AMF和植物富集土壤中铅和镉的效应

为了筛选更适合修复土壤重金属污染的丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)和寄主植物组合,对二月兰(Orychophragum violaeeus)、龙葵(Solanum nigrum)和麦冬(Ophiopogon japonicus)接种AM真菌摩西管柄囊霉(Funneliformis mosseae)和根内球囊霉(Glomus intraradices),通过测定Pb(1 000 mg/kg)和Cd(1.5 mg/kg)污染土壤中上述3种植物生长状况及其对Pb和Cd吸收与富集能力的影响,旨在获得富集重金属能力较强的AM真菌+植物组合。结果表明,施加Cd土壤中二月兰和麦冬的生物量高于对照,施加Pb或Cd处理显著降低龙葵的生长。龙葵对Pb和Cd富集能力最强,麦冬最弱;二月兰对Pb和Cd的转移能力最强。供试植物对Cd的富集能力和转移能力均大于对Pb的富集能力和转移能力。在Pb和Cd的胁迫下,摩西管柄囊霉和根内球囊霉均能促进供试植物的生长发育,并增加植株对Pb和Cd的富集系数,其中,摩西管柄囊霉对龙葵生物量、Pb和Cd富集系数的效应最大。综合考虑植物本身的生物量、对Pb和Cd的耐受力和富集能力,结论认为摩西管柄囊霉+龙葵组合是修复Pb或Cd污染土壤的高效AM真菌+植物组合之一,相关机制有待进一步研究。     

镉胁迫对绢毛委陵菜-丛枝菌根真菌共生体根系结构和生理的影响

为从生理水平上揭示绢毛委陵菜（Potentilla sericea L.）-丛枝菌根真菌共生体对镉胁迫的应答机制,以绢毛委陵菜多年生植株为试验材料,分别接种根内根生囊霉（Rhizophagus intraradices）和摩西球囊霉（Funneliformis mosseae）,80 d后以不同浓度的镉胁迫处理并测定菌根侵染率,研究侵染率较高菌种的共生体植株的生理指标变化和结构变化。结果表明：摩西球囊霉较根内根生囊霉对绢毛委陵菜菌根侵染率高,达100%,而根内根生囊霉侵染率为89.33%;接种摩西球囊霉真菌的植物,当镉质量浓度达10 mg?L^-1时,细胞壁小范围破裂、液泡出现变小的趋势,高浓度镉（20 mg?L^-1）处理时,根系细胞壁破裂,细胞无法维持原有形态;镉胁迫下,Cd（5 mg?L^-1）~ Cd（10 mg?L^-1）MDA含量显著上升（P<0.05）,Cd（0 mg?L^-1）~Cd（5 mg?L^-1）SOD活性和脯氨酸含量变化显著（P<0.05）,可溶性蛋白含量和叶绿素含量显著减少（P<0.05）,Cd（10 mg?L^-1）~Cd（15 mg?L^-1）可溶性蛋白含量和叶绿素含量变化不显著（P>0.05）,植物可以抵抗一定浓度范围的镉胁迫。综合来看,接种摩西球囊菌可以增强绢毛委陵菜耐镉胁迫能力,为利用绢毛委陵菜修复镉污染土壤提供了理论依据。     

