The production of ectomycorrhizal mycelium in forests: Relation between forest nutrient status and local mineral sources

Due to acid rain and nitrogen deposition, there is growing concern that other mineral nutrients, primarily potassium and phosphorus, might limit forest production in boreal forests. Ectomycorrhizal (EcM) fungi are important for the acquisition of potassium and phosphorus by trees. In a field investigation, the effects of poor potassium and phosphorus status of forest trees on the production of EcM mycelium were examined. The production of EcM mycelium was estimated in mesh bags containing sand, which were buried in the soil of forests of different potassium and phosphorus status. Mesh bags with 2% biotite or 1% apatite in sand were also buried to estimate the effect of local sources of nutrients on the production of EcM mycelium. No clear relation could be found between the production of EcM mycelium and nutrient status of the trees. Apatite stimulated the mycelial production, while biotite had no significant effect. EcM root production at the mesh bag surfaces was stimulated by apatite amendment in a forest with poor phosphorus status. The contribution of EcM fungi to apatite weathering was estimated by using rare earth elements (REE) as marker elements. The concentration of REE was 10 times higher in EcM roots, which had grown in contact with the outer surface of apatite-amended mesh bags than in EcM roots grown in contact with the biotite amended or sand-filled mesh bags. In a laboratory study, it was confirmed that REE accumulated in the roots with very low amounts <1 translocated to the shoots. The short-term effect of EcM mycelium on the elemental composition of biotite and apatite was investigated and compared with biotite- and apatite-amended mesh bags buried in trenched soil plots, which were free from EcM fungi. The mesh bags subjected to EcM fungi showed no difference in chemical composition after 17 months in the field. This study suggests that trees respond to phosphorus limitation by increased exploitation of phosphorus-containing minerals by ectomycorrhiza. However, the potential to ameliorate potassium limitation in a similar way appears to be low.     

菌根真菌的生理生态功能

菌根真菌是土壤中重要生物成员之一,不仅具有丰富的遗传多样性和物种多样性,其功能也是丰富多样,主要体现在：1）影响陆生植物起源、进化、演化与分布;2）促进植物的生长发育;3）提高植物的抗逆性;4）修复污染与退化土壤、改善土壤质量与健康状况;5）促进农林牧业的生产;6）保持生态平衡、稳定生态系统及其可持续生产力.随着技术发展和研究的深入,菌根真菌新功能将会不断被发现.     

Solid cultures of thrips-pathogenic fungi Isaria javanica strains for enhanced conidial productivity and thermotolerance

Entomopathogenic fungi have great potential to control agricultural and horticultural insect pests, however optimizing conidial production systems to demonstrate high productivity and stability still needs additional efforts for successful field application and industrialization. Although many virulent entomopathogenic fungal isolates have been viewed as potential candidates in a laboratory environment, very few of the isolates are being used in practice for application in agricultural fields as commercial products. I. javanicus is an entomopathogenic fungus that is parasitic to various diverse coleopteran and lepidopteran insects and thought good candidate as biopesticdes. In this work, the basic characteristics of two entomopathogenic fungi, I. javanica FG340 and Pf04, were investigated in morphological examinations, genetic identification, and virulence against Thrips palmi, and then the feasibility of various grains substrates for conidial production was assessed, particularly focusing on conidial productivity and thermotolerance. Isaria javanica FG340 and Pf04 conidia were solid-cultured on 12 grains for 14?days in a Petri dish. Of the tested Italian millet, perilla seed, millet and barley-based cultures showed high conidial production. The four-grain media yielded >1?×?10⁹ conidia/g of I. javanica FG340 and Pf04. Pf04 strain had enhanced thermotolerance up to 45?°C when cultured on Italian millet. In application, it was easy to make a conidial suspension using the cultured grains, and several surfactants were tested to release the conidia. This work suggests several possible inexpensive grain substrates by which to promote conidial production combined with enhanced stability against exposure to high temperature.     

