丛枝菌根真菌对金叶六道木镉吸收及根际真菌群落结构的影响

为明确丛枝菌根(AM)真菌对促进绿化苗木镉(Cd)吸收的影响,通过盆栽试验比较接种不同AM真菌对12种绿化苗木Cd吸收的差异,并进一步分析接种对金叶六道木根际微生物数量和AM真菌群落结构的影响.结果表明,12种绿化苗木,加Cd处理6个月后,其叶片浓度的变化范围为0.25～2.59 mg·kg–1.接种AM真菌处理组的叶...     

Effects of arbuscular mycorrhizal inoculation and phosphorus supply on the growth and nutrient uptake of Kandelia obovata (Sheue,Liu & Yong) seedlings in autoclaved soil

This study evaluated the interactive effect of arbuscular mycorrhizal fungi (AMF) inoculation and exogenous phosphorus supply on soil phosphotases, plant growth, and nutrient uptake of Kandelia obovata (Sheue, Liu & Yong). We aimed to explore the ecophysiological function of AMF in mangrove wetland ecosystems, and to clarify the possible survival mechanism of mangrove species against nutrient deficiency. K. obovata seedlings with or without AMF inoculation (mixed mangrove AMF), were cultivated for six months in autoclaved sediment medium which was supplemented with KH₂PO₄ (0, 15, 30, 60, 120 mg kg−¹). Then the plant growth, nitrogen and phosphorus content, root vitality, AMF colonization and soil phosphatase activity were analyzed. The inoculated AMF successfully infected K. obovata roots, developed intercellular hyphae, arbuscular (Arum-type), and vesicle structures. Arbuscular mycorrhizal fungi colonization ranged from 9.04 to 24.48%, with the highest value observed under 30 and 60 mg kg⁻¹ P treatments. Soil P supply, in the form of KH₂PO₄, significantly promoted the height and biomass of K. obovata, enhanced root vitality and P uptake, while partially inhibiting soil acid (ACP) and alkaline phosphotase (ALP) activities. Without enhancing plant height, the biomass, root vitality and P uptake were further increased when inoculated with AMF, and the reduction on ACP and ALP activities were alleviated. Phosphorus supply resulted in the decrease of leaf N–P ratio in K. obovata, and AMF inoculation strengthened the reduction, thus alleviating P limitation in plant growth. Arbuscular mycorrhizal fungi inoculation and adequate P supply (30 mg kg⁻¹ KH₂PO₄) enhanced root vitality, maintained soil ACP and ALP activities, increased plant N and P uptake, and resulted in greater biomass of K. obovata. Mutualistic symbiosis with AMF could explain the survival strategies of mangrove plants under a stressed environment (waterlogging and nutrient limitation) from a new perspective.     

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.     

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。     

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。     

Effect of arbuscular mycorrhizal fungi on rhizosphere organic acid content and microbial activity of trifoliate orange under different low P conditions

ABSTRACT

Arbuscular mycorrhizal (AM) fungi can improve plant phosphorus (P) uptake; however, information about how AM fungi affect rhizosphere organic acid and microbial activity to alleviate citrus low P stress is limited. Here, a pot experiment was conducted to evaluate the effect of AM fungi (Rhizophagus intraradices, Ri) inoculation on rhizosphere organic acid content, microbial biomass (MB) and enzyme activity of trifoliate orange (Poncirus trifoliata L. Raf.) seedlings grown under three low P conditions. The results showed that mycorrhizal seedlings all recorded higher P concentrations, plant biomass and better root morphology with more lateral and fine roots, but lower root mass ratios, irrespective of P conditions. Mycorrhizal P absorption contribution did not differ significantly among three P conditions. Mycorrhizal seedling rhizosphere soil exhibited lower organic acid content, soil organic P content and ratio of MB-carbon (C)/MB-P, but higher MB and enzyme activity. Additionally, the main organic acids showed a negative relationship with mycorrhizal colonization rate and hyphal length; however, phosphatase and phytase activity had a significantly positive relationship with MB. Therefore, the results suggest that AM fungi inoculation may help citrus to efficiently utilize organic P source by improving microbial activity under low available P conditions.     

