Response of native soil microbial functions to the controlled mycorrhization of an exotic tree legume, <Emphasis Type="Italic">Acacia holosericea</Emphasis> in a Sahelian ecosystem

Fifty years of overexploitation have disturbed most forests within Sahelian areas. Exotic fast growing trees (i.e., Australian Acacia species) have subsequently been introduced for soil improvement and fuelwood production purposes. Additionally, rhizobial or mycorrhizal symbioses have sometimes been favored by means of controlled inoculations to increase the performance of these exotic trees in such arid and semiarid zones. Large-scale anthropogenic introduction of exotic plants could also threaten the native biodiversity and ecosystem resilience. We carried out an experimental reforestation in Burkina Faso in order to study the effects of Acacia holosericea mycorrhizal inoculation on the soil nutrient content, microbial soil functionalities and mycorrhizal soil potential. Treatments consisted of uninoculated A. holosericea, preplanting fertilizer application and arbuscular mycorrhizal inoculation with Glomus intraradices. Our results showed that (i) arbuscular mycorrhizal (AM) inoculation and prefertilizer application significantly improved A. holosericea growth after 4 years of plantation and (ii) the introduction of A. holosericea trees significantly modified soil microbial functions. The results clearly showed that the use of exotic tree legume species should be directly responsible for important changes in soil microbiota with great disturbances in essential functions driven by microbial communities (e.g., catabolic diversity and C cycling, phosphatase activity and P availability). They also highlighted the importance of AM symbiosis in the functioning of soils and forest plantation performances. The AM effect on soil functions was significantly correlated with the enhanced mycorrhizal soil potential recorded in the AM inoculation treatment.     

Effect of AMF inoculum from field isolates on the yield of green pepper,parsley, carrot,and tomato

Inoculum of an indigenous mixture of arbuscular mycorrhizal fungi (AMF) containingGlomus mosseae, Glomus fasciculatum, Glomus etunicatum, Glomus intraradices andScutellospora sp. was applied to four of the most frequently used crop species in Slovenia: green pepper (Capsicum annuum), parsley (Petroselinum crispum), carrot (Daucus carrota) and tomato (Lycopersicon esculentum). A simple, feasible, and effective protocol for application of AMF biotechnology in horticulture was adopted.Mycorrhizal inoculation significantly increased the plant biomass parameters of pepper, and parsley and the root biomass of carrots. Statistically significant correlations between biomass parameters of pepper, parsley, and the root biomass of carrots with mycorrhizal colonization parameters (mycorrhizal frequency (F%), global mycorrhizal intensity (M%) and arbuscular richness (A%) were calculated. A significant increase in chlorophyll content was observed in mycorrhizal parsley and a significant increase in carotenoids was observed in mycorrhizal parsley, carrots, and tomato fruits. A significant increase in titratable acidity of fruits from inoculated tomato plants indicates prolonged fruiting period of mycorrhizal tomatoes. In addition, inoculation with an indigenous AMF mixture significantly increased the mycorrhizal potential of soil and thus the growth of non-inoculated plants in the second season. Thus, the results confirmed the potential of applying mycorrhizal biotechnology in sustainable horticulture.     

