苹果树VA菌根形态结构观察

研究了苹果树ＶＡ菌根在自然条件下的发育状况。观察结果表明：ＶＡ菌根结构主要位于各供试品种新生根的成熟区和伸长区，在根皮层细胞内具有典型的泡囊和丛枝。根内和根外菌丝的直径为２．１～４．５μｍ，泡囊主要呈椭圆形和圆形。不同品种之间的泡囊数、丛枝百分率、根上菌丝着生位点数及侵染率存在显著差异。不同粗度的根系ＶＡ菌根真菌的侵染情况存在着差异，其中直径０．１～０．５ｍｍ的细根，ＶＡ菌根真菌的侵染率最高。不同土层内的菌根形态差异不显著，但侵染率及发育状况不同。     

彩色豆马勃与松树形成内外生菌根的研究

采用组培菌根合成技术、纸—三明治菌根快速合成技术和圃地截根菌根化育苗技术使彩色豆马勃RG310和RG49菌株在马尾松、火炬松、湿地松上形成内外生菌根,不同菌根化技术形成菌根的过程和类型有差异。在组培菌根合成的条件下,菌与根接触后的第3—4d首先开始形成菌丝套,第8d开始形成哈蒂氏网,第18d菌丝进入皮层细胞内,哈蒂氏网由单列变为多列菌丝细胞组成;采用纸—三明治菌根快速合成技术进行截根菌根化,促进了菌根真菌的定殖,以截面伤口侵入为主要的侵入方式,扩大了根内外菌根侵染区(MIZ),定殖、侵染同时发生,菌丝套、哈蒂氏网和胞内菌丝结构几乎同时形成,仅在2．5h内就开始形成,菌根真菌的菌丝进入了内外皮层和髓部;采用圃地截根菌根化育苗技术,仍然形成内外生菌根,但菌丝不侵入内皮层以内的根组织。根据研究提出“菌根类型”假说,即树木形成的菌根类型不但随菌根真菌和树木种类而异,而且随菌根化方法、生态条件等其它因子而异。     

陕西省杨树外生菌根种类的调查研究

对陕西省３５种杨树外生菌根的调查研究，鉴定出９种外生菌根真菌。研究证明，一种外生菌根真菌可侵染不同种杨树；一种杨树又可被不同的菌根真菌侵染，并观察到在同一小根上顶端形成菌套，中部和下部形成泡囊丛枝这一混合型菌根形态。     

不同套种模式云南核桃丛枝菌根与土壤因子的相关性研究

为探明不同套种模式核桃根际丛枝菌根(AM)与土壤因子之间的相关关系,采用菌根形态学的研究方法,研究了核桃根系中丛枝菌根真菌(AMF)定殖状况和根际土壤中AMF的孢子密度,运用相关分析、主成分分析和通径分析方法,研究了核桃AMF与土壤因子的相关性。结果表明:核桃根系能与AMF形成良好的共生关系,不同套种模式之间核桃根系中AMF定殖率以及孢子密度差异显著,套种茶树的种植园中AMF的侵染率和孢子密度最高,套种豌豆的种植园中AMF侵染率和孢子密度最低;AMF孢子密度与土壤有机质、pH值、碱性磷酸酶和脲酶活性显著正相关;AMF总侵染率与pH值显著正相关;AMF总侵染率、菌丝侵染率和孢子密度与全磷显著负相关;丛枝侵染率与全氮和碱性磷酸酶活性显著正相关;菌丝侵染率与pH值极显著正相关;菌丝圈侵染率与全氮和碱性磷酸酶活性显著正相关;泡囊侵染率与过氧化氢酶活性显著正相关,与水解氮和速效钾极显著负相关,与土壤有机质和全氮显著负相关。土壤中的有机质、全氮和全磷是云南高原山区核桃菌根真菌定殖和发育的主要影响因子。     