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.     

丛枝菌根真菌(Glomus caledonium)对铜污染土壤生物修复机理初探

利用盆栽试验,研究了丛枝菌根真菌(Glomus.caledonium)在不同程度铜污染土壤上对玉米苗期生长的影响。结果表明,即使在土壤施铜量达150mg/kg时,菌根真菌对玉米仍有近55%的侵染率;接种菌根真菌,能显著促进玉米根系的生长。菌根玉米的根系生物量和根系长度,平均较未接种处理分别提高108.4%和58.8%;接种处理的植株地上部生物量达到每盆(3株)10.58g,显著高于不施铜的非菌根玉米。这些结果表明,丛枝菌根真菌对铜污染具有较好的抗性;并且由于菌根的形成,使宿主植物明显地改善了对磷的吸收和运输,并能通过抑制土壤酸化、降低土壤可溶态铜的浓度等机制,增强宿主植物对铜污染的抗(耐)性。在150mg/kg施铜水平时,与非菌根玉米相比,菌根玉米地上部和根系铜浓度分别降低24.3%和24.1%,吸铜量分别提高了28.2%和60.0%,表明菌根植物对铜污染土壤具有一定的生物修复作用。     

接种丛枝菌根真菌(AMF)对施磷石膏云烟87的生长以及砷污染的影响

【目的】丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)能够促进作物养分的吸收及生长,且对土壤砷污染有一定的抗性。磷石膏(phosphogypsum,PG)因含有丰富的磷、硫等养分可以为作物生长提供必要的养分,同时也可能带来砷污染的风险。【方法】为了探讨接种AMF对云烟87生长的影响以及磷石膏农用可能引起的砷污染风险,通过盆栽模拟试验研究了不同PG添加量(0和40 g/kg以PG0、PG40表示)和接种不同AMF[不接种None mycorrhizal(NM)、接种G.mosseae丛枝菌根真菌(GM)、接种G.aggregatum丛枝菌根真菌(GA)]对云烟87苗期生长及其磷、硫、砷吸收的影响。【结果】试验结果表明:无论接种与否,PG40处理的云烟87植株磷含量、吸收量及吸收效率均显著增加,其地上部硫含量及吸收量也显著增加;除NM处理外,添加PG均显著增加了云烟87根系的硫含量、硫吸收量及吸收效率,并显著增加了其植株的生物量。相同PG添加水平下,与NM处理相比,接种GM显著增加了云烟87根系的磷、硫吸收效率和植株的磷、硫含量及吸收量,另外,GM处理显著降低了其地上部砷含量及吸收量但显著增加了其植株的磷砷吸收比。在PG0处理下,接种GA显著增加了云烟87植株的磷含量及吸收量,并显著增加了其地上部硫含量及吸收量。在PG40处理下,接种GA显著增加了云烟87根系的硫含量和吸收量以及植株的生物量。无论是否添加PG,接种GA不同程度地降低了云烟87地上部砷含量和吸收量从而增加了其地上部的磷砷吸收比。【结论】在所有复合处理中,以添加磷石膏40 g/kg和接种GM对云烟87生长的促进效果较好,对施用磷石膏造成的砷污染有一定程度的抵御作用。     

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     

不同外源碳对AM真菌吸收氮源合成精氨酸的影响

本文意在探究外源碳对丛枝菌根（arbuscular mycorrhiza, AM）真菌吸收氮源合成精氨酸(Arg)的影响。采用三室隔离盆栽培养系统,以高粱（Sorghum bicolor L. Moench）为宿主植物,接种AM真菌Glomus intraradices,在菌丝室施加4 mmol/L的NH4NO3,同时在根室施加不同形式的碳源,测定分析不同外源碳条件下根外菌丝体（ERM）、菌根和植物茎叶中的Arg含量和总氮含量。结果表明ERM和菌根中的Arg含量远远高于茎叶中;虽然不同形式外源碳提高了AM真菌的ERM干重和菌根侵染率,但是葡萄糖降低了ERM、菌根和茎叶中的Arg含量,蔗糖和甘油对Arg含量没有显著的影响,只有外源Arg和谷氨酰胺（Gln）使ERM中的Arg含量显著增加;不同外源碳对菌根和茎叶的总氮含量没有显著影响。由上述结果分析可知在根室施加外源碳对AM真菌的氮代谢和宿主植物氮素营养水平没有显著影响,Arg合成所需的碳可能大多来自宿主植物供给的碳水化合物;但是施加外源碳能够促进AM真菌的生长繁殖。     