接种后共培养时间对丛枝菌根喜树幼苗喜树碱含量的影响

在前期工作中利用蜜色无梗囊霉(Acaulospora mellea)和根内球囊霉(Glomus intraradices)从接种时期角度分析了喜树碱含量与菌根形成过程对应关系的基础上,通过温室盆栽接种试验,继续观察了这两种丛枝菌根真菌接种后与喜树(Camptothecaacuminata)幼苗的共培养时间对喜树幼苗喜树碱积累的影响。分别用两种菌根真菌每隔7d接种一批喜树幼苗,第5批接种7 d后采样,获得菌根真菌与喜树幼苗共培养时间分别为35、28、21、14、7 d的喜树幼苗样品,测定了菌根浸染状况和喜树碱含量。结果表明:(1)接种两种丛枝菌根真菌均促进了喜树幼苗喜树碱的积累,表现为喜树碱含量和产量(单株幼苗所含的喜树碱量,喜树碱含量与幼苗生物量的乘积)的显著提高。(2)从接种后共培养时间的效果看,两种菌根幼苗各器官(根、茎、叶)及全株喜树碱含量和产量均呈现随着丛枝菌根真菌与喜树幼苗共培养时间的增加而增加的趋势。两种菌根幼苗的根和茎、根内球囊霉菌根幼苗的叶片和全株的的喜树碱含量和产量,在共培养时间增加至21 d时趋于稳定,而蜜色无梗囊霉菌根幼苗的叶片和全株的喜树碱含量和产量在共培养时间增加至28 d时达到最高,其后略有降低。(3)两种丛枝菌根真菌的侵染率和侵染强度同样随共培养时间的增加而增加,至共培养28 d后无显著变化。在一定共培养时间范围内,喜树碱含量和产量的变化与丛枝菌根真菌的侵染及菌根形成之间具有对应性。     

Effectiveness of arbuscular mycorrhizal fungi in phytoremediation of lead- contaminated soil by vetiver grass

A greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of lead (Pb)-contaminated soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design. Factors included four Pb levels (50, 200, 400, and 800 mg kg^?1) as Pb (NO₃)₂, AM fungi at three levels (non mycorrhizal (NM) control, Rhizophagus intraradices, Glomus versiforme). Shoot and root dry weights (SDW and RDW) decreased as Pb levels increased. Mycorrhizal inoculation increased SDW and RDW compared to NM control. With mycorrhizal inoculation and increasing Pb levels, Pb uptake of shoot and root increased compared to those of NM control. Root colonization increased with mycorrhizal inoculation but decreased as Pb levels increased. Phosphorus concentration and uptake in shoot of plants inoculated with AM fungi was significantly higher than NM control at 200 and 800 mg Pb kg^?1. The Fe concentration, Fe and Mn uptake of shoot in plants inoculated with Rhizophagus intraradices in all levels of Pb were significantly higher than NM control. Mycorrhizal inoculation increased Pb extraction, uptake and translocation efficiencies. Lead translocation factor decreased as Pb levels increased; however inoculation with AM fungi increased Pb translocation.     

接种AMF对菌根植物和非菌根植物竞争的影响

为了研究丛枝菌根真菌(arbuscular mycorrhizal fungus, AMF)对菌根植物与非菌根植物种间竞争的影响,以玉米(菌根植物)和油菜(非菌根植物)作为供试植物,分别进行间作、尼龙网分隔和单作,模拟这两种植物之间不同的竞争状态,接种丛枝菌根真菌Glomus intraradices和Glomus mosseae,比较菌根植物和非菌根植物的生长和磷营养状况,分析AMF侵染对植物种间竞争作用的影响。结果显示,与单作相比,间作模式下玉米的生物量及磷营养状况有所降低,但其菌根依赖性却有所提高。与不接种相比,接种处理显著降低了间作体系油菜根系的磷含量和磷吸收量,但趋于改善菌根植物玉米的磷营养状况。因此,接种AMF可以降低非菌根植物的磷营养状况及生物量,使得菌根植物的相对竞争能力明显提高,说明AMF在维持物种多样性方面有着重要的作用。     

Increasing phosphorus removal in willow and poplar vegetation filters using arbuscular mycorrhizal fungi

