不同氮磷比例营养液对AM真菌生长发育的影响

温室条件下,研究不同氮磷比例营养液对丛枝菌根(Arbuscular.mycorrhizae,AM)真菌(Glomus.mosseae)生长发育的影响。结果表明:在一定磷水平条件下增加氮的水平,有利于菌根真菌的生长发育,但超过一定水平则会抑制菌根真菌的生长发育,说明氮水平也会影响菌根真菌的生长发育,这种影响与氮磷比例有关。综合比较菌根长度、根外菌丝量及孢子数三项指标,在20%浓度Hoagland营养液的基础上,将氮磷比例提高到4∶2有利真菌生长。在AM菌剂生产中,通过营养液中氮磷比例的调控能获得较大数量的侵染根段、菌丝及孢子等繁殖体。     

柑橘砧木和砧穗组合对丛枝菌根发育的影响

倍体体细胞杂种砧木)对丛枝菌根发育的影响。结果表明,柑橘丛枝菌根侵染幅度为 4.88 % ~ 40.52 %,土壤内孢子密度不等,大致在 347 ~ 750 个孢子/kg(干土)内。田间菌根侵染率和孢子密度在不同土层深度的分布以深度 10 ~20 cm 为最高。遗传关系相近的国庆 1 号/枳和国庆 4 号/枳组合间以及红肉脐橙/罗伯逊脐橙 36 号/枳和纽荷尔脐橙/罗伯逊脐橙 36 号/枳间的丛枝菌根发育没有显著差异,与红肉脐橙和纽荷尔脐橙遗传关系远的脐血橙组合,较红肉脐橙和纽荷尔脐橙组合的孢子密度间有极显著差异。红桔 枳的菌根侵染率和土壤孢子密度均最高,且显著高于其他 4 种砧木。盆栽砧木孢子密度与菌根侵染率呈显著正相关性。10 种试材的根围土壤孢子密度与菌根侵染率间呈极显著正相关性。     

土壤因子对西藏高原草地植物AM真菌的影响

于西藏高原中部地区就土壤因子对草地植物AM真菌的影响进行的研究表明：AM真菌孢子密度与菌根侵染率、菌根侵染强度无相关性；土壤质地对AM真菌孢子密度的影响明显大于土壤类型，壤土、粉砂土中AM真菌对植物根系的侵染率高于砂壤土；土壤pH与植物根围土壤孢子密度、菌根侵染率分别呈显著正相关和正相关，与菌根侵染强度则呈负相关；土壤有机质与AM真菌孢子密度呈负相关，菌根侵染效果则随土壤有机质含量的增加而提高；高磷土壤环境对AM真菌产孢和侵染均具不同程度的抑制作用，其中植物菌根侵染率随土壤有效磷含量的提高而呈显著下降；AM真菌对莎草科植物矮生嵩草、扁穗莎草根系具有良好的侵染效应。     

藏北高寒草原土壤活性有机碳对AM真菌物种多样性的影响

基于孢子形态学鉴定,通过研究土壤活性有机碳（ASOC）质量分数对丛枝菌根真菌（AMF）物种多样性及侵染效应的影响,为基于土壤环境调控的菌根生物技术的应用探寻新的途径和方法。结果表明,ASOC质量分数在0.30～0.80、0.81～1.40、1.41～4.00 g/kg范围内,Glomus属真菌对AMF的种群构成均具重要作用,且其影响随ASOC质量分数的增加而提高;由Glomus属真菌构成的优势种,特别是一些共有优势种对AMF的种群发育具有主导作用;ASOC质量分数与孢子密度呈显著正相关,较低的ASOC质量分数极显著促进了菌根侵染。从综合影响看,调控ASOC质量分数至较低（0.81～1.40 g/kg）水平,可能充分发挥AMF在高寒草原中的重要作用,这为探寻适度的农业工程调控措施,以强化ASOC对AMF物种多样性及菌根侵染的重要影响,促进多菌种以及多优势种的协同作用,稳定高寒草原环境提供了重要信息。     