丛枝菌根真菌对砷胁迫下棉花根系形态和生理特征的影响

以棉花品种‘大铃棉69号’为材料,通过室内盆栽试验,将两种丛枝菌根真菌根——内根孢囊霉(Rhizophagus intraradices,RI)和摩西斗管囊霉(Funneliformis mosseae,FM)分别接种棉花根部,分析不同土壤砷浓度(0、100、200 mg/kg)条件下丛枝菌根真菌对棉花生长、根系特征、细胞膜透性、抗氧化酶活性以及砷在棉花体内积累和转移的影响,为丛枝菌根真菌在土壤砷污染修复中的合理应用提供理论支撑。结果表明:(1)随着砷胁迫的加重,棉花生长、根系发育、根系活力、抗氧化酶系统(SOD、POD、CAT)和渗透调节系统(可溶性糖、可溶性蛋白、脯氨酸)均受到明显抑制。(2)接种RI和FM显著提高了棉花的株高、生物量、根冠比,根系活力;降低了棉花地上和地下部的砷含量和砷转移系数;提高了棉花总根长、根表面积、根体积、根尖数、根叉数等根系形态指标,并降低其0～0.2 mm径级的根长百分比,增加其0.5～1.0 mm和1.0 mm径级的根长百分比;促使棉花叶和根中可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质含量和SOD、POD、CAT等抗氧化酶活性不同程度升高,并使相对电导率、MDA含量降低;其中,摩西斗管囊霉接种效果优于根内根孢囊霉。研究发现,在土壤砷胁迫条件下,接种丛枝菌根真菌可促进棉花生长和根系发育,降低棉花体内砷浓度并抑制其向地上转移,同时激活抗氧化系统和渗透调节系统来减轻砷对棉花的毒害作用,增强棉花对土壤砷胁迫的耐受能力,且摩西斗管囊霉接种效果更佳。     

AM真菌摩西管柄囊霉对干旱胁迫下枳抗氧化酶基因表达的影响

测定分析了接种丛枝菌根（AM）真菌摩西管柄囊霉Funneliformis mosseae对正常供水与干旱处理的盆栽枳Poncirus trifoliata实生苗生长、活性氧代谢及抗氧化酶基因表达量的影响。结果表明,7周干旱处理显著降低了根系菌根侵染率。接种摩西管柄囊霉显著促进了干旱处理的枳植株生长,增加了根系体积和叶片相对含水量,显著降低了叶片脯氨酸含量,同时也上调了干旱处理的枳叶片精氨酸脱羧酶基因（PtADC1和PtADC2）和超氧化物歧化酶基因（PtFe-SOD和PtMn-SOD）、过氧化物酶基因（PtPOD）和过氧化氢酶基因（PtCAT1）的表达,因而维持了一个相对更低的活性氧水平（如过氧化氢）,有利于增强植株的抗旱性。     

AM真菌对百合调节激素平衡与细胞渗透性以及改善耐盐性的研究

该试验以东方百合(Lilium brownii)品种‘西伯利亚’和丛枝菌根(AM)真菌摩西斗管囊霉(Funneliformis mosseae)、变形球囊霉(Glomus versiforme)为材料,在温室盆栽条件下,设置NaCl胁迫(0、0.4%、0.8%和1.2%NaCl溶液处理)和接种AM真菌[接种摩西斗管囊霉、变形球囊霉、摩西斗管囊霉+变形球囊霉及未接种对照]双因素试验,分析各处理百合的激素平衡与细胞渗透性变化特征,以明确AM真菌提高百合耐盐性的效应,初步探索AM真菌增强百合耐盐性的作用机制。结果表明:(1)接种AM真菌能有效增加盐胁迫下百合植株的株高和生物量,显著提高百合耐盐系数,双接种处理的株高及地上、地下部分干重在1.2%NaCl胁迫下分别比未接种对照显著增加8.9%、14.5%和11.2%。(2)接种AM真菌能显著提高盐胁迫下百合植株叶片的矿质元素P、K、S含量,显著降低叶片内Na和Fe含量,双接种处理的P、K、S含量在1.2%NaCl胁迫下分别比对照提高10.9%、8.3%、13.7%,而其Na和Fe含量分别显著下降28.4%和66.4%。(3)接种AM真菌能显著提高盐胁迫下百合内源激素吲哚乙酸(IAA)和脱落酸(ABA)含量,双接种处理在1.2%NaCl胁迫下百合内源IAA、ABA含量分别是对照的1.2和1.5倍。(4)接种AM真菌能显著提高盐胁迫下百合可溶性蛋白含量,显著降低其脯氨酸含量,双接种处理在1.2%NaCl胁迫下比对照的升降幅度分别为69%和31%。(5)接种AM真菌能显著降低盐胁迫下百合叶片丙二醛和相对电导率,双接种处理在1.2%NaCl胁迫下比对照分别显著下降58.1%和9.0%。研究发现,AM真菌可以通过增强百合对养分的吸收、降低氧化胁迫造成的伤害、调节植物内源激素平衡状况与细胞渗透性来增强自身的耐盐能力,且双接种处理的效果优于单一接种。     