文冠果VA菌根真菌的分离、扩繁及幼苗菌根化效果的研究

本文以我国北方唯一的木本油料树种——文冠果为目标,对与其共生的VA菌根真菌进行了采集、分离和扩繁,并进行了文冠果幼苗的菌根化试验。在采集到的文冠果根系中发现了VA菌根真菌共生结构,其自然侵染率约为20.5%左右;从根际土中分离出典型孢子,经初步检索鉴定其为球孢囊霉属的某个种(Glomus sp.);利用高丹草作为载体进行该菌种的扩大繁殖培养,培养60d后采集根样进行镜检,可明显观察到菌根孢子在根表的侵染点、菌丝及在根皮层细胞内形成的丛枝结构,表明VA菌根真菌的孢子已经与高丹草根系发生了有效侵染。利用继代培养后的接种体进行文冠果幼苗的菌根化回接试验,1年生菌根化幼苗苗高、地径、地上、地下部鲜重与对照相比分别提高了5.9%、7.2%、8.8%和7.4%,差异显著,表明文冠果幼苗期菌根化效果显著。     

菌根直菌在林业上的应用

菌根,就是土壤中真菌与根的木栓化幼嫩部分形成的共生联合体.形成菌根的真菌叫做菌根菌.菌根能促进寄主的生长,在有效磷低的土壤中,它能成倍地促进植物的生长.菌根有两种类型:一种叫外生型菌根.真菌的菌丝包在幼根的外面或侵入皮层细胞的间隙中,使根毛不发达,甚至没有而被菌丝所代替.如松、山毛榉、麻栎等;另一种叫内生型菌根.菌丝穿过细胞壁侵入细胞内,并同细胞原生质体混在一起,在表皮细     

菌根对植物营养的作用

植物的根与真菌形成菌根,产生互利的共生作用。大多数植物都具有菌根,而不只是根的本身。只有几个科的植物不能形成菌根。菌根一般有三种类型:外生菌根、内生菌根和内外生菌根。侵染根部的真菌对根的影响及其致病作用,现在还只对前两种类型作了研究。森林树种主要形成外生菌根,特别是松科、壳斗科、桦木科、桃金娘科和担子菌纲与子囊菌纲共生的菌根。真菌在根表面形成密集的菌丝覆盖层,并在皮层的细胞间隙生长。与没有菌根的根系比较,有     

印度东北部黄兰种植区丛枝菌根真菌的侵染和分布(英文)

调查了印度东北部梅加拉亚邦(Meghalaya)3个黄兰种植区(Umdihar,Umsaw和Mawlein)内丛枝菌根真菌和暗隔真菌的侵染。分离和鉴定了丛枝菌根真菌孢子,根据不同黄兰种植区内菌根菌种分布和丰富度评价了菌根菌多样性和寄主选择性。结果表明,丛枝菌根真菌侵染显著高于暗隔真菌。丛枝菌根真菌和暗隔真菌的侵染分别是50.91%～58.95%和1.84%～4.11%。真菌孢子密度在三个种植区内变化较大(p0.05)。在所鉴定的7个属29个菌种中,球囊霉属菌种的丰富度最高。Sorenson系数在0.35-7.0之间。种植区内菌种丰富度在2.0～2.9之间。总的菌种丰富度与总的相对丰富度显著相关(p=0.001)。真菌分布、相对丰富度和主成分分析结果表明,大果球囊霉(Glomus macrocarpum)、Glomus multicaulic、缩不囊霉(G.constrictum)和无梗囊霉是黄兰最偏好的菌种,可能是由于寄主的营养获得和生长较为适当。图6表5参27。     

外生菌根菌剂在华山松育苗上的应用技术

外生菌根真菌是指可与大多数被子植物、裸子植物的根结合,在吸收根表面形成菌套或菌鞘,并在植物皮层细胞间隙形成哈蒂氏网的一类真菌。真菌的菌丝（真菌的营养体呈丝状）大部分生长在共生植物幼根的表面,少量菌丝侵入到皮层细胞间隙中,这样的共生植物根毛不发达,菌丝代替了根毛的作用。外生菌根可增加共生植物的养分吸收、提高水分的传递速率、抗旱性及抗病性,     

VA菌根菌对红桂木的接种效应试验

VA菌根真菌(Vesicular Arbuscular mycorrhiza),为泡囊-丛枝状菌根菌,是一种分布极广的内生菌根真菌.菌根真菌侵染植物根部,与根部共生,形成菌根.由于菌根的形成具有促进植物对土壤养分的吸收、增强植物的抗逆性、改善植物的生长,提高植物的生长质量等作用,因此,近年来人工菌根菌接种作为一种环保而有效的生物技术,逐渐在农林业生产上得到研究和应用.     

