Arbuscular mycorrhizal fungi and Trichoderma viride mediated Fusarium wilt control in tomato

The biocontrol potential of two arbuscular mycorrhizal fungi (AMF) (Funneliformis mosseae and Acaulospora laevis) and Trichoderma viride was assessed against tomato wilt caused by Fusarium oxysporum Schlecht. f. sp. lycopersici under pot condition. All the bioagent showed appreciable results in increasing plant growth. Combined inoculation of F. mosseae, A. laevis and T. viride showed maximum increases in plant height, shoot fresh weight, root dry weight, number of leaves and number of branches per plant while dual inoculation of F. mosseae and T. viride increased rest of the growth parameters like shoot dry weight, root fresh weight, root length and leaf area. AM colonisation and spore number was found highest in single inoculation of AMF, which decreases with the addition of T. viride. But, this decrease has no effect on biocontrol efficiency of bioagents. Photosynthesis, chlorophyll content and nutrient content were markedly decreased by pathogen infection. Bioagent application overcomes this effect and a remarkable increase in the plant phosphorus and nitrogen content was recorded. Among both the AMF, F. mosseae proved to be more effective strain compared to A. laevis for tomato. Maximum reduction in disease incidence and severity was recorded in combined inoculation of F. mosseae, A. laevis and T. viride. Whereas control plants without any bioagent showed maximum occurrence of disease. The findings of this study concludes that soil inoculation with F. mosseae along with root inoculation with conidial suspension of T. viride before transplantation offered better survival and resistance to tomato seedlings against Fusarium wilt.     

Asymmetric facilitation induced by inoculation with arbuscular mycorrhizal fungi leads to overyielding in maize/faba bean intercropping

Understanding the effects of arbuscular mycorrhizal fungi (AMF) under different environmental contexts on overyielding in intercropping systems can be instructive in optimizing productivity and ecosystem services. A greenhouse study was conducted with maize and faba bean monocultures or intercropping at low phosphorus (P) and high P levels with three different water availabilities, and inoculated with or without AMF species Funneliformis mosseae. At low P level, overyielding was mainly due to the increase of maize biomass promoted by AMF relative to faba bean. Whereas in high P soils, overyielding was observed at all treatments, regardless of AMF. Inoculation of AMF significantly improved maize rather than faba bean P uptake, water use efficiency and photosynthesis rate, in particular at the low P level. This study identified the context dependence of AMF in influencing overyielding in maize/faba bean intercropping and demonstrates the importance of AMF in sustainable agricultural production.     

内蒙古中部地区马铃薯根际和根系丛枝菌根真菌类群的多样性

【背景】丛枝菌根真菌(arbuscular mycorrhizal fungus,AMF)是菌根真菌中分布最广泛的一类真菌,能够与90%以上的植物形成菌根共生体,并通过调节宿主体内的代谢活动增强植物的抗逆性。【目的】揭示内蒙古马铃薯主产区土壤中AMF的结构与组成,解析马铃薯不同发育阶段以及连作对AMF类群的影响。【方法】以内蒙古中部地区大井村、徐麻夭村和红格尔图村采集的马铃薯根系及根际土为材料,通过PCR扩增建立18S rRNA基因文库,研究不同地点、不同马铃薯生育阶段以及连作对马铃薯根系内和根际土中的AMF类群组成和多样性的影响。【结果】大井村和红格尔图村马铃薯根际土中的AMF的类群多样性优于徐麻夭村,其中Glomus为大井村和红格尔图村马铃薯根际土样本中AMF的优势菌群,而徐麻夭村样本根际土中的优势类群为Diversispora。马铃薯根系中的AMF多样性的研究结果表明,3个供试地点根系内AMF类群的类型没有显著差异,但是AMF类群的比例却不同。大井村根系样本中AMF的优势菌为Diversispora,而Rhizophagus是红格尔图村和徐麻夭村根系样本中的优势AMF类群。同一供...     