丛枝菌根真菌对百喜草的生理特性的影响

采用盆栽法研究了丛枝菌根（AM）真菌摩西球囊霉（Glomus mosseae）对水分胁迫条件下百喜草（Paspalum notatum）生长、渗透调节及抗氧化酶的影响。结果表明：接种AM真菌显著提高了百喜草的株高、地上部与根部鲜重、地上部P、K、Mn及根部P、Ca、Mn含量,明显降低了地上部Zn及根部Fe、B、Cu水平;随着干旱程度的加深,接种株的地上部相对含水量及叶绿素含量相对稳定且均显著高于未接种株,接种株地上部相对电导率、MDA含量均显著低于未接种株,接种株的地上部POD活性与脯氨酸含量均显著增加且均显著高于未接种株,AM侵染对SOD活性的影响较小。可见,接种AM真菌Glomus mosseae提高了植株体内保护酶活性（如POD）及渗透调节能力（如脯氨酸、P、K、Ca等渗透调节物含量的增加）,从而显著增强了百喜草的抗旱性。     

丛枝菌根真菌对百喜草的生理特性的影响

采用盆栽法研究了丛枝菌根（AM）真菌摩西球囊霉（Glomus mosseae）对水分胁迫条件下百喜草（Paspalum notatum）生长、渗透调节及抗氧化酶的影响。结果表明：接种AM真菌显著提高了百喜草的株高、地上部与根部鲜重、地上部P、K、Mn及根部P、Ca、Mn含量,明显降低了地上部Zn及根部Fe、B、Cu水平;随着干旱程度的加深,接种株的地上部相对含水量及叶绿素含量相对稳定且均显著高于未接种株,接种株地上部相对电导率、MDA含量均显著低于未接种株,接种株的地上部POD活性与脯氨酸含量均显著增加且均显著高于未接种株,AM侵染对SOD活性的影响较小。可见,接种AM真菌Glomusmossecte提高了植株体内保护酶活性（如POD）及渗透调节能力（如脯氨酸、P、K、Ca等渗透调节物含量的增加）,从而显著增强了百喜草的抗旱性。     

AM真菌对采煤沉陷区黄花菜生长及根际土壤养分的影响

于陕北黄土沟壑采煤沉陷区内布设试验小区,对黄花菜(Hemerocallis citrina Baroni)接种丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)—摩西管柄囊霉菌,通过测定黄花菜光合性能、植株生长、抗逆性、土壤养分含量、根际微生物数量等,揭示AM真菌对黄花菜生长和土壤养分的影响。结果表明,黄花菜种植3—5个月后,接种AM真菌显著提高了黄花菜株高、冠幅及其根系菌根侵染率、菌丝密度。与不接种对照区相比,接种AM真菌后黄花菜叶片的光合速率、可溶性糖含量和过氧化氢酶活性分别提高了51%、12%、79%。接种AM真菌处理区黄花菜根际土壤的电导率、有机质、碱解氮和速效钾含量等均显著高于对照区,细菌数量和磷酸酶活性的菌根贡献率分别达77%和24%。表明采煤沉陷区扰动土壤接种AM真菌具有增强土壤微生物活性、改善土壤肥力和提高黄花菜植株抗逆性的作用,对促进陕北黄土沟壑采煤沉陷区经济作物生长和提高土壤质量具有重要现实生态意义。     

