General and specialized metabolites in peanut roots regulate arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae(AM)fungi form symbiotic associations with plant roots,providing nutritional benefits and promoting plant growth and defenses against various stresses.Metabolic changes in the roots during AM fungal colonization are key to understanding the development and maintenance of these symbioses.Here,we investigated metabolic changes in the roots of peanut(Arachis hypogaea L.)plants during the colonization and development of AM symbiosis,and compared them to uncolonized roots.The primary changes during the initial stage of AM colonization were in the contents and compositions of phenylpropanoid and flavonoid compounds.These compounds function in signaling pathways that regulate recognition,interactions,and pre-colonization between roots and AM fungi.Flavonoid compounds decreased by 25%when the symbiosis was fully established compared to the initial colonization stage.After AM symbiosis was established,general metabolism strongly shifted toward the formation of lipids,amino acids,carboxylic acids,and carbohydrates.Lipid compounds increased by 8.5%from the pre-symbiotic stage to well-established symbiosis.Lyso-phosphatidylcholines,which are signaling compounds,were only present in AM roots,and decreased in content after the symbiosis was established.In the initial stage of AM establishment,the content of salicylic acid increased two-fold,whereas jasmonic acid and abscisic acid decreased compared to uncolonized roots.The jasmonic acid content decreased in roots after the symbiosis was well established.AM symbiosis was associated with high levels of calcium,magnesium,and D-(+)-mannose,which stimulated seedling growth.Overall,specific metabolites that favor the establishment of AM symbiosis were common in the roots,primarily during early colonization,whereas general metabolism was strongly altered when AM symbiosis was well-established.In conclusion,specialized metabolites function as signaling compounds to establish AM symbiosis.These compounds are no longer produced after the symbiosis between the roots and AM becomes fully established.

Improved observation of colonized roots reveals the regulation of arbuscule development and senescence by drought stress in the arbuscular mycorrhizae of citrus

Citrus is the typical mycorrhizal fruit tree species establishing symbiosis with arbuscular mycorrhizal (AM) fungi. However, arbuscule development and senescence in colonized citrus roots, especially in response to drought stress, remain unclear, which is mainly due to the difficulty in clearing and staining lignified roots with the conventional method. Here, we improved the observation of colonized roots of citrus plants with the sectioning method, which enabled the clear observation of AM fungal structures. Furthermore, we investigated the effects of one week of drought stress on arbuscule development and senescence with the sectioning method. Microscopy observations indicated that drought stress significantly decreased mycorrhizal colonization (F%and M%) although it did not affect plant growth performance. Fluorescence probes (WGA 488 and/or Nile red) revealed that drought stress inhibited arbuscule development by increasing the percentage of arbuscules at the early stage and decreasing the percentages of arbuscules at the midterm and mature stages. Meanwhile, drought stress accelerated arbuscule senescence, which was characterized by the increased accumulation of neutral lipids. Overall, the sectioning method developed in this study enables the in-depth investigation of arbuscule status, and drought stress can inhibit arbuscule development but accelerate arbuscule senescence in the colonized roots of citrus plants. This study paves the way to elaborately dissecting the arbuscule dynamics in the roots of fruit tree species in response to diverse abiotic stresses.

A test of the mycorrhizal-associated nutrient economy framework in two types of tropical rainforests under nutrient enrichments

Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.

Efficacy of Mycorrhizae Based Manure on the Vegetative Growth of Rice Grown within Bauchi State, Nigeria

Background: Rice is one of the staple crops in the African continent for its ability to give maximum yields which can help to achieve food security under the sustainable development goals (SDGs);to those effects, the incessant use of inorganic fertilizer has been employed which proved to have devastating effect in the environment and the ecosystem at large. Therefore, the thirst for an alternative method to ensure bumper production of rice cannot be overemphasized so as to prevent soil alteration and environmental damage. Objective: This study aimed at determining the efficacy of mycorrhizae-based manure on the vegetative growth of rice as compared to inorganic fertilizer and its sustainability. Methods: Soil samples were collected from seven (7) locations (M1 - M7). Mycorrhiza were isolated from the soils and mass produced, mixed with organic waste to form manure (biofertilizer) and were applied at concentrations of 50 g, 100 g and 150 g to the potted rice in tree (3) replicates. Growth parameters observed were plant height, girth diameter, leaf broadness and leaf number. Results: The result revealed mycorrhizal spore count ranging from 1.7 × 107 - to 4.1 × 107 across the locations. The mycorrhizae-based manure gives the highest plant height of 45.33 cm as compared with the least plant height of 18.5 cm from the inorganic fertilizer. Furthermore, the biofertilizer gives a positive influence on the other parameters observed in comparison with the inorganic fertilizer. Statistical analysis shows that, the means of all the parameters except for leaf numbers were significantly different at p ≤ 0.05 across the sampling locations. Conclusions: Mycorrhizae-based manure proves to be an effective replacement of inorganic fertilizer that can boost rice production at a cheaper cost.

