Biodiversity of arbuscular mycorrhizal fungi in <Emphasis Type="Italic">Amygdalus scoparia</Emphasis> Spach plantations and a natural stand

The biodiversity of arbuscular mycorrhizal fungi (AMF) was surveyed in the Kolm region of Iran in three adjacent sites, a natural stand, a 10-year-old and a 15-year-old plantation of Amygdalus scoparia. To date, there have been few studies of AMF biodiversity in Iran, especially in the western forests of the country. For this study, soil and root samples were taken from A. scoparia rhizosphere soil in spring and autumn. Almost half of the root length was colonized by AMF. We identified 13 AMF species belonging to Glomeraceae, Claroideoglomeraceae or Diversisporaceae. The three plantations differed in terms of soil electrical conductivity, organic C and P. Spore density was significant correlated with P concentration. Root length colonization was correlated only with soil Ca. Species diversity and richness were significantly correlated with soil N, P, organic C and spore density. AMF diversity in 15-year-old plantations was more similar to that in the natural stand than in the 10-year-old plantation. We confirmed that a 15-year-old plantation is not similar in terms of AMF colonization to natural stands. We conclude that more than 15 years are required for AMF colonization of plantations to resemble that of natural stands.     

Biodiversity of arbuscular mycorrhizal fungi in different trees of madhupur forest, Bangladesh

Roots and rhizosphere soils of Acacia auriculiformis A. Cunn. ex Benth., A. mangium Wild., Artocarpus heterophyUus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Eucalyptus camaldulensis Dehnn., Hevea brasiliensis （Wild. ex Juss） Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. were collected from different locations of Madhupur forest area to study the biodiversity of Arbuscular Mycorrhizal （AM） fungal colonization and spore population. All the plants showed AM colonization. Out of eight selected plants, mycelial colonization was lowest in the roots of A. heterophyllus （22%） and the highest was in the roots of H. brasiliensis （78%）. Mycelial intensity was observed poor （25%-77%） and moderate （23%-57%） in all plants species and abundant （11%-40%） was in most of the plant species. Vesicular colonization was observed in five plant species. The lowest was recorded in E. camaldulensis （4%） and the highest was in H. brasiliensis （21%）. Poor （24%-56%）, moderate （16%-100%） and abundant （11%-40%） type of vesicular intensity were observed. Arbuscular colonization was observed in three plants. The highest was in A. mangium （72%） and the lowest was in S. macrophylla （17%）. Arbuscular intensity was recorded as poor （12%-44%）, moderate （22%-100%） and abundant （4%-47%）. The highest AM fungal spore population was in A. auriculiformis （714） and the lowest was in D. sissoo （102）. Five AM fungal genera were recorded. Glomus was found to be dominant. A few spores remained unidentified. Significant correlation was observed between percent coloniza- tion and spore population. The results of the present study indicate the occurrence of AM fungi and the mycotrophism of the plants of Madhupur forest area and the applicability of AM technology in the forest management of Madhupur forest.     

孟加拉国Madhupur林区内不同森林树种中丛枝菌根多样性的研究

从 Madhupur 林区的不同地点采集了 Acacia auriculi-formis A. Cunn. ex Benth., A. mangium Wild., Artocarpus het-erophyllus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Euca-lyptus camaldulensis Dehnn., Hevea brasiliensis (Wild. ex Juss) Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. 8个树种的根和根际土。采用简单常规的根围土壤真菌孢子分离、形态鉴定和树木细根染色、显微镜观察等方法,进行了孟加拉国Madhupur林区内不同森林树种中丛枝菌根多样性的研究。图2表2参46。     

Dieback and decline of wild almond (Amygdalus scoparia Spach) in the Harat protected forest of Yazd Province,Iran