内蒙古盐碱土中AM真菌的多样性与分布

在内蒙古盐碱土13种主要植物分离到3属26种AM真菌,其中球囊霉属(Glomus)22种,无梗囊霉属(Acaulospora)3种,原囊霉属(Archaeospora)1种。地球囊霉(Glomus geosporum)和地表球囊霉(Glomus ver-siforme)是该区域盐碱土中的优势种。13种主要植物均能被AM真菌侵染,其中玉米和马蔺的侵染率最高,达100%;根际土壤中AM真菌孢子密度范围为29~182个g-1烘干土,其中稻的孢子密度最高,达182个g-1烘干土;在不同土壤类型条件下植物的菌根侵染率具有明显的差异,其规律为草甸盐土>碱化盐土>盐化草甸土>碱化草甸土;根际土壤中孢子密度以碱化草甸土最高(101个g-1烘干土),其次为碱化盐土、草甸盐土和盐化草甸土。相关分析表明,根际土壤中AM真菌孢子密度与菌根侵染率无显著相关性。     

丛枝菌根育苗缓解西瓜枯萎病的机制

西瓜易受尖孢镰刀菌侵害发生枯萎病。植物形成丛枝菌根（AM）可有效促进养分吸收和病害防控。在田间直接接种丛枝菌根菌时,侵染效率和生态效应多数会受到限制。采用育苗期接种丛枝菌根菌（Rhizophagus intraradices,R.i）培养菌根苗,成苗后移栽入盆钵,研究西瓜丛枝菌根苗在抗西瓜枯萎病中的作用及其机制。将西瓜丛枝菌根苗移栽入大田,研究丛枝菌根西瓜苗在田间防控西瓜枯萎病及改善磷营养的效果。结果表明,苗期形成的丛枝菌根苗,在移栽后上调几丁质酶编码基因ClPR4、ClaPR5在根系的表达量,上调β-1,3-葡聚糖酶编码基因ClGlu3和苯丙氨酸解氨酶编码基因ClPAL4、ClPAL11在根系的表达量;西瓜丛枝菌根育苗提高了根际土壤酸性磷酸酶活性,提高土壤有效磷含量,改善磷营养,提高西瓜植株抗枯萎病的能力。同时丛枝菌根育苗提高了西瓜根际土壤中的丛枝菌根菌孢子数,降低了根际土壤中病原菌数量,降低西瓜枯萎病发病率及病情指数。因此,丛枝菌根育苗上调了西瓜植株抗性相关酶基因表达,提高西瓜抗病性;同时提高了根际酸性磷酸酶活性而改善了磷营养,提高植株抗病能力,降低枯萎病发病率和发病指数。     

VA菌根对植物耐旱、涝能力的影响

以黄淮海壤质黄潮土为供试土壤,在盆栽条件下研究不同水分条件对VA菌根侵染白三叶草的影响以及菌根的抗旱能力。结果表明,在所有水分处理中,接种VA菌根后,可促进菌根的侵染和植物对氮、磷的吸收,增加植物的生长量,并显著地增强了白三叶草的抗旱能力。干旱条件下,VA菌根的侵染、菌丝的发育均良好,而过高的水分不利于菌根的侵染和菌丝的发育。     

接种丛枝菌根真菌对脱毒马铃薯微型薯生长及产量的影响

在大田条件下采用混合菌种(Glomus mosseas+Glomus intraradices)作为接种剂,研究了接种丛枝菌根真菌对脱毒马铃薯微型薯菌根侵染、磷吸收和产量的影响。结果表明,接种菌根真菌,马铃薯菌根侵染率增加73.3%,植株吸磷量增加15.4%,块茎产量增加8.0%。上述结果证明,在大田条件下,接种菌根真菌能侵染马铃薯根部,促进植株对磷的吸收,从而增加产量。     

