华南主要树木丛枝菌根真菌物种多样性调查研究

为调查华南地区丛枝菌根（arbuscular mycorrhiza,AM）真菌的物种多样性与资源分布状况,本研究对该区域红花羊蹄甲（Bauhinia blakeana）、黄梁木（Neolamarckia cadamba）、构树（Broussonetia papyrifera）、尾叶桉（Eucalyptus urophylla）和杧果（Mangifera indica）5种主要树木AM真菌侵染状况进行研究,通过形态学特征及核糖体18S rRNA基因序列分析鉴定AM真菌种类。结果表明:1）5种树木均能形成丛枝菌根,红花羊蹄甲和尾叶桉为疆南星型（Arum-type）,杧果、构树和黄梁木为重楼型（Paris-type）。红花羊蹄甲和杧果的菌根侵染率高、孢子密度大,构树、黄梁木和尾叶桉的AM真菌侵染率和孢子密度相对较低。2）鉴定出AM真菌5属8种,分别为无梗囊霉属（Acaulospora）的浅窝无梗囊霉（Acaulospora lacunosa）和刺无梗囊霉（Acaulospora spinosa）,斗管囊霉属（Funneliformis）的摩西斗管囊霉（Funneliformis mosseae）,根孢囊霉属（Rhizophagus）的根内根孢囊霉（Rhizophagus intraradices）,以及球囊霉属（Glomus）的3种Glomus spp.和硬囊霉属（Sclerocystis）1种Sclerocystis sp.。3）球囊霉属的AM真菌广泛分布在红花羊蹄甲、杧果和构树根际,刺无梗囊霉分布在杧果和尾叶桉根际,摩西斗管囊霉为优势种,分布在构树和黄梁木根际;而浅窝无梗囊霉和硬囊霉只分布在1种树根际,表明其宿主专一性相对较强。结果显示华南树木根际土壤中AM真菌物种多样性较高,同时本研究为深入研究该地区林木根际AM真菌功能多样性提供了初步科学依据。     

混合接种Glomus与Pisolithus菌株对尾叶桉矿质营养吸收的影响

对混合接种ＶＡ菌根真菌苏格兰球菌霉和ＥＣＭ真菌彩色豆马勃影响尾叶桉苗期矿质营养元素吸收情况进行了研究。接种苗根真菌对苗木吸收Ｎ、Ｐ、Ｋ和Ｂ产季了较大的影响,主要体现在促进苗木对上述营养元素的吸收和积累。     

ADDRESS BY THE HON. W. A. MAREE,MINISTER OF FORESTRY,TO THE SOUTH AFRICAN LUMBER MILLERS ASSOCIATION

This article deals with statistical inference in forestry reasearch. After an introductory review of definitions, the applications, limitations and range of validity of statistical tests of significance and their use in the analysis of variance are discussed.

The basic principles of various experimental designs are briefly outlined.     

Colonization with endo-mycorrhiza affects the resistance of safflower in response to salinity condition

Two Safflower (Carthamus tinctoriusL.) cultivars' seeds were used to study the influence of inoculation with mycorrhiza arbuscular fungi under salinity stress condition. Factorial experiment based on completely randomized design (three-way analysis of variance (ANOVA)) with 3 replications was used. Salinity treatment with 3 levels (0.5, 6, and 12 dS/m) and mycorrhizal arbuscular inoculation with two species (three levels consist of non-inoculation, and inoculation with Glomus intraradices and G. moseae) were applied on two cultivars of safflower (Goldasht and Padide) in this experiment. Some important biochemical, mineral, and growth traits were measured in this study. Salinity had a significant negative effect on all growth and morphological parameters including shoot and root dry weight, stem and root height. On the other hand, colonized plants showed better growth parameters under saline conditions compared with the control. The colonization of both mycorrhizal species decreased with salinity. Sugar and pigment content decreased with salinity, but their levels in colonized plants under saline conditions were higher than that in non-colonized plants. Mineral elements including phosphorus (P), nitrogen (N), and magnesium (Mg) were higher in colonized plants, while salinity decreased the absorption of these elements in both inoculated and non-inoculated plants. Higher activity of the enzymatic antioxidant means higher removal of these compounds and higher resistance to stress condition. Overall, it is clear that salinity had a negative effect on both cultivars of safflower, but these negative effects were lower in inoculated plants than in the non-inoculated ones; so, the use of mycorrhizal inoculation is a proper way to control the effect of salinity and maintain plant production.     