Arbuscular mycorrhizal induced changes to plant growth and root system morphology in Prunus cerasifera

We compared root system morphogenesis of micropropogated transplants of Prunus cerasifera L. inoculated with either of the arbuscular mycorrhizal (AM) fungi Glomus mosseae or Glomus intraradices or with the ericoid mycorrhizal species Hymenoscyphus ericae. All plants were grown in sand culture, irrigated with a nutrient solution that included a soluble source of phosphorus, for 75 days after transplanting. Arbuscular mycorrhizal colonization increased both the survival and growth (by over 100%) of transplants compared with either uninoculated controls or transplants inoculated with H. ericae. Arbuscular mycorrhizal colonization increased root, stem and leaf weights, leaf area, root length and specific leaf area, and it decreased root length/leaf area ratio, root/shoot weight ratio and specific root length. Both uptake of phosphorus and its concentration in leaves were increased by AM infection, although the time course of the relationships between intensity of AM infection and P nutrition were complex and suggested a role for factors other than nutrition. The time course for the development of infection varied. It was most rapid with G. mosseae, but it was ultimately higher with G. intraradices. None of the treatments significantly affected the lengths of adventitious roots or the first-, second- or third-order laterals that developed from them. Arbuscular mycorrhizal colonization increased the intensity of branching in all root orders with the effect being most obvious on first-order lateral roots where the number of branches increased from under 100 to over 300 brances m(-1). As a result, although first-order laterals made up 55% of the root systems of control plants, the comparable value was 36% in AM-infected plants. In contrast, second-order laterals represented 25% of control root systems, but 50% of AM-colonized root systems. Glomus intraradices but not G. mosseae increased root diameter. Anatomical studies revealed no changes in the overall form of the root tip, although there were changes in the diameter of the root cap, cell numbers and cell size. Hymenoscyphus ericae increased the duration of the metaphase index. Both AM fungal treatments increased the concentrations of soluble proteins in root extracts and modified the protein profiles by the elimination and addition of protein bands detected by PAGE analysis. We conclude that AM fungal inoculation influenced processes in the root system at different levels, but not all effects were due to improved P nutrition or increased physiological age.     

Arbuscular mycorrhizal symbioses in a cut-and-carry forage production system of legume tree Gliricidia sepium and fodder grass Dichanthium aristatum

Arbuscular mycorrhizal (AM) symbioses may alter the competitive abilities of plant species and facilitate positive interactions such as nutrient transfer between plants. They are therefore particularly interesting components in agroforestry systems. We studied spatial variation of AM colonisation on a cut-and-carry fodder production site (agroforestry plot) of the legume tree Gliricidia sepium and the fodder grass Dichanthium aristatum. Roots of the two plant species were sampled under the tree canopies and on the adjacent grass plot at 1 and 3.5 m from the first tree row where G. sepium roots also occur. Roots of D. aristatum were also sampled on a nearby grass monocrop. Colonisation of arbuscules, vesicles and hyphae in root samples was visually determined, and AM fungal species were identified by DNA sequencing. Colonisation and frequency of types of AM formations varied statistically significantly between the species and sampling points. Arbuscular colonisation in G. sepium roots was higher under the tree canopies than on the adjacent grass plot. Soil nutrient content, particularly P and N, and interspecies competition are the most probable explanations for the observed variation in AM colonisation. Both arbuscular colonisation and arbuscule:vesicle ratio in D. aristatum roots was lower on the D. aristatum monocrop than on the agroforestry plot under or near the tree canopies. Intercropping could stimulate AM symbiosis in D. aristatum. Both plant species formed symbiosis with Rhizophagus intraradices, indicating potential for interplant N transfer via common mycelial networks of AM-forming fungi.     

Dynamics of symbiotic establishment between an IAA-overproducing mutant of the ectomycorrhizal fungus Hebeloma cylindrosporum and Pinus pinaster

To clarify the early steps of symbiotic establishment, we studied the dynamics of Pinus pinaster (Ait.) Sol. tap root colonization and mycorrhiza formation by an IAA-overproducing mutant of the ectomycorrhizal fungus Hebeloma cylindrosporum Romagnesi and by the corresponding wild type strain. Differences between wild type and mutant strains were quantitative rather than qualitative and were detected two days after inoculation. Both fungal strains established a typical Hartig net when they colonized the tap roots. Consequently, colonized tap roots exhibited features of a true mycorrhiza and fungal colonization enhanced plant growth. Fungal colonization and Hartig net formation were more rapid with the mutant than with the wild type. Colonization, especially with the mutant strain, increased rhizogenesis and the production of mycorrhizas. The mutant formed a hypertrophic Hartig net in tap roots and mycorrhizal short roots and we obtained evidence that the process of short root transformation into mycorrhiza started before their emergence from the tap root. Hyphae of the Hartig net in the tap root penetrated the cortex of young lateral roots at the beginning of their elongation, after the endodermis layer broke under the pressure of the elongating lateral root. Colonization was inhibited when triiodobenzoic acid was added to the culture medium, providing circumstantial evidence that auxin is involved in mycorrhiza formation.     