植物地下觅养性状对土壤富磷斑块塑性响应的研究进展

磷是影响植物生长的关键养分元素之一,地下细根觅养塑性是植物提高土壤磷吸收的重要方式。在自然环境条件下,土壤养分具有异质性或斑块状分布特点,特别是相对固定的养分(如磷)。植物如何调整地下觅养性状对养分斑块的塑性响应尚不清楚,特定细根性状预测地下觅养性状塑性响应更具有较大不确定性。本研究总结植物地下觅养塑性的影响因素,阐述细根(形态、构型、增殖、化学、生理)和菌根真菌性状对富磷斑块的塑性响应,从真菌侵染方式、根系形态结构、养分获取策略等方面分析地下觅养性状及其塑性响应在丛枝菌根和外生菌根树种间的差异。基于地下觅养的碳成本假设,指出细根形态塑性和生理塑性在许多情况下是资源竞争的结果。真菌菌丝的增殖塑性更能提高植物养分获取效率,但当根系和菌根真菌均存在于养分斑块时,根系增殖比真菌反应更敏感。本研究还探讨细根性状对地下觅养塑性的预测,指出细根直径是地下觅养性状变化的重要预测指标。围绕当前植物地下觅养塑性研究存在的不足,从地下觅养塑性框架、地下觅养机制、细根性状对植物养分获取塑性的预测、细根觅养塑性与防御塑性之间的关系等方面提出今后的研究方向,深入理解植物地下磷养分获取策略及其对环境变化的适应机制。

接种丛枝菌根真菌对盐胁迫下月见草生理及次生代谢产物的影响

以月见草为试验材料,进行盆栽试验。采取双因素试验设计,设置无NaCl对照和150 mmol/L NaCl胁迫处理以及分别接种幼套近明球囊霉(Claroideoglomus etunicatum)、摩西斗管囊霉(Funnelifor mismosseae)、根内根孢囊霉(Rhizophagus intraradices)和不接种丛枝菌根真菌(AMF)处理,研究接种不同的AMF对盐胁迫下月见草的生长、生理以及次生代谢产物的影响,以期为增强月见草的耐盐性提供新方法。结果表明:盐胁迫下,与未接种AMF的月见草相比,接种AMF的月见草的株高、根长、基径、地上干质量和地下干质量均显著提高,同时,月见草叶片的叶绿素、可溶性糖、可溶性蛋白、脯氨酸、总黄酮和总酚的质量分数均显著提高,此外,净光合速率和抗氧化酶活性也显著增强,然而,丙二醛质量摩尔浓度显著降低。说明接种AMF可以提高盐胁迫下月见草的光合能力和渗透调节能力,增加抗氧化酶活性,促进次生代谢产物的积累,从而促进其生长发育。综合月见草的各个指标发现,接种AMF能够提高月见草的抗盐能力,不同AMF对月见草耐盐性的提升效果不同。其中以接种根内根孢囊霉对提高月见草耐盐性的效果最为显著,摩西斗管囊霉次之,幼套近明球囊霉的效果较差。

菌根共生体及其在生态系统中的功能概述

菌根是土壤中的菌根菌与植物根系形成的互惠共生体,在地球化学循环,特别是碳循环方面扮演着重要角色。本文综述了菌根的类型及其对植物群落多样性、生态系统生物地球化学循环的影响,尤其介绍了其对碳固定和碳排放的意义,以期为中学生物学教学中关于菌根在生态系统中的功能及其对碳中和的作用提供参考资料。

