目前AM真菌培养特性方面研究的基本概况

从盆钵培养,双相培养和纯培养3个层次讨论了当前探索丛枝菌根（AM）真菌培养特性的研究现状,并探讨了当前培养AM真菌的动向与展望。     

日本蚱的生活史及其它生物学特性

日本蚱Tetrix japonica是一种广布于东亚地区的直翅目昆虫。本文通过野外观察与室内饲养相结合的方法,研究了日本蚱的卵块和各虫龄的形态特征、生活史、若虫及成虫的主要生活习性。结果表明：日本蚱喜欢栖息于具苔藓的矮草地表,主要取食幼嫩苔藓及腐殖质;在羽化7 d后开始出现交配现象,交配时间为1~1.5 h;交配后1~3 d内将大米粒状卵粒产于苔藓泥土中,卵块的形状近似橘瓣状,卵粒数目通常为10~30粒;卵经过6~10 d可孵化为若虫;雄性共有6龄,雌性共有7龄,每个虫龄历期随虫龄的增长而增加;不同虫龄的日本蚱在形态上具有一定的差异。此外,研究还发现日本蚱的前胸背板与翅型存在多态现象,可能在进化适应中起重要作用。     

与盾叶薯蓣细胞共生培养的内生真菌分离及其生物学特性

从盾叶薯蓣根状茎中分离到一株与盾叶薯蓣细胞共生培养的内生真菌（RE0105）。测定了该菌ITS1-5．8S rDNA—ITS2序列并构建了系统发育树,发现RE0105与Libertella属形成一个类群,具有较近亲缘关系。该真菌能产生与宿主植物相同的代谢产物——薯蓣皂苷元。对RE0105培养特性研究表明：富含有机营养的培养基有利于其生长;盾叶薯蓣细胞提取物可明显刺激其生长;20μmol／L生长素NAA和2,4-D能够促进RE0105的生长。200μmol／L细胞分裂素KT和BA对RE0105生长具有一定的促进作用,但与生长素相比,细胞分裂素对RE0105生长的刺激作用较小。蔗糖、葡萄糖、果糖、乳糖、木糖和NH4NO3是RE0105生长的良好C源和无机N源,但NH4Cl和（NH4）2SO4对该菌生长具有明显抑制作用,并且显著影响其形态特征。     

蝉拟青霉LB菌株的生物学特性

本文研究碳源、氮源、温度、湿度、pH值和光照等对蝉拟青霉LB菌株生长、产孢和孢子萌发的影响.结果表明,适合该菌株菌落生长和产孢的最佳碳源是可溶性淀粉和蔗糖,最佳氮源为蛋白胨;菌丝生长和孢子萌发的最适温度范围是25℃～27℃,产生分生孢子的最适温度是25℃;分生孢子萌发所需湿度范围是RH 90%～100%,当RH低于90%时很难萌发;在pH值4～10的范围内该菌能生长和产孢,菌丝生长最适pH为6,产生分生孢子和孢子萌发最适pH范围为6-7;光照处理对该菌产孢有一定的影响;分生孢子的致死条件为55℃ 10min.生物学特性显示,蝉拟青霉LB菌株是一株对营养要求不高、对环境适应能力较强的昆虫病原真菌.     

目前AM真菌培养特性方面研究的基本概况*

从盆钵培养、双相培养和纯培养3个层次讨论了当前探索丛枝菌根(AM)真菌培养特性的研究现状,并探讨了当前培养AM真菌的动向与展望。     

产紫杉醇内生真菌EFY-21的鉴定与生物学特性研究

利用PCR技术克隆了产紫杉醇内生真菌EFY-21的18S rDNA序列,通过同源性分析,初步确定该菌与拟盘多毛孢属(Pestalotiopsis)有较高的同源性,相似性为99%。为了进一步了解EFY-21的有关生物学特性,分别选用PDA、PSA、查氏、玉米粉琼胶、牛肉膏蛋白胨5种培养基,按照常规方法培养,用十字法测量菌落直径;同时选用查氏培养基为基本培养基,分别观察不同碳源葡萄糖、甘露醇、麦芽糖、果糖、可溶性淀粉,不同氮源KNO3、Ca(N03)2、(NH4)2SO4、NH4N03、(NH4)2HPO4、蛋白胨、尿素,不同培养温度10,15,20,25,28,30,37℃,不同pH值4,5,6,7,8,9对内生真菌菌丝的影响。试验结果表明:EFY-21在PDA培养基上生长最快,生长状况最好;供试的碳氮源中,对EFY-21菌丝生长影响的大小顺序为葡萄糖甘露醇果糖麦芽糖可溶性淀粉;蛋白胨KNO3Ca(N03)2NH4N03(NH4)2HPO4(NH4)2SO4尿素;最适培养温度为25～30℃;最适pH为5～7。     