分根装置中接种AMF对12 mm土壤水稳性团聚体的影响

采用分根装置研究了丛枝菌根真菌侵染白三叶草（Trifolium repens）后对中性紫色土12 mm土壤水稳性团聚体（WSA1-2mm）含量的影响,并运用通径分析对其主要影响因子进行了量化比较。结果表明,接种Glomus intraradices、G. mosseae和G. etunicatum的菌根室土壤有机质、球囊霉素相关土壤蛋白（GRSP）含量均有增加的趋势; 接种3种菌种都显著增加了菌根室土壤WSA1-2mm含量。通径分析结果表明,菌丝密度对WSA1-2mm含量有较大的直接效应（直接通径系数 0.678）,而GRSP对WSA1-2mm的影响系数较小,既有直接效应又有间接效应,但以直接效应为主。菌丝和GRSP对12mm 土壤水稳性团聚体作用大小的差异可能源于二者作用机制的不同。     

红壤中丛枝菌根真菌对污泥态铜生物有效性的影响

以玉米为宿主植物 ,研究了不同污泥量 (0、1 %、4% )施入红壤后接种丛枝菌根真菌Acaulosporalaevis、Glomuscaledonium和Glomusmanihotis对菌根侵染率、孢子密度、玉米生长和铜生物有效性的影响。结果表明 ,施用 1 %的污泥可增加接种A laevis的菌根侵染率和孢子密度 ,其玉米地上部和地下部生物量也有显著增加 ,而不接种 (含土著菌根真菌 )、接种G caledonium和G manihotis的菌根侵染率、孢子密度、玉米地上部和地下部生物量却有显著下降 (p<0 0 5 )。施用 1 %的污泥时接种A laevis降低了玉米地上部铜浓度 ,而接种G caledonium和G manihotis却增加了玉米地上部铜浓度 ,另外 ,接种处理增加玉米根部对铜的吸收总量。不同的菌根真菌对重金属的耐受力是不同的 ,只有施入一定的污泥量即在一定污染程度下才能发挥菌根真菌A laevis对污染土壤的修复作用     

Mycorrhizal colonization with Glomus intraradices and development stage of transformed tomato roots significantly modify the chemotactic response of zoospores of the pathogen Phytophthora nicotianae

The chemotaxic response of zoospores of the plant pathogen, Phytophthora nicotianae, towards exudates from mycorrhizal and non-mycorrhizal transformed tomato roots was studied. A bi-compartmental in vitro system was used to grow Ri T-DNA-transformed tomato roots colonized or non-colonized with the arbuscular mycorrhizal fungus, Glomus intraradices, and to collect root and mycorrhizal exudates. The root and mycorrhizal growth dynamics were first characterized in order to determine two times of exudate sampling. Exudates collected from 16-wk-old mycorrhizal roots were significantly more attractive for P. nicotianae zoospores than exudates from non-inoculated roots. On the contrary, concentrated exudates harvested from 24-wk-old mycorrhizal roots were repulsive to zoospores compared to exudates from non-colonized roots and the water control. In exudates of G. intraradices-inoculated roots, HPLC–MS analyses revealed significantly higher concentrations of proline and isocitrate after 24 wk of growth, while after 16 wk of growth, proline concentration did not differ between exudate types, and the isocitrate concentration was lower in mycorrhizal root exudates. Mycorrhizal inoculation had no effect on the amounts of other amino acids and organic acids and on the sugars quantified within exudates. Our results suggest that modification in exudate composition of mature roots by mycorrhizal colonization may provoke the repulsion of P. nicotianae, and that their capacity to infect host roots may in this manner be reduced.     

