Arbuscular Mycorrhizal Fungi and Acclimatization of Micropropagated Citrus

Micropropagated plantlets lack mycorrhizal symbionts and therefore present some physiological hindrances when transferred from axenic to ex vitro conditions. The purpose of the present study was to research the effects of Glomus mosseae and G. versiforme on growth, photosynthesis, and nutrient uptake of micropropagated citrus plantlets at the acclimatization stage. The two mycorrhizal fungi successfully colonized the roots of citrus plantlets after an acclimatization period of 170 days, and the mycorrhizal developments were apt to low levels. Inoculation with G. mosseae improved acclimatized growth performance; increased photosynthetic rates, transpiration rates, and stomatal conductance; and stimulated the accumulations of nitrogen (N), phosphorus (P), calcium (Ca), copper (Cu), zinc (Zn), and manganese (Mn) in leaves and roots compared to the noninoculated treatment. These observations suggested that only G. mosseae was the more efficient fungus, exhibited better adaptation to transplanted conditions, and therefore is appropriate to introduce into the micropropagation protocol of citrus.     

丛枝菌根真菌对镉胁迫下黑麦草光合生理的响应

为探究镉(Cd)胁迫下丛枝菌根(AM)真菌对黑麦草(Lolium perenne)光合生理的影响,盆栽条件下以Cd浓度为0、5、15和30 mg·kg-1分别对黑麦草接种AM真菌摩西斗管囊霉(FM)、变形球囊霉(GV)、混合处理(FM+GV)以及不接种对照(NM)共16个处理。结果表明,Cd降低了AM真菌侵染;接种AM真菌则提高了黑麦草株高、叶绿素含量、荧光参数、地上部和根系氮(N)、Cd含量,增强光合作用,显著提高植物体内生理活性。在Cd浓度为30 mg·kg-1水平下,FM+GV处理的菌根侵染率最大,为42.7%,与NM相比,FM+GV处理的黑麦草叶片叶绿素含量、地上部和根系N含量分别提高26.2%、70.6%和85.3%;株高和地上干重分别提高34.1%和18.8%;PSⅡ最大光化学效率和PSⅡ潜在活性分别提高4.9%和19.7%;净光合速率、蒸腾速率和气孔导度分别增加19.8%、28.3%和14.7%;超氧化物歧化酶、过氧化物酶活性、可溶性蛋白含量分别是NM的1.3、1.5和1.8倍,丙二醛含量相较NM下降50.0%。土壤中Cd浓度与植株地上部和根内的Cd含量呈显著正相关,FM+GV处理的黑麦草地上部和根系Cd含量分别达到88.1和606.7 mg·kg-1。总体来看,FM+GV处理增加黑麦草光合生理抗性、吸收固持Cd能力的效果最为显著。     

供硫和丛枝菌根真菌对洋葱生长和品质的影响

以珍珠岩为植物的生长基质盆栽试验,分别供给0.1、1.75和4 mmol/L三个不同硫水平的Long Ashton营养液,研究接种丛枝菌根真菌Glomus versiform对洋葱（Allium cepa L.）生长和品质的影响。结果表明,接种丛枝菌根真菌显著的改善了宿主植物的磷营养水平,促进了洋葱的生长;而硫处理对洋葱生长的影响差异不显著,但随着供硫水平的提高植株地上部全硫含量和有机硫含量显著增加。接种菌根真菌对洋葱硫营养的影响受外界供硫水平的影响,在供硫0.1 mmol/L时降低了洋葱植株的硫含量;而在供硫1.75和4 mmol/L时显著改善了洋葱的硫营养状况,宿主植物的酶解丙酮酸（enzyme produced pyruvic acid, EPY）的含量也显著增加。说明丛枝菌根真菌能够帮助宿主植物吸收外界环境中硫营养成分,改善洋葱的硫营养状况及品质。     

AM真菌生长发育影响因素及其对植物作用的研究

由真菌与植物根系共生形成的AM菌根在自然界中分布广泛,其生长发育受温度、土壤湿度等条件的影响;AM菌根可以促进宿主植物的生长已经在许多植物上得到证实,此外,此类菌根对提高植物的耐盐性、抗旱性及抗重金属毒性方面都有显著的作用。     