Fast growing woody species are increasingly used in vegetation filters for wastewater treatment. Their efficiency in phosphorus (P) removal notably depends on plant uptake and storage in aboveground tissues. In this study, Populus NM5 (P. nigra × P. maximowiczii), Salix miyabeana (SX64) and Salix viminalis (5027) were planted in pots to evaluate the influence of colonization by arbuscular mycorrhizal fungi (AMF) Glomus intraradices on P uptake using two different P concentrations in irrigation water. Based on analysis of the foliar and woody components, our results show that the two treatments (inoculation with G. intaradices and P-irrigation) interact differently with total P content. Foliar P content is principally enhanced by the P-irrigation concentration, whereas the mycorrhizal colonization increases stem P content. In the presence of G. intraradices, both S. miyabeana and S. viminalis showed a 33% increase in stem P content. The latter finding is mainly due to an increase in biomass production, without modification of the P concentration, indicating that AMF associations affect P use efficiency. Thus, using arbuscular mycorrhizal fungi for phytoremediation strategies may increase biomass productivity and hence improve pollutant uptake.     

Interaction between the root-lesion nematode Pratylenchus vulnus and the mycorrhizal association of Glomus intraradices and Santa Lucia 64 cherry rootstock

The effects of the interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus intraradices on growth and nutrition of Santa Lucia 64 cherry rootstock was studied under microplot conditions during one growing season. Fresh top weight, and stem diameter of mycorrhizal plants and high P treatments with and without P. vulnus were significantly higher than those of non-mycorrhizal plants. The lowest shoot length and fresh root weights were recorded in nematode inoculated plants in low P soil. Mycorrhizal infection did not affect the number of nematodes per gram of root in plants infected with P. vulnus. In the presence of the nematode, internal spore production by G. intraradices was significantly reduced. No nutrient deficiencies were detected through foliar analysis, although low levels of Ca, Mn and Fe were detected in nematode treatments. Mycorrhizal plants achieved the highest values for N, P, S, Fe, and Zn, whereas high P treatments increased absorption of Ca and Mn. Early mycorrhizal infection of Santa Lucia 64 cherry rootstock by G. intraradices confers increased growth capacity in the presence of P. vulnus.     

The differential behavior of arbuscular mycorrhizal fungi in interaction with Astragalus sinicus L. under salt stress

Three arbuscular mycorrhizal (AM) fungi (Glomus mosseae, Glomus claroideum, and Glomus intraradices) were compared for their root colonizing ability and activity in the root of Astragalus sinicus L. under salt-stressed soil conditions. Mycorrhizal formation, activity of fungal succinate dehydrogenase, and alkaline phosphatase, as well as plant biomass, were evaluated after 7 weeks of plant growth. Increasing the concentration of NaCl in soil generally decreased the dry weight of shoots and roots. Inoculation with AM fungi significantly alleviated inhibitory effect of salt stress. G. intraradices was the most efficient AM fungus compared with the other two fungi in terms of root colonization and enzyme activity. Nested PCR revealed that in root system of plants inoculated with a mix of the three AM fungi and grown under salt stress, the majority of mycorrhizal root fragments were colonized by one or two AM fungi, and some roots were colonized by all the three. Compared to inoculation alone, the frequency of G. mosseae in roots increased in the presence of the other two fungal species and highest level of NaCl, suggesting a synergistic interaction between these fungi under salt stress.     

Response of mycorrhizal grapevine to Armillaria mellea inoculation: disease development and polyamines

A study was conducted with the vine rootstock Richter 110 (Vitis berlandieri Planch. x Vitis rupestris L.) in order to assess whether the colonisation by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices (BEG 72) can delay the disease development in plants inoculated with the root-rot fungus Armillaria mellea (Vahl:Fr) Kummer, and to elucidate if the levels of polyamines (PAs) are modified in response to G. intraradices, A. mellea or by the dual infection. Four treatments were considered: control and G. intraradices-inoculated plants infected or not with A. mellea. Plant growth, mycorrhizal colonisation and disease development were monitored throughout the experiment. High performance liquid chromatography (HPLC) in combination with fluorescence spectrophotometry was used to separate and quantify free root and leaf polyamines. The slower development of pathogenic symptoms and the higher plant biomass of mycorrhizal plants inoculated with A. mellea indicate an increase of tolerance due to the AMF inoculation. The variations in free PA levels detected at the beginning of the pathogenic infection suggest that PAs may have a potential role in the signalling mechanisms of the tolerance of mycorrhizal plants against A. mellea.     

