Weed control and cover crop management affect mycorrhizal colonization of grapevine roots and arbuscular mycorrhizal fungal spore populations in a California vineyard

Arbuscular mycorrhizal (AM) fungi naturally colonize grapevines in California vineyards. Weed control and cover cropping may affect AM fungi directly, through destruction of extraradical hyphae by soil disruption, or indirectly, through effects on populations of mycorrhizal weeds and cover crops. We examined the effects of weed control (cultivation, post-emergence herbicides, pre-emergence herbicides) and cover crops (Secale cereale cv. Merced rye, × Triticosecale cv.Trios 102) on AM fungi in a Central Coast vineyard. Seasonal changes in grapevine mycorrhizal colonization differed among weed control treatments, but did not correspond with seasonal changes in total weed frequency. Differences in grapevine colonization among weed control treatments may be due to differences in mycorrhizal status and/or AM fungal species composition among dominant weed species. Cover crops had no effect on grapevine mycorrhizal colonization, despite higher spring spore populations in cover cropped middles compared to bare middles. Cover crops were mycorrhizal and shared four AM fungal species (Glomus aggregatum, G. etunicatum, G. mosseae, G. scintillans) in common with grapevines. Lack of contact between grapevine roots and cover crop roots may have prevented grapevines from accessing higher spore populations in the middles.     

AM真菌种间差异对枳壳生长及耐热性效应的研究※

用地表球囊霉、莫西球囊霉、珠状巨孢球囊霉及其混合菌剂接种无菌根枳壳幼苗进行盆栽试验,25℃培养4个月,观察对枳壳菌根形成和营养生长的影响,在40℃高温胁迫30d,调查分析菌根枳壳的耐热性。试验结果表明:接种AM真菌的根系形成了20%～80%的菌根侵染率;菌根枳壳的苗高、苗质量、节间长、茎基粗、须根数量和须根长度等营养生长显著增加;叶片中的SOD,POD活性和根系活力显著增强,可溶性蛋白、可溶性糖含量显著升高,叶片中的MDA含量降低,膜透性显著变小,枳壳苗的耐热性显著提高;但是,AM真菌在促进枳壳苗菌根化、营养生长和提高耐热性方面存在着种间差异,地表球囊霉、莫西球囊霉、珠状巨孢球囊霉、混合菌剂与枳壳根系形成丛枝菌根的侵染率依次为20.4%±1.2%、61.8%±3.4%、85.7%±2.7%、83.3%±2.2%,促进枳壳苗营养生长提高枳壳苗耐热能力的AM真菌依次为:地表球囊霉<莫西球囊霉<珠状巨孢球囊霉<混合菌剂,认为珠状巨孢球囊霉和莫西球囊霉是枳壳耐高温胁迫菌根化育苗的重要优良菌种。     

Glomales species associated with surface and deep rhizosphere of Faidherbia albida in Senegal

 Five arbuscular mycorrhizal (AM) fungal species were isolated and propagated from surface and deep rhizospheres of Faidherbia albida trees growing in two ecoclimatic zones of West Africa: the semi-arid Sahelian and the more humid Sudano-Guinean areas. Of these species, Glomus aggregatum, Glomus caledonium, and Glomus mosseae were trapped by F. albida roots when cultivated with either surface or deep soils. Glomus fasciculatum was found exclusively at the semi-arid Sahelian sites of Louga and Diokoul and Gigaspora margarita was isolated only from 16.5-m and 34-m-deep samples. Comparable glomalean fungal species richness was identified in deep (1.5–34 m) and surface (0.15 m) samples. The isolation and the propagation of glomalean fungi from F. albida rhizospheres confirmed the presence of viable AM fungal propagules, down to the water table, as deep as 34 m. Accepted: 27 August 2000     