与植物共生的难培养菌物及其培养特性研究进展

与植物共生难培养菌物的分类地位与生活史复杂多样,与植物共生程度各异。在其他一定种类生物(如植物、细菌等)存在的条件下,大多与植物共生难培养菌物能完成生活史,而且一些非专性非活体营养的共生菌物较专性活体营养的共生菌物更容易获得纯培养。在简要介绍与植物共生难培养菌物分类地位、生活史与共生类型的基础上,重点探讨了与植物共生难培养菌物的培养特性和培养方法,并讨论了该领域的研究动向与展望,旨在为当前和今后开展难培养菌物纯培养研究提供思路、依据和工作基础。     

冰核真菌胞外冰核产生条件、成冰生物学特性及其分离纯化的研究

果糖和葡萄糖作碳源、硫酸铵作氮源、培养温度25℃以下,培养液初始pH5-7和少量通气都利于胞外冰核产生,最佳培养时间受培养温度和接种菌龄的制约,而低温处理,光照及加丝裂霉素C和HNPA对胞外冰核产生无明显影响。胞外冰核耐热（40℃处理后仍保持较高活性）,酸碱适应性强（pH2-13);温度50℃以上,蛋白酶K和高浓度脲处理可完全失活或严重破坏其冰核活性,表明蛋白和真菌胞外冰核的必需成分;胞外冰核溶液中盐浓度高于50mmol/L时,活性才受抑制。25％冰乙醇可有效沉淀真菌胞外冰核,同时又保持较高活性;分离纯化的初步研究显示真菌胞外冰核分子量很大,电荷组成和分布上不均一,所带净电荷为负,本研究加深了对真菌胞外冰核的认识,为进一步纯化奠定了基础。     

高中生物学新课程标准教材研讨"遗传的细胞基础"的教学思考与探讨

“遗传的细胞基础”是必修模块2“遗传与进化”中的一部分,它从细胞水平阐述遗传的基本原理。这部分教学内容有助于学生理解遗传现象的本质。1教学内容与要求课标规定的内容包括：①阐明细胞的减数分裂并     

大鼠骨髓基质细胞的培养及生物学特性鉴定

目的:分离、培养大鼠MSCs,对其生物学特性进行鉴定.方法:取大鼠长骨中的骨髓组织,以贴壁法培养分离大鼠MSCs,经多次传代得到较纯的MSCs,倒置相差显微镜下观察细胞形态,应用免疫细胞化学方法对细胞的表面抗原标志进行检测.取3代MSCs,B-ME诱导6小时候后,倒置相差显微镜下观察细胞形态,应用免疫细胞化学方法鉴定诱导后细胞的表型特征.结果:倒置相差显微镜观察发现,接种后24h,细胞开始贴壁.培养3代以后,细胞呈梭形或多角形,折光性好,核为圆形、居中.免疫细胞化学检测细胞表面抗原显示:CD34-、CD45-、CD29+、CD44+、CD90+.诱导后细胞发出突起,逐渐生长延伸并彼此相连,形态学上具有神经细胞的明显特征.免疫细胞化学显示诱导后细胞NSE(神经元特异性烯醇化酶)阳性.结论:所采用的细胞分离培养方法简便可行,所获得的细胞其表型特征与文献报道一致,且具有向神经细胞分化的潜能.     

Arbuscular mycorrhizal fungi and biological control of Verticillium-wilted cotton plants

The interaction of arbuscular mycorrhizal fungi (Glomus etunicatum, Glomus intraradices, and Glomus versiforme) with a wilt-causing soil-borne pathogen, Verticillium dahliae, was studied in cotton. It was found that establishment by arbuscular mycorrhizal fungi reduced disease index. In diseased cotton plants colonised by G. etunicatum, the disease index was less than other diseased mycorrhizal and non-mycorrhizal ones. In diseased cotton plants, chlorophyll content was lower than others. Three Glomus species significantly increased content of sugar and protein in shoot and root. Pathogen-infected plants had higher proline concentration in shoot and root than healthy plants. On the other hand, the increased content of proline as stress sensor showed that Verticillium accelerates senescence and reduces yield. These results suggest that the beneficial effects of mycorrhiza can alleviate the pathogenesis effects of V. dahliae partly, and also there is a competitive interaction between the pathogenic and symbiotic fungi.     