Soil fumigation and phosphorus supply affect the formation of Pisolithus-Eucalyptus urophylla ectomycorrhizas in two acid Philippine soils

To examine the effects of microbial populations and external phosphorus supply of two Philippine soils on mycorrhizal formation, Eucalyptus urophylla seedlings were inoculated with two Pisolithus isolates and grown in fumigated, reinfested and unfumigated soil fertilized with four rates of phosphorus. The Pisolithus isolates used were collected from under eucalypts in Australia and in the Philippines. Soils were infertile acid silty loams collected from field sites in Pangasinan, Luzon and Surigao, Mindanao.Significant interaction was observed between inoculation, soil fumigation and phosphorus supply on mycorrhizal formation by the Australian isolate in Surigao soil but not in Pangasinan soil. Soil fumigation enhanced mycorrhizal formation by the Australian isolate but did not affect root colonization by the Philippine isolate. Root colonization by the Australian isolate was highest in the reinfested soil while for the Philippine isolate it was highest in the unfumigated soil. The Australian isolate was more effective than the Philippine isolate in promoting growth and P uptake of E. urophylla seedlings in both soils. Total dry weight and P uptake of E. urophylla seedlings inoculated with the Australian isolate were maximum in fumigated and in the reinfested Pangasinan and Surigao soils supplied with 8 mg P kg^-1 soil. In the unfumigated soil, growth of seedlings inoculated with the Australian isolate was significantly reduced. Seedlings inoculated with the Philippine isolate had the largest dry weights and P contents in unfumigated Pangasinan and Surigao soils supplied with 8 mg P kg^-1 soil.These results indicate that the performance of the Australian Pisolithus isolate was markedly affected by biological factors in unfumigated soil. Thus, its potential use in the Philippines needs to be thoroughly tested in a variety of unfumigated soils before its widespread use in any inoculation programme.     

Phytoextraction of heavy metals by two Salicaceae clones in symbiosis with arbuscular mycorrhizal fungi during the second year of a field trial

We evaluated the potential of Salix viminalis (5027) and Populus × generosa for the phytoextraction of heavy metals (HM) inoculated or not with an arbuscular mycorrhizal (AM) fungus Glomus intraradices during a second year of growth in a randomized complete block field trial on a slightly contaminated site. Both plant clones produced high aboveground biomass yields, however P. × generosa produced significantly more biomass than S. viminalis. The two plant clones accumulated high concentrations of Cd and Zn in their shoots, while Cu and Pb were stored in their roots. In general, S. viminalis accumulated higher concentrations of HM. The inoculation of G. intraradices in the previous year did not influence plant clones’ biomass yields during the second growing season. However, Cu and Cd translocation to shoots was limited, and Cu was preferentially concentrated in roots of inoculated plants, compared to non-inoculated plants, which were also colonized by native AM fungi taxa. Efficiency of S. viminalis and P. × generosa for Cd and Zn rehabilitation in slightly contaminated soil has been demonstrated, but mycorrhizal inoculation did not significantly increase HM extraction.     

Phosphate transporters expression in rice (Oryza sativa L.) associated with arbuscular mycorrhizal fungi (AMF) colonization under different levels of arsenate stress

