铁皮石斛优良共生菌的抗旱机理

为阐明细胞膜保护酶在菌根提高铁皮石斛抗旱能力过程中的作用,采用模拟自然干旱胁迫的方法,对胁迫过程中菌根化铁皮石斛细胞膜保护酶的活性变化进行研究。结果表明:铁皮石斛菌根真菌(JSAFC003、JSAFC004)能够在一定程度上提高植株的抗旱能力,SOD、POD活性与植株抗旱能力呈正相关,MDA含量与植株抗旱能力呈负相关,表明细胞膜保护酶的调节作用在菌根提高铁皮石斛抗旱能力过程中发挥了一定作用。     

氮沉降对植物-丛枝菌根共生体影响的研究进展

氮沉降是影响陆地生态系统的重要环境因子。丛枝菌根真菌(AMF)作为一种能够与绝大多数植物共生并广泛存在的土壤微生物,对植物生长、养分吸收以及抗逆性等均具有重要的调节作用,而针对氮沉降对植物-丛枝菌根共生体影响的研究往往被忽视。基于此,笔者从氮沉降对菌根侵染特性、菌根多样性、菌根对宿主植物生长发育、氮代谢、磷吸收以及对宿主植物生物多样性影响等方面进行了归纳总结,并提出应重点关注的研究方向,旨为菌根生理生态学的研究提供一定的科学依据。     

盐分和重金属胁迫下AM真菌对小果白刺生长的影响

【目的】探究接种丛枝菌根（Arbuscular mycorrhizal,AM）真菌对不同程度盐分和重金属胁迫下小果白刺Nitraria sibirica Pall.生长的影响,为重金属污染盐渍化土壤的植物-微生物联合修复提供科学依据和数据支持。【方法】采用温室盆栽的方法,模拟不同程度重金属Cd污染(干土中含0、2、5 mg·kg^-1 Cd)NaCl型(干土中含0、1.5 g·kg^-1 Na⁺)盐渍化土壤（Cd0Na0、Cd0Na1.5、Cd2Na0、Cd2Na1.5、Cd5Na0、Ca5Na1.5）,研究接种AM真菌Funneliformis mosseae对Cd和NaCl胁迫下小果白刺的菌根侵染、元素吸收、离子平衡、生物量、Na⁺和Cd含量与吸收的影响。【结果】在重金属Cd和NaCl胁迫下,接种F. mosseae的植物根系平均菌根侵染率为12.68%～21.90%。与不接种CK相比,接种AM真菌使不同处理小果白刺总干质量增加101.35%～215.29%;地上部矿质营养元素增加47.55%～21...     

丛枝菌根真菌改善镉胁迫下植物根系和土壤微环境的效应

为探究Cd胁迫下丛枝菌根真菌(AMF)对植物根系和土壤微环境的影响,以黑麦草为供试植物、变形球囊霉(Glomus versiforme)为供试AMF,以Cd浓度(0、10、20、30 mg·kg^-1)和是否对黑麦草接种AMF为双因素,设计8个处理,开展盆栽试验。结果显示:随着Cd浓度增加,AMF侵染率和孢子数量显著(P<0.05)降低。相同Cd浓度下,接种AMF显著(P<0.05)改善了黑麦草的根系构型(根系总长度、根系总投影面积、根系总体积、根尖数、根分叉数)。在相同Cd浓度下,接种AMF显著(P<0.05)增加了土壤中真菌、细菌和放线菌的数量,土壤微生物生物量碳、微生物生物量氮含量,以及土壤多酚氧化酶活性,和土壤易提取球囊霉素相关土壤蛋白和总球囊霉素相关土壤蛋白含量。这说明,接种AMF能够通过改善植物根系和微生物环境、提高土壤相关酶活性和球囊霉素含量等,增加植物抗性。     