基于meta分析的丛枝菌根对小麦产量和品质的影响

小麦是人类种植的最为重要的作物之一,对保障粮食安全有着极其重要的作用,因此,小麦的高产、稳产、优质一直是研究的热点科学问题;而丛枝菌根(arbuscular mycorrhizae,AM)是存在于植物根系的最广泛共生体,能够改善植物营养、提高植物产量和提升植物品质。为了系统、全面地评估AM在小麦生产方面的功能,筛选有利于小麦生产的高效AM真菌,本研究采用meta分析方法,基于171篇相关研究文献建立了数据库,整体评价了AM对小麦产量和品质的影响,并探讨了不同AM真菌的效应差异。结果表明,AM能通过提高17.1%的穗粒数和15.7%的千粒重,而实现小麦增产24.2%;同时,AM改善了小麦的品质,使籽粒蛋白质含量提高15.7%,P和Zn含量分别增加15.2%和21.5%;AM对小麦产量和品质的改善可能是基于改善了小麦植物营养状况和叶片叶绿素含量,其提高小麦植株地上部N含量8.4%、P 16.2%、Ca 91.2%和Zn 11.3%,并提高叶绿素含量27.5%。不同属或种的AM真菌对小麦产量和品质的影响存在明显差异,其中,斗管囊霉属真菌的效应更显著和稳定。本研究全面评价了AM对小麦产量和品质的影响,探讨了其作用机制,分析了不同AM真菌的效应差异,以期为丛枝菌根应用于小麦生产,以及选择高效的AM真菌提供理论和实践依据。

弱光及干旱条件下AMF对切花月季光合和AsA-GSH循环的影响

旨在探究弱光及干旱条件下丛枝菌根真菌(AMF)对切花月季光合、AsA-GSH循环以及渗透调节物质的影响。盆栽条件下设置100%全光照(L1)、50%全光照(L2)2个光照处理组,80%土壤持水量(W1)和40%土壤持水量(W2)2个水分处理组,接种AMF[变形球囊霉(Glomus versiforme)+异形根孢囊霉(Rhizophagus irregularis)]及不接种对照(CK)共8个处理。结果表明,AMF能够侵染切花月季根系,显著提高切花月季生长品质。弱光和/或干旱胁迫下,与不接种对照相比,接种AMF能有效地促进切花月季叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s))和水分利用效率(WUE)增加,降低细胞间隙CO_(2)浓度(C_(i));在L2W2处理条件下,与不接种对照相比,接种AMF使切花月季叶片中的抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、单脱氢抗坏血酸还原酶(MDAR)和脱氢抗坏血酸还原酶(DHAR)活性分别提高5.2%、15.4%、21.7%和35.9%;接种AMF的抗坏血酸(AsA)含量与对照处理无显著差异,还原型谷胱甘肽(GSH)含量提高8.1%,GSH/GSSG比值增加7.9%;接种AMF后切花月季丙二醛(MDA)含量显著降低,可溶性糖、可溶性蛋白和脯氨酸(Pro)含量明显增加。结论认为AMF通过维持AsA/DHA和GSH/GSSG的稳定,提高AsA-GSH循环中相关酶活性,增加切花月季叶片可溶性糖、可溶性蛋白和脯氨酸含量而降低MDA含量来适应水分和光照的变化,形成适应光照和水分条件变化的生理生态对策来改善切花月季生长品质。

设施蔬菜土壤丛枝菌根真菌多样性及群落构建的季相变化

为研究设施生态系统丛枝菌根(Arbuscularmycorrhiza,AM)真菌群落变化的关键驱动过程,采集设施番茄不同生长季(休耕、花期、果期)土壤样品,利用IlluminaMiSeq高通量测序技术分析AM真菌物种和谱系多样性及群落结构变化特征,并结合群落谱系分析方法探讨不同生长季随机性过程和确定性过程之间的相对贡献。结果表明,不同生长季AM真菌的物种多样性和谱系多样性均发生显著改变:相比于休耕期,番茄生育期(花期、果期)土壤中AM真菌丰富度、Shannon多样性、Pielou均匀度、谱系多样性(PD)和平均成对谱系距离(MPD)分别显著下降了42.82%~59.18%、43.25%~48.31%、17.46%~25.40%、57.14%~67.86%和50.00%;除球囊霉属相对多度显著增加,近明球囊霉属和类球囊霉属相对多度均显著下降,原囊霉属相对多度先增加后降低。置换多元方差分析(PERMANOVA)和非度量多维度分析(NMDS)结果表明休耕期基于物种组成和谱系组成的AM真菌群落结构显著差别于番茄生育期,但花期和果期之间差异不显著。谱系分析结果显示,休耕期净亲缘关系指数NRI=0,表明AM真菌在谱系结构上是随机的,花期和果期NRI>0,表明谱系聚集,暗示了AM真菌群落构建由随机性过程主导向确定性过程主导的转变,中性群落模型(NCM)结果也支持该推断。Mantel检验结果显示,土壤pH、养分(有机碳、全量氮磷钾和有效磷)、盐分含量以及土壤温湿度作为确定性因素显著影响AM真菌群落的季相变化。综上所述,设施生态系统高集约化生产方式促进了AM真菌群落构建从随机性过程主导向确定性过程主导转变,导致多样性降低和群落结构变化,研究结果对揭示设施蔬菜栽培条件引起的土壤质量退化及其过程中的微生物组演变规律具有重要意义。