大豆丛枝菌根共生结构和多聚磷累积双定位方法

【目的】多聚磷是丛枝菌根内磷的主要贮存形式,定性、定量观察多聚磷对于解析菌根中磷代谢具有重要意义。随着植物体内越来越多的参与菌根真菌与寄主植物之间营养交换过程的基因被鉴定,迫切需要进一步提高根内菌根共生结构和多聚磷累积的染色和定位分析技术。【方法】本研究利用丛枝菌根真菌Glomus mosseae侵染的大豆植株,采集新鲜根样制片,一部分薄根片利用低浓度荧光染料麦胚凝集素,室温染色30 min,在波长488 nm的蓝光激发下使用荧光显微镜观察拍照;另一部分薄根片利用荧光染料4’,6-二脒基-2-苯基吲哚二盐酸盐(DAPI)进行染色,在波长405 nm紫外光激发下观察并拍照;进一步取新鲜制备的薄根片,先后用以上两种荧光染料进行染色,分别在波长405 nm和488 nm的激发光下观察并拍照,完成了菌根共生结构和多聚磷的共定位。【结果】1)使用荧光染料麦胚凝集素,大豆丛枝菌根真菌侵染结构的荧光标记活性染色法,可以清晰地检测到大豆丛枝菌根中所有的共生结构,包括丛枝,泡囊和根内菌丝等。2)在丛枝菌根真菌侵染的根中,各种共生结构都呈现出黄色荧光,为DAPI与多聚磷结合在紫外光激发下的呈色。根段中部分细胞内的蓝白色斑点为DAPI与细胞核中DNA结合的显色结果。在含有成熟丛枝结构的细胞中,也可观察到大部分丛枝呈蓝白色,主要是丛枝膜质结构的呈色。因此,利用荧光染料4’,6-二脒基-2-苯基吲哚二盐酸盐染色法定位多聚磷,能很好地区分多聚磷酸盐、DNA和膜质。3)在以上研究的基础上,通过荧光光路的切换,可以同时观察到菌根共生结构和多聚磷的共定位。处于发育阶段的整个丛枝中多聚磷累积的亮黄色清晰可见。在成熟的丛枝中,由于膜质结构发达,对累积在丛枝结构中的多聚磷的染色观察产生了一定影响,导致仅仅局部的多聚磷累积清晰可见。【结论】本研究建立的大豆菌根共生结构与多聚磷累积的双定位分析系统,能够直观观察植物与丛枝菌根真菌的养分交换,清晰地对丛枝菌根共生结构中多聚磷的累积进行定位分析,可作为从组织和细胞水平研究菌根共生体的重要技术手段。     

AM真菌生长发育影响因素及其对植物作用的研究

由真菌与植物根系共生形成的AM菌根在自然界中分布广泛，其牛长发育受温度、土壤湿度等条件的影响；AM菌根可以促进宿主植物的生长已经在许多植物上得到证实，此外。此类菌根对提高植物的耐盐性、抗旱性及抗重金属毒性方面都有显著的作用。     

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(P0.05)根内球囊霉。     

Control of Fusarium Wilt of Cucumber Seedlings by Inoculation with an Arbuscular Mycorrhical Fungus

A glasshouse pot experiment was conducted to investigate the impact of inoculation of cucumber at the germination stage with Glomus etunicatum BEG168 on plant yield and incidence of Fusarium oxysporum f.sp. cucumerinum inoculated 28 days after the start of the experiment. Inoculation with the AM fungus decreased both disease incidence and disease index. Mycorrhizal inoculation also increased P concentrations in the cucumber seedlings. The mycorrhizal seedlings had higher concentrations of proline and polyphenol oxidase activity but lower malondialdehyde than non-mycorrhizal seedlings, indicating that AM inoculation may have protected membrane permeability and reduced the extent of the damage caused by F. oxysporum. The results indicate that the mycorrhizal fungus may influence plant secondary metabolites and increase resistance to wilt disease in cucumber seedlings and may therefore have some potential as a biological control agent.     

Effects of early mycorrhization and colonized root length on low‐soil‐phosphorus resistance of West African pearl millet

Phosphorus (P) deficiency at early seedling stages is a critical determinant for survival and final yield of pearl millet in multi‐stress Sahelian environments. Longer roots and colonization with arbuscular mycorrhizal fungi (AMF) enhance P uptake and crop performance of millet. Assessing the genotypic variation of early mycorrhization and its effect on plant growth is necessary to better understand mechanisms of resistance to low soil P and to use them in breeding strategies for low P. Therefore, in this study, eight pearl millet varieties contrasting in low‐P resistance were grown in pots under low P (no additional P supply) and high P (+ 0.4 g P pot^?1) conditions, and harvested 2, 4, 6, and 8 weeks after sowing (WAS). Root length was calculated 2 WAS by scanning of dissected roots and evaluation with WinRhizo software. AM infection (%) and P uptake (shoot P concentration multiplied per shoot dry matter) were measured at each harvest. Across harvests under low P (3.3 mg Bray P kg^?1), resistant genotypes had greater total root length infected with AMF (837 m), higher percentage of AMF colonization (11.6%), and increased P uptake (69.4 mg P plant^?1) than sensitive genotypes (177 m, 7.1% colonization and 46.4 mg P plant^?1, respectively). Two WAS, resistant genotypes were infected almost twice as much as sensitive ones (4.1% and 2.1%) and the individual resistant genotypes differed in the percentage of AMF infection. AMF colonization was positively related to final dry matter production in pots, which corresponded to field performance. Early mycorrhization enhanced P uptake in pearl millet grown under P‐deficient conditions, with the genotypic variation for this parameter allowing selection for better performance under field conditions.     