水分胁迫下AM真菌对沙打旺生长和抗旱性的影响

利用盆栽试验研究了水分胁迫条件下接种AM真菌对优良牧草和固沙植物沙打旺(Astragalus adsurgens Pall.)生长和抗旱性的影响。在土壤相对含水量为70%、50%和30%条件下,分别接种摩西球囊霉(Glomus mosseae)和沙打旺根际土著菌,不接种处理作为对照。结果表明,水分胁迫显著降低了沙打旺植株(无论接种AM真菌与否)的株高、分枝数、地上部干重和地下部干重,并显著提高了土著AM真菌的侵染率,对摩西球囊霉的侵染率无显著影响。接种AM真菌可以促进沙打旺生长和提高植株抗旱性,但促进效应因土壤含水量和菌种不同而存在差异。不同水分条件下,接种AM真菌显著提高了植株菌根侵染率、根系活力、地下部全N含量和叶片CAT活性。土壤相对含水量为30%和50%时,接种株地上部全N、叶片叶绿素、可溶性蛋白、脯氨酸含量和POD活性显著高于未接种株;接种AM真菌显著降低了叶片MDA含量;接种土著AM真菌的植株株高、分枝数、地上部和地下部干重显著高于未接种株。土壤相对含水量为30%时,接种AM真菌显著增加了地上部全P含量和叶片相对含水量;接种摩西球囊霉的植株株高、分枝数、地上部和地下部干重显著高于未接种株。水分胁迫40d,接种AM真菌显著提高了叶片可溶性糖含量。水分胁迫80d,接种株叶片SOD活性显著增加。菌根依赖性随水分胁迫程度增加而提高。沙打旺根际土著菌接种效果优于摩西球囊霉。水分胁迫和AM真菌的交互作用对分枝数、菌根侵染率、叶片SOD、CAT和POD活性、叶绿素、脯氨酸、可溶性蛋白、地上部全N和全P、地下部全N和根系活力有极显著影响,对叶片丙二醛和地下部全P有显著影响。AM真菌促进根系对土壤水分和矿质营养的吸收,改善植物生理代谢活动,从而提高沙打旺抗旱性,促进其生长。试验结果为筛选优良抗旱菌种,充分利用AM真菌资源促进荒漠植物生长和植被恢复提供了依据。     

EFFECTS OF AM FUNGI AND WATER STRESS ON DROUGHT RESISTANCE OF ARTEMISIA ORDOSICA IN DIFFERENT SOILS

 利用两种不同土壤研究了水分胁迫和接种AM真菌(摩西球囊霉(Glomus mosseae)和油蒿(Artemisia ordosica)根际土著AM真菌)对毛乌素沙地重要演替物种油蒿生长和抗旱性的影响。结果表明, 两种土壤中水分胁迫没有显著影响油蒿的植株形态和含水量, 但严重抑制了菌根侵染率。水分胁迫促使油蒿提高叶片保水能力, 抑制N、P在地上部的分配。在胁迫前期SOD活性较高, 而POD活性在后期较高。同一水分条件下接种AM真菌显著提高了AM真菌侵染率, 土壤中孢子数显著增多, 提高了植株分枝数并促进侧根发育, 显著提高根冠比和植株保水能力, 加强了根系对全磷、全氮的吸收。接种AM真菌的植株可溶性糖和丙二醛含量较低, 可溶性蛋白含量无显著变化, SOD和POD活性提高, 油蒿抗旱性加强。水分胁迫下在不同土壤中接种不同AM真菌对油蒿的促进效应差异较大, 接种土著AM真菌的效果优于摩西球囊霉单一接种。干旱导致菌根侵染率下降是宿主植物吸水能力下降的原因之一, 在植物生长前期接种AM真菌可以增强植物抵抗生长中后期环境干旱的能力。     