小麦蚕豆间作对蚕豆根际微生物群落功能多样性的影响及其与蚕豆枯萎病发生的关系

通过田间小区试验,研究了小麦与蚕豆间作对蚕豆枯萎病发生和根际微生物代谢功能多样性的影响。结果表明,小麦与蚕豆间作使蚕豆枯萎病的发病率和病情指数分别比单作显著降低20%和30.4%。与单作处理相比,间作显著增加了蚕豆和小麦根际微生物对31种碳源的平均利用率（AWCD）,其中间作蚕豆的AWCD值最高,比单作增加82.7%,单作蚕豆最低。间作蚕豆和间作小麦根际微生物的Shannon多样性指数与丰富度指数均显著高于单作,间作使蚕豆和小麦的丰富度指数分别增加29.2%和30.3%。根际微生物对六类碳源的利用强度百分比以糖类、羧酸类和氨基酸最高,分别为41.96%,19.80%和18.13%。主成分分析表明,小麦与蚕豆间作改变了根际微生物的群落组成;相关分析表明,糖类、羧酸类和氨基酸类碳源是区分单间作处理差异的主要碳源,其中氨基酸类碳源是最敏感的碳源。小麦与蚕豆间作增加了根际微生物活性,提高了Shannon多样性指数和丰富度指数,改变了微生物群落功能多样性,是抑制蚕豆枯萎病的有效措施。该研究为阐明根际微生物功能多样性变化在间作体系病害控制中的作用与机制奠定了理论基础。     

西北半干旱区紫花苜蓿-小黑麦间作对根际土壤养分和细菌群落的影响

我国西北半干旱区土地贫瘠,土壤pH和碳酸盐含量高,容易形成盐碱地,抑制土壤微生物活性,导致土壤养分匮乏。为了改善西北干旱地区土壤健康状况,本研究通过连续3年田间试验,探讨了紫花苜蓿-小黑麦间作对根际土壤养分和根际土壤细菌群落结构的影响。结果表明: 根际土壤中,间作紫花苜蓿有机质含量显著大于单作紫花苜蓿,而pH及速效钾含量显著低于单作紫花苜蓿;间作小黑麦有机质、碱解氮、有效磷及速效钾含量均显著大于单作小黑麦。细菌序列数、种群分类单元(OTU)、丰富度和多样性均表现为间作大于单作。在门水平上,变形菌门和拟杆菌门分别占总分类单元的31.1%～33.4%和22.4%～32.2%,且间作下拟杆菌门比例高于单作。放线菌门数量在单作下显著大于间作,酸杆菌门数量在小黑麦间作下显著大于单作,疣微菌门数量在紫花苜蓿间作下显著大于单作。在属水平上,噬冷菌属、黄杆菌属、Gp6和Chryseolinea数量均表现为单作大于间作,纤维弧菌属相反。相关性分析表明,变形菌门、拟杆菌门与pH呈显著负相关,拟杆菌门与有机质、全氮、碱解氮呈显著正相关;而绿弯菌门、浮霉菌、酸杆菌门、疣微菌门和芽单胞菌门与有机质和碱解氮呈显著负相关。紫花苜蓿-小黑麦间作是改善西北半干旱区土壤的一种有效措施。     

Arbuscular mycorrhizal fungi associated with Artemisia umbelliformis Lam, an endangered aromatic species in Southern French Alps, influence plant P and essential oil contents

Root colonization by arbuscular mycorrhizal (AM) fungi of Artemisia umbelliformis, investigated in natural and cultivated sites in the Southern Alps of France, showed typical structures (arbuscules, vesicles, hyphae) as well as spores and mycelia in its rhizosphere. Several native AM fungi belonging to different Glomeromycota genera were identified as colonizers of A. umbelliformis roots, including Glomus tenue, Glomus intraradices, G. claroideum/etunicatum and a new Acaulospora species. The use of the highly mycorrhizal species Trifolium pratense as a companion plant impacted positively on mycorrhizal colonization of A. umbelliformis under greenhouse conditions. The symbiotic performance of an alpine microbial community including native AM fungi used as inoculum on A. umbelliformis was evaluated in greenhouse conditions by comparison with mycorrhizal responses of two other alpine Artemisia species, Artemisia glacialis and Artemisia genipi Weber. Contrary to A. genipi Weber, both A. umbelliformis and A. glacialis showed a significant increase of P concentration in shoots. Volatile components were analyzed by GC–MS in shoots of A. umbelliformis 6 months after inoculation. The alpine microbial inoculum increased significantly the percentage of E-β-ocimene and reduced those of E-2-decenal and (E,E)-2-4-decadienal indicating an influence of alpine microbial inoculum on essential oil production. This work provides practical indications for the use of native AM fungi for A. umbelliformis field culture.     