Wild almond (Amygdalus scoparia) is a dominant shrub species in mountain forests of the Irano‐Turanian region. Dieback and decline symptoms of wild almond shrubs were first observed in Harat protected forest (Yazd, Iran) in the autumn of 2014. Since then, the incidence and severity of the disease have increased. To study the aetiology and estimate losses from the disease, field studies were conducted in 2016 and 2017. For this purpose, eight stands were selected, in which 24%–99% of the trees were wild almond in their species composition. In total, 50 cankers and 50 infected twigs of wild almond shrubs were collected. Fungal isolates were identified based on morphological and cultural characteristics, as well as sequence data of ITS1 + 5.8S + ITS2 rDNA. Pathogenicity of fungi was checked on detached shoots and evaluated after 40 days by measuring the discoloured lesion length at the inoculation site. Among 681 wild almond shrubs checked, 84.44% showed decline symptoms with different severities; only 15.56% did not show observable disease symptoms. The most frequent colonizers of infected tissues taken from cankers were Wilsonomyces carpophilus (56%), Thyrostroma cornicola (40%) and Collophorina paarla (30%). Infected twigs were extensively colonized by W. carpophilus (36%), Th. cornicola (24%) and Ulocladium consortiale (24%). Other species, such as Endoconidioma populi, Microsphaeropsis olivacea, Trichoderma asperellum, Paecilomyces formosus, Saccothecium rubi, Preussia sp. and Chaetomium globosum, had lower isolation frequencies. W. carpophilus, Th. cornicola, C. paarla and U. consortiale were found as pathogens on detached wild almond shoots. Based on the frequency of the isolates and the pathogenicity tests, four fungi, such as W. carpophilus, Th. cornicola, C. paarla and U. consortiale, are considered serious contributing agents playing a significant role in the dieback and decline of wild almond. All isolated species are reported for the first time on the wild almond shrubs of the world.     

Tree species as hosts for arbuscular mycorrhizal and dark septate endophyte fungi

A survey of 35 tree species(belonging to 28 genera in 19 families) in Aliyar,South India was carried out to ascertain their arbuscular mycorrhizal(AM) and dark septate endophyte(DSE) fungal status.All the tree species examined had AM association.AM and DSE colonization is reported for the first time in 20 and 14 species respectively.Cooccurrence of AM and DSE was observed in 14(40%) tree species.The extent of DSE colonization was inversely related to the extent of AM fungal colonization.Six tree species had Arum-type,18 had intermediatetype and 11 had typical Paris-type AM morphology.AM fungal spore morphotypes belonging to 11 species in two genera were isolated from the rhizosphere soil.AM fungal spore numbers were not related to the extent of AM colonization and Glomus dominated spore diversity.AM association individually and along with DSE were found respectively in the 63% and 44% of the economically important tree species.The occurrence of AM and DSE fungal association in economically important indigenous tree species indicates the possibility of exploiting this association in future conservation programmes of these species.     

Diversity of mycorrhizal fungi and soil indicative species in coastal plantations of northeast Brazil

The aim of this work was to evaluate arbuscular mycorrhizal(AM) fungi as soil indicators and the mycorrhization of native and exotic tree species planted in the Acaraú basin, a transition area from the coast to the Brazilian semiarid region. Plots with 6-year-old trees of four native and three non-native species as well as one non-forested area were evaluated in terms of the diversity of AM fungi in the mycorrhizosphere and the root colonization by AM and ectomycorrhizal(EcM) fungi. Twenty-four AM fungi were identified; Claroideoglomus etunicatum, Glomus sinuosum, Paraglomus albidum, Acaulospora laevis, and Acaulospora brasiliensis were abundant in the forest soil. Diversity, dominance, evenness and richness indices of AM fungi were higher in plots with native trees. All root samples were colonized by AM fungi and only A nadenanthera colubrina,Acacia mangium, Casuarina equisetifolia and Eucalyptus urophylla formed associations with EcM fungi. Acaulospora morphotypes served as soil indicators for coverings with the native species Astronium fraxinifolium and Colubrina glandulosa. Exotic species may favor the proliferation of rarer AM fungi. These fungi–plant relationships may be important in the management of forest systems, and the evidence with mycorrhizal associations allows the inclusion of Brazilian species in tropical reforestation.     