Collembola grazing on arbuscular mycorrhiza fungi modulates nutrient allocation in plants

Arbuscular mycorrhiza (AM) mycelia networks are important for nutrient allocation in many plants, but fungivorous soil invertebrates such as Collembola can modulate the symbiosis by grazing on the extra-radical mycelium (ERM). This study employs a dual biomarker approach with stable isotopes and fatty acids to disentangle trophic interactions of Collembola in a plant-fungal soil system with maize (Zea mays) and the AM fungus Glomus mosseae. To separate ERM and root mediated effects, root (RC) and hyphal compartments (HC) were used, and the latter was spiked with labeled ¹⁵N substrate. The euedaphic Collembola species Protaphorura fimata was introduced as the fungal and root grazer. Generally, the presence of Collembola in RC fostered biomass and phosphorous uptake in roots colonized with AM. Nitrogen transport from HC to RC was not altered, indicating that Collembola did not disrupt the ERM network via grazing. Collembola–fungus interactions fostered AM hyphal proliferation in HC, whereas in RC it induced a change from fungal senescence with build-up of storage reserves, to an active foraging phase. A distinct diet switch by Collembola between HC and RC indicated different ERM palatability meditated by the presence or absence of the host plant. Overall, Collembola grazing increased ERM nutrient sequestration, particularly phosphorus, and in turn plant performance. Collembola modified fungal phenology, favoring fungal colonization over reproductive phases. These trophic interactions were strongly determined by fungal life stage, with the establishment of a functional mycorrhiza as a crucial factor.     

Susceptibility and effectiveness of vesicular-arbuscular mycorrhizae in wheat cultivars under different growing conditions

Summary Wheat cultivars assumed to be non-susceptible to vesicular-arbuscular (VA) mycorrhizae became colonized, and this effect persisted under different growth conditions. Colonization of all cultivars was similar regardless of the amount of inoculum and the time interval of inoculation. Different plant growth temperatures and the support given by the culture media, inoculation with different endophytes, and inoculation with sterilized and unsterilized spores affected VA colonization levels, although the level of colonization reached in cv. Champlein was similar to that reached in cv. 7-Cerros under each condition. VA mycorrhizal colonization was also affected by different plant growth conditions. After VA reinoculation, the plant dry weight of Castan and 7-Cerros increased, but not Negrillo and Champlein cultivars. VA mycorrhizae increased the shoot dry weight of 7-Cerros only, but not of Champlein, when grown at 35/24°C, and had no effect on the dry weight of either cultivar grown at 18/12°C and 42/24°C. Inoculation with Glomus mosseae increased the dry weight of the cultivars more than inoculation with G. fasciculatum or G. agregatum. The effect on the plant dry weight was greater in plants grown in soil than in sand/vermiculite pots. Inoculation with sterilized and unsterilized spores of G. mosseae, either in soil pots or in sand/vermiculite tubes, did not increase the plant dry weight. Our results indicate that there was no close relationship between the level of root colonization and the effect on plant growth. The effects of accompanying microorganisms in the VA inoculum on VA mycorrhizal symbiosis are discussed.     

Grazing preferences of some collembola for endomycorrhizal fungi

The ability of five collembolan species to distinguish and graze selectively on vesicular-arbuscular mycorrhiza (VAM) has been verified. Four species preferred the food infected by VAM fungi. All collembolan species showed more of less significant preferences for one species/isolate of the VAM fungi.     

Shoot‐produced,light‐dependent factors are partially involved in the expression of the arbuscular mycorrhizal (AM) status of AM host and non‐host plants

Arbuscular mycorrhizal (AM) colonization and hyphal attachment to the roots of a host plant, bean, and a non‐host plant, lupin, were compared when grown either with light or in the dark with the AM fungus Glomus mosseae. When grown with light, bean roots were heavily colonized whereas lupin roots showed no signs of colonization, no formation of appressoria and only scarce hyphal attachment to the roots. In contrast to roots of plants grown with light, to living roots of beans and lupins grown in the dark many hyphae were attached and appressoria were formed. The role of shoot produced, light‐dependent factors in the expression of the AM mycotrophic status of AM host and non‐host plants is discussed.<?show $6#>     

植物泡囊丛枝菌根及其应用展望

阐述了植物泡囊丛枝菌根(VA菌根)的形态特征、对植物的营养作用及其与根瘤菌等微生物的关系,分析了环境条件、栽培管理和耕作制度等对VA菌根的影响.提出应加强VA菌根的基础研究,试验接种外来菌源以及利用土壤的原有菌源,以充分利用VA菌根这一潜在的生物资源使农作物持续稳定增产.     

VA菌根对黄檗幼苗抗性生理指标的影响

通过盆栽接种试验,研究VA菌根对黄檗（Phellodendron amurense）1年生实生苗的抗性生理指标的影响。结果表明,VA菌根可明显提高黄檗幼苗的抗性指标。可溶性糖含量随着侵染率的增加而增大,并能促进黄檗叶片中可溶性糖向根系中转移,游离脯氨酸和MDA含量逐渐降低,呼吸酶活性和保护酶活性增强。接种Glomus diaphanum的苗木可溶性糖,游离脯氨酸、CAT活性及POD活性变化最为明显,叶片可溶性糖含量为0.5736%,叶片脯氨酸含量为16.27 μg/g,叶片CAT活性为0.3186 mg/(g?min),叶片POD活性为258.32 u/(g?min)。接种G. mosseae对黄檗苗木MDA含量、呼吸酶活性及SOD活性影响最大,叶片MDA含量为0.0119 μmol/g,叶片抗坏血酸氧化酶活性为0.2714 mg/(g?min),叶片多酚氧化酶活性为0.3487 mg/(g?min),叶片SOD活性为274.18 u/(g?FW)。