转Bt基因作物对丛枝菌根真菌的影响研究进展

在过去的十年里，世界范围内转基因作物尤其是抗虫性转Bt基因作物的品种和种植面积迅速增加。同时，转Bt基因作物的环境安全性评价问题成为人们关注和研究的热点。丛枝菌根真菌（AMF）是生态系统中普遍存在的土壤微生物，能与绝大多数植物种类形成共生关系，在农业生态系统中起重要作用。转Bt基因作物环境释放后，其与AMF问的共生关系是否受所转入Bt基因的影响，以及影响机制需要及时研究。为此，综述了转Bt基因作物与AMF共生特征方面的研究进展，并根据Bt毒素发生的空间和时间规律提出了危害机制以及转Bt基因植物的规模化种植将降低农田系统中的AMF的生物多样性的观点。     

Exudates of dark septate endophyte (DSE) modulate the development of the arbuscular mycorrhizal fungus (AMF) Gigaspora rosea

Exudates of a dark septate endophyte (DSE) identified as Dreschlera sp., a common endophyte isolated by the inner cortical cells of the grass Lolium multiflorum, were put in contact with the arbuscular mycorrhizal fungus (AMF) Gigaspora rosea. These exudates stimulated the hyphal length and the hyphal branching of the AMF. A negative effect on the extramatrical phase of the AMF was detected. This is the first report to show how exudates of DSE can affect the development of AMF. These results show that DSE could be modifying the mycorrhizal status of the plants, modulating a different symbiosis in the rhizosphere.     

Effect of peat on mycorrhizal colonization and effectiveness of the arbuscular mycorrhizal fungus Gigaspora margarita

Abstract

The influence of the addition of Chinese peat and Canadian peat on arbuscular mycorrhizal colonization, mycorrhizal effectiveness and host-plant growth was investigated in a pot experiment. Chinese peat or Canadian peat was mixed with Masa soil (weathered granite soil) at different levels (0, 25, 50, 100, 150 or 200 g kg^?1) into which an arbuscular mycorrhizal fungus (AMF) Gigaspora margarita Becker & Hall was inoculated, and seedlings of Miscanthus sinensis Anderess were planted. There was a significant increase in plant growth with increasing amounts of Chinese peat. The growth-promoting effect of the AMF on the host was enhanced when the addition of Chinese peat was increased from 25 to 100 g kg^?1. Root colonization and the number of spores proliferating increased with increases at low levels of Chinese peat (from 25 to 100 g kg^?1), and decreased gradually with higher Chinese peat increments. Although plant growth and root colonization with the addition of Canadian peat increased slightly, Canadian peat suppressed mycorrhizal effectiveness. In contrast to Canadian peat, the addition of Chinese peat improved considerably the physical and chemical properties of the soil, which might result in the promotion of AM formation and mycorrhizal effectiveness.     

不同磷肥水平下丛枝菌根菌对玉米修复芘污染土壤的影响

盆栽试验研究了不同磷肥水平下接种丛枝菌根菌（Arbuscular mycorrizal fungi,AMF）对玉米修复芘污染土壤的影响。结果表明,在施磷水平为20和80 mg/kg条件下,50 mg/kg芘处理土壤中丛枝菌根菌能够正常侵染玉米根系,侵染率没有显著变化;土壤芘污染对玉米的生长有抑制作用,缺磷土壤中施磷能够缓解土壤芘对玉米生长的抑制作用。培养60 d后,高磷（80 mg/kg）和低磷（20 mg/kg）条件下,玉米接种AMF处理土壤芘残留浓度分别比相应的不接种处理降低了38%和35%,比相应无玉米的对照处理降低了53%和58%。表明玉米接种混合AMF能够显著降低土壤芘残留浓度,促进土壤芘的去除。与P 20 mg/kg处理相比,P 80 mg/kg处理玉米接种及不接种AMF的土壤芘残留浓度分别降低了16%和19%,表明缺磷土壤中施磷对玉米及菌根玉米去除土壤芘均有一定促进作用。土壤微生物碳量与土壤芘的去除率显著正相关,接种AMF和P 80 mg/kg处理均能够显著增加土壤微生物碳量,因此土壤微生物数量的增加可能是其促进土壤芘的去除的重要原因。     