AMF根外菌丝对重金属铅的吸收与转运

【目的】探讨丛枝菌根真菌（arbuscular mycorrhiza fungi,AMF）异形根孢囊霉（Rhizophagus irregularis,Ri）和摩西斗管囊霉（Funneliformis mosseae,Fm）根外菌丝对重金属铅的吸收及转运能力,为明确AMF根外菌丝的铅转运能力提供依据。【方法】以菌根植物蒺藜苜蓿（Medicago truncatula,寄主）和非菌根植物油菜（Brassica napus）为试验材料,采用三室培养系统（菌根室-施铅室-非菌根室）进行研究,其中菌根室种植蒺藜苜蓿并进行AMF处理,包括接种Ri、Fm和未接种对照（CK）3个处理;施铅室（中间隔室）设置0和800 mg/kg 2个铅处理;非菌根室种植油菜,试验共设CK、Ri、Fm、Pb、Ri×Pb、Fm×Pb 6个处理,研究铅胁迫下2种AMF根外菌丝对植物生长及铅离子富集的影响。【结果】（1）与CK处理比,Ri和Fm处理蒺藜苜蓿总生物量分别提高了43.55%和256.98%,铅胁迫对Ri和Fm处理蒺藜苜蓿的生物量无显著影响。（2）0 mg/kg 铅胁迫下,2种AMF均能够与蒺藜苜蓿形成良好共生关系,Fm和Ri处理菌根侵染率达到90%以上。Fm和Fm×Pb处理侵染根段丛枝丰度分别是Ri和Ri×Pb处理的8.75和2.51倍。（3）与Ri处理比,Ri×Pb处理菌根室培养基质中菌丝密度显著提高231.57%,施铅室培养基质中菌丝密度显著降低49.56%;与Fm处理比,Fm×Pb处理菌根室培养基质中菌丝密度提高314.09%,施铅室培养基质中菌丝密度降低21.09%。（4）Ri×Pb、Fm×Pb处理蒺藜苜蓿地上部铅含量分别是CK处理的3.60和8.45倍,根系铅含量分别是CK处理的7.45和217.87倍;Fm×Pb处理油菜根系铅含量是CK处理的62.15倍。【结论】AMF根外菌丝能够直接吸收并转运铅至寄主植物根部,并可能借由“外排”效应将铅运输至非菌根植物根系,且Fm促进植物生长及根外菌丝吸收转运铅的能力显著高于Ri。     

丛枝菌根真菌对鸢尾的促进作用研究

为高效利用水陆两栖植物鸢尾修复污染水体,本研究通过测定不同的丛枝菌根真菌(AMF)与鸢尾构建共生体系的生长指标、土壤理化性质及植物光合作用指标,探讨不同AMF对水生植物鸢尾的促进作用。结果表明:AMF对鸢尾的促进作用主要体现在地上及地下两部分,其中地下部分通过利用其庞大的菌丝网络吸收土壤中的营养物质,进而促进了鸢尾的生长,其中对比无菌剂侵染的空白植物,摩西球囊霉作用的鸢尾对氮元素的吸收率提高71.75%,磷元素的吸收率提高8.36%,而根内球囊霉作用的鸢尾对氮元素的吸收率提高42.55%,磷元素的吸收率提高9.5%;而地上部分则是通过加强叶片气孔导度的开启来调控植物净光合速率与蒸腾速率之间的平衡,进而提高了鸢尾的最优水资源利用率,加快植物的新陈代谢,最终促进植物的生长发育。其中对于鸢尾光合作用的调节摩西球囊霉的促进效果显著好于(P<0.05)根内球囊霉。     

Plant pathogen protection by arbuscular mycorrhizas: A role for fungal diversity?

Arbuscular mycorrhizal (AM) fungi can confer protection to host plants against some root pathogens, and several mechanisms for these phenomena have been proposed. If AM fungal taxa vary in the ways that they limit the negative effects of pathogens on host plants, additive and/or synergistic interactions among members of diverse AM fungal assemblages and communities may result in a greater pathogen protection than is currently predicted. However, in a review of the literature on interactions between AM and pathogenic fungi, we found few examples that compared the effectiveness of single- and multi-species AM fungal assemblages. Here, we briefly recount the generally recognized mechanisms of pathogen protection by AM fungi and present evidence, where appropriate, for functional diversity among AM fungal taxa with regard to these mechanisms. We propose that functional complementarity of AM fungal taxa in interactions with pathogens could mimic, or even be the cause of, previously observed relationships between AM fungal diversity and plant productivity.     