丛枝菌根真菌对牡丹生长及相关生理指标的影响

以采自山东省菏泽牡丹园的牡丹'凤丹'种子为试材,采用盆栽的方法研究了接种丛枝菌根(Arbuscular mycorrhizal,AM)真菌Glomus mosseae、Glomus versiforme和Glomus intraradices对牡丹幼苗生长及生理生化特性的影响.结果表明:(1)不同AM真菌的侵染率不同,并以G.mosseae的侵染率最高,为48.3%;(2)AM真菌能够促进牡丹幼苗生长,接种G.mosseae的植株干重比对照显著提高了69.5%;(3)AM真菌能够提高牡丹的叶绿素、可溶性糖、可溶性蛋白、矿质元素(N、P、K)含量和硝酸还原酶活性,并对可溶性蛋白含量和硝酸还原酶活性的影响达显著水平.(4)植株总干重与菌根侵染率、硝酸还原酶活性、叶绿素含量呈极显著正相关,与可溶性糖、可溶性蛋白含量呈显著正相关.研究发现,G.mosseae是最适宜牡丹接种的优良菌种.     

Xyloglucanases in the interaction between saprobe fungi and the arbuscular mycorrhizal fungus Glomus mosseae

We studied the production of xyloglucanase enzymes of pea and lettuce roots in the presence of saprobe and arbuscular mycorrhizal (AM) fungi. The AM fungus Glomus mosseae and the saprobe fungi Fusarium graminearum, Fusarium oxysporum-126, Trichoderma harzianum, Penicillium chrysogenum, Pleurotus ostreatus and Aspergillus niger were used. G. mosseae increased the shoot and root dry weight of pea but not of lettuce. Most of the saprobe fungi increased the level of mycorrhization of pea and lettuce, but only P. chrysogenum and T. harzianum inoculated together with G. mosseae increased the dry weight of pea and lettuce respectively. The AM and saprobe fungi increased the production of xyloglucanases by plant roots. The level of xyloglucanase activities and the number of xyloglucanolytic isozymes in plants inoculated with G. mosseae and most of the saprobe fungi tested were higher than when both microorganisms were inoculated separately. The possible relationship between xylogucanase activities and the ability of AM and saprobe fungi to improve the dry weight and AM root colonization of plants was discussed.     

Superoxide dismutase and total peroxidase activities in relation to drought recovery performance of mycorrhizal shrub seedlings grown in an amended semiarid soil

We studied the effect of inoculation with a mixture of three arbuscular mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) and addition of a composted organic residue on plant growth, nutrient uptake, mycorrhizal colonisation and superoxide dismutase (SOD, EC 1.15.1.1) and total peroxidase (POX, EC 1.11.1.7) activities in shoots of Juniperus oxycedrus seedlings after well-watered, drought and recovery periods. The mycorrhizal inoculation and composted residue addition significantly increased the growth, foliar nutrients (N, P, K) and shoot water content of the plants, independent of the water regime. POX activity in control plants increased during drought (about 250% higher than under well-watered conditions) and returned to initial levels after re-watering. The seedlings inoculated with AM fungi showed the highest values of POX activity, followed by the plants grown in the amended soil, which varied little during the drought and recovery periods. Drought decreased the SOD activity in shoots of both J. oxycedrus seedlings inoculated with AM fungi and those grown with composted residue, but did not affect that of control plants. After re-watering, the SOD activity in mycorrhizal or residue-amended plants increased, showing values similar to control plants.     

AM真菌种间差异对枳壳生长及耐热性效应的研究※

用地表球囊霉、莫西球囊霉、珠状巨孢球囊霉及其混合菌剂接种无菌根枳壳幼苗进行盆栽试验,25℃培养4个月,观察对枳壳菌根形成和营养生长的影响,在40℃高温胁迫30d,调查分析菌根枳壳的耐热性。试验结果表明:接种AM真菌的根系形成了20%～80%的菌根侵染率;菌根枳壳的苗高、苗质量、节间长、茎基粗、须根数量和须根长度等营养生长显著增加;叶片中的SOD,POD活性和根系活力显著增强,可溶性蛋白、可溶性糖含量显著升高,叶片中的MDA含量降低,膜透性显著变小,枳壳苗的耐热性显著提高;但是,AM真菌在促进枳壳苗菌根化、营养生长和提高耐热性方面存在着种间差异,地表球囊霉、莫西球囊霉、珠状巨孢球囊霉、混合菌剂与枳壳根系形成丛枝菌根的侵染率依次为20.4%±1.2%、61.8%±3.4%、85.7%±2.7%、83.3%±2.2%,促进枳壳苗营养生长提高枳壳苗耐热能力的AM真菌依次为:地表球囊霉<莫西球囊霉<珠状巨孢球囊霉<混合菌剂,认为珠状巨孢球囊霉和莫西球囊霉是枳壳耐高温胁迫菌根化育苗的重要优良菌种。     

