高 ,35～ 5 0d呈迅速下降趋势 ,至 70d时酶活性仍下降且趋于平缓。G .spp酶活性则一直处于较低水平 ,随生长时间的延长略有起伏。即接种不同丛枝菌根真菌时 ,根内菌丝碱性磷酸酶活性高的菌根真菌对玉米生长促进作用较大 ,可提高玉米P营养状况 ;反之则对玉米生长和P营养状况无明显促进作用 ,且与对照无显著差异。出苗后 35d时根内菌丝碱性磷酸酶活性是预测丛枝菌根真菌对玉米生长效应的有效生理指标之一。     

土地利用方式对酸性红壤丛枝菌根真菌群落的影响

为了研究土地利用方式对酸性红壤丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)群落的影响,调查了酸性红壤4种土地利用方式(草地、玉米、花生和大豆)下非根际和根际土壤AMF群落多样性和组成结构。结果表明：土地利用方式显著影响了AMF群落优势属球囊霉属(Glomus)和巨孢囊霉属(Paraglomus)的相对丰度,但是根际作用影响不明显。土地利用方式而非根际作用显著影响了AMF群落香农指数和物种丰富度,其中大豆地表现出最低的香农指数和物种丰富度。土地利用方式和根际作用都显著影响AMF群落组成结构,但是土地利用方式的作用强度明显高于根际作用。球囊霉属主要解释了不同土地利用方式之间的AMF群落组成差异。土壤p H是影响土壤AMF群落结构的最关键因子。因此,土地利用方式比根际作用表现出对酸性红壤AMF群落更大的影响,展现了土地利用变化在影响土壤AMF群落方面的重要作用。     

毛乌素沙地典型克隆植物根际AM真菌多样性研究

为阐明毛乌素沙地3种典型克隆植物沙鞭[Psammochloa villosa(Trin.)Bor.]、羊柴(Hedysarum leaveMaxim)和油蒿(Artemisia ordosica Krasch.)根际AM真菌多样性,2006年的5月、7月、10月从毛乌素沙地选取东北缘的中国科学院植物研究所鄂尔多斯沙地草地生态研究站和西南缘的陕西榆林珍稀沙生植物保护基地两个样地,按0~10 cm、10~20 cm、20~30 cm、30~40 cm、40~50 cm 5个土层采集3种克隆植物根际土壤样品,研究了其根际AM真菌物种多样性和生态分布。在分离出的4属23种AM真菌中,球囊霉属(Glomus)15种,无梗囊霉属(Acaulospora)5种,巨孢囊霉属(Gigaspora)2种,盾巨孢囊霉属(Scutellospora)1种。摩西球囊霉(G.mosseae)是沙鞭根际的优势种,黑球囊霉(G.melanosporum)是3种克隆植物共同的常见种;不同属种的AM真菌生态分布亦存在差异。AM真菌孢子密度、种的丰度和物种多样性指数均表现为在研究站样地的羊柴根际最高。该研究结果表明,毛乌素沙地的3种典型克隆植物与AM真菌之间形成良好的共生关系,这对开发漠境AM真菌资源和利用菌根生物技术维护沙地生态系统结构的完整性具有重要意义。     

AM真菌与地上草食动物的互作及其对宿主植物的影响

丛枝菌根是自然生态系统中广泛存在的一种植物根系与菌根真菌的共生体.放牧是草原生态系统的一种重要生态学功能.目前,关于AM真菌和植物的关系,以及草食动物与植物的相互作用研究已经非常深入,但有关AM真菌-植物-草食动物的多重相互作用研究尚处于发展初期.本文从揭示AM真菌-植物-草食动物三者相互作用机理的角度出发,围绕动物采食作用对AM真菌的侵染、孢子群落组成的变化及其作用机理,丛枝菌根对动物采食行为的影响,以及植物个体与群落对二者共同作用的响应等方面,对AM真菌-植物-草食动物研究领域最新的成果进行综述,并在此基础上,提出AM真菌-植物-草食动物相互作用领域未来的研究方向.     