Persistence of introduced Glomus intraradices in the field as influenced by repeated inoculation and cropping system

We studied the persistence of an introduced vesicular-arbuscular mycorrhizal (VAM) fungus in the field under the influence of a mycorrhizal host, a non-mycorrhizal host, and when the field was left fallow. There was a significantly greater, build-up of the mycorrhizal fungus in plots cropped with mycorrhizal hosts (finger millet or field beans) compared to plots cropped with a nonmycorrhizal host (mustard) or left fallow. Glomus intraradices, the introduced fungus, was further monitored by the electrophoretic mobility of the isozymes of malate dehydrogenase extracted from the resting spores of the fungus. The zymogram from G. intraradices spores showed three distinct isozyme bands: 1,3 and 7. A zymogram of malate dehydrogenase spores isolated from plots inoculated with G. intraradices for three seasons exhibited similar bands. Spores isolated from plots inoculated with G. intraradices for one or two seasons showed only one weak band, corresponding to isozyme band 7. The results indicated that the introduced fungus persisted in the field for only one season.     

VA菌根菌丝对紧实土壤中磷的吸收

本文采用三室隔网盆栽试验方法,选择三种土壤容重(1.3;1.6;1.8g/cm3)来模拟自然条件下不同紧实度对植物根系生长的抑制情况,探讨了接种VA菌根真菌Gmosseae对三叶草植株生长和对土壤磷吸收的影响。结果表明随着土壤容重的增加,三叶草根系生长受到抑制的程度随之加重。当土壤容重为1.8g/cm3时,根系基本不能生长,而菌丝却能在其中伸展并吸收养分。表现为1.8土壤容重的处理菌根植物的含磷量明显高于无菌根植物。而在低容重的处理中两者却没有显著差异。说明VA菌根真菌能缓解甚至消除土壤机械阻力对植物生长的胁迫。     

Interactions of Glomus clarum with Acetobacter diazotrophicus in infection of sweet potato (Ipomoea batatas), sugarcane (Saccharum spp.), and sweet sorghum (Sorghum vulgare)

Summary Spores of the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus clarum obtained from sweet potatoes grown in soil inoculated with this fungus and with an enrichment culture of Acetobacter diazotrophicus contained A. diazotrophicus and several other bacteria, including a diazotrophic Klebsiella sp. Inoculation of micropropagated sweet potatoes with G. clarum and A. diazotrophicus enhanced spore formation in soil compared to VAM inoculation alone. Plants inoculated with VAM spores containing the bacteria showed additional increases in the number of spores formed within roots. A. diazotrophicus infected aerial plant parts only when inoculated together with VAM or when present within VAM spores. Micropropagated sugarcane seedlings inoculated with the same VAM spores containing the diazotrophs also contained much higher numbers of A. diazotrophicus in aerial parts than seedlings inoculated in vitro with the bacteria alone. When grown in non-sterile soil, the sugarcane seedlings again showed the greatest infection of aerial parts after inoculation with VAM spores containing the diazotrophs. This treatment also increased VAM colonization and the numbers of spores formed within roots. Similar effects were observed in sweet sorghum except that the aerial plant parts were not infected by A. diazotrophicus.     

EFFECT OF THE ECTOMYCORRHIZAL FUNGUS PAXILLUS INVOLUTUS ON GROWTH AND CATION (POTASSIUM,CALCIUM, AND MAGNESIUM) NUTRITION OF PINUS SYLVESTRIS L. IN SEMI-HYDROPONIC CULTURE

A semi-hydroponic culture was used to compare growth and cation nutrition of mycorrhizal (Paxillus involutus) and non-mycorrhizal Scots pine seedlings. When roots and hyphae grew together, concentrations and contents of macronutrients in needles and roots were not significantly different between mycorrhizal and non-mycorrhizal plants. When grown in two separate compartments, root potassium (K) concentrations, concentrations and contents of calcium (Ca) in needles and roots, needle nitrogen (N) concentrations, total N content and contents of root K and Mg were significantly reduced in mycorrhizal plants. Whereas ¹⁵N abundance increased in roots of mycorrhizal plants. The results indicated that the extraradical mycelium of the fungus strain used was able to transport N to the plant but did not contribute to long-term cation uptake and growth of host plants. An insufficient supply of macro-elements [N, phosphorus (P)] may account for the reduced growth of mycorrhizal plants and the differences in cation uptake between mycorrhizal and non-mycorrhizal plants.     