Changes in microbial communities and carbohydrate profiles induced by the mycorrhizal fungus (Glomus intraradices) in rhizosphere of olive trees (Olea europaea L.)

The influence of inoculation of olive trees with arbuscular mycorrhizal (AM) fungi, Glomus (G) intraradices, on microbial communities and sugar concentrations, were examined in rhizosphere of olive trees (Olea europaea L.). Analyses of phospholipid and neutral lipid fatty acids (PLFA and NLFA, respectively) were then used to detect changes in microbial community structure in response to inoculation of plantlets with G. intraradices.Microscopic observations studies revealed that the extraradical mycelium of the fungus showed formation of branched absorbing structures (BAS) in rhizosphere of olive tree. Root colonization with the AM fungi G. intraradices induced significant changes in the bacterial community structure of olive tree rhizosphere compared to non-mycorrhizal plants. The largest proportional increase was found for the fatty acid 10Me18:0, which indicated an increase in the number of actinomycetes in mycorrhizal rhizosphere soil, whereas the PLFAs i15:0, a15:0, i16:0, 16:1ω7 and cy17:0 which were used as indicators of bacteria decreased in mycorrhizal treatment compared to non-mycorrhizal control treatment. A highest concentration of glucose and trehalose and a lowest concentration of fructose, galactose, sucrose, raffinose and mannitol were detected in mycorrhizal rhizosphere soil. This mycorrhizal effect on rhizosphere communities may be a consequence of changes in characteristics in the environment close to mycorrhizal roots.     

AM真菌对烟苗生长及某些生理指标的影响

在低浓度营养液条件下,利用漂浮育苗技术培育烟苗,于播种期、小十字期、生根期分别接种不同的AM真菌,研究了它们对烟苗生长、营养和某些生理指标的影响。结果表明,越早接种AM真菌,其侵染率越高;播种期接种,侵染率达到39.2%～59.6%。AM真菌的菌根效应因菌种(株)不同而异,接种球囊霉真菌（BEG-141）后,显著增加烟苗干重、磷含量、氮磷钾吸收量、叶绿素含量,以及根系硝酸还原酶、超氧化物歧化酶和几丁质酶活性。表明在漂浮育苗技术中,播种期接种适宜的AM真菌是培育壮苗的有效措施。     

Chronic nitrogen deposition and the composition of active arbuscular mycorrhizal fungi

A growing body of evidence indicates that atmospheric nitrogen (N) deposition can alter the composition and function of arbuscular mycorrhizal fungi (AMF) associated with plant roots. We studied the community of AMF actively transcribing ribosomal genes in the forest floor of northern hardwood forests dominated by sugar maple (Acer saccharum Marsh.) that have been exposed to experimental N deposition since 1994 (30 kg NO₃⁻-N ha⁻¹ year⁻¹). Our objective was to evaluate whether previously observed declines in AM root infection and mycelial production resulted in a compositional shift in the AM fungi actively providing resources to plant symbionts under chronic N deposition. To accomplish this task, we cloned and sequenced the LSU of reverse-transcribed AM fungal rRNA extracted from the forest floor under ambient and experimental N deposition treatments. We found that experimental N deposition did not alter the active community of AMF or AMF diversity, but we did observe a significant decrease in rare taxa under chronic N deposition. Our results indicate that chronic N deposition, at levels expected by the end of this century, can exert a moderate influence on the composition and abundance of AMF associated with plant roots in a wide-spread forest ecosystem in the northeastern North America.