The arbuscular mycorrhizal fungi status of selected tree nurseries in the Ethiopian highlands

We investigated the arbuscular mycorrhizal fungi(AMF) status of ten nurseries suitable for restoration of dry evergreen Afromontane forests in Ethiopia. We quantified AMF root colonization(RC) and spore abundance(SA) in seedlings of nine native tree species namely Acacia abyssinica Hochst. ex Benth., Cordia africana Lam., Dovyalis abyssinica(A. Rich.) Warb., H agenia abyssinica J.F. Gmel., Juniperus procera Hochst. ex Endl., Millettia ferruginea(Hochst.) Baker, Olea europaea L. subsp. c uspidata(Wall. ex G. Don) Cif., Podocarpus falcatus(Thunb.) R. Br. ex Mirb. and Prunus africana(Hook. f.) Kalkman. We used the ink and vinegar method to stain AMF in roots. RC levels ranged from 8.00 to 99.67% and were generally higher than the RC levels reported from other similar nurseries in Ethiopia. SA levels ranged from 1 to 25 spores g~(-1) and werecomparable with some reports from the field in Ethiopia but they were lower than levels reported by another similar study. RC was more affected by host species than nursery location, while the reverse was true for SA. The results also showed that nursery management could improve AMF status among seedlings. When all nursery tree species were considered, RC and SA levels were unrelated. No strong correlation existed between the nursery management variables considered and RC or SA. However, considering C. africana, J. procera and P. falcatus separately, RC-age(r_s = 0.829, P = 0.042) correlation for O. europaea and RC-pot diameter( r_s = 0.820, P = 0.046), RC-pot volume( r_s = 0.928, P = 0.008) and SA-age( r_s = 0.943, P = 0.005) correlations for C. africana, were significant, strong and positive. Generally, most of the tree species and particularly, early-mid successional tree species had sufficient AMF inoculum. Hence, only the mid-late successional tree species; J. procera, P. falcatus, and P. africana may require AMF inoculation, preferably, during filed planting. Based on our results, age and pot volume were identified to be important variables potentially affecting RC and SA. To better understand the effects of these and other nursery management variables, additional study is required. We demonstrated for the first time that black Hero ink is suitable for staining root AMF and can be used in future AMF research.     

Distribution,colonization and diversity of arbuscular mycorrhizal fungi associated with central Himalayan rhododendrons

The objective of the present study was to investigate arbuscular mycorrhizal status of five species of rhododendrons distributed in Kumaun region of the Indian Central Himalaya. Root and rhizosphere soil samples of all the five species of rhododendrons, namely, Rhododendron anthopogon, R. arboreum, R. campanulatum, R. barbatum and R. lepidotum were collected from temperate, sub-alpine to alpine location in altitudinal range from 1500 to 4500 m amsl. The arbuscular mycorrhizal colonization in root samples ranged from 28 to 42%; and maximum and minimum colonization was observed in R. arboreum and R. lepidotum, respectively. The highest number of intraradical vesicles (12.5 ± 2.8 cm⁻¹ root segment) was recorded in R. arboreum and the lowest (7.0 ± 1.7 cm⁻¹ root segment) in R. barbatum; vesicles were not observed in R. lepidotum. Spores were extracted from the rhizosphere soil by wet sieving to perform microscopic identification of the species. The maximum and minimum populations of spores were detected in the rhizosphere soil samples of R. anthopogon (52.0 ± 1.5 spores 25 g⁻¹ soil) and R. lepidotum (32.0 ± 2.5 spore 25 g⁻¹ soil), respectively. Spore populations were found to belong to five genera—Acaulospora, Glomus, Gigaspora, Sclerocystis and Scutellispora; genus Glomus was found to be dominant in the rhizosphere soil samples of all the rhododendron species. The most frequent and abundant species was G. fasciculatum, however, this species was not isolated from the rhizosphere soil of R. barbatum. Finger millet (Eleucine coracana) was used to cultivate the trap culture of arbuscular mycorrhizal fungi to confirm the species identity. Spores of Glomus pustulatum, not detected in the rhizosphere soil, were recovered from the trap culture. Contrary to this, genus Gigaspora, which was present in the rhizosphere soil, did not sporulate in the trap culture. Shannon and Wiener index of diversity and Simpson's index of dominance indicated that the species richness, dominance and diversity of arbuscular mycorrhizal fungi decrease with increasing altitude. In two species of rhododendrons, namely R. campanulatum and R. anthopogon, dark septate mycelium was also observed.     