Interactions between Lotus japonicus genotypes and arbuscular mycorrhizal fungi

Abstract

Interactions between three genotypes (Ljsym 71-1, Ljsym 71-2 and Ljsym 72) of Lotus japoicus and one isolate from each of four species of arbuscular mycorrhizal fungi (Glomus sp. R-10, Glomus intraradices, Glomus etunicatum, and Gigaspora margarita) were investigated and compared with the wild-type ‘Gifu’ B-129. All the three genotypes showed no or defective internal colonization after inoculation with these AM fungi. In Ljsym72 mutant, the AM fungi produced deformed appressoria on the root surface, but failed to form any internal structures (internal hyphae, arbuscules and vesicles) except only in Glomus intraradices. The Ljsym71-1 and Ljsym71-2 mutants had more deformed appressoria and occasionally formed internal hyphae, arbuscules and vesicles, depending on AM fungi used. Wild-type ‘Gifu’ (nod⁺myc⁺) plants had typical colonization. The colonization of mutants by several fungi varied and provides a basis for studying recognition and compatibility between plants and mycorrhizal fungal species. These mutants also will be useful in studies of the genetics of the symbiosis between plant species and AM fungi.     

不同pH水平下两种菌根真菌对紫云英生长的影响及其相互作用

设计在不同pH水平（4.3、5.1、5.8、6.8）下两种VA菌根真菌Glomus mosseae和Gigaspora margarita对紫云英Astragalus sinicus进行单接种、混合接种及无接种对照的盆栽实验。对紫云英地上和地下部分生物量、根部侵染率、SDH和ALP酶活进行了检测。实验结果表明：紫云英的生长效应与VA菌根真菌的侵染率及两种酶活成明显相关性。土壤pH升高,单接种Glomus mosseae和混合接种的侵染率也随之升高,而单接种Gigaspora margarita的侵染率呈现     

Impact of arbuscular mycorrhizal fungal inoculants on subsequent arbuscular mycorrhizal fungi colonization in pot-cultured field pea (Pisum sativum L.)

The use of commercial inoculants containing non-resident arbuscular mycorrhizal fungi (AMF) is an emerging technology in field crop production in Canada. The objective of this study was to assess the impact of AMF inoculants containing either a single species (Glomus irregulare) or mixed species (G. irregulare, Glomus mosseae, and Glomus clarum) on AMF root colonization and consequent plant growth parameters of field pea grown using pot cultures. Field pea was grown in both sterilized and non-sterile (i.e., natural) field-collected soil containing resident AMF and received three inoculation treatments: uninoculated control, G. irregulare only, and a mixture of AMF species of G. irregulare, G. mosseae, and G. clarum. After 42 days, the AMF community assembled in field pea roots was assessed by cloning and sequencing analysis on the LSU-ITS-SSU rDNA gene, together with a microscopic assessment of colonization, biomass production, nutrient uptake, and N₂ fixation. The identity of AMF inoculants had a significant effect on field pea performance. The mixed species AMF inoculant performed better than the single species G. irregulare alone by promoting mycorrhizal colonization, field pea biomass, N and P uptake, and N₂ fixation and did not result in a significant compositional change of the AMF community that subsequently assembled in field pea roots. In contrast, the single species G. irregulare inoculant did not significantly enhance field pea biomass, N and P uptake, and N₂ fixation, although a significant compositional change of the subsequent AMF community was observed. No significant interactions affecting these measurements were detected between the resident AMF and the introduced AMF inoculants. The observation that the mixed species AMF inoculant promoted plant growth parameters without necessarily affecting the subsequent AMF community may have important implications regarding the use of non-resident AMF inoculants in agricultural production.     