Effect of peat on mycorrhizal colonization and effectiveness of the arbuscular mycorrhizal fungus Gigaspora margarita

Abstract

The influence of the addition of Chinese peat and Canadian peat on arbuscular mycorrhizal colonization, mycorrhizal effectiveness and host-plant growth was investigated in a pot experiment. Chinese peat or Canadian peat was mixed with Masa soil (weathered granite soil) at different levels (0, 25, 50, 100, 150 or 200 g kg^?1) into which an arbuscular mycorrhizal fungus (AMF) Gigaspora margarita Becker & Hall was inoculated, and seedlings of Miscanthus sinensis Anderess were planted. There was a significant increase in plant growth with increasing amounts of Chinese peat. The growth-promoting effect of the AMF on the host was enhanced when the addition of Chinese peat was increased from 25 to 100 g kg^?1. Root colonization and the number of spores proliferating increased with increases at low levels of Chinese peat (from 25 to 100 g kg^?1), and decreased gradually with higher Chinese peat increments. Although plant growth and root colonization with the addition of Canadian peat increased slightly, Canadian peat suppressed mycorrhizal effectiveness. In contrast to Canadian peat, the addition of Chinese peat improved considerably the physical and chemical properties of the soil, which might result in the promotion of AM formation and mycorrhizal effectiveness.     

丛枝菌根真菌降低辣椒镉吸收和果实镉积累的机制

目的丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)与作物存在互利共生关系,可增强宿主对镉(Cd)的耐受能力。研究AMF对不同Cd积累型辣椒Cd吸收积累的影响,探索AMF降低辣椒可食部位Cd的生理生化机制。方法采用盆栽试验,供试土壤为石灰性黄壤,该土壤上已连续种植辣椒8年。丛枝菌根处理包括接菌(+AMF)和不接菌（−AMF);Cd浓度包括3个水平：0、5、10 mg/kg,分别记作Cd0、Cd5、Cd10;辣椒品种包括Cd高积累型‘辣研101’和Cd低积累型‘辣研201’,3个因素共组成12个处理。辣椒移栽90天后收获,分别测定了辣椒根、地上部和果实干重、Cd含量,以及根际土壤养分含量、根系分泌物成分。结果Cd处理抑制了辣椒生长,随施Cd浓度的增加,株高、地上部和根部生物量显著下降;Cd10处理下,与−AMF处理相比,+AMF处理‘辣研101’地上部生物量增加了31.72%,‘辣研201’ 增加了20.09%;‘辣研 101’根部Cd含量显著降低了30.75%;‘辣研 201’增加了41.93%;+AMF处理下‘辣研101’ Cd的转运系数(地上部/根部)显著增加了48.96%,而‘辣研 201’降低了24.04%。+AMF处理降低了各Cd浓度下两品种辣椒果实Cd的富集系数,改变了辣椒根系分泌物化学组成及相对含量,不同品种间有所差异。结构方程模型分析表明,接菌、根部Cd含量对辣椒果实Cd含量表现出显著负向调节作用。结论在Cd胁迫条件下,AMF通过减少低积累型辣椒(辣研201)根部Cd向地上部的转运,降低可食部位Cd积累;通过减少高积累型辣椒(辣研101)地上部Cd向果实的转运,降低可食部位Cd积累。     