Arbuscular mycorrhizal colonization of vascular plants from the Yungas forests, Argentina

In Argentina, the Yungas forests are among the ecosystems most affected by human activity, with loss of biodiversity. To assess the mycorrhizal status in these ecosystems, the roots of 41 native plant species belonging to 25 families were collected throughout the year from two sites of the Yungas forests. Roots were washed and stained to study the presence of arbuscular mycorrhizas (AM). Morphological types of arbuscular mycorrhizas (Arum and Paris-type) and colonization patterns were identified and photographed. All plants presented AM colonization. The AM colonization patterns varied from single intracellular aseptate hyphae, coils, appresoria, to vesicles and/or arbuscules. Among the species studied, the Paris-type colonization showed to be dominant. Results confirmed that AM hosts are predominant in the Yungas of South American forests.     

Temporal allocation of (14)C to extramatrical hyphae of ectomycorrhizal ponderosa pine seedlings

Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches before they were transplanted to root-mycocosms (P seedlings), or at the time of transfer to root-mycocosms (V seedlings). Uninoculated seedlings served as controls (U seedlings). The use of root-mycocosms allowed examination of portions of hyphae separate from roots and rooting substrate but still in symbiosis with the host. The results thus provided a quantitative basis for estimating hyphal mass and carbon allocation to extramatrical hyphae. The amount of (14)CO(2) fixed after a 2-h exposure was greatest for P seedlings and least for uninoculated seedlings. Four and nine days after exposure, (14)C content was greatest in uninoculated seedlings and least in inoculated seedlings. In isotope distribution and dry mass accumulation, V seedlings were more similar to U than to P seedlings. Calculated on a dry weight basis, the allocation of isotope to mycelium suggested that extramatrical hyphae of P seedlings were a stronger sink for carbon than extramatrical hyphae of V seedlings. Differences in inoculation methods resulted in differences in carbon allocation and physiology of extramatrical hyphae that could affect seedling establishment and survival. Seedlings inoculated by one method cannot serve as surrogates for mycorrhizal seedlings produced by other inoculation techniques.     

Growth of Nursery-grown Bamboo Inoculated with Arbuscular Mycorrhizal Fungi and Plant Growth Promoting Rhizobacteria in two Tropical Soil Typeswith and without Fertilizer Application

A nursery experiment was conducted to assess the effect of bioinoculants (Glomus aggregatum, Bacillus polymixa, Azospirillum brasilense) on seedling growth promotion of bamboo (Dendrocalamus strictus (Roxb.) Nees.) in two soil types (alfisol, vertisol) with or without fertilizer application. Bamboo seedlings were grown in the presence or absence of bioinoculants either individually or in all combinations for 180 days in field soil under tropical nursery conditions. Shoot, rhizome and root length, dry masses, nutrient concentrations and arbuscular mycorrhizal (AM) colonized root lengths were determined at harvest. Under the experimental condition tested combined inoculation of AM fungi, PSB and A. brasilense resulted in maximum growth response both under fertilized and unfertilized conditions in both soil types. Fertilizer application enhanced the efficiencies of N, P and K uptake, whereas reduced their usage efficiencies. Though soil type did not affect microbial inoculation response, fertilizer application significantly affected plant response to microbial inoculation.     