不同种植年限苜蓿地球囊霉素相关土壤蛋白含量及其影响因素

球囊霉素相关土壤蛋白(GRSP)是丛枝菌根真菌(AMF)分泌的一种糖蛋白,有利于土壤团聚体形成。本研究借助于黄土高原半干旱区的长期定位试验,以不同建植年限(L2019、L2012、L2003)紫花苜蓿(Medicago sativa)草地为研究对象,玉米(Zea mays)田为对照,研究GRSP含量的主要调控因子及其与土壤有机碳和团聚体结构特征的关系。结果表明,随苜蓿种植年限增加,AMF丰度(侵染率、菌丝密度)和GRSP含量显著提高(P<0.05),线性回归分析结果表明,总提取球囊霉素相关土壤蛋白(T-GRSP)含量与土壤有机碳和微生物生物量碳之间显著正相关(P<0.05),而易提取球囊霉素相关土壤蛋白(EE-GRSP)和总提取球囊霉素土壤蛋白含量均与水稳性团粒特征平均重量直径(MWD)和大于0.25 mm的团聚体含量(R0.25)之间显著正相关(P<0.05),冗余分析(RDA)结果表明,影响土壤AMF丰度和GRSP含量的主要环境因子是土壤速效磷(P=0.002)和微生物量碳(P=0.002)。与农田相比,T-GRSP含量在土壤有机碳中的比例随苜蓿种植年限的增加而提高,说明持续多年种植苜蓿引起GRSP含量增加,促进GRSP含量在土壤有机碳中的积累,提高了GRSP含量对土壤团聚体稳定性和有机碳的贡献。该研究结果可为黄绵土GRSP研究及紫花苜蓿栽培草地可持续利用提供理论依据。

基于Meta分析菌根菌对植物叶片生理的影响

叶片作为植物的重要器官,其养分、光合色素、可溶性糖、可溶性蛋白等含量,以及各种酶活性都是表征其生理的重要参数;而光合作用、蒸腾作用则是叶片重要的生理活动指标。菌根菌是一类与绝大多数植物形成共生的土壤微生物,能够影响叶片生理。本研究选择分布最广泛的丛枝菌根菌(arbuscular mycorrhizal fungi, AMF),针对以往大多数研究只关注单一植物接种AMF探究其生理功能的问题,采用Meta分析(Meta-analysis)的定量研究方法,对152篇相关文献整理建库,评估了AMF对植物叶片生理的影响,探究了不同分类水平上AMF的效应。结果表明:AMF显著提高了叶片氮、磷、钾、钙、镁和锌含量,提高了12.6%~26.3%;增加了叶绿素、叶绿素a和叶绿素b含量,分别增加了16.3%、12.1%和11.1%;对可溶性糖和可溶性蛋白则分别提升了34.8%和18.4%;同时,AMF提高了叶片各种酶活性,分别为过氧化物酶31.3%、超氧化物歧化酶17.8%、过氧化氢酶23.3%、多酚氧化酶59.1%、苯丙氨酸解氨酶65.3%;AMF提高了叶片的净光合速率(27.7%)和蒸腾速率(31.1%)。表明AMF因分类(科、属、种)不同,对叶片生理的影响也存在差异。本研究系统评价了AMF对叶片生理的影响,丰富了AMF的功能多样性理论,为筛选改善叶片生理的高效AMF提供了切实的依据。