It is known that arsenate and phosphate (P) share the same transporters in plants, and arbuscular mycorrhizal fungi (AMF) influence the expressions of Pi transporters (OsPT1–13) in rice. In order to study the effects of AMF on arsenate accumulation in rice, Glomus intraradices (AH01) was inoculated to rice and treated with different levels of arsenate (0, 2 and 8 μM). Results revealed that OsPT11 was increased whereas OsPT2 decreased (P < 0.05) in mycorrhizal plants. The increased expression of OsPT11 was one of the most important factors that led to the significantly higher P concentration (P < 0.05) in plant tissues, which compensated the down-regulation of OsPT2. The symbiosis of G. intraradices with rice slightly decreased (P > 0.05) the arsenate concentration in plant tissues but markedly enhanced (P < 0.05) plant biomass. The higher P content in mycorrhizal plants led to the higher P/As molar ratio (P < 0.05) and lower As uptake ratio (P < 0.05) in mycorrhizal plants treated by 2 μM arsenate. Mycorrhizal plants under such an arsenate treatment took up less As by per unit of root dry mass. The inoculation of G. intraradices was not able to transform the inorganic As to organic As. Further studies should be conducted focusing on the transport activities of each Pi transporter using yeast or oocyte expression system to identify which Pi transporters are responsible for the accumulation of arsenate.     

Effects of single and mixed inoculation with two arbuscular mycorrhizal fungi in two different levels of phosphorus supply on β-carotene concentrations in sweet potato (Ipomoea batatas L.) tubers

Aims

This study aimed to determine the effect of arbuscular mycorrhizal (AM) fungi and phosphorus (P) supply levels on β-carotene concentrations in sweet potato (Ipomoea batatas L.) tubers.

Methods

Two commercial AM fungal isolates of Glomus intraradices (IFP Glintra) and Glomus mosseae (IFP Glm) which differ in their life cycles were used. Sweet potato plants were grown in a horizontal split-root system that consisted of two root compartments. A root-free fungal compartment that allowed the quantification of mycelial development was inserted into each root compartment. The two root compartments were inoculated either with the same or with different AM isolates, or remained free of mycorrhizal propagules. Each fungal treatment was carried out in two P supply levels.

Results

In the low P supply level, mycorrhizal colonization significantly increased β-carotene concentrations in sweet potato tubers compared with the non-mycorrhizal plants. Glomus intraradices appeared to be more efficient in increasing β-carotene concentrations than G. mosseae. Dual inoculation of the root system with the two mycorrhizal fungi did not result in a higher increase in tuber β-carotene concentrations than inoculation with the single isolates. Improved P nutrition led to higher plant tuber biomass but was not associated with increased β-carotene concentrations.

Conclusions

The results indicate a remarkable potential of mycorrhizal fungi to improve β-carotene concentrations in sweet potato tubers in low P fertilized soils. These results also suggest that β-carotene metabolism in sweet potato tubers might be specifically activated by root mycorrhizal colonization.     

Accumulation and Speciation of Selenium in Plants as Affected by Arbuscular Mycorrhizal Fungus <Emphasis Type="BoldItalic">Glomus mosseae</Emphasis>

Effects of arbuscular mycorrhizal fungus (Glomus mosseae) on the accumulation and speciation of selenium (Se) in alfalfa, maize, and soybean were investigated by using Se(IV)-spiked soil. Mycorrhizal inoculation decreased Se accumulation in roots and shoots of all the plants at Se spiked level of 0 or 2 mg kg⁻¹, while an increased Se accumulation was observed in alfalfa shoots and maize roots and shoots at the spiked level of 20 mg kg⁻¹. Concentration of inorganic Se (especially Se(VI)) in roots and shoots of the three plants was much higher in mycorrhizal than non-mycorrhizal treatment. Mycorrhizal inoculation decreased the portion of total organic Se in plant tissues with the exception of alfalfa and maize shoots at Se spiked level of 20 mg kg⁻¹, in which organic Se portion did not reduced greatly (<5%) for mycorrhizal treatment. Mycorrhizal effects on alfalfa and maize were more obvious than on soybean in terms of root colonization rate, biomass, and Se accumulation.     