Arbuscular mycorrhizal adaptation,spore germination,root colonization,and host plant growth and mineral acquisition at low pH

Arbuscular mycorrhizal (AM) fungi colonize plant roots and often enhance host plant growth and mineral acquisition, particularly for plants grown under low nutrient and mineral stress conditions. Information about AM fungi and mycorrhizal ( +AM) host plant responses at low pH ( < 5) is limited. Acaulospora are widely reported in acid soil, and Gigaspora sp. appear to be more common in acid soils than Glomus sp. Spores of some AM fungi are more tolerant to acid conditions and high Al than others; t Acaulospora sp., Gigaspora sp., and Glomus manihotis are particularly tolerant. Root colonization is generally less in low than in high pH soils. Percentage root colonization is generally not related to dry matter (DM) produced. Maximum enhancement of plant growth in acid soil varies with AM fungal isolate and soil pH, indicating adaptation of AM isolates to edaphic conditions. Acquisition of many mineral nutrients other than P and Zn is enhanced by +AM plants in acid soil, and the minerals whose concentration is enhanced are those commonly deficient in acid soils (Ca, Mg, and K). Some AM fungal isolates are effective in overcoming soil acidity factors, especially Al toxicity, that restrict plant growth at low pH.     

Effect of Arbuscular Mycorrhizal Inoculations on Seedling Growth and Biomass Productivity of Two Bamboo Species

A study was conducted to identify suitable arbuscular mycorrhizal (AM) fungi for inoculation of Bambusa bambos and Dendrocalamus strictus at nursery stage for increasing growth and productivity. Twelve AM species, isolated from bamboo and other common trees of Bundelkhand were used for inoculations. In B. bambos, total dry weight and phosphorus (P) uptake were significantly increased by all studied fungi and shoot length was increased by eight AM inoculants. Maximum mycorrhizal dependency (MD) was recorded for Acaulospora scrobiculata (44.2%), followed by Glomus cerebriforme (41.6%) and G. intraradix (41.0%). In D. strictus, all tested AM inoculants significantly increased shoot length, dry shoot weight and P uptake, except Glomus 1. Dry root weight was significantly increased by only two inoculants namely, G. cerebriforme and G. etunicatum. Total dry weight was significantly increased by eight AM fungi. Maximum MD was recorded for G. cerebriforme (62.9%), followed by G. diaphanum (55.0%) and G. etunicatum (51.3%). Thus, the results showed that utilization of effective AM fungi can enhance the productivity of bamboo in the region.     

Field microplot performance of the peach-almond hybrid GF-677 after inoculation with arbuscular mycorrhizal fungi in a replant soil infested with root-knot nematodes

The effects of arbuscular mycorrhizae (AM) on the development and nutrition of the peach almond hybrid GF-677 rootstock in a replant soil heavily infested with Meloidogyne javanica were evaluated in field microplot conditions for two growing seasons. There was a significant beneficial effect of mycorrhizal inoculation on plant growth and nutrition in previously pasteurized replant soil. In natural replant soil, early inoculation with a mixed AM inoculum of Glomus intraradices, Glomus mosseae and Glomus etunicatum did not affect growth parameters. Whilst inoculation with these AM fungi led to suppression of root-knot nematode reproduction, natural mycorrhizal colonization of the replant soil with native AM fungi did not. Accepted: 6 December 2000     

Field response of wheat to arbuscular mycorrhizal fungi and drought stress

Mycorrhizal plants often have greater tolerance to drought than nonmycorrhizal plants. This study was conducted to determine the effects of arbuscular mycorrhizal (AM) fungi inoculation on growth, grain yield and mineral acquisition of two winter wheat (Triticum aestivum L.) cultivars grown in the field under well-watered and water-stressed conditions. Wheat seeds were planted in furrows after treatment with or without the AM fungi Glomus mosseae or G. etunicatum. Roots were sampled at four growth stages (leaf, tillering, heading and grain-filling) to quantify AM fungi. There was negligible AM fungi colonization during winter months following seeding (leaf sampling in February), when soil temperature was low. During the spring, AM fungi colonization increased gradually. Mycorrhizal colonization was higher in well-watered plants colonized with AM fungi isolates than water-stressed plants. Plants inoculated with G. etunicatum generally had higher colonization than plants colonized with G. mosseae under both soil moisture conditions. Biomass and grain yields were higher in mycorrhizal than nonmycorrhizal plots irrespective of soil moisture, and G. etunicatum inoculated plants generally had higher biomass and grain yields than those colonized by G. mosseae under either soil moisture condition. The mycorrhizal plants had higher shoot P and Fe concentrations than nonmycorrhizal plants at all samplings regardless of soil moisture conditions. The improved growth, yield and nutrient uptake in wheat plants reported here demonstrate the potential of mycorrhizal inoculation to reduce the effects of drought stress on wheat grown under field conditions in semiarid areas of the world.     