不同持水量和氮肥形态对丛枝菌根真菌调节柑橘幼苗生长和氮积累的影响

以柑橘幼苗为研究对象,采用分室(分生长室与菌丝室)根箱装置,比较了不同水分处理[60%WFPS(Water-filled pore space);80%WFPS]与两种氮肥形态(NH_(4)^(+);NO_(3)^(-))下,丛枝菌根真菌(CK:无菌丝无根系;AMF:有菌丝无根系;RAMF:有菌丝有根系)对土壤氮含量、植株生物量和氮积累的影响.结果表明:水分水平、氮肥形态和丛枝菌根真菌均显著影响土壤氮含量、柑橘幼苗生物量及植株氮积累量;与60%田间持水量相比,80%田间持水量的土壤硝态氮和总有效氮含量分别降低了26.42%和8.28%,柑橘地上部和总生物量分别显著提高了20.66%和8.93%,柑橘地上部和总氮积累量分别提高了13.57%和6.21%;与添加铵态氮相比,添加硝态氮的柑橘地上部和总氮积累量分别提高了12.59%和5.64%,柑橘地上部和总生物量分别提高了15.68%和9.56%;不同水分和氮形态处理下,AMF均能促进柑橘幼苗生长和植株氮积累;与CK处理相比,AMF处理的地上部和总生物量分别提高了18.57%和15.06%,而RAMF处理分别提高了26.60%和25.48%;AMF处理柑橘地上部和总氮积累量分别较CK处理提高了19.49%和12.88%,RAMF处理分别提高了23.10%和20.10%.因此,不同水分和氮形态下,丛枝菌根真菌与柑橘根系共生均能促进柑橘幼苗生长,提高氮素积累能力.

广西金花茶根系丛枝菌根真菌染色方法探讨

金花茶(Camellia nitidissima)为山茶科山茶属植物,属于国家一级保护植物,具有很高的观赏价值及药用价值。但目前金花茶野生资源少,因此寻找高效的人工种植方法快速繁殖金花茶优良种苗,进而大幅度提高规模化种植金花茶的产量十分必要。丛枝菌根(arbuscular mycorrhiza,AM)真菌能显著促进植物生长发育、提高作物产量、增强植物抗逆性和抗病性,金花茶接种AM真菌,对金花茶有积极的影响。由于几乎所有的AM真菌接种试验均涉及菌根发育状况观察与侵染率测定,而目前AM侵染状况的观察测定方法种类繁多,良莠不齐,因此本研究探究一种金花茶根系AM真菌检测的最佳染色方法,以便更好地观察AM真菌对金花茶根系的侵染情况。本研究以金花茶健康植株根系为试验材料,探讨5种染色剂(苏丹红Ⅳ、酸性品红、苯胺蓝、台酚蓝、醋酸墨水)对金花茶根系AM真菌的染色效果。研究表明:5%醋酸墨水染色液的染色效果最佳,根皮层细胞内AM真菌的菌丝、泡囊、孢子等结构清晰可见,且能够明确分辨AM真菌与其他未知真菌,根的染色效果可以长久保存;利用苏丹红Ⅳ和酸性品红染色的AM真菌菌丝、泡囊与背景反差不明显,而且酸性品红的染色效果保存时间短,不利于观察;苯胺蓝和台酚蓝的染色效果略次于醋酸墨水,且价格昂贵,成本高。除醋酸墨水外,其他4种染色剂均是疑似致癌物,长期使用对操作人员的健康产生非常大的安全隐患。醋酸墨水染色操作简便、毒性低、成本低廉、染色效果极佳,适用于金花茶根系AM真菌的染色和制片观察。本研究结果可为今后金花茶菌根种苗的应用提供新的思路。

Inoculation Effects of Dendrobium officinale Mycorrhizal Fungi on Their Plantlets