丛枝菌根真菌通过改变植物基因表达水平和微生物群落结构促进红叶石楠对镉的吸收

作为一种非必需元素,重金属镉(cadmium,Cd)的污染对植物、环境乃至人类健康具有严重影响.利用绿化苗木移栽修复Cd污染土壤具有广阔的应用前景.为了明确丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)对红叶石楠(Photinifraseri frase) Cd吸收的促进作用,本研究利...     

Nutritional status,essential oil changes and water-use efficiency of rose geranium in response to arbuscular mycorrhizal fungi and water deficiency stress

Stress induced by water deficit is considered to be a global problem and one of the most important factors limiting crop production in arid and semi-arid regions of the world. Application of certain microorganisms, including arbuscular mycorrhizal fungi (AMF), is considered to be an effective and sustainable strategy to mitigate the problem. A pot experiment was conducted in the field (from Feb. to Sep. in 2013–2014 in Isfahan, Iran) to assess the effectiveness of AMF inoculation on changes in biomass, essential oils, nutrient uptake and water-use efficiency of rose geranium (Pelargonium graveolens L.) experiencing stress induced by a deficit of water. The experiment was planned as a factorial experiment, using a completely randomized design, with two factors, including four AMF inoculation (non-mycorrhizal, Rhizophagus intraradices and Funneliformis mosseae inoculated, and the combination of both species) and three irrigation levels including well-watered (WW), moderate water deficiency (MWD) and severe water deficiency (SWD). The results indicated the occurrence of an adverse effect of water deficit on plant total biomass; however, AMF inoculation positively increased plant biomass compared to the non-inoculated ones under three irrigation levels. MWD condition resulted in higher essential oil (EO) content (12.4 %), water-use efficiency (WUE) (29.5 %) and glomalin-related soil proteins (GRSP) (19.1 %) in the plants compared to WW condition. Furthermore, all AMF inoculation improved EO content by at least 12 k%. The results also showed that severe water deficiency adversely affected the uptake of most nutrients by plants especially in non-inoculated plants. The results also revealed that, although EO production was under the control of irrigation regime, nutrient uptake was critically dependent on an association with mycorrhizae. Notwithstanding the fact that rose geranium can tolerate moderate drought stress, the high responsiveness of rose geranium to AMF under water deficiency stress confirms the key role of AMF in facilitating the production of this valuable crop in harsh environments. Dual infection of rose geranium with two AMF species could also synergistically affect biomass, essential oil content and mineral elements absorption.     

贵州煤矸石山香根草根系及根际土丛枝菌根真菌(AMF)群落的季节动态研究

以煤矸石山种植年限为17年的香根草Vetiveria zizanioides为研究对象,采用高通量测序技术研究香根草根系及根际土丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落的季节动态.并利用Spearman、NMDS、RDA和Mantel-test等统计学方法分析了 AMF孢子密...     