Host-related variability in arbuscular mycorrhizal fungal structures in roots of <Emphasis Type="Italic">Hedera rhombea</Emphasis>, <Emphasis Type="Italic">Rubus parvifolius</Emphasis>, and <Emphasis Type="Italic">Rosa multiflora</Emphasis> under controlled conditions

The arbuscular mycorrhizal (AM) morphology of three host plant species inoculated with single and mixed fungal culture and the distribution of AM fungal species in roots of the hosts treated with a mixed culture of AM fungi were determined. The aim was to investigate the effect of host plants and AM fungi on AM morphology of coexisting plant species. Noncolonized rooted cuttings of Hedera rhombea (Miq) Bean, Rubus parvifolius L., and Rosa multiflora Thunb. were inoculated with five fungal species as single and mixed culture inocula. The fungal species used were Gigaspora rosea and Scutellospora erythropa, previously isolated from H. rhombea; Acaulospora longula and Glomus etunicatum from R. parvifolius; and Glomus claroideum from both plant species. A few hyphal and arbusculate coils were seen in the mixed culture-inoculated roots of R. parvifolius; all fungal treatments produced this Paris-type AM in H. rhombea and Arum-type AM in R. parvifolius, and R. multiflora indicates that AM morphology is strongly controlled by the identity of the host plants used in this study. AM fungal rDNA was extracted separately from roots of each replicate plant species inoculated with the mixed fungal culture, amplified, cloned, sequenced, and analyzed to determine the AM fungal species and their respective proportions in roots of each plant species. Glomus etunicatum and G. claroideum of the family Glomaceae generally occurred more frequently in R. parvifolius and R. multiflora, which form Arum-types, whereas S. erythropa, of the family Gigasporaceae, was the most frequently detected species in H. rhombea, which produced Paris-type AM. Although the genotype of the plant species used appears to determine the AM morphologies formed, there was preferential association between the hosts and AM fungal inoculants.     

不同pH水平下两种菌根真菌对紫云英生长的影响及其相互作用

设计在不同pH水平(4.3、5.1、5.8、6.8)下两种VA菌根真菌Glomus mosseae和Gigaspora margarita对紫云英Astragalus sinicus进行单接种、混合接种及无接种对照的盆栽实验.对紫云英地上和地下部分生物量、根部侵染率、SDH和ALP酶活进行了检测.实验结果表明:紫云英的生长效应与VA菌根真菌的侵染率及两种酶活成明显相关性.土壤pH升高,单接种Glomus mosseae和混合接种的侵染率也随之升高,而单接种Gigaspora margarita的侵染率呈现出先上升后下降的趋势.本实验设计了特异性扩增Glomus mosseae和Gigaspora margarita的引物gml和gigl,在混合接种实验中,nested PCR扩增结果显示:在低pH水平下(4.3-5.1)大多数根段为Gigaspora margarita所侵染,在高pH水平下(5.8-6.8)Glomusmosseae表现出较强的竞争力,但并没有检测到两种VA真菌存在于同一条侵染根段;对比单接种实验,在低pH水平下,Glomus mosseae显著抑制了Gigaspora margarita的侵染,而在高pH水平下Gigasporamargarita明显促进Glomus mosseae的侵染.     