[Objective] This study aimed to explore the inoculation effects of Dendrobium officinale mycorrhizal fungi on their plantlets. [Method] Endophytic strains Tj1, Tj2 and Tj3 were obtained by isolation and purification from mycorrhiza of wild Dendrobium officinale and inoculated on the root system of Dendrobium officinale for inoculation test. [Result] Under tissue-culture conditions, at early stage, Tj1 strain hadn＇t shown promotion effect on Dendrobium officinale, Tj2 strain had shown relatively strong promotion effects, and Tj3 strain had promoted the growth of roots; at late stage, Tj1 strain had shown relatively strong promotion effects, Tj2 strain had shown the best inoculation effects and the strongest promotion effects, while Tj3 strain had caused root and seedling rot problems of the plantlets; under outdoor conditions, after inoculation with Tj2 strain, the number of leaves and lateral buds were increased, the growth of lateral root and the increase of plant height were significant, the leaves of Dendrobium officinale plantlets were large and dark green and an obvious root enlargement phenomenon was observed. [Conclusion] The two inoculation methods both indicate that Tj2 strain has relatively strong promotion effects on the growth of Dendrobium officinale roots and shoots, the increase of plant number and plant height, and the germination of new shoots and roots, which proved the effective establishment of symbiotic relationship between Tj2 strain and Dendrobium officinale. Therefore, T2 strain has practical application values on the successful cultivation of Dendrobium officinale plantlets.

氮沉降对4个树种外生菌根群落结构和酶活性功能的影响

【目的】氮沉降水平不断上升对森林生态系统产生了不同程度的影响。过量的有效氮输入导致植物根系对养分获取策略发生变化,从而改变了土壤重要微生物,如树木根系外生菌根ECM群落的结构和生态功能。了解和确定森林主要树种根系微生物群落活动受氮沉降影响的变化阈值,对于研究森林养分循环特征和可持续经营管理具有重要的指导意义。【方法】采用室内盆栽试验,选取马尾松、华山松、湿地松和火炬松4个树种进行5个梯度的氮施加(0、15、30、60、150 kg·hm^(-2)·a^(-1)),通过检测树苗的养分含量、ECM根尖酶活性,以及提取鉴定DNA,分析不同松树在氮沉降水平下外生菌根群落结构和酶活性功能的动态变化。【结果】1)大多数松科树苗的菌根胞外酶活性在氮浓度30 kg·hm^(-2)·a^(-1)时达到了阈值;以分解纤维素为主的G酶在华山松、湿地松和火炬松中随着N浓度增加而持续提高,即便施氮水平达到当地氮沉降水平的10倍(150 kg·hm^(-2)·a^(-1)),酶活性仍未达到阈值;2)对菌根群落进行分析得出,棉革菌属Tomentella在4个树种中都为优势物种,而须腹菌属Rhizopogon、深色内隔菌Phialocephala会因宿主不同呈现不同的侵染丰度;3)华山松和火炬松的ECM菌根群落酶活性在不同氮浓度间无明显差异,即呈现生态冗余。【结论】在长期氮输入水平升高的情况下,ECM群落组成会因宿主植物和氮沉降水平的变化发生调整,而这一过程中会以变化阈值作为判断标准,该过程对于土壤养分循环中碳氮磷循环以及森林经营管理具有重要的指导意义。

两种丛枝菌根真菌定殖青山杨后对舞毒蛾的抗性研究

【目的】研究丛枝菌根真菌(AMF)对青山杨抗虫性的影响以及舞毒蛾对AMF定殖青山杨的适应能力,为AMF定殖青山杨后抗虫性的研究提供科学依据。【方法】分别以对照(CK,无AMF定殖)、根内根孢囊霉(GI)或摩西管柄囊霉(GM)定殖的青山杨叶片饲喂舞毒蛾幼虫,统计3、4、5龄幼虫的体重、体长、头壳宽和食物利用率,测定4、5龄幼虫解毒酶酸性磷酸酯酶(ACP)和碱性磷酸酯酶(AKP)的活性。【结果】GI组3、4龄幼虫的体重显著高于对照组(P<0.05),5龄与对照组差异不显著,GM组5龄幼虫的体长、体重、头壳宽、食物利用率均显著高于对照组。GI组3龄幼虫取食量显著高于对照组(P<0.05),4、5龄显著低于对照组,GM组5龄显著高于对照组,3、4龄与对照组差异不显著。GI组ACP显著低于对照组(P<0.05),AKP在4龄显著高于对照组,5龄AKP活性显著低于对照组。GM组两种解毒酶活性均显著高于对照组。【结论】GI定殖的青山杨能促进舞毒蛾低龄幼虫的生长,对舞毒蛾老熟幼虫的生长影响不显著。GM定殖青山杨叶片促进了舞毒蛾幼虫的生长发育,提高了食物的利用效率,激发了幼虫体内磷酸酯酶活性,表明舞毒蛾对GM定植的青山杨有更好的适应性。AMF对树木及植食性昆虫的影响具有种类特异性,GI定殖对青山杨的抗虫性的影响呈中性,GM定殖对青山杨的抗舞毒蛾产生负效应。