MES [2-(N-morpholine)-ethane sulphonic acid] buffer promotes the growth of external hyphae of the arbuscular mycorrhizal fungus Glomus intraradices in an alkaline sand

In this work we investigated the hypothesis, suggested by unpublished experiments carried out previously, that application of MES [2-(N-morpholino)-ethane sulphonic acid] buffer to the substrate of plants hosting the arbuscular mycorrhizal fungus Glomus intraradices might favour the growth of external hyphae. The substrate of Trifolium pratense plants, with or without G. intraradices inoculum, was treated twice weekly, between weeks 5 and 11 of growth, plant with distilled water, P-supplemented 10% Hewitt nutrient solution (H+P), 51mM in H+P or 1mM TRIS-HCl in H+P. MES buffer increased the length of external G. intraradices hyphae and the density of propagules in the substrate, but plant growth was not affected. Although both TRIS-HCl and MES caused substrate pH to fall (from 8.51 to 7.35 and 7.17, respectively), only MES induced a significant increase in external hypha length. We conclude that the effect of MES on external hypha length was not due to plant growth or to substrate pH per se. Received: 10 March 1996     

丛枝菌根真菌(Glomus mosseae)对玉米吸镉的影响

盆栽试验研究了不同培养条件(土壤与河沙)下,3种施Cd水平(0、5、50 mg kg-1)对菌根玉米生长、根系侵染率及重金属Cd吸收的影响。结果表明:施Cd水平显著影响玉米吸Cd能力。随Cd浓度增加,各处理根系与地上部分Cd浓度和吸收量显著增加,各施Cd水平下玉米根系Cd浓度和吸收量远远高于地上部分。不同培养条件下,各处理也表现出明显的差异。以河沙为培养基质,接种菌根真菌显著增加玉米的生物量及根系侵染率;在高Cd水平下,接种处理玉米根系中的Cd浓度和吸收量较对照显著增加,但地上部分的Cd浓度和吸收量却相应降低。以土壤为培养基质,随施Cd水平提高,植株吸Cd量增加,但接种处理植株根部与地上部Cd浓度均显著低于对照。试验表明,丛枝菌根真菌Glomus mosseae可减少重金属Cd向玉米植株地上部的运输,将更多的Cd固持在菌根之中,这可能是菌根减轻宿主植物Cd毒害的一个重要机制。     

Suppressive effects of seed-applied fungicides on arbuscular mycorrhizal fungi (AMF) differ with fungicide mode of action and AMF species

Seed-applied fungicides are commonly used to prevent or suppress fungal disease organisms in pulse crop production. However, non-target beneficial fungi, such as arbuscular mycorrhizal fungi (AMF), also may be affected. Seed-applied fungicides Agrox^® FL (active ingredient: captan), Allegiance™ FL (metalaxyl), Apron Maxx^® RTA^® (fludioxonil and metalaxyl), Thiram 75WP (thiram), Vitaflo^® 280 (carbathiin and thiram), Crown^® (carbathiin and thiabendazole), and Trilex^® AL (trifloxystrobin and metalaxyl) were assessed in a greenhouse study for their effects on colonization and development of AMF in pea and chickpea, and the consequent impact on plant growth. In the absence of disease pressure, systemic fungicides Allegiance™ FL, Apron Maxx^® RTA^®, Vitaflo^® 280, Crown^® and Trilex^® AL restricted mycorrhizal colonization, host growth and P uptake to different levels. In contrast, contact fungicides Agrox^® FL and Thiram 75WP had minimal effects on mycorrhizal colonization, host growth and P uptake. Although consequent sporulation and glomalin-related protein production were not significantly affected by fungicides at an early host growth stage, the compositional structure of the AMF community in host roots was significantly altered in response to Agrox^® FL, Allegiance™ FL, Apron Maxx^® RTA^®, and Trilex^® AL as revealed by pyrosequencing-based analysis of fungal 18S rRNA. These results indicate that the suppressive effects of seed-applied fungicides on AMF development depend on specific fungicide-AMF interactions.     

Arbuscular mycorrhizal colonization of selected herbaceous plants under arid protected area in Tunisia

Arbuscular mycorrhizal fungi (AMF) play an important role in plants growth and soils dynamic in all most ecosystems. The main objective of the present study was to evaluate the plant-AMF interactions on soil functions under arid protected area ‘Zarat-Gabès’ in Tunisia.