Spore production by the vesicular-arbuscular mycorrhizal fungus Glomus monosporum as related to host species,root colonization and plant growth enhancement

Summary The vesicular-arbuscular mycorrhizal fungus Glomus monosporum was inoculated on grapevine (Vitis vinifera), red clover (Trifolium pratense), meadow grass (Poa pratensis) and onion (Allium cepa) as hosts in two experiments carried out in different environments. Grapevine and clover showed the largest growth response and spore production. Mycorrhizal infection was lowest in meadow grass. Very poor correlations were observed, on an overall basis, between spore production and per cent root infection or infected root length. Spore production per unit infected root length for each host species was a comparatively stable parameter; it was largest for grapevine and smallest for meadow grass in both experiments. Sporulation was positively correlated with growth enhancement by mycorrhizal plants, and growth increments per unit infected root followed the same trend as spore numbers per unit infected root, i.e. largest for grapevine and lowest for meadow-grass. It is concluded that the ability of G. monosporum to produce spores and to enhance plant growth per unit infected root length depends on the host plant species.     

Effects of benomyl on vesicular‐arbuscular mycorrhizal infection of red clover (Trifolium pratense L.) and consequences for phosphorus inflow.

The roots of red clover plants inoculated with the vesicular‐arbuscular mycorrhizal fungus Glomus clarus Nicolson & Schenck were treated with a drench of benomyl at a time when mycorrhizal infection was already well established. Benomyl halted further infection and reduced phosphorus inflow by one order of magnitude compared to untreated controls. The fungicide also decreased the rate of plant growth probably as a consequence of reduced phosphorus inflow.     

Influence of mycorrhizal inoculation on carrot growth,metabolites and nutrition

Mycorrhizae are fungal symbionts forming mutualistic relationships with plant roots. This study was undertaken to evaluate the overall influence of arbuscular mycorrhizal fungi (AMF) on the overall growth and development of carrot plant. Surface-sterilized seeds of carrot were sown in earthen pots filled with sterile soil. Half of the pots were inoculated with AMF spores; the other half without any AMF inoculation represented control. After germination inoculated plants, along with the controls, were sampled at 20, 40, 60 and 80 days of growth after seedling emergence. There is a progressive net increase in growth with each 20-day interval after seedling emergence. Storage roots of carrot had a higher level of metabolites and nutrients like nitrogen, phosphorus and potassium in mycorrhiza colonized plants than the control. High performance liquid chromatography analysis indicated an increase in the carbohydrate fractions in AMF-inoculated roots. Thus, mycorrhiza has been found increasing the growth, metabolites and nutrition of carrot plant.     

Inoculation of seeds and soil with basidiospores of mycorrhizal fungi

It was demonstrated that basidiospores of the fungus Rhizopoyon luteolus, mycorrhizal for Pinus radiata, could be used successfully as seed inoculum after freeze-drying and storage for 3 months at 22°C, provided the inoculum level was increased 100-fold. Spore inoculum applied to seed could be held dry for at least 2 days before planting provided inoculum was increased 10-fold. On sowing freshly inoculated seed to sterile soil, 3 × 10³ basidiospores/seed were adequate for infection but maximum mycorrhizal infection occurred with 3 × 10⁴ spores/seed.A dose-response curve was obtained for mycorrhizal infection when basidiospores were applied to soil. As few as 100 spores/290 cm³ pot were sufficient for mycorrhizal infection although infection increased with greater spore dose to a maximum of 10⁵ spores/pot. Plant growth response was related to intensity of infection. It is suggested that the percentage germination of basidiospores in the rhizosphere may be considerably greater than those reported in studies with synthetic medium. A rhizosphere effect on germination of basidiospores was demonstrated and a method developed to facilitate studies of spore germination in the rhizosphere.     

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#>