当归不同生长时期根际丛枝真菌分布及土壤养分和酶活性的动态变化

【目的】探讨当归不同生长时期丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)的分布及土壤养分和土壤酶活的变化,以期了解当归不同生长时期AMF与土壤养分和土壤酶活的关系,为AMF在当归种植的应用提供理论依据。【方法】在当归不同生长时期分别采集根际土壤样品,测定其土壤养分、土壤酶活、AMF孢子密度和球囊霉素等因子,分析当归不同生长时期根际土壤AMF孢子密度、土壤养分和土壤酶活等指标的动态变化和相关性。【结果】随着当归生育期的完成,根际土壤AMF孢子密度先降低后持续升高;易提取球囊霉素(Easily extractable glomalin,EEG)和总球囊霉素(Total glomalin,TG)平稳增加,而且EET与TG和脲酶活性呈显著正相关(P0.01),EET和TG与根际土壤有机质和全氮含量以及酸性和中性磷酸酶活性均显著正相关(P0.05);根际土壤有机质和全氮表现为增加的总趋势;有效磷含量呈现为生长前期保持不变、中期显著降低、后期逐渐升高的趋势,而有效钾含量先逐渐增加,生长中后期显著降低的趋势;根际土壤酸性和中性磷酸酶活性均呈现逐渐增加趋势,而脲酶活性表现为生长前期逐渐增加,中后期显著降低;p H值在当归不同生长时期有所波动。相关性分析结果表明,AMF孢子密度与土壤酸性磷酸酶酶活性呈显著正相关,而酸性磷酸酶酶活性与根际土壤全氮、有机质、易提取球囊霉素和总球囊霉素呈显著正相关,与有效磷和有效钾含量呈显著负相关,表明AMF对根际土壤养分和酶活性具有一定的调节作用;主成分分析结果表明,不同生长时期是影响当归根际土壤理化指标的主要因素。【结论】AMF孢子密度在当归根际的动态变化一定程度上反映出了AMF分泌球囊霉素的能力,以及球囊霉素对增加根际土壤碳氮储存的贡献,同时表明球囊霉素影响了当归根际土壤酶活性和其它养分的代谢循环,对改良土壤和促进当归生长发挥重要的作用。     

连作花魔芋软腐病株与健株根域丛枝菌根真菌群落多样性

【目的】解析不同连作年限花魔芋软腐病株、健株根域的丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性。【方法】使用AMF 18S SSU rRNA基因特异引物AMV4.5NF/AMDGR对正茬及连作2年和3年的软腐病株、健株魔芋根系和根际土壤DNA扩增建库,通过高通量测序和生物信息学分析探究魔芋软腐病与其根域AMF群落多样性的关系。【结果】魔芋根系具有明显的AMF菌丝、泡囊和丛枝等结构。在相同连作年限条件下,健株根系AMF总侵染率、侵染强度和孢子密度均显著高于病株(P<0.05);在不同连作年限条件下,病株根系AMF总侵染率和侵染强度随连作年限延长而降低。从所有样品中共鉴定到9属53种AMF,其中有49个已知种和4个新种。球囊霉属(Glomus)和类球囊霉属(Claroideoglomus)是AMF群落的优势属,其AMF种分别占总AMF种数的41.5%和26.4%;丰度最高的Paraglomus sp.VTX00308是所有样品的共有种。连作、软腐病及二者的交互作用显著影响根系AMF群落的Shannon指数和Simpson指数及根际土壤AMF的Chao1指数(P<0.05)。通过丰度差异分析发现6个在连作软腐病发生后丰度差异显著的AMF种(P<0.05);NMDS分析表明,不同连作年限的魔芋软腐病株与健株之间的根域AMF菌种组成、相对丰度和群落结构存在差异。相关性分析表明,软腐病发病率和病情指数与魔芋根系和根际土壤AMF的Shannon指数、根系AMF的Chao1和Simpson指数以及AMF总侵染率、侵染强度和孢子密度极显著负相关(P<0.01)。【结论】比对健株,连作魔芋软腐病株根际土壤AMF孢子密度以及根系AMF侵染率、种数和多样性均降低,其群落结构显著改变。     

Arbuscular mycorrhizal fungi regulate the oxidative system,hormones and ionic equilibrium to trigger salt stress tolerance in Cucumis sativus L.

Arbuscular mycorrhizal fungi (AMF) association increases plant stress tolerance. This study aimed to determine the mitigation effect of AMF on the growth and metabolic changes of cucumbers under adverse impact of salt stress. Salinity reduced the water content and synthesis of pigments. However, AMF inoculation ameliorated negative effects by enhancing the biomass, synthesis of pigments, activity of antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase, and the content of ascorbic acid, which might be the result of lower level lipid peroxidation and electrolyte leakage. An accumulation of phenols and proline in AMF-inoculated plants also mediated the elimination of superoxide radicals. In addition, jasmonic acid, salicylic acid and several important mineral elements (K, Ca, Mg, Zn, Fe, Mn and Cu) were enhanced with significant reductions in the uptake of deleterious ions like Na+. These results suggested that AMF can protect cucumber growth from salt stress.     