丛枝菌根真菌(Glomus caledonium)对铜污染土壤生物修复机理初探

利用盆栽试验,研究了丛枝菌根真菌(Glomus.caledonium)在不同程度铜污染土壤上对玉米苗期生长的影响。结果表明,即使在土壤施铜量达150mg/kg时,菌根真菌对玉米仍有近55%的侵染率;接种菌根真菌,能显著促进玉米根系的生长。菌根玉米的根系生物量和根系长度,平均较未接种处理分别提高108.4%和58.8%;接种处理的植株地上部生物量达到每盆(3株)10.58g,显著高于不施铜的非菌根玉米。这些结果表明,丛枝菌根真菌对铜污染具有较好的抗性;并且由于菌根的形成,使宿主植物明显地改善了对磷的吸收和运输,并能通过抑制土壤酸化、降低土壤可溶态铜的浓度等机制,增强宿主植物对铜污染的抗(耐)性。在150mg/kg施铜水平时,与非菌根玉米相比,菌根玉米地上部和根系铜浓度分别降低24.3%和24.1%,吸铜量分别提高了28.2%和60.0%,表明菌根植物对铜污染土壤具有一定的生物修复作用。     

丛枝菌根真菌对西藏高原固沙植物吸磷效率的影响

采用盆栽方法,就外源菌种、土著菌种(含混合菌种)对固沙植物白草(Pennisetum.flaccidum)生长和吸磷效率的影响进行了研究。结果表明,白草具有较高的菌根依赖性(平均达166.4%);不同AM真菌(或真菌组合)对白草根系均具显著的侵染效应。随菌根侵染率的提高,植株生物量、吸磷量均呈显著增加(相关系数分别为0.7465*、0.6000*);菌根菌丝对白草吸收土壤磷素的贡献十分明显,各接种处理菌根菌丝对植物吸收土壤磷素的贡献量、贡献率分别在3.2～11.6.mg/pot和61.5%～85.3%之间;接种菌根处理植株吸磷量呈Glomus.intraradicesG.mosseae+G.etunicatum+G.intraradices+Scutellospora.erythropaG.mosseae(外源菌种)G.mosseae+G.intraradices+Scutellospora.calosporaG.mosseae-I(土著菌种)G.etunicatum的趋势。此外,不同AM真菌对寄主植物地上部、根部生物量和吸磷量的影响程度明显不同,一般呈地上部根系的趋势,但寄主植物根系的生长速率相对较快;土著菌种中,多菌混合接种对寄主植物的侵染效应明显高于单一接种。     

不同氮素形态比例条件下接种AMF对玉米氮同化关键酶的影响

以珍珠岩为基质,通过供应3种不同的NH4+∶NO3ˉ比例营养液,研究了接种丛枝菌根真菌对玉米氮同化关键酶活性的影响。结果看出,与不接种的玉米植株相比,接种Glomus intraradices和Glomus mosseae分别在NH4+∶NO3ˉ=3∶1和NH4+∶NO3ˉ=1∶3形态下提高了植物叶片的硝酸还原酶活性;接种AMF对叶片谷氨酰胺合成酶活性（GS）影响不大,但在NH4+∶NO3ˉ=3∶1形态下接种3种AMF处理均显著提高了根系GS活性,相对提高了铵态氮在地下部的同化比例。在铵态氮比例较高时,接种AMF的促生效应较好,且AMF提高根系GS活性作用较大。表明丛枝菌根真菌在促进宿主植物对铵态氮的利用作用较大。     

不同种植密度下丛枝菌根真菌对玉米磷吸收的影响

【目的】利用土著丛枝菌根真菌(arbuscular mycorrhizal fungi,AM真菌)与作物形成互惠互利的共生关系提高作物对土壤磷的利用效率是解决农业生产中磷供需矛盾的主要途径之一,本研究在大田玉米不同种植密度条件下,研究AM真菌对玉米根系的侵染及磷吸收作用,为揭示集约化玉米高效获取磷的机理提供理论依据。【方法】以大田作物玉米的两种种植密度(5104 plants/hm2和9104 plants/hm2)体系为研究对象,在田间原位埋设PVC管装置,通过测定菌丝生长室中的菌丝密度和有效磷耗竭来确定不同种植密度体系条件下AM真菌对玉米磷吸收的作用。【结果】相对于低密度种植群体,高密度群体显著降低了玉米拔节期土壤有效磷的耗竭量,同时增加了玉米地上部的磷含量,即磷吸收效率,增幅达20%; 在玉米拔节期,增加种植密度使根际的根外菌丝生物量(菌丝密度)降低了4%,而非根际土壤中的根外菌丝生物量(菌丝密度)增加了37%; 高密度玉米种植密度群体中AM真菌的根外菌丝对土壤有效磷耗竭的贡献增加了22%。【结论】集约化玉米生产中土著AM真菌依然帮助植株从土壤中吸收有效磷; 高密度体系下玉米对磷的吸收更加依赖于AM真菌。高密度种植增加AM真菌对玉米的侵染、 根外菌丝量和对土壤有效磷的吸收。