Arbuscular mycorrhizas and performance of Polylepis australis trees in relation to livestock density

Polylepis australis trees endemic to Argentina dominate the canopy of subtropical high altitude forests. Here, livestock rearing is the main economic activity and is suspect of the low performance of P. australis trees through direct and indirect effects which could include the reduction in arbuscular mycorrhizal fungi (AMF) and their benefit to trees. To elucidate the role of AMF, we compare plant performance indicators, arbuscular mycorrhizal (AM) colonization and AMF communities in 20 trees distributed in two areas of central Argentina which differed in livestock grazing intensity. The area with high livestock density presented more soil degradation and trees with a lower overall plant performance than the area with reduced livestock density. The AM colonization values of P. australis were considerably higher than reported for other tree species and the area with high livestock density had a lower proportion of arbuscules and higher proportion of hyphae, while vesicles and AM colonization – all structure considered together – did not differ between areas. Overall AMF spore number and of most species when considered separately was significantly higher in the area with high livestock density, suggesting a high tolerance and adaptation of AMF to livestock. We conclude that a reduction in livestock improves the performance of P. australis, that this improvement could be mediated by an increase in the proportion of arbuscules, but there does not appear to be any limitation in AM colonization or AMF spore number which could otherwise be limiting forest restoration.     

Coinoculation of bioinoculants improve <Emphasis Type="Italic">Acacia auriculiformis</Emphasis> seedling growth and quality in a tropical Alfisol soil

We conducted a study to find out if arbuscular mycorrhizal (AM) fungi (Acaulospora scrobiculata, Scutellospora calospora) and phosphate solubilizing bacteria (PSB, Paenibacillus polymyxa) inoculation either individually or in combinations can improve Acacia auriculiformis seedling growth, uptake of nutrients and quality in a phosphorus deficient tropical Alfisol. The seedlings were assessed for various growth and nutrient uptake parameters after 60 days of treatment. Inoculation with P. polymyxa stimulated mycorrhizal formation. Seedling height, stem girth, taproot length, number of leaves and leaf area, plant dry matter production, nodulation, and nodular dry weight were significantly higher for seedlings that were either dual inoculated or triple inoculated compared to individual inoculation of AM fungi or PSB, and uninoculated seedlings. Dual and triple application of AM fungi and PSB also significantly improved the nutrient contents of shoots and roots and nutrient uptake efficiencies. The calculated seedling quality indexes of the AM fungi and PSB inoculated seedling were 25–208% higher than uninoculated seedlings. These findings show that A. auriculiformis seedlings when dual inoculated or triple inoculated performed better than seedlings inoculated with the microbes individually and compared with uninoculated control seedlings. We conclude that bioinoculation is important for the production of high-quality A. auriculiformis seedlings in tree nurseries for planting in nutrient deficient soils.     

Inoculation of Acacia holosericea with ectomycorrhizal fungi in a semiarid site in Senegal: growth response and influences on the mycorrhizal soil infectivity after 2 years plantation

The main objectives of this study were to determine the influence of several strains of ectomycorrhizal fungi on the growth of Acacia holosericea in a dry tropical environment and their short-term effect on indicators of ecosystem soil conditions such as biological soil properties (microbial biomass, mycorrhizal soil infectivity). Three fungal strains have been tested: Pisolithus albus IR100, P. albus COI024 and Scleroderma dictyosporum IR109. Ectomycorrhizal inoculation has significantly enhanced the growth (shoot and root biomass) of A. holosericea seedlings after 4 months culture in glasshouse conditions in a disinfected soil. In field conditions, the transplanting shock was less important for the ectomycorrhized trees. After 2 years, the inoculated trees had a better growth than that recorded in the control treatment. Ectomycorrhizal inoculation has significantly stimulated height, leave and wood biomass, root biomass of A. holosericea trees. Moreover, this fungal inoculation has significantly modified the leaf nutrient contents for P, N and phenols. Microbial biomass and mycorrhizal soil infectivity were also larger in the inoculated plots.Ectomycorrhizal inoculation could be of great relevance to improve the reafforestation process of degraded areas with legumes fast growing trees. This biological practice could also ameliorate soil characteristics such as microbial biomass or mycorrhizal soil infectivity.     

印度西高止山药用植物丛枝菌根真菌多样性

调查了印度西高止山脉南北Goal区内25个科的36种药用植物的丛枝菌根真菌多样性。30个物种带有丛枝菌根真菌,其余6个物种没有丛枝菌根真菌定植。在根际士壤中,共发现了来自5个菌属（球囊霉属、无梗囊霉、盾巨孢囊霉、巨孢囊霉属和Ambispora）的42种丛枝菌根真菌。本研究区内,球囊霉属是优势属,聚线绣球菌是优势种。定植百分比和孢子密度间存在显著负相关。南、北Goa区内,Simpson和ShannonWeiner多样性指数差异不显著,说明该区具有稳定、多样的植物群落。