Arbuscular mycorrhizal fungi, Collembola and plant growth

Arbuscular mycorrhizal fungi are ubiquitous in field soils, as are mycophagous animals such as Collembola. It has been suggested that these animals reduce the functioning of the mycorrhiza and are thus detrimental to plant growth. However, recent choice experiments suggest that Collembola preferentially feed on nonmycorrhizal fungi in the rhizosphere. If these preferences also occur in field soils, then Collembola might indirectly benefit plants through an enhancement of mycorrhizal functioning and indirect multitrophic links to foliar-feeding insect herbivores.     

Arbuscular mycorrhizal fungi and nitrogen uptake

Nitrogen (N) is among the most important macro-nutrients significantly affecting plant growth and yield production. Accordingly, N must be supplied adequately so that optimum amounts of yield are resulted. There are different ways of supplying N to the plant including the use of chemical and biological fertilization. The chemical properties of N make it very mobile, especially under humid conditions. Hence, N must not be overfertilized with respect to the economical and environmental points of view. N Biological fertilization includes the use of plant growth-promoting rhizobacteria (PGPR) including the N-fixing bacteria, rhizobium. There are also arbuscular mycorrhizal (AM) fungi in the soil, which are symbiotic to most terrestrial plants enhancing plant growth and yield production through increasing the uptake of water and nutrients by the host plant. Numerous experiments have indicated the important role of AM fungi in enhancing P uptake by plant. However, it is yet a matter of debate that how AM fungi may affect soil N dynamic and hence plant N uptake. Some of the most important and recent aspects regarding such effects by AM fungi are highlighted, which can be of significance to health and productivity of the ecosystem.     

Arbuscular mycorrhizal fungi influence life history traits of a lepidopteran herbivore

Results from pot and microcosm studies in the greenhouse have shown that plant growth and foliar chemistry is altered by the presence and species composition of arbuscular mycorrhizal fungi (AMF). The growth and survival of herbivores which feed on plants could, as a consequence, also be affected by these mutualistic soil fungi. Consequently, interactions between AMF, plants and herbivores could occur. To test this, larvae of the common blue butterfly, Polyommatus icarus (Lycaenidae), were fed with sprigs of Lotus corniculatus (Fabaceae) plants which were inoculated with one of two different AMF species, with a mixture of these AMF species or with sprigs of plants which were not inoculated with AMF. Survival and larval weight of third instar larvae fed with plants colonised by AMF were greater than those of larvae fed with non-mycorrhizal plants. Survival of larvae feeding on non-mycorrhizal plants was 1.6 times lower than that of larvae feeding on plants inoculated with a mixture of AMF species and 3.8 times lower than that of larvae feeding on plants inoculated with single AMF species. Furthermore, larvae fed with non-mycorrhizal plants attained only about half the weight of larvae fed with mycorrhizal plants after 11 days of growth. These differences in larval performance might be explained by differences in leaf chemistry, since mycorrhizal plants had a 3 times higher leaf P concentration and a higher C/N-ratio. Our results, thus, show that the presence of belowground mutualistic soil fungi influences the performance of aboveground herbivores by altering their food quality. Larval consumption, larval food use and adult lipid concentrations of the common blue butterfly differed between larvae which were fed with plants inoculated with different AMF species. This suggests that the performance of herbivores is not only influenced by the presence of AMF but also depends on the identity of the AMF species colonising the host plants. Moreover, a significant interaction term between AMF species and maternal identity of the larvae occurred for adult dry weight, indicating that the performance of offspring from different females was differently influenced by AMF species composition. To our knowledge, these results show for the first time that the species composition of AMF communities can influence life-history traits of butterfly larvae and possibly herbivores in general.     

未来的一种生物肥料:丛枝菌根真菌*

丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)存在于几乎所有类型的土壤中,可以与绝大多数被子植物的根共生。大多数农作物、果树、蔬菜、观赏植物和花卉等都能形成丛枝菌根。AMF能促进作物吸收利用矿质养分和水分,提高作物抗逆性和抗病性,改良土壤、提高苗木移栽成活率、促进生长、提高产量和改善品质,并且可用于改善退化生态系统的土壤肥力,维持农林业的可持续发展,将成为一种新型的生物肥料被用于农林业生产。本文讨论了影响菌根侵染率的因素、AMF的生态效应和在生态农业中的应用现状和前景。     

Arbuscular mycorrhizal structure and fungi associated with mosses

We investigated the colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with 24 moss species belonging to 16 families in China. AM fungal structures, i.e. spores, vesicles, hyphal coils (including intracellular hyphae), or intercellular nonseptate hyphae, were found in 21 moss species. AM fungal structures (vesicles, hyphal coils, and intercellular nonseptate hyphae) were present in tissues of 14 moss species, and spores and nonseptate hyphae on the surface of gametophytes occurred in 15 species. AM fungal structures were present in 11 of the 12 saxicolous moss species and in six of the ten terricolous moss species, but absent in two epixylous moss species. AM fungal structures were only observed in moss stem and leaf tissues, but not in rhizoids. A total of 15 AM fungal taxa were isolated based on trap culture with clover, using 13 moss species as inocula. Of these AM fungi, 11 belonged to Glomus, two to Acaulospora, one to Gigaspora, and one to Paraglomus. Our results suggest that AM fungal structures commonly occur in most mosses and that diverse AM fungi, particularly Glomus species, are associated with mosses.     