AMF colonization was evaluated by visual observation of AMF in fine roots of eight herbaceous plants. The level of mycorrhizal colonization varied between plants. Astragalus corrugatus and Hippocrepis areolata showed the highest mycorrhizal performance. The relative spore number was significantly different across rhizosphere soils. Statistical analysis showed a clearly positive correlation between the number of spores and plant-mycorrhizal intensity.

For microbiological parameters, our results showed that mycorrhizal plants improved significantly the various microbiological parameters. Rhizosphere soils of Astragalus corrugatus and Hippocrepis areolata presented the necessary microbial densities and microorganisms more stable compared to unplanted soil. This study allowed obtaining a new result that challenges us about the need for efficient management of natural resources in the objective of nature conservation.     

Underground communication of root hormones by common mycorrhizal network between trifoliate orange and white clover

Common mycorrhizal network (CMN) links up several coexisting plant individuals via underground root communication for resource sharing, while it is not known whether phytohormones participate in such communication. A two-chambered rootbox separated through 37-μm mesh was used to establish the CMN by Diversispora spurca between trifoliate orange (TO) and white clover (WC). After 20 weeks of inoculation, the CMN was established, as evident from high mycorrhizal buildup under supplier (mycorrhizal inoculation) TO–target (non-mycorrhizal inoculation) WC association. This CMN was eventually responsible for the significant increase in plant biomass of these associated plants. CMN decreased root abscisic acid (ABA) level in supplier and target plants, but increased root indole-3-acetic acid (IAA) level in supplier plant alone. CMN mediated significantly higher gibberellins (GAs) and zeatin riboside (ZR) concentration in roots of target plant, leaving supplier plant unaffected. Root ZR was bidirectionally transferred through the CMN. A higher root methyl jasmonate (MeJA) concentration was observed in supplier WC–target TO or supplier TO–supplier WC association, indicating an unidirectional communication from WC to TO. It suggested that except IAA, GAs, brassinosteroid (BR), and ABA, root MeJA and ZR were apparently involved in the underground communication by CMN.     

Extraction of Glomalin and Associated Compounds with Two Chemical Solutions in Cultivated Tepetates of Mexico

Glomalin is a glycoprotein produced by the hyphae of arbuscular mycorrhizal fungi (AMF). The chemical methods usually employed to extract glomalin from the soil obtain something more than this pure glycoprotein, and therefore it would be better to call this fraction soil protein related to glomalin (SPRG) or glomalin associated with humic substances (GAHS). On this account, its isolation is controversial. The SPGR or GAHS has a significant influence on the physical, chemical, and biological properties of soils and could then be considered as an indicator of soil use change. In the present study, the storage of SPRG was evaluated, as well as carbon (C) associated with the latter (CG) and the content of soil organic C (SOC) in cultivated tepetates in the State of Mexico. Tepetates are hardened volcanic tuffs of the fragipan type, ameliorated for agricultural production. The specific objectives of the present study were (1) to evaluate the SPRG levels in tepetates, (2) measure the contribution of carbon (C) made by the SPRG to soil organic C (SOC), and (3) compare the extraction of SPRG with sodium pyrophosphate and sodium citrate. The samples used in this experiment came from 87 tepetate-cultivated plots (0–20 cm) located in the Texcoco River basin, State of Mexico. The levels of SPRG were observed among traces, 2.3 mg g^–1 for citrate and up to 5.6 mg g^–1 for pyrophosphate. The latter reactive allowed us to extract nearly three times more SPRG and two times more C-SPRG than sodium citrate (P?=?0.05) in the tepetates having about 4% of SOC; yet when the latter was less than 0.5%, the extraction levels with both solutions were similar. The SPRG and CG were closely correlated with SOC (r > 0.90). Tepetates have levels of SPRG similar to those observed in arid soils.     

Growth and nutrient uptake of tomato in response to application of saline water,biological fertilizer,and surfactant

The importance of using low-quality water, such as saline waters, for food production has been increased in the recent decades. An experiment was conducted to evaluate the effect of diluted seawater (electrical conductivity (EC) of 6 dS m^?1) on growth and nutrient uptake of tomato. We examined if surfactant (0, 1, 2, 4 mg L^?1) and biological fertilizer (compost tea + arbuscular mycorrhizal fungi propagules) have potential to alleviate the adverse effects of salinity on tomato plant. Salinity stress significantly reduced all plant growth parameters. Under salinity stress, nitrogen (N) and potassium (K) contents in tomato shoot were lower, while phosphorus (P), sodium (Na), and calcium (Ca) contents were higher than non-salinized plants; showing ionic imbalance in this condition. Biological fertilizer improved root weight in saline condition. Under salinity stress surfactant application at the rate of 1 mg L^?1 helped tomato plants to maintain their ionic balance, especially declining Na uptake, and improved plant growth.     