孟加拉国Dinajpur农林复合区内不同树种和作物种中丛枝菌根分布和孢子群落多样性的研究

从孟加拉国Dinajpur地区采集了不同农林复合区内树种和作物种,对采集植物的丛枝菌根多样性进行了研究.在3个取样地采集了18种植物的根和根际土,取样地和被采取植物分别为：取样地Dashmail为黄豆树 （Albizia procera Benth.）、小指椒 （Capsicum frutescens L）、姜黄（Curcuma domestica Vahl）、印度黄檀 （Dalbergia sissoo Roxb.） 和大叶桃花心木（Swietenia macrophylla）5种植物; 取样地Kantaji为姜黄（C.Domestica）、印度檀 （D.Sissoo）、赤桉 （Eucalyptus camaldulensis Dehnn.）、石梓（Gmelina arborea （Roxb） DC） 和水稻 （Oryza sativa L.） 5种植物; 取样地Ramsagar为姜黄（C.Domestica）, 印度檀 （D.Sissoo）, Litchi chinensis Sonn.和水稻.在取样地Dashmail,植物丛枝的分布范围在36%-79%,其中分布最高的是小指椒,达到79%,而C.Domestica仅占36%.取样地 Kantaji丛枝的分布范围在33%-70%之间,其中分布最高的是石梓,达到79%,而O.Sativa分布最低,仅36%.取样地 Ramsagar丛枝的分布范围在35%-70%之间,印度檀丛枝分布在该地最高, 达70%,而水稻丛枝在该地的分布最小,仅35%.在采样地Dashmail,每100克干土中所含采样植物丛枝菌根孢子群落54-140个;孢子群落最多的是印度檀（140/100g dry soil）,最低的是姜黄（C.Domestica） （40/100g dry soil）.在采样地Kantaji,孢子群落在63-221/100g dry soil,石梓具有的群落最高,为221/100g dry soil;印度檀为63/100g dry soil.在采样地Ramsagar, 所具有的最高和最低群落分别是 160/100g dry soil （D.Sissoo）和69/100g dry soil（L.Chinensis）.土壤Ph值与土壤中丛枝分布和菌根孢子群落无显著相关性.Simpson多样性指数和Shannon多样性指数在取样地Kantaji 的印度檀土壤中最高;而在取样地Ramsagar的水稻土壤中最低.研究表明孟加拉国Dinajpur地区丛枝菌根的存在、树种和作物种中的营养性质、丛枝菌根的必要性和贡献以及复合农林植物生长与丛枝?     

Effects of arbuscular mycorrhizal fungi on the drought tolerance of Cyclobalanopsis glauca seedlings under greenhouse conditions

Cyclobalanopsis glauca is an important afforestation tree species that is widely used for revegetating the karst region of southwest China. Vegetation in this region is regularly commonly subjected to drought stress because of the geology and water shortages. Here, we investigated the influence of two arbuscular mycorrhizal fungi (AMF) Glomus mosseae and Glomus intraradices on the drought tolerance of C. glauca seedlings under greenhouse conditions. AMF-treated and non-AMF-treated C. glauca seedlings were maintained under two different water regimes (well watered: 80 % field capacity; drought stress: 40 % field capacity) for 90 days. The AMF colonization rate was higher under well-watered conditions compared to drought stress conditions. The growth and physiological performance of C. glauca seedlings were significantly affected by drought stress. Under drought stress conditions, mycorrhizal seedlings had greater height, base diameter, leaf area, and biomass compared to non-mycorrhizal seedlings. In addition, under drought conditions, AMF-inoculated seedlings had greater superoxide dismutase and peroxidase activity, higher soluble sugar content, and lower proline content compared to non-inoculated seedlings. Furthermore, AMF colonization increased the phosphorus and potassium content of seedling shoots under both well-watered and drought stress conditions. Therefore, AMF colonization enhanced the drought tolerance of C. glauca seedlings by improving growth performance, nutrient content, the quantity of osmotic adjustment compounds, and antioxidant enzyme activity. The results indicate that AMF are of potential use for the restoration of vegetation in the karst region of southwest China.     