低温型真菌抗肿瘤活性次级代谢产物研究进展

真菌栖息生境及物种的多样性使其次级代谢产物化学结构和生物活性呈多样性特点,结构与功能多样的真菌次级代谢产物已成为新药先导化合物发现的重要资源。低温型真菌因其独特而恶劣的生存环境进化出特有的适冷特性及代谢途径,使其产生结构新颖、活性显著的次级代谢产物的几率大大提升,已成为药物研发的热点领域。近年来,研究者陆续从高海拔地区、南北极地和深海地带等低温生境分离鉴定出上百种结构新颖的次级代谢产物,并显示出抗肿瘤、抗菌、抗病毒和免疫调节等多种活性。本文对近10年来源于上述生境的低温型真菌抗肿瘤活性次级代谢产物的研究进展进行综述,为其用于创制抗肿瘤新药提供新思路。     

Fungal Deterioration of Barrier Concrete used in Nuclear Waste Disposal

Fungal biogeochemical activity over a long-term scale may have negative environmental consequences for the management of barrier materials used in nuclear waste disposal. Fungal deterioration of barrier concrete was studied in microcosms simulating a heterogeneous environment with an external source of nutrients for the fungi. Fungi successfully colonized barrier concrete, generally avoiding granite aggregates, and biochemically (by excretion of protons and ligands) and biomechanically deteriorated the concrete. Fungi dissolved the cement matrix leaching structural elements and accumulating them within the fungal biofilm and associated microenvironment. Oxalate-excreting Aspergillus niger formed abundant calcium oxalate crystals on the concrete and encrusting fungal hyphae.     

云南食用菌眼蕈蚊分类及优势种分析

本文报道了云南省各食用菌栽培地眼蕈蚊科（Sciaridae）害虫共6属11种, 其中异迟眼蕈蚊Bradysia difformis Frey为中国新纪录种, 独刺普眼蕈蚊Cosmosciara perniciosa Edwards为中国新记录属和种, 并提供了云南省食用菌眼蕈蚊种类检索表。研究标本均保存于云南农业大学昆虫系标本室。根据各地标本采集数据对不同食用菌上眼蕈蚊种类优势度进行了分析, 结果表明平菇厉眼蕈蚊Lycoriella pleuroti Yang et Zhang和异迟眼蕈蚊B. difformis Frey为云南省食用菌上眼蕈蚊的主要优势种类。     

紫杉醇产生菌及其工程菌株之间的AFLP遗传差异分析

采用AFLP技术对三株紫杉醇产生菌(HQD33、HQD43、HQD54)及HQD33菌株经复合诱变后再经原生质体诱变得到的两株诱变株UL50-6和UV40-19及其融合菌株J1-3进行了分析,结果表明三株紫杉醇产生菌分属不同的种属,同时首次从分子水平上证实Z35-8,J1-3为两株不同的融合子,为下一步的基因工程育种工作中的基因定位和分子克隆提供丰富可靠的分子标记。     

白腐菌对染料脱色和降解作用的研究进展

白腐菌应用于废水处理始于二十世纪八十年代。本文对印染废水的处理方法、白腐菌及其对污染物的降解机理作了简要概述 ,着重介绍了白腐菌对染料脱色和降解作用的研究进展。白腐菌对染料的脱色解降作用机理有部分尚待进一步研究 ;同时 ,白腐菌的吸附作用亦不容忽视。     

Spatiotemporal distribution of fruitbodies of ectomycorrhizal fungi in an Abies firma forest

 Spatial associations between ectomycorrhizal (ECM) fungi and their presumed host trees, and spatiotemporal associations among ECM fungi were surveyed for 3 years in an Abies firma-dominated forest in central Japan. A total of 39 species in 13 genera of ECM fungi were recorded, with more species in the Russulaceae than any other family. Russula ochroleuca, Russula sp.1 and Strobilomyces confusus tended to produce their fruitbodies on the forest floor directly under the crown of A. firma, whereas those of Inocybe cincinnata, Gomphus floccosus and G. fujisanensis were aggregated in limited areas outside the A. firma crown. Interspecific spatial associations were analysed for Russula sp.1, which was the most dominant species, and three other frequent species, I. cincinnata, S. confusus and R. ochroleuca. Pairwise, Russula sp.1 with I. cincinnata, with S. confusus or with R. ochroleuca showed an association which was exclusive, overlapping or independent, respectively. Fruiting phenologies differed in that S. confusus showed a peak density in the summer, whereas the other three species peaked in the autumn. These results suggest that the formation of ECM fruitbodies can be partitioned among the species both spatially and temporally. Accepted: 7 July 1998