Effect of arbuscular mycorrhizal fungal inoculation on heavy metal accumulation of maize grown in a naturally contaminated soil

A pot culture experiment was carried out to study heavy metal (HM) phytoaccumulation from soil contaminated with Cu, Zn, Pb, and Cd by maize (Zea mays L.) inoculated with arbuscular mycorrhizal (AM) fungi (AMF). Two AM fungal inocula--MI containing only one AM fungal strain (Glomus caledonium 90036) and MII consisting of Gigaspora margarita ZJ37, Gigaspora decipens ZJ38, Scutellospora gilmori ZJ39, Acaulospora spp., and Glomus spp.--were applied to the soil under unsterilized conditions. The control received no mycorrhizal inoculation. The maize plants were harvested after 10 wk of growth. MI-treated plants had higher mycorrhizal colonization than MII-treated plants. Both MI and MII increased P concentrations in roots, but not in shoots. Neither MI nor MII had significant effects on shoot or root dry weight (DW). Compared with the control, shoot Cu, Zn, Pb, and Cd concentrations were decreased by MI but increased by MII. Cu, Zn, Pb, and Cd uptake into shoots and roots all increased in MII-treated plants, while in MI-treated plants Cu, Zn, and Pb uptake into shoots and Cd uptake into roots decreased but Cu, Zn, and Pb uptake into roots and Cd into shoots increased. MII was more effective than MI in promoting HM extraction efficiencies. The results indicate that MII can benefit HMphytoextraction and, therefore, show potential in the phytoremediation of HM-contaminated soils.     

接种AM真菌对短命植物生长发育及矿质养分吸收的影响

 采用分室培养方法研究接种幼套球囊霉(Glomus etunicatum,BEG168)、摩西球囊霉(G. mosseae, BEG167)、混合菌剂(M)对两种沙漠早春短命植物小车前(Plantago minuta)和尖喙牻牛儿苗（Erodium oxyrrhynchum）生长发育及矿质养分吸收的影响。结果表明,接种AMF处理的小车前和尖喙牻牛儿苗根系形成了典型的菌根结构,侵染率为22 %～60%;接种AMF提高了小车前和尖喙牻牛儿苗两种植物的生物量、株高及N、P养分吸收量。小车前单独接种BEG167、BEG168以及混合接种都显著提高了单株种子数量,其增幅分别 为67%、50%和78%。上述结果说明,在极端贫瘠和干旱的古尔班通古特沙漠中,丛枝菌根真菌对于早春短命植物小车前和尖喙牻牛儿苗的生态适应性的贡献表现为促进营养生长、提高后代（种子）繁殖数量。     

Antioxidant enzyme activities in shoots from three mycorrhizal shrub species afforested in a degraded semi-arid soil