Influence of improved fallow systems and phosphorus application on arbuscular mycorrhizal fungi symbiosis in maize grown in western Kenya

A field study was carried out on a six-year-old on-farm field trial during long-rains season (April–August) 2003 to investigate the effect of improved fallow systems and phosphorus application on arbuscular mycorrhiza fungi (AMF) symbiosis in maize. The trial comprised of maize rotated with a fast growing leguminous Crotalaria grahamiana fallow and a non-leguminous Tithonia diversifolia fallow for 3 years followed by continuous maize. The experiment was randomized complete block design with three cropping (continuous maize, Crotalaria fallow and Tithonia fallow) systems and two phosphorus levels (0 and 50 kg P/ha). AMF colonization in maize roots, maize yield and macro-nutrients uptake were recorded. Phosphorus applications improved (P < 0.05) early (<8 weeks old maize) AMF colonization, nutrient uptake and maize yield in improved fallow systems. Greater differences due to phosphorus application were noted in maize in Tithonia fallow than in Crotalaria fallow. Following phosphorus application, a positive relationship existed between early AMF colonization and maize yield (r = 0.38), and phosphorus and nitrogen uptake (r = 0.40 and r = 0.43, respectively), demonstrating the importance of phosphorus fertilization in enhancing low-input technologies (improved fallows systems) in phosphorus deficient and acidic soils of western Kenya.     

Cultured arbuscular mycorrhizal fungi and native soil inocula improve seedling development of two pioneer trees in the Andean region

The tree species Alnus acuminata and Morella pubescens, native to South America, are candidates for soil quality improvement and afforestation of degraded areas and may serve as nurse trees for later inter-planting of other trees, including native crop trees. Both species not only form symbioses with arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF), but also with N₂-fixing actinobacteria. Because tree seedlings inoculated with appropriate mycorrhizal fungi in the nursery resist transplanting stress better than non-mycorrhizal seedlings, we evaluated for A. acuminata and M. pubescens the potential of inoculation with mycorrhizal fungi for obtaining robust tree seedlings. For the first time, a laboratory-produced mixed AMF inoculum was tested in comparison with native soil from stands of both tree species, which contains AMF and EMF. Seedlings of both tree species reacted positively to both types of inocula and showed an increase in height, root collar diameter and above- and belowground biomass production, although mycorrhizal root colonization was rather low in M. pubescens. After 6 months, biomass was significantly higher for all mycorrhizal treatments when compared to control treatments, whereas aboveground biomass was approximately doubled for most treatments. To test whether mycorrhiza formation positively influences plant performance under reduced water supply the experiment was conducted under two irrigation regimes. There was no strong response to different levels of watering. Overall, application of native soil inoculum improved growth most. It contained sufficient AMF propagules but potentially also other soil microorganisms that synergistically enhance plant growth performance. However, the AMF inoculum pot-produced under controlled conditions was an efficient alternative for better management of A. acuminata and M. pubescens in the nursery, which in the future may be combined with defined EMF and Frankia inocula for improved management practices.     

Estimation of the biomass of fine roots and mycorrhizal fungi: a case study in a Japanese red pine (Pinus densiflora) stand

As part of a study on soil carbon flow in forest ecosystems, the biomass of fine roots (2.0mm in diameter) and root-associated fungi, including ectomycorrhizal fungi, were estimated in the summer season in 1998 at a Pinus densiflora (Japanese red pine) stand in western Japan. Fine roots of pine were classified into three categories: class I roots (0.5–2.0mm in diameter), long class II roots (long roots with diameter 0.5mm; II_L), and short class II roots (short roots with diameter 0.5mm; II_S). Total biomass of fine roots (I + II_L + II_S) at this stand was estimated to be 91.0gm^–2, about 23% of which was class II roots (II_L + II_S). Ergosterol, which is a component of fungal membranes, was analyzed to estimate the biomass of root-associated fungi in roots. In the upper soil layers (from the surface to 13.4cm in depth), ergosterol contents in the class I, II_L and II_S roots were in the ranges 43.1–82.2, 126.1–196.3 and 271.2–321.0µgg^–1 root DW, respectively. The ergosterol content was converted to fungal biomass using the median (minimum–maximum) value of ergosterol concentration reported for ectomycorrhizal fungi. Root-associated fungal biomass in this stand was estimated to be 2.0 (0.5–9.6) gm^–2. The data suggest the biomass of ectomycorrhizal fungi in the P. densiflora stand is small compared with that in other forest ecosystems.     