The Effect of Arbuscular Mycorrhizal Fungi Inoculation in Mitigating Salt Stress of Pea (Pisum Sativum L.)

ABSTRACT

Salinity is one of the major threats to an agriculture production system and limits crop growth and productivity. Arbuscular mycorrhizal fungi (AMF) form a mutualistic association with majority of land plants and play important role in stress tolerance. In the present study, effect of three mycorrhizal treatments, i.e., single-species AMF (Rhizoglomus intraradices), formulated AMF (Funneliformis mosseae and R. intraradices), and multispecies AMF (Rhizoglomus fasciculatum and Gigaspora sp.) along with control (nonmycorrhizal) on growth, yield performance, and metabolic changes in pea crop under salinity stress was examined in completely randomized design with four replications. The results revealed that AMF inoculation mitigated negative effects of salinity in pea due to higher nutrient uptake, accumulation of compatible osmolytes, and lower cellular leakage of electrolyte which in turn enhanced biomass production, chlorophyll synthesis, yield, and growth attributes. Overall, consortium-based application of R. fasciculatum and Gigaspora sp. was found most suitable approach to ameliorate the salt stress in pea crop and enhanced the yield by ~11%, 24%, and 54% than single-species, multispecies, and control treatments, respectively. The variation in results under different mycorrhizal treatment might be due to specific compatibility relationships that exist between symbionts.     

Molecular identification of arbuscular mycorrhizal fungal spores associated to the rhizosphere of Retama raetam in Tunisia

ABSTRACT

Arbuscular mycorrhizal fungi (AMF) are found in the soil of most ecosystems where they form mutualistic associations that affect plants growth. We have investigated the community structure of AMF associated to Retama raetam growing in five regions of Tunisia. The total number of spores was significantly different across sites, ranging from 633 to 1062 spores per 100 g dry soil. A dominance of small spores was revealed. The large subunit region of the rDNA of AMF spores associated to the rhizosphere of R. raetam was sequenced. Sequences clustered into 13 operational taxonomic units. Phylogenetic analysis revealed that the majority of sequences were grouped within Glomeraceae and Claroideoglomeraceae families. Only two sequences were affiliated to the Scutellospora genus. These results suggest the dominance of the genus Glomus in the soil rhizosphere of R. raetam. A correlation between phylogenetic analysis, soil chemicals properties, and AMF community richness was also detected.     

Arbuscular mycorrhizal fungi in tree-based intercropping systems: A review of their abundance and diversity

Arbuscular mycorrhizal (AM) fungi are important components of agroecosystems as they form symbiotic associations with the majority of agricultural crops. The mycorrhizal association is normally mutualistic and can provide a number of benefits to the host plant including increased nutrient uptake, improved water relations, and protection from pathogens. However, conventional agricultural practices have been shown to have a negative impact on the abundance and diversity of AM fungi. The use of more diverse and sustainable land use practices such as tree-based intercropping can have the potential to reduce the negative impact of agricultural practices on AM fungi. This paper reviews the literature to investigate the effect of temperate and tropical tree-based intercropping systems on the abundance and diversity of AM fungi. Evidence from these studies suggests that tree-based intercropping systems support a more abundant and diverse AM fungal community compared to conventionally managed systems. However, there are studies that observed zero or negative significant effects on the AM fungal community as a result of incorporating trees into agricultural systems. The variable effect of tree-based intercropping systems on AM fungi observed may be a function of the different cultivation techniques, climatic variation, or diverse tree-crop combinations used within the different tree-based intercropping systems. To further our understanding of AM fungal dynamics in tree-based intercropping systems, future research should focus on the influence of tree species with varying mycorrhizal associations and the functional role of common mycelial networks in these systems, while utilizing applicable molecular techniques.     