丛枝菌根真菌对植物根尖分生区和根冠细胞的侵染*

一般说来,从枝菌根（ＡＭ）真菌大多数是从植物根系根毛区（成熟区）侵入和扩展的,在显微镜下往往看不到根尖分生区和根冠表皮细胞被ＡＭ真菌侵染的特征。这就很容易给人们造成一种假象,似乎ＡＭ真菌不能侵染根尖分生区和根冠表皮细胞,即它们对ＡＭ真菌是免疫的。然而笔者多次于显微镜下看到ＡＭ真菌侵染根尖分生区和根冠表皮细胞,并形成典型的泡囊、丛枝、菌丝等结构。这一现象导致作者在温室盆栽和大田条件下研究了玫瑰红巨孢囊霉（ Ｇｉｇａｓｐｏｒａ　ｒｏｓｅａ Ｎｉｃｏｌ　＆ Ｓｃｈｅｎｃｋ）、珠状巨孢囊霉（Ｇｉｇａｓｐｏｒａ　ｍａｒｇａｒｉｔａ　Ｂｅｃｋｅｒ　＆　Ｈａｌｌ）、根内球囊霉（Ｇｌｏｍｕｓ　ｏｍｔｒａｒａｄｉｃｅｓ　ｓｃｈｅｎｃｋ　＆　Ｓｍｉｔｈ、摩西球囊霉（Ｇｌｏｍｕｓ ｍｏｓｓｅａｅ （Ｎｉｃｏｌ　＆ Ｇｅｒｄ．） Ｇｅｒｄｅｍａｎｎ　＆ Ｔｒａｐｐｅ）、地表球囊霉（ Ｇｌｏｍｕｓ ｖｅｒｓｉｆｏｒｍｅ（ Ｋａｒｓｔｅｎ）Ｂｅｒｃｈ）和弯丝硬囊霉（ Ｓｃｌｅｒｏｃｙｓｔｉｓ　ｓｉｎｕｏｓａ　Ｇｅｒｄｅｍａｎｎ　＆ Ｂａｋｈｉ）对棉花（Ｇｏｓｓｙｐｉｕｍ　ｈｉｒｓｕｔｕｍ　Ｌ．）、烟草（Ｎｉｃｏｔｉａｎａ　 ｔａｂａｃｕｍ Ｌ．）和白     

Arbuscular mycorrhizal colonization of tomato by Gigaspora and Glomus species in the presence of root flavonoids

The effect of flavonoids isolated from arbuscular mycorrhizal (AM) colonized and noncolonized clover roots on the number of entry points and percentage of root colonization of tomato (Lycopersicum esculentum L.) by Gigaspora rosea, Gi margarita, Glomus mosseae and G. intrarradices symbionts was determined. With fungi of both genera, a correlation between the number of entry points and the percentage of root colonization was found in the presence of some of the tested flavonoids. The flavonoids acacetin and rhamnetin, present in AM clover roots, inhibited the formation of AM penetration structures and the AM colonization of tomato roots, whereas the flavonoid 5,6,7,8,9-hydroxy chalcone, which could not be detected in AM clover root, inhibited both parameters. The flavonoid quercetin, which was present in AM clover roots, stimulated the penetration and root colonization of tomato by Gigaspora. However, the flavonoids 5,6,7,8-hydroxy-4'-methoxy flavone and 3,5,6,7,4'-hydroxy flavone, which was not found in AM clover root, increased the number of entry points and the AM colonization of tomato roots by Gigaspora. These results indicated that flavonoids could be imnplicated in the process of regulation of AM colonization in plant root, but its role is highly complex and depend not only on flavonoids, but also on AM fungal genus or even species.     