Diversity of arbuscular mycorrhizal fungi in <Emphasis Type="Italic">Tectona grandis</Emphasis> Linn.f. plantations and their effects on growth of micropropagated plantlets

Regeneration of stands of valuable tropical hardwood tree species for sustainable harvest requires production of seedlings with high probabilities of survival. One way to enhance the vigor of plants for outplanting is pre-colonization of roots by arbuscular mycorrhizal (AM) fungi. We pursued the strategy that the most promising AM fungus candidates for inoculation would be those associated with the tree of interest in the field. AM fungus communities were assessed in five plantations of Tectona grandis Linn.f. A total of 18 AM fungal morphotypes were found, representing four families: Glomeraceae (49.6%), Acaulosporaceae (24.9%), Claroideoglomeraceae (20.8%), and Gigasporaceae (4.8%). AM fungus spore density was negatively correlated with soil organic carbon. Some of these AM fungi, plus Rhizophagus irregularis, were established in pot culture and in vitro with transformed carrot roots, and subsequently used to inoculate micropropagated plantlets of T. grandis. Tectona grandis plantlets inoculated in vitro were successfully colonized by all AM fungi studied. Plants inoculated with Funneliformis mosseae were taller than uninoculated plants. Tectona grandis plantlets inoculated with the AM fungus Claroideoglomus etunicatum PBT03 were taller than uninoculated controls in ex vitro experiments. This study provides early insight for the targeted use of the AM symbiosis in production of important tree species in future greenhouse studies and reforestation.     

Diversity and abundance of arbuscular mycorrhizal fungi spores under different coffee production systems and in a tropical montane cloud forest patch in Veracruz, Mexico

We evaluate the arbuscular mycorrhizal fungi (AMF) community as measured by spores in different coffee production systems (at the depth of 0?C15?cm). In addition, we analyze the similarities between the AMF communities in coffee production systems and those that occur in a tropical montane cloud forest patch in order to evaluate the capacity of coffee production systems to preserve the native AMF community. We carried out four samplings in five coffee production systems representative of a vegetation structure gradient, and in a forest. From 120 soil samples, 33 morphospecies were detected. In all the sites, the dominant morphospecies were Glomus clarum and Glomus sp. 3. We found no significant difference in AMF spore richness between sites. Diversity was similar in most of the coffee production systems. Significant differences were only detected in spore abundance; during the dry season the forest, shaded traditional rustic system and shaded simple system presented the highest spore abundance. With the exception of one species exclusive to the forest, the coffee production systems all share the same AMF species as the forest. The coffee production systems with the greatest similarity to cloud forest were the shaded traditional rustic system and the shaded simple system. It is suggested that control of weeds and fertilization could be important factors influencing the composition and abundance of AMF spores in coffee production systems.     

Effects of arbuscular mycorrhizal fungi on leaf solutes and root absorption areas of trifoliate orange seedlings under water stress conditions

The effects of the arbuscular mycorrhizal (AM) fungus Glomus mosseae on plant growth, leaf solutes and root absorption area of trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings were studied in potted culture under water stress conditions. Inoculation with G. mosseae increased plant height, stem diameter, leaf area, shoot dry weight, root dry weight and plant dry weight, when the soil water content was 20%, 16% and 12%. AM inoculation also promoted the active and total absorption area of root system and absorption of phosphorus from the rhizosphere, enhanced the content of soluble sugar in leaves and roots, and reduced proline content in leaves. AM seedings had higher plant water use efficiency and higher drought tolerance than non-AM seedlings. Effects of G. mosseae inoculation on trifoliate orange seedlings under 20% and 16% soil water content were more significant than under 12% soil water content. AM infection was severely restrained by 12% soil water content. Thus, effects of AM fungi on plants were probably positively related to the extent of root colonization by AM fungi. The mechanism of AM fungi in enhancing drought resistance of host plants ascribed to greater osmotic adjustment and greater absorption area of root system by AM colonization. __________ Translated from Journal of Plant Physiology and Molecular Biology, 2005, 30(5): 583–588 [译自: 植物生理与分子生物学报, 2005, 30(5): 583–588]     