Fungal mutualists enhance growth and phytochemical content in Echinacea purpurea

An emerging paradigm in sustainable biotechnique is the use of mutualists to enhance plant growth and secondary metabolism. Our objective was to determine impact of two groups of fungal mutualists on growth and phytochemistry of Echinacea purpurea. Growth, development, and phytochemical concentration were measured in greenhouse-grown 12-week-old plants colonized by arbuscular mycorrhizal fungi (AMF) (Rhizophagus intraradices and Gigaspora margarita) or the endophytic entomopathogen, Beauveria bassiana. In one experiment, all measured growth parameters were increased in mycorrhizal plants. Biomass of AMF-colonized plants was over 13-fold greater than non-mycorrhizal controls receiving the same levels of phosphorous, and over 4-fold greater than non-mycorrhizal controls given additional phosphorous. Endophytic colonization by B. bassiana had minor effects on growth. Colonization by AMF and B. bassiana alone or in combination altered concentrations of phytochemicals (pigments, polyphenolics, alkylamides, and terpenes). Mycorrhizal plants produced up to 4.6-fold higher concentration of polyphenolics. Specific alkylamides increased 1.7 fold in plants colonized only with B. bassiana and up to a 2.4-fold increase in plants colonized by both mutualists. Changes in other phytochemical classes were related to differences in plant size induced by AMF. Phytochemical content (concentration × biomass) was increased up to 30-fold in mycorrhizal plants. Phytochemical relationships to plant biomass were confirmed in a second experiment in which non-mycorrhizal plants were fertilized to produce biomass equivalent to that of mycorrhizal plants. Based on this study, mycorrhizal colonization of E. purpurea enhances phytochemical content; this has major implications for the natural product industries and growers of E. purpurea.     

Interaction of Vesicular-Arbuscular Mycorrhizae and Cultivars of Alfalfa Susceptible and Resistant to Meloidogyne hapla

The interaction between vesicular-arbuscular mycorrhizal (VAM) fungi and the root-knot nematode (Meloidogyne hapla) was investigated using both nematode-susceptible (Grasslands Wairau) and nematode-resistant (Nevada Synthetic XX) cultivars of alfalfa (Medicago sativa) at four levels of applied phosphate. Mycorrhizal inoculation improved plant growth and reduced nematode numbers and adult development in roots in dually infected cultures of the susceptible cultivar. The tolerance of plants to nematode infection and development when preinfected with mycorrhizal fungi was no greater than when they were inoculated with nematodes and mycorrhizal fungi simultaneously. Growth of plants of the resistant cultivar was unaffected by nematode inoculation but was improved by mycorrhizal inoculation. Numbers of nematode juveniles were lower in the roots of the resistant than of the susceptible cultivar and were further reduced by mycorrhizal inoculation, although no adult nematodes developed in any resistant cultivar treatment. Inoculation of alfalfa with VAM fungi increased the tolerance and resistance of a cultivar susceptible to M. hapla and improved the resistance of a resistant cultivar.     

干旱条件下AM真菌对植物生长和土壤水稳定性团聚体的影响

采用分室培养系统,模拟正常水分和干旱胁迫两种环境条件,探讨不同丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)对紫花苜蓿(Medicago sativa L.)生长和土壤水稳性团聚体的影响.试验条件下,Glomus intraradices对苜蓿根系的侵染率均显著高于Acaulospora scrobiculata和Diversispora spurcum接种处理.正常水分条件下,供试AM真菌均能显著提高植株生物量及磷浓度.干旱胁迫显著抑制了植株生长和菌根共生体发育,总体上菌根共生体对植株生长没有明显影响,接种D.spurcum甚至趋于降低植株生物量;同时,仅有G.intraradices显著提高了植株磷浓度.AM真菌主要影响到＞2mm的水稳性团聚体数量,以G.intraradices作用效果最为显著.在菌丝室中,G.intraradices显著提高了总球囊霉素含量.研究表明AM真菌对土壤大团聚体形成具有积极作用,而菌根效应因土壤水分条件和不同菌种而异,干旱胁迫下仅有G.intraradices对土壤结构和植物生长表现出显著积极作用.在应用菌根技术治理退化土壤时,需要选用抗逆性强共生效率高的菌株,对于不同AM真菌抗逆性差异的生物学与遗传学基础尚需进一步研究.     

