丛枝菌根真菌对温室黄瓜生长及产量品质的影响

以黄瓜为材料于温室盆栽条件下,研究丛枝菌根真菌(arbuscular mycorrhizas fungi,AMF)Glomous ver-siforme(GV)对黄瓜生长的影响。结果表明:苗期接种GV真菌后可提高黄瓜的株高,叶片中叶绿素a、叶绿素b、类胡萝卜素及可溶性糖含量;提高了黄瓜产量;黄瓜中总糖、干物质重量和维生素C、N、P、K、Zu、Cu等营养物质含量也有增加。     

8种豆科灌木栽培种丛枝菌根真菌种类及分布

采集人工栽培决明(Cassia tora)、假木豆(Dendrolobium triangulare)、紫穗槐(Amorpha fruticosa)、白刺花(Sophora davidii)、猪屎豆(Crotalaria pallida)、多花木蓝(Indigofera amblyantha)、木豆(Cajanus cajan)和银合欢(Leucaena leucocephala)8种豆科灌木植物根际5-10、10-20和20-30 cm 3个土层的土样,研究其根际丛枝菌根(AM)真菌的侵染率、孢子密度、种类及多样性。结果表明,8种豆科灌木植物AM真菌侵染率普遍较高,最高的为猪屎豆,80.8%;土壤速效磷含量与侵染率呈显著负相关(r=-0.733,P=0.039);根际土壤中的AM真菌孢子主要分布于5-20 cm土层,5-10 cm土层猪屎豆孢子密度最大,为115.33个·10 g-1土壤;宿主植物种类与土壤层位对孢子密度交互效应影响显著(F=100.497,P0.001);AM真菌优势种枫香球囊霉(Glomus liquidambaris)、脆无梗囊霉(Acaulospora delicate)在8种豆科灌木植物的土壤中均有分布。本研究表明,喀斯特地区适生豆科灌木植物具有丰富的AM真菌资源,今后可以在喀斯特地区开展豆科灌木植物接种优势AM真菌和根瘤菌等相关研究,这将对农牧业生产和退化生态系统修复效应的影响具有重要意义。     

Morpho-Physiological Responses of Grape Rootstock ‘Dogridge’ to Arbuscular Mycorrhizal Fungi Inoculation Under Salinity Stress

Effects of arbuscular mycorrhizal fungi (AMF) alone or in combination with bacterial consortium (AMF+BC) inoculation prior to induced salinity (NaCl @ 150 or 250 mM) were studied on root growth; plant biomass; leaf area; Na⁺ and K⁺ contents; leaf water potential (Ψ_w); osmotic potential (Ψ_π); photosynthesis rate (P_n); and contents of chlorophyll, phytohormones, and polyamines in the grape rootstock ‘Dogridge’, popular among Indian vine growers. AMF inoculation in the NaCl untreated rootstocks plants increased root growth, root and shoot biomass, and leaf area and improved leaf Ψ_w, Ψ_π, P_n, and chlorophyll content, and also countered the stress-induced decline in the NaCl treated plants. The abscisic acid (ABA), cytokinins, and polyamine-spermidine and spermine contents in the leaves of NaCl untreated or treated were significantly increased by the AMF inoculation. Among the treatments, AMF with BC was relatively more effective than AMF alone with respect to changes in above morpho-physiological characters. The results depicted that AMF (AMF alone or AMF+BC) inoculation significantly improved salinity tolerance of grape rootstock and tolerance is induced by improvements in plant water balance, K⁺:Na⁺ ratio, and P_n, besides distinct accumulations in ABA and polyamines-spermine and spermidine. The above findings have potential in suggesting the AMF usefulness in improving the efficacy of ‘Dogridge’ rootstock in grape cultivation under salt affected soils.     

蓝桉和尾叶桉混合菌根研究 Ⅰ.菌根合成及真菌间的相互作用

采用蜡磨菌与ＶＡ 菌根真菌分别对蓝桉和尾叶桉进行单接种或混合接种,研究结果表明,两种菌根类型的真菌均能在桉树苗木根系上成功地定殖,分别合成了外生菌根、ＶＡ 菌根和混合菌根,证实了桉树不仅是菌根营养型树种,而且能形成多种菌根类型。ＶＡ 菌根感染率在接种初期较高,但随时间的推移有降低的趋势;而外生菌根菌初期合成菌根的速度较慢,但单位长度根段内菌根根尖数目有明显增加的趋势。与单接种ＶＡ菌根真菌苗木相比,外生菌根真菌抑制了ＶＡ 菌根菌在根系上的进一步侵染,体现在较低的ＶＡ 菌根感染率;而外生菌根菌显示出了较强的竞争能力,并能在接种后９ 周时开始形成子实体。在混合菌根中,外生菌根有逐步替代ＶＡ 菌根的发展趋势,两种类型的菌根真菌间存在一定的竞争性作用关系。基质磷（Ｐ）素水平对菌根的形成也有一定的影响     