Diversity and seasonal variations of mycorrhiza and rhizosphere bacteria in three common plant species at the Slovenian Ljubljana Marsh

Interactions between plants and microorganisms can significantly affect plant health and productivity as well as ecosystem functioning. Detailed knowledge of the tripartite relationships between plants, fungi, and bacteria, and their environment is still limited. In the present study, the soils adjacent to three plant species (Cruciata laevipes, Mentha piperita, Equisetum arvense) in the Ljubljana Marsh and the bulk, plant-free soil were analyzed for their bacterial community structure in June and October 2006. The terminal restriction fragment length polymorphism analysis indicated a different bacterial community structure in the rhizosphere and in bulk soil, however, with almost no seasonal changes between late spring and autumn samples and no apparent impact of the three plant species. In addition, root colonization of the three plant species by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) was microscopically assessed monthly from May until October 2006. A presumably accidental correlation between monthly precipitation and the degree of arbuscule formation, with the latter lagging 1 month, was noted for M. piperita, the most heavily colonized of the three plant species. With all three plants, the phosphorus content in roots correlated positively with most AMF structures. Microsclerotia of DSE were mainly abundant in autumn samples. Fungal diversity in roots was estimated using temporal temperature gradient gel electrophoresis separation of the fungal polymerase chain reaction products obtained for both 18S-rDNA and the 5.8S-ITS2-28S rDNA segments. No specific effects of either plant species or seasonal changes on mycorrhizal community structure were discernible.     

Liquid organic fertilizer sprayed on shoots of Phaseolus vulgaris stimulates arbuscular mycorrhiza colonization and phosphate solubilizing microorganisms in soil

Processed organic agricultural byproducts such as liquid organic fertilizer (LOF) are promising alternatives that can improve crop productivity while reducing mineral fertilizer use and improving sustainability. The effects on beneficial soil organisms, such as arbuscular mycorrhizal (AM) fungi and phosphate solubilizing microorganisms (PSM), caused by LOF spraying on shoots is poorly understood. Therefore, we evaluated how AM colonization and soil PSM are affected by LOF spraying on common beans (Phaseolus vulgaris L.) grown in a greenhouse. The LOF was obtained by anaerobically fermenting a mixture of fresh water, cattle manure, bovine milk, sugarcane molasses and mineral salts. LOF was applied twice on the plant shoots. Fresh and dry mass of root and shoot, P content, P accumulation in the shoots and AMF spore counts in the soil were not LOF dose dependent. However, we found that a 5% LOF application stimulated AM colonization and led to dose-dependence for calcium and aluminium phosphate solubilizing bacteria and fungi. These results show that LOF sprayed on shoots causes responses on soil communities. We therefore endorse the use of LOF in low input agriculture.     

烟草与丛枝菌根真菌的共生效应研究进展

丛枝菌根(Arbuscular mycorrhiza,AM)真菌是陆地生态系统中广泛存在的一类专性共生土壤微生物,是根系土壤区域中重要的功能菌群之一.AM真菌可侵染植物根系形成丛枝菌根共生体,改变植物根系形态和改善营养状况,从而提高宿主植物的生长发育、产量、质量和抗逆性.目前从烟草根系土壤分离报道的AM真菌已达13属5...     

Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in the field

Allelopathy is a biological phenomenon where plants have harmful effects on growth of surrounding plants through the production of chemical substances. Here we focus on allelochemical processes which operate belowground, can influence plant interactions and therefore potentially affect plant community structure. Soil hyphae of arbuscular mycorrhizal fungi (AMF) may enhance transport processes in the soil matrix by providing direct connections between plants facilitating infochemical exchange.In a two-component field study we showed that soil hyphae likely play a crucial role in movement of allelochemicals in natural soils and greatly expand bioactive zones by providing effective transport pathways for chemical compounds. First, we tested the effects of Juglans regia leaf litter extract addition in intact or disrupted hyphal networks and simultaneously determined growth reducing effects on sensitive Lycopersicon lycopersicum plants. Second, we analyzed the effect of juglone on tomato by directly adding leaf litter. In both approaches we found an increase of juglone transport if a hyphal network was present, resulting in reduced growth of target plants.Our results, together with previous work, add to the body of evidence for hyphae of soil fungi playing an important role in the transfer of allelochemicals and effectively acting as transport highways in the field. We suggest that hyphal connections, mostly formed by AMF, increase the effectiveness of allelochemicals in natural systems and can play a crucial role in chemical interaction processes in the soil.