Mycorrhizae may help plants to thrive in Mediterranean semi-arid ecosystems by altering antioxidant enzyme activities. Our objective was to determine the influence of mycorrhizal inoculation with an allochthonous arbuscular mycorrhizal (AM) fungus, Glomus claroideum , Schenck & Smith, or with a mixture of native AM fungi, on the activity of antioxidant enzymes from shoots of Olea europaea L. ssp. sylvestris , Retama sphaerocarpa (L.) Boissier and Rhamnus lycioides L. seedlings afforested in a degraded Mediterranean semi-arid soil. One year after planting, shoot biomass of inoculated O. europaea seedlings was about 630%, of non-inoculated plants. Shoot biomass of G. claroideum -colonized R. sphaerocarpa was greater than that of seedlings inoculated with the mixed native AM fungi after 12 months. Inoculation with a mix of native AM fungi was the most effective treatment for increasing shoot biomass and N, P and K contents in shoot tissues of R. lycioides . Both mycorrhizal inoculation treatments increased the nutrient contents in shoots of O. europaea and R. lycioides . In O. europaea plants, the inoculation treatments increased catalase, ascorbate peroxidase and dehydroascorbate reductase activities, but not monodehydroascorbate reductase and glutathione reductase activities. Inoculation with G. claroideum increased the activities of all antioxidant enzymes in R. sphaerocarpa . Monodehydroascorbate reductase, glutathione reductase and superoxide dismutase activities in R. lycioides leaves were preferentially increased by inoculation with the mixture of native AM fungi. This work support the view that increased antioxidant enzyme activities could be involved, at least in part, in the beneficial effects of mycorrhizal colonization on the performance of shrub species grown under semi-arid Mediterranean conditions.     

Cu2+污染土壤接种AM真菌对紫云英生长的影响

通过5个土壤Cu2 水平(0,20,50,100,150mgkg-1)的盆栽试验,研究了不同土壤Cu2 水平接种AM真菌对紫云英生长的影响。结果表明:(1)随着土壤Cu2 水平升高,紫云英生物量下降,与未接种相比,接种AM真菌明显提高了紫云英的生物量,接种G.intraradices对紫云英生物量的提高比接种G.mosseae更为明显,两者间呈显著性差异。(2)随着土壤Cu2 水平升高,紫云英根段浸染率下降,菌丝琥珀酸脱氢酶、碱性磷酸酶活性也下降。(3)在相同土壤Cu2 水平接种不同的AM真菌,紫云英根段浸染率有显著差异,接种G.intraradices的紫云英根段浸染率显著高于接种G.mosseae的处理,其菌丝琥珀酸脱氢酶活性及碱性磷酸酶活性也显著高于接种G.mosseae的处理。(4)接种G.intraradices能显著抑制Cu2 从紫云英地下部分向地上部分的运转,降低Cu2 的毒害,接种G.mosseae相对促进了Cu2 的运转。以上结果显示,Cu2 污染土壤中接种G.intraradices对紫云英生长具有促进作用。     

Cadmium accumulation in sunflower plants influenced by arbuscular mycorrhiza

In order to investigate the cadmium (Cd) accumulation patterns and possible alleviation of Cd stress by mycorrhization, sunflower plants (Helianthus annuus L.) were grown in the presence or absence of Cd (20 micromol L(-1)) and inoculated or not inoculated with the arbuscular mycorrhizal fungus (AMF) Glomus intraradices. No visual symptoms of Cd phytotoxicity were observed; nevertheless, in non-mycorrhizal plants the presence of Cd decreased plant growth. The addition of Cd had no significant effect on either mycorrhizal colonization or the amount of extra-radical mycelia that was produced by the AMF. Cd accumulated mainly in roots; only 22% of the total Cd absorbed was translocated to the shoots, where it accumulated to an average of 228 mg Cd kg(-1). Although the shoot-to-root ratio of Cd was similar in both the AMF inoculated and non-inoculated plants, the total absorbed Cd was 23% higher in mycorrhizal plants. Cd concentration in AMF extra-radical mycelium was 728 microg g(-1) dry weight. Despite the greater absorption of Cd, mycorrhizal plants showed higher photosynthetic pigment concentrations and shoot P contents. Cd also influenced mineral nutrition, leading to decreased Ca and Cu shoot concentrations; N, Fe and Cu shoot contents; and increased S and K shoot concentrations. Cd induced guaiacol peroxidase activity in roots in both mycorrhizal and non-mycorrhizal plants, but this increase was much more accentuated in non-mycorrhizal roots. In conclusion, sunflower plants associated with G. intraradices were less sensitive to Cd stress than non-mycorrhizal plants. Mycorrhizal sunflowers showed enhanced Cd accumulation and some tolerance to excessive Cd concentrations in plant tissues.