Arbuscular mycorrhizal fungi in terms of symbiosis-parasitism continuum

Arbuscular mycorrhizal fungi are forming the most wide-spread mycorrhizal relationships on Earth. Mycorrhiza contributes to phosphorous acquisition, water absorption and resistance to diseases. The fungus promotes the absorption of nutrients and water from soil, meanwhile the host plant offers photosynthetic assimilates in exchange, like carbohydrates, as energy source. The plant benefits from the contribution of symbiotic partner only when nutrients are in low concentrations in soil and the root system would not be able to absorb sufficiently the minerals. When the help of mycorrhizal fungi is not necessarily needed, the host plant is making an economy of energy, suppressing the development of fungi in the internal radicular space. In this moment, the nature of relationship turns from symbiotic to parasitic, triggering a series of defensive reactions from the plant. Also, there were several cases reported when the presence of arbuscular mycorrhizal fungi negatively influenced the host plant. For example, in adverse environmental conditions, like very high temperatures, instead of determining a higher plant biomass and flowering, the mycorrhiza reduces the growth of the host plant. We conducted a pot experiment with hydroponic culture to examine the effect of arbuscular mycorrhiza on development of French marigold as a host plant. As experimental variants, the phosphorous content in nutrient medium and temperature varied. Plants were artificially infected with arbuscular mycorrhizal fungi using a commercial inoculum containing three fungal species, as following: Glomus intraradices, Glomus etunicatum and Glomus claroideum. Colonization intensity and arbuscular richness were checked using root staining with aniline blue and estimation with the Trouvelot method. To observe the differences between plants from the experimental variants, we examined the number of side shoots, flower buds and fully developed flowers, fresh biomass and total leaf area. Results show that adverse climatic conditions, like temperature shock at the beginning of growing period modified the nature of symbiosis. In this case, the physiological parameters were reduced at colonized plants, while usual, constant growing conditions permitted the normal, efficient and beneficial development of symbiosis.     

Arbuscular mycorrhizal fungi: genetics of multigenomic, clonal networks and its ecological consequences

Arbuscular mycorrhizal fungi are thought to have remained asexual for 400 million years, although recent studies have suggested that considerable genetic and phenotypic variation could potentially exist in populations. A brief discussion of these multigenomic organisms is presented.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 59–60.     

Arbuscular mycorrhizal fungi alter plant allometry and biomass-density relationships

Background and Aims

Plant biomass–density relationships during self-thinning are determined mainly by allometry. Both allometry and biomass–density relationship have been shown to vary with abiotic conditions, but the effects of biotic interactions have not been investigated. Arbuscular mycorrhizal fungi (AMF) can promote plant growth and affect plant form. Here experiments were carried out to test whether AMF affect plant allometry and the self-thinning trajectory.

Methods

Two experiments were conducted on Medicago sativa L., a leguminous species known to be highly dependent on mycorrhiza. Two mycorrhizal levels were obtained by applying benomyl (low AMF) or not (high AMF). Experiment 1 investigated the effects of AMF on plant growth in the absence of competition. Experiment 2 was a factorial design with two mycorrhizal levels and two plant densities (6000 and 17 500 seeds m⁻²). Shoot biomass, root biomass and canopy radius were measured 30, 60, 90 and 120 d after sowing. The allometric relationships among these aspects of size were estimated by standardized major axis regression on log-transformed data.

Key Results

Shoot biomass in the absence of competition was lower under low AMF treatment. In self-thinning populations, the slope of the log (mean shoot biomass) vs. log density relationship was significantly steeper for the high AMF treatment (slope = –1·480) than for the low AMF treatment (–1·133). The canopy radius–biomass allometric exponents were not significantly affected by AMF level, but the root–shoot allometric exponent was higher in the low AMF treatment. With a high level of AMF, the biomass–density exponent can be predicted from the above-ground allometric model of self-thinning, while this was not the case when AMF were reduced by fungicide.

Conclusions

AMF affected the importance of below-ground relative to above-ground interactions and changed root vs. shoot allocation. This changed allometric allocation of biomass and altered the self-thinning trajectory.