Effects of Different Arbuscular Mycorrhizal Fungi on Physiology of <i>Viola prionantha</i> under Salt Stress

Arbuscular mycorrhizal (AM) fungi distribute widely in natural habits and play a variety of ecological functions. In order to test the physiological response to salt stress mediated by different AM fungi, Viola prionantha was selected as the host, the dominant AM fungus in the rhizosphere of V. philippica growing in Songnen saline-alkali grassland, Rhizophagus irregularis, and their mixtures were used as inoculants, and NaCl stress was applied after the roots were colonized. The results showed that V. philippica could be colonized by AM fungi in the field and the colonization rate ranged from 73.33% to 96.67%, and Claroideoglomus etunicatum was identified as the dominant AM fungi species in the rhizosphere of V. philippica by morphology combined with sequencing for AM fungal AML1/AML2 target. Inoculation with both the species resulted in the formation of mycorrhizal symbiosis (the colonization rate was more than 70%) and AM fungi significantly enhanced plants’ tolerance to salt stress of varying magnitude. Higher activity of antioxidant enzymes and augmented levels of proline and other osmoregulators were observed in AM plants. The content of MDA in CK was higher than that in the inoculations with the stress of 100, 200, and 250 mM. All indices except soluble protein content and MDA content were significantly correlated with AM fungal colonization indices. The analysis for different AM fungal effects showed that the mixtures and R. irregularis worked even better than C. etunicatum. These results will provide theoretical support for the exploration and screening of salt-tolerant AM fungi species and also for the application of AM-ornamental plants in saline-alkali urban greening.     

五指山常见热带树种的丛枝菌根真菌多样性

采用野外调查的方法,分析了五指山不同海拔高度7个科10种常见热带树种形成丛枝菌根(Arbuscular Mycorrhizal,AM)的状况及其根际土壤中AM真菌的多样性。结果表明,所调查的10种热带常见树种都能形成AM共生体,其菌根侵染率随寄主植物的不同,从21.8%～90.5%变化不等,同时,在10种常见植物的根系中也都观察到了AM真菌的典型结构——丛枝和泡囊。从10种植物的根际土壤中共分离到36种AM真菌,隶属于Acaulospora,Glomus,Gigaspora和Scutellospora4个属,其中,Glomus属的真菌是该地区的优势类群,其出现频度和相对多度分别为84%和56%。在所调查的10种热带常见树种中,Swietenia macrophylla根际AM真菌的孢子最丰富,密度高达7.32;Machilus namu根际的AM真菌种类则最为丰富,多样性指数达到1.6548。通过对不同海拔高度Swietenia macrophylla根际AM真菌分布的分析表明,海拔高度显著影响着AM真菌的分布,Gigaspora属的真菌随海拔高度的增加显著升高,Scutellospora属的真菌则显著降低。     

Flavonoids exclusively present in mycorrhizal roots of white clover exhibit a different effect on arbuscular mycorrhizal fungi than flavonoids exclusively present in non-mycorrhizal roots of white clover

Abstract

The flavonoids 5,6,7,8,9-hydroxy chalcone, 3,7-hydroxy-4′methoxy flavone, 5,6,7,8-hydroxy-4′-methoxy flavone and 3,5,6,7,4′-hydroxy flavone can be detected only in non-mycorrhizal roots of white clover, but not in mycorrhizal roots, whereas the flavonoids acacetin, quercetin and rhamnetin are only present in mycorrhizal roots. We tested the effect of several concentrations of these compounds on spore germination, hyphal growth, hyphal branching, formation of clusters of auxiliary cells and of secondary spores of the arbuscular mycorrhizal fungi Gigaspora rosea, Gigaspora margarita, Glomus mosseae and Glomus intraradices. Our results indicate that depending on the flavonoid, the tested compounds are involved at different stages in the regulation of mycorrhization. This hypothesis is strengthened by their differing effect on several AM fungal growth parameters. Furthermore, our study provides more data on the AM fungus genus/species specificity of flavonoids.     