接种丛枝菌根真菌对土沉香幼苗耐旱性的影响

接种不同地区的幼套近明球囊霉(Claroideoglomusetunicatu,CE1、CE2)和摩西斗管囊霉(Funneliformismosseae,FM1、FM2)于珍贵树种土沉香(Aquilaria sinensis)幼苗,采用模拟土壤干旱胁迫,研究接种菌根真菌对土沉香的耐旱性影响。结果表明,随着土壤干旱胁迫的加剧,未接菌组的叶绿素a和叶绿素总含量呈显著下降趋势,接菌组叶绿素含量高于未接菌组;在干旱胁迫下,接菌组的可溶性蛋白含量上升,中度干旱胁迫以上,接菌FM1和FM2组可溶性蛋白含量显著高于CK组。随着干旱胁迫程度的增大,接菌组幼苗SOD酶和POD酶活性呈先上升后下降趋势,但接菌组SOD酶和POD酶活性高于CK组。土壤干旱使植物体内MDA含量上升;在中度干旱时接菌组MDA含量高于CK组;当土壤水分达到重度干旱胁迫时,接种FM2、CE1和CE2处理组MDA含量显著高于CK组。研究表明,在干旱胁迫下,土沉香菌根化苗能提高植物体内渗透调节物质和抗氧化酶活性,维持较高的叶绿素含量,从而提高植物耐旱性。模糊隶属函数值分析结果表明,无论是轻度干旱还是重度干旱,接种菌根真菌幼苗的耐旱能力强于未接菌组,接种摩西斗管囊霉菌种强于接种幼套近明球囊霉菌种,其耐旱能力从大到小依次为菌株FM1FM2CE2CE1。     

Morphological and physiological studies on densely branched lateral roots triggered by localized phosphate in Sesbania cannabina

Densely branched lateral roots (DBLRs) in Sesbania cannabina are formed in response to patchily distributed phosphorus (P) in volcanic soils. Little attention has been paid to morphological and physiological responses of DBLRs. Here, we investigated the relation between plant growth and DBLR development, enzymatic activities involved in P acquisition, and the influence of arbuscular mycorrhizal fungi (AMF), which contribute to P uptake, to clarify the function of DBLRs. We investigated DBLR development induced by localized application of P fertilizer and we compared the activities of phosphoenolpyruvate carboxylase (PEPCase) and acid phosphatase (APase) between DBLRs and non‐DBLRs. Additionally, plants were grown with or without AMF to investigate the effect of AMF colonization on the numbers of DBLRs and plant P uptake, and we compared AMF colonization between DBLRs and non‐DBLR roots. Secondary to quaternary lateral DBLRs were produced after the primary lateral roots passed near P fertilizer. P_i content per DBLR increased as DBLRs developed, promoting higher shoot growth. Under P deficiency, PEPCase and APase activities increased in non‐DBLR, but were significantly lower in DBLRs in the same plants. AMF inoculation changed the root system architecture by significantly decreasing the number of DBLRs, and AMF colonization was lower in DBLRs than in non‐DBLRs. Our results indicate that DBLR formation is a P‐coacquisition strategy of S. cannabina grown in P‐deficient andosolic soil. Roots that form DBLR are clearly different from non‐DBLR roots in morphological and biochemical response and AMF symbiosis.     

Long-term grazing exclusion influences arbuscular mycorrhizal fungi and their association with vegetation in typical steppe of Inner Mongolia,China

It is not certain that long-term grazing exclusion influences arbuscular mycorrhizal(AM) fungi and their association with steppe vegetation. In this study, soil and plant samples were collected from two sites of grazing exclusion since 1983(E83) and 1996(E96), and one site of free-grazing(FG) in the typical steppe of Xilinguole League, Inner Mongolia, China, and assayed for soil basic physicochemical properties, AM fungal parameters, aboveground biomass and shoot phosphorus(P) uptake as well. The results showed that long-term grazing exclusion of E83 and E96 led to less drastic seasonal changes and significant increases in spore density, hyphal length density and root colonization intensity of AM fungi and even soil alkaline phosphatase activity, by up to 300, 168, 110 and 102%, respectively, compared with those of FG site. In addition, the total aboveground biomass and shoot P uptake of E83 and E96 were 75–992% and 58–645%, respectively, higher than those of FG. Generally, the root colonization intensity, spore density, and hyphal length density of AM fungi were all positively correlated with the aboveground biomass and even shoot P uptake of plant. These results may imply that grazing exclusion play a critical role in increasing the growth of AM fungi, and subsequently, may increase plant P uptake and aboveground biomass production. Moreover, the spore density could sensitively reflect the impacts of long-term grazing exclusion on AM fungi since survival strategy of spores in soil.     