The effects of laurel (Laurus nobilis L.) on development of two mycorrhizal fungi

Hundreds of aromatic plant species are growing naturally around Mediterranean. Plant essential oils are incorporated in aromatic plant material and follow the litter fall. During litter degradation, the presence of essential oils can affect soil microorganisms. Mycorrhizal fungi have never been investigated so far under the presence of volatile oils. The aim of this study was to explore the effect of aromatic Laurus nobilis L. on development of two mycorrhizal species Glomus deserticola and Glomus intraradices. The response of fungi colonization and host growth were monitored under different concentrations of L. nobilis leaves and essential oil. The major compounds of L. nobilis essential oil were 1,8-cineole (49.6%), sabinene (7.8%), ??-pinene (6.0%), eugenole (5.6%), ??-terpinyl acetate (5.2%) and ??-pinene (5.1%). Both mycorrhizal fungi colonized successfully the host plants whose growth was positively influenced by mycorrhizal fungi. G. deserticola presented higher infection level than G. intraradices. The addition of L. nobilis leaves in the soil resulted in mycorrhiza inhibition. The level of inhibition was positively correlated with the added amount of aromatic leaves in the soil. The essential oil presented a little higher inhibition than the leaves. The presence of this aromatic plant in many different ecosystems could contribute in mycorrhiza inhibition and it is suggested, when it’s possible, reduction of laurel litter before reforestation programs.     

Induction of glycyrrhizin and total phenolic compound production in licorice by using arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi have mutualistic symbiosis with higher plants, increasing plant resistance to environmental stresses and nutrient uptake and improving soil. During arbuscular mycorrhizal symbiosis, a range of chemical and biological factors are affected. In this study, two species of arbuscular mycorrhiza (Glomus mosseae and G. intraradices) were used to assess the effects of inoculation on licorice growth and secondary metabolite production. After successful inoculation, the increase in the growth rate, P and Zn uptake, and the accumulation of secondary metabolites in licorice (Glycyrrhiza glabra L.) roots were observed in two periods of 3 and 6 months compared to control. After 6 months, more increments in growth, secondary metabolites, and P and Zn uptake were observed compared with the first 3-months period. Two groups of secondary metabolites arising from phenolic and terpenoid metabolism obviously responded to mycorrhizal fungi colonization in licorice roots.     

Arbuscular Mycorrhizal Fungi (AMF) and Biosolids Enhance the Growth of a Native Australian Grass on Sulphidic Gold Mine Tailings

We tested the effect of the addition of biosolids combined with a native mycorrhizal inoculum (Arbuscular Mycorrhizal Fungi [AMF]) on growth of a native Australian grass, and on trace element stabilization of sulphidic gold mine tailings. A glasshouse trial was established on four substrates: tailings (T); tailings with a layer of 5 cm topsoil (TS); tailings amended with 100 dry t ha^?1 biosolids (LB), and tailings amended with 500 dry t ha^?1 biosolids (HB). Pots of 1.2 L of capacity were established; some were inoculated with a mixture of Glomus sp. (WUM51–9227), Scutelospora aurigloba (WUM51–53), and Acaulospora levis (WUM46) culture mix, and others were uninoculated controls. Seeds of the native Australian grass, Bothriochloa macra were sown in the pots. Root infection, plant biomass production, nutrients and trace element concentrations in shoots were investigated. Addition of biosolids significantly increased AMF infection of roots compared to unamended substrates. No clear qualitative differences in colonization were detected. Addition of biosolids and AMF together clearly improved the establishment and growth of the native grass. Similar trends in nutritional status were shown for biosolids and inoculation with AMF treatments. Mycorrhizal inoculation increased plant biomass production and the effectiveness of nutrient uptake. The combined use of biosolids and mycorrhizal inoculation could be a reliable method for phytostabilization purposes in polluted substrates.