13C and 15N isotopic fractionation in trees, soils and fungi in a natural forest stand and a Norway spruce plantation

¹⁵N and ¹³C natural abundances of foliage, branches, trunks, litter, soil, fungal sporophores, mycorrhizas and mycelium were determined in two forest stands, a natural forest and a Norway spruce plantation, to obtain some insights into the role of the functional diversity of saprotrophic and ectomycorrhizal fungi in carbon and nitrogen cycles. Almost all saprotrophic fungi sporophores were enriched in ¹³C relative to their substrate. In contrast, they exhibited no or very little shift of δ¹⁵N. Judging from the amount of C discrimination, ectomycorrhizal fungi seem to acquire carbon from their host or from dead organic matter. Some ectomycorrhizal species seem able to acquire nitrogen from dead organic matter and could be able to transfer it to their host without nitrogen fractionation, while others supply their host with ¹⁵N-depleted nitrogen. Moreover ectomycorrhizal species displayed a significant N fractionation during sporophore differentiation, while saprotrophic fungi did not.     

红树林真菌的生物多样性和生物工程应用潜力(英文)

本文对现今红树林真菌研究的热点领域进行了综述,包括红树林真菌的生物多样性,生态作用,新颖的代谢产物和生物工程应用前景四个方面。首先,红树林真菌按照其生态作用被分为腐生,寄生和内生真菌。其中腐生真菌对于红树林生态系统的降解和能量循环方面起着重要的作用,另外,它们也会产生一些毒素:寄生真菌对于红树林的存活,长势和健康程度起着重要的作用;而内生真菌分布于大部分红树之中,所产的活性物质是红树林真菌中最丰富的。其次,虽然已有大量文献报道了红树林真菌可以产生很多新酶和具有’抑菌,杀虫及其它活性的物质,并且很多由内生真菌产生的活性物质被认为对红树起着重要作用,但只有少量研究对此提供了有力的证据,因此,本文对现今应用分子技术来将红树林真菌的生态作用与其代谢产物联系起来的进展进行了讨论。最后,本文还讨论了利用代谢工程和后基因组技术来生产大量新酶和活性物质并将其商业化应用的前景。     

Response of Acacia senegal (L.) Willd. to inoculation with arbuscular mycorrhizal fungi isolates in sterilized and unsterilized soils in Senegal

The benefits of inoculation with six arbuscular mycorrhizal fungi (AMF) isolates (Glomus aggregatum, G. fasciculatum, G. intraradices, G. manihotis, G. mosseae, and G. verriculosum) were investigated on seedlings of Acacia senegal (L.) Willd., a multipurpose tree legume highly valued for arabic gum production. Mycorrhizal root colonization, plant growth and relative mycorrhizal dependency (RMD) were measured in A. senegal seedlings growing in soils from three geographical sites in Senegal (Dahra, Bambey and Goudiry) and two soil conditions (sterilized vs unsterilized) in the glasshouse. The impact of inoculation on mycorrhizal root colonization and plant growth depended on AMF isolates, soil origins and soil conditions. Mycorrhizal root colonization and plant growth were increased in sterilized soils regardless of soil origin and AMF isolates. The degree of RMD of A. senegal seedlings varied with soil origin, soil condition and AMF isolates. A. senegal showed the highest RMD values, reaching a maximum of 45 %, when inoculated with G. manihotis. However, in unsterilized soils, no significant effect of AMF inoculation on plant growth was observed despite significant root colonization with certain AMF isolates in Dahra and Goudiry soils. This indicates that the most infective AMF isolates were not the most effective and unsterilized soils may contain effective mycorrhizal propagules. In conclusion, it is important to consider the native mycorrhizal component of the soils before harnessing mycorrhizal inoculation programs for sustainable agroforestry systems.