Bacterial communities in a crude oil gathering and transferring system (China)

Bacterial communities in crude oil and oil field production water samples from an oil gathering and transferring system in Changqing Oil field in China were investigated by 16S rRNA denaturing gradient gel electrophoresis (DGGE) analysis followed by gene cloning and sequencing. DGGE profiles showed that bacterial communities are far more rich in the water samples than that in the crude oil samples, and that bacteria related to Ochrobactrum sp. and Stenotrophomonas sp. were detected in all crude oil and oil field water samples. Bacteria related to Burkholderia sp., Brevundimonas sp., and Propionibacterium sp. were detected in the crude oil samples but not in water samples. Bacteria related to Hippea sp., Acidovorax sp., Arcobacter sp., Pseudomonas sp., Thiomicrospira sp., Brevibacterium sp., Tissierella sp. and Peptostreptococcus sp. were detected in the water samples but not in crude oil samples. Using an archaea-specific primer set, methanogens related to Methanomicrobials and Methanosarcinales were found in water samples but not in crude oil samples. The comparability of the microbial communities in the water and crude oil phase during the period of oil gathering and transferring process was 83.3% and 88.2%, respectively, indicating a stable structure of the microbial communities.     

Relative contributions of soil chemistry, plant physiology and rhizosphere induced changes in speciation on Ni accumulation in plant shoots

The aim of this study is to rank the relative importance of soil properties, root uptake and root-to-shoot redistribution on the transfer of the trace element nickel from soil to the shoots of non hyperaccumulatings plants. Two contrasting soils and seven plant species have been studied using the radioactive isotope, ⁶³Ni. Shoots and roots were analysed separately and the specific activity of each plant has been measured. The isotopic exchange properties of rhizosphere soil where compared with control non rhizosphere soil. Possible changes in Ni speciation in the rhizosphere have been assessed by comparing the isotopic exchange properties of the rhizosphere and control soil and by comparing the specific activities of Ni in each plant. The capacity of soil to immobilise added radiotracer largely determines root uptake, leading to between a 4- and 40-fold difference between soils for a given species. The redistribution of nickel from roots to shoots was fairly constant for plants grown on the rendzina, but varied strongly between species for the acid soil. This variation enhanced the contrast between species of the soil-to-shoot transfer factor. Root action significantly enhanced immobilisation of added nickel in an acid soil due to the modification of speciation of initially non exchangeable soil nickel, but had little effect on a neutral rendzina. Changes in rhizosphere pH were similar on the two soils. In the acid soil, these pH changes were accompanied by changes in Ni speciation but a causative link has not been established. In the neutral soil pH changes may have modified root uptake properties.     

Effects of climatic and edaphic factors on arbuscular mycorrhizal fungi in the rhizosphere of Hippophae rhamnoides in the Loess Plateau, China

In order to investigate the effects of climatic and edaphic factors on arbuscular mycorrhizal (AM) fungi in the rhizosphere of Hippophae rhamnoides in the Loess Plateau, spore density, mycorrhizal colonization and gene diversity were analyzed by using the methods of microscopy and polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE) respectively. The results showed that H. rhamnoides could form strong symbiotic relationships with AM fungi. There existed obvious differences in AM fungal colonization among five sampling sites in the Loess Plateau (P < 0.05). Correlation analysis showed that AM fungal colonization and spore density were closely related with climatic and edaphic factors. 42 different species (band types) were found in the DGGE gel. Based on analysing the position and intensity of AM fungal DGGE bands, the gene diversity indices, including species richness, evenness, Simpsom’s and Shannon-Weiner index, showed significant differences among five sampling sites (P < 0.05). All the AM species could be classified into four groups in the biplot of canonical correspondence analysis (CCA), and each group had various responses to climatic and edaphic factors. Monte Carlo random test indicated that soil available phosphorus (F = 2.26, P = 0.025) and spore density (F = 1.76, P = 0.006) were the dominating factors affecting AM fungal communities. In conclusion, AM fungal colonization and community diversity in the rhizosphere of H. rhamnoides showed obvious spatial heterogeneity among the different areas of the Loess Plateau, and climatic and edaphic conditions were important factors affecting the AM fungal communities. Therefore, screening and application of AM fungal strains in the Loess Plateau need to fully consider the local climatic and edaphic conditions.