Effect of arbuscular mycorrhiza on the growth of Camptotheca acuminata seedlings

Camptotheca acuminata seeds were sown in sterilized sands in the greenhouse in February of 2005. After 90-day growth, seedlings were inoculated with three species of arbuscular mycorrhizal fungi （AMF）, Acaulospora mellea, Glomus diaphanum and Sclerocystis sinuosa.. The height, biomass, and absorptions of nitrogen and phosphorus of C. acuminata seedlings inoculated with AMF were investigated. The results showed that the formation of AM promoted the height growth and biomass accumulation of seedlings significantly and improved the absorption of phosphorus in seedlings. The height and biomass of mycorrhizal seedlings were 1.2 and 1.6 times higher than those of the non-mycorrhizal seedlings. The absorption of nitrogen was less influenced by the formation of AM. The nitrogen content in mycorrhizal seedling was equal to that of non-mycorrhizal seedlings. Compared with non-mycorrhizal seedlings, the nitrogen content of mycorrhizal seedlings inoculated with A. mellea changed considerably in the root, stem and leaves. The difference in nitrogen content was not significant between mycorrhizal seedlings inoculated with G. diaphanum and S. sinuosa. The AM formation stimulated the absorption of phosphorus, especially in roots, and also changed the allocation of nitrogen and phosphorus in different organs of seedlings. Compared with non-mycorrhizal seedlings, the ratio of nitrogen and phosphorus in mycorrhizal roots increased, but reduced in stem and leaves.

施氮下接种丛枝菌根真菌对太行山南麓典型灌木荆条生长性状的影响

为明确施氮与接种丛枝菌根真菌(AMF)对植物生长的联合效应,选取太行山区典型灌木物种荆条为研究对象,探究施氮、接种丛枝菌根真菌及二者交互作用对荆条各项生长指标的影响。结果显示,施氮处理对荆条株高无显著影响,接种菌根真菌以及与施氮联合处理使株高显著增加25%和28%,不同处理对基径均无显著影响;施氮和接种菌根真菌显著促进地上与地下生物量积累,其中二者联合处理效果更好,且植株根冠比显著低于其他处理;三种处理均显著增加荆条叶片净光合速率、荧光参数、植株总根长、根表面积和根体积,联合处理对荆条叶面积和叶绿素含量影响最为显著;接种AMF处理和联合处理导致根直径显著降低。研究表明,施氮和接种丛枝菌根真菌对荆条地上部分生长及根系形态和生物量均有一定促进作用,菌根共生能够明显改善施氮条件下荆条生长状况,影响根系构型,提高光合作用,有助于荆条有效应对太行山区逆境条件,推动区域植被恢复与重建。

不同AMF菌肥对桑树“嘉陵30”生长和叶品质的影响

“嘉陵30”是我国西南地区大面积推广种植的优质果叶两用桑树(Morus alba)品种,为了研究不同丛枝菌根真菌(AMF)菌肥对其生长和桑叶品质的影响,实验添施了5种AMF菌肥,并比较桑树植株的色素含量、生长发育和叶片品质在施加前后的差异,以此筛选出适合“嘉陵30”的最佳菌肥。结果显示:(1)色素含量方面,与对照相比,施加隐类球囊霉(Paraglom occultum)菌肥的植株叶绿素b、总叶绿素和类胡萝卜素含量均显著增加,分别提高30.00%、21.96%和21.35%。(2)生长发育方面,与对照相比,施加隐类球囊霉菌肥的植株株高、基径、叶面积、叶干重、茎干重、总干重均显著增加,分别提高50.32%、21.06%、31.68%、27.25%、98.39%和39.01%。(3)叶片品质方面,与对照组相比,施加根内球囊霉(Glomus intraradices)的植株叶C、N、粗蛋白以及总氨基酸含量均显著增加,分别提高4.07%、3.94%、4.51%和7.14%,而生物碱显著降低64.30%。上述结果表明,施加隐类球囊霉菌肥在促进植株生长发育和增加生物量的积累方面效果最佳,而施加根内球囊霉菌肥在提高桑叶品质方面效果更好。