不同种植年限宁夏枸杞根际微生物的群落多样性

为了解长期人工种植宁夏枸杞根际土壤微生物群落结构特征及其与AM真菌侵染率的关系,本研究分析测定了种植5、10、15 a和24 a宁夏枸杞根际AM真菌的定殖情况和土壤理化性质,并利用PCR-DGGE技术分析了不同种植年限宁夏枸杞根际土壤微生物多样性。结果表明,不同种植年限宁夏枸杞根际土壤pH、速效磷、速效钾、硝态氮存在显著差异,速效磷、速效钾、硝态氮含量在10 a达到最大,这可能与长期施肥及植物对氮磷钾的利用率有关。测序结果表明,随着种植年限的增长,宁夏枸杞根际土壤的微生物多样性呈一定程度的下降趋势,宁夏枸杞根际AM真菌的香农指数在种植5 a时最高,条带数最多,为11条,在种植10 a时显著降低（与种植5 a枸杞相比）,在种植24 a时达到最低。根际细菌的香农指数在种植5 a时最高,条带数最多,为31条,说明5 a生宁夏枸杞根际根中细菌种类最多,在种植15 a时显著降低（与种植10 a相比）。通过相关性分析发现,孢子密度差异显著,孢子密度与铵态氮显著正相关,菌根侵染率与铵态氮呈负相关。AM真菌物种丰度与速效钾、硝态氮显著正相关,与土壤pH显著负相关,均匀度指数与pH正相关,与速效磷、铵态氮显著负相关。由此可见,树龄和土壤因子在一定程度上影响根际微生物群落结构。     

Effect of native and allochthonous arbuscular mycorrhizal fungi on Casuarina equisetifolia growth and its root bacterial community

Exotic trees are often planted to recover degraded lands. Inoculation with mycorrhizal fungi can improve their survival. Plant growth is partly dependent on the strain used, but little attention has been paid to the selection of mycorrhizal fungi. The aim of this study was to determine whether the growth of Casuarina equisetifolia L. (Johnson) is affected by two different mycorrhizal inocula generated using fungal spores retrieved from an Australian site (allochthonous soil) and a Senegalese site (native soil) under C. equisetifolia trees. Comparative experiments were conducted with plants in a Senegalese soil, previously sterilized or not, and grown in a greenhouse. At harvest, parameters related to plant growth and mycorrhization were evaluated and soil bacterial communities were compared. Tree growth was significantly influenced by both types of inoculants. In unsterilized soil, plants inoculated with the native inoculant were taller than plants inoculated with the allochthonous inoculant and control plants. The frequency of mycorrhization with both inoculants was higher in unsterilized soil. The strongest effects of the mycorhizosphere on the soil microbiome were obtained with the allochthonous inoculum, and analysis of the taxonomic composition revealed mycorrhizal communities specific to each inoculum. These results suggest that the development of C. equisetifolia and its root bacterial community are dependent on the composition of the mycorrhizal inoculum. The functional consequences of this rhizosphere effect in terms of soil fertility should be further studied to better guide reforestation operations.     

广西红壤区甘蔗根际土壤丛枝菌根真菌种类的 18S rDNA 基 因序列分析鉴定及多样性分析

为探明广西红壤区甘蔗根际土壤丛枝菌根（Arbuscular mycorrhizal,AM）真菌多样性特点,本研究通过 18S rDNA 基因序列分析对来自广西红壤蔗区 33 个样地的甘蔗根系和根际土壤样品的 AM 真菌种属进行了鉴定,并分析了 土壤理化性质对 AM 真菌侵染率和多样性的影响。结果表明：3 类红壤类土壤中,赤红壤的根外菌丝量、根内菌丝和 丛枝平均侵染率最高,分别为 13.59%、24.18%、1.29%;砖红壤的泡囊平均侵染率最高,为 19.17%。所构建的 AM 真 菌克隆文库中共发现了 24 个 OTU,分别属于 AM 真菌的 7 科 12 属 24 种,其中球囊霉科含 5 属 10 种,多样孢囊霉科 含 1 属 2 种、无梗囊霉科含 1 属 1 种、巨孢囊霉科含 2 属 2 种,近明囊霉科含 1 属 5 种,原囊霉科和类球囊霉科各含 1 属 2 种;3 类土壤的优势科和优势属分别为球囊霉科和根生囊霉属。红壤的 AM 真菌物种丰富度和香浓维纳指数最高, 砖红壤最低。3 类土壤的理化因子与 AM 真菌的物种丰富度均无显著相关。3 类土壤的根内菌丝侵染率与 pH 值均呈正 相关,与有机质、总氮及有效磷含量呈负相关。