The effect of soil phosphorus on the external mycelium growth of arbuscular mycorrhizal fungi during the early stages of mycorrhiza formation

The effects of soil P amendments and time of application on the formation of external mycelium by different arbuscular mycorrhizal (AM) fungi were studied. In the first experiment the external mycelium produced in the soil by the AM fungus Glomus etunicatum Beck. and Gerd., during the early stages of root colonization (7 and 14 days after inoculation), was quantified by the soil-agar film technique. A Brazilian Oxisol was used with three different phosphate levels, varying from deficient to supra-optimal for the plant. Significant differences were observed in the phosphate and inoculation treatments for plant dry weight, P content in the tissue, root length and root colonization, at fourteen days after planting. At 7 days, mycelium growth, root colonization and their relationship were reduced at supra-optimal P concentrations. Applications of P one week after planting reduced mycelium growth and root colonization more than when applied to the soil before planting. In a second experiment the arbuscular mycorrhizal (AM) fungi, Scutellospora heterogama (Nicol. and Gerd.) Walker and Sanders and E3 were tested and compared with Glomus etunicatum. For the species studied, the length of external hyphae per unit of colonized root length was affected by small P additions but no further significant differences were observed at high P levels. The three AM endophytes showed marked differences in their response to P in the soil: Scutellospora heterogama, although producing external mycelium more profusely than the Glomus spp., showed a higher sensitivity to soil P supply.     

Occurrence of arbuscular mycorrhiza in Castanospermum australe A. Cunn. & C. Fraser and effects on growth and production of castanospermine

 Castanospermum australe A. Cunn. & C. Fraser is the only species of the genus Castanospermum (the Moreton Bay chestnut or black bean) native to NE Australia. One constituent of the plant, castanospermine, can inhibit the AIDS virus. The present study investigated possible symbioses between its roots and arbuscular mycorrhizal (AM) fungi. The effects of mycorrhizal fungi on the growth of the plant and yield of alkaloid castanospermine were also studied. The mycorrhizosphere soil and roots of C. australe collected from various sites in and around Sydney, Australia showed AM symbiotic associations with roots, with arbuscules and vesicles in the root cortices. Wet sieving and decanting yielded AM fungal spores, mainly Glomus spp. A positive correlation was found between AM fungal infection and the castanospermine content of seeds of field-grown trees. Field study results were confirmed by growing seedlings under greenhouse conditions and inoculating them with Glomus intraradices Schenck and Smith (INVAM isolate KS906) and Gigaspora margarita Becker & Hall (INVAM isolate BR444–2). The AM fungi increased the growth and P contents of plants and the yield of castanospermine in the leaves, irrespective of the P treatment. No correlation was found between the alkaloid contents of leaves from mycorrhizal seedlings and from non-mycorrhizal plants which received P. No significant difference in the production of castanospermine was found between P treatments when G. margarita was used as inoculum. Accepted: 14 April 1999     

Diversity of Arbuscular Mycorrhizal Fungi Associated with Plants Growing in Fly Ash Pond and Their Potential Role in Ecological Restoration

Root colonization and diversity of arbuscular mycorrhizal fungi (AMF) were analyzed in plants growing in fly ash pond. Eight species could be separated morphologically, while phylogenetic analyses after PCR amplification of the ITS region followed by RFLP and sequencing revealed seven different AM fungal sequence types. Phylogenetic analysis showed that these sequences cluster into four discrete groups, belonging to the genus Glomus and Archaeospora. Inoculation of plants with spores of AM fungal consortia (Glomus etunicatum, Glomus heterogama, Glomus maculosum, Glomus magnicaule, Glomus multicaule, Glomus rosea, Scutellospora heterogama, and Scutellospora nigra) along with colonized root pieces increased the growth (84.9%), chlorophyll (54%), and total P content (44.3%) of Eucalyptus tereticornis seedlings grown on fly ash compared to non-inoculated seedlings. The growth improvement was the consequence of increased P nutrition and decreased Al, Fe, Zn, and Cu accumulations. These observations suggested that the inoculation of tree seedlings with stress adapted AM fungi aid in the reclamation of fly ash ponds.