丛枝菌根真菌对番茄植株内源激素含量的影响

于温室盆栽条件下对番茄(Lycospersicon esukurentamu)幼苗接种丛枝菌根(AM)真菌摩西球囊霉(Glomusmosseae)、地表球囊霉(Glomus versiforme)、根内球囊霉(Glomus intraradices)、幼套球囊霉(Glomus etunicatum)或珠状巨孢囊霉(Gigaspora margarita)10d后定期采样,应用间接酶联免疫吸附分析法(ELISA)测定各处理番茄植株根和叶片内源激素吲哚乙酸(IAA)、赤霉素(GA)、玉米素核苷(ZR)和脱落酸(ABA)含量。接种20d G.mosseae处理的番茄根系菌根侵染率高达68.5%,显著高于其他接种处理;供试AM真菌显著增加了番茄植株鲜重、株高、地上部和地下部干重、其根或叶内IAA、GA、ZR和ABA含量均显著高于不接种对照,以G.mosseae处理的根或叶中IAA、GA、ZR和ABA含量最高。     

The Tripartite Symbiosis Formed by Indigenous Arbuscular Mycorrhizal Fungi, Bradyrhizobium japonicum and Soya Bean Under Field Conditions

The tripartite symbiosis formed by indigenous arbuscular mycorrhizal fungi (AMF), Bradyrhizobium japonicum (Kirchner) Jordan and soya bean (Glycine max L. Merr. cv. Evans) was investigated under field conditions to test the hypotheses that: (i) the tripartite symbiosis enhances nodulation and nodule activity; and (ii) its establishment does not rely on improved phosphorus (P) uptake through the fungal partner. Soil tillage was used to produce treatments with contrasting AMF colonization potentials while the amount of B. japonicum inoculum was kept constant. Nodulation, AMF colonization and the P and nitrogen (N) nutrition of plants were evaluated at 10 and 51 (full‐bloom) days after emergence. N₂ fixation was estimated by the difference method and by the isotopic dilution method. At the early stage of plant growth, AMF hyphal colonization and nodulation were, respectively, 16 % and 33 % greater in plants from untilled than from rototilled soil. The establishment of the tripartite symbiosis was observed under field conditions, and factors other than P nutrition were critical to its formation. However, the tripartite symbiosis did not promote N₂ fixation under the high soil P conditions of this study.     

Can the arbuscular mycorrhizal fungus Glomus intraradices actively mobilize P from rock phosphates?

Plants colonized by arbuscular mycorrhizal (AM) fungi have been shown to respond positively to the application of insoluble forms of inorganic phosphorus (P) such as rock phosphates (RPs). The mechanism(s) underlying such responses remain(s) unknown and although it has been hypothesized, there is no experimental support for the production of chelating agents by AM fungal hyphae. Here we investigate whether AM fungi can solubilize P from RPs and transfer it to plant roots. Using root-organ cultures of Daucus carrota L. inoculated or not with Glomus intraradices Schenk & Smith and containing P from different RP sources, we predicted that: (1) roots inoculated with G. intraradices would take up more P than those uninoculated; that (2) the amount of P taken up by roots through G. intraradices would be positively correlated with the RP reactivity; and that (3) G. intraradices would have access to RP through localized alterations of pH and/or by the production of organic acid anions that may act as chelating agents. The RP reactivity was positively correlated with P uptake. However, mycorrhizal roots grew initially slower and did not respond differently to any P treatment than those uninoculated. There was no evidence of localized changes in pH in proximity of G. intraradices hyphae, indicating that responses to RP by mycorrhizal plants observed in previous studies do not appear to result from the release of H⁺ ions alone or in combination with organic acid anions.