AM真菌诱导的番茄信号物质及其对根结线虫的 抑制 效应

丛枝菌根(AM)真菌能诱导植物合成一些信号物质,如茉莉酸(JA)、水杨酸(SA)、一氧化氮(NO)、H2O2等,这些信号在AM真菌与植物识别、共生体建立和激活植物防御系统过程中发挥着重要作用[1].     

摩西球囊霉对紫花苜蓿烟色织孢霉根腐病的影响

紫花苜蓿Medicago sativa是一种优质的多年生豆科牧草,素有"牧草之王"的美称。根腐病是紫花苜蓿生产中的主要限制因素,可抑制植物生长,严重时导致植物死亡,造成巨大的经济损失。丛枝菌根真菌（Arbuscular mycorrhizal fungi,AM）广泛存在于农业系统中,可与植物根系形成内生菌根,提高宿主植物对营养元素和水分的吸收,增加植物产量和抗逆性。本研究以紫花苜蓿为试验材料,探究接种AM真菌摩西球囊霉Glomus mosseae对紫花苜蓿根腐病烟色织孢霉Microdochium tabacinum的影响。结果表明,摩西球囊霉可抑制烟色织孢霉的侵染,植株发病率降低了20.78%;病原菌的侵染显著抑制紫花苜蓿根系生长和养分吸收,植物地下生物量降低12.87%,根长降低20.52%,根系P含量降低了18.29%,丙二醛（MDA）含量提高了12.78%;AM真菌可以缓解病原菌的危害,促进紫花苜蓿生长,与不接种AM真菌的处理相比,地上生物量、地下生物量、根长分别提高了47.77%,38.67%和20.67%;防御酶超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性分别提高了42.25%、26.05%和33.62%;地上部分和地下部分P含量分别提高了58.63%和75.38%。     

AM真菌对加拿大一枝黄花与菌根植物和非菌根植物种间作用的影响

为明确丛枝菌根(arbuscular mycorrhizal,AM)真菌对加拿大一枝黄花Solidago canadensis与本地菌根植物和非菌根植物种间竞争格局的调控作用,采用温室盆栽试验,通过接种摩西球囊霉Glomus mosseae(GM)、根内球囊霉G. intraradices(GI)及其混合菌种(GM+GI)3种处理,分析AM真菌对加拿大一枝黄花与本地菌根植物玉米Zea mays和非菌根植物油菜Brassica campestris种间作用的影响。结果表明:与对照相比,接种AM真菌均显著提高了加拿大一枝黄花和玉米的菌根侵染率,菌根侵染率为13.720%～50.015%,且前者的菌根侵染率明显高于后者。单独种植时,与对照相比,接种AM真菌尤其是接种混合菌种显著提高了加拿大一枝黄花的株高、叶片数和总干重。在加拿大一枝黄花与玉米混合种植时,与单独种植相比,加拿大一枝黄花的株高、叶片数、根长和总干重均较低;同时,与对照相比,接种AM真菌显著提高了玉米的相对竞争强度而对加拿大一枝黄花的相对竞争强度没有显著影响。在加拿大一枝黄花和油菜混合种植时,与对照相比,接种AM真菌则显著提高了加拿大一枝黄花的株高、叶片数、净光合速率和总干重;同时,接种AM真菌促进了入侵种的竞争优势而抑制了非菌根植物油菜的生长。说明加拿大一枝黄花与本地种的竞争格局受到与之混生物种的菌根依赖性强度以及AM真菌的种类差异影响。     

无毒稻瘟菌株AM16诱导水稻稻瘟病抗性研究

利用病原菌无毒或弱毒菌株诱导植物抗病性是植物病害生物防控的重要研究方向。前期研究中,鉴定了一株对所有测试水稻都不致病的无毒稻瘟菌株AM16。本研究通过AM16菌株与致病稻瘟菌株对峙培养试验结果表明,AM16菌株对致病稻瘟菌株生长无拮抗作用。利用AM16培养液处理水稻幼苗,能显著增强水稻植株的稻瘟病抗性,处理后48～72 h抗性最强。温室和大田试验结果表明,喷施AM16培养液能增强分蘖期和抽穗期水稻植株的抗瘟性,防效在40%以上。进一步研究发现,AM16培养液处理的水稻植株,体内防御相关酶PPO、PAL、SOD、POD、APX和CAT活性有不同程度的上升,SA和JA通路关键基因（Os PAL1、Os NPR1和Os AOS2）和防御相关基因（Os Chit1、OsPR10b、Os PR1a和OsPR1b）表达上调。该研究为AM16菌株在稻瘟病生物防治中的开发利用奠定了重要基础。     

AM真菌和根结线虫互作对黄瓜生长及生理特征的影响

通过盆栽试验研究了丛枝菌根真菌Arbuscularmycorrhiza（AM）和南方根结线虫Meloidogyneincognita互作对黄瓜幼苗生长及生理特征的影响。结果表明,预先接种地表球囊霉Glomusversi—forme再接种线虫处理的鲜、干重较只接种线虫的处理显著增加;预先接种AM真菌再接种线虫处理的根结线虫病情指数、AM真菌侵染率较只接种线虫的处理明显降低;接种线虫使黄瓜植株的过氧化物酶（POD）、过氧化氢酶（CAT）及苯丙氨酸解氨酶（PAL）、总酚含量有不同程度提高,其中预先接种根内球囊霉G．intraradices对黄瓜植株起到了较好的保护作用;与对照相比,只接种线虫处理的叶片磷含量降低了25．26％,预先接种AM真菌再接种线虫处理的叶片磷含量较只接种根结线虫的含量高。     

丛枝菌根(AM)与桃树根癌病关系初探

通过对上海市奉贤区桃树果园调查发现,桃树丛枝菌根(AM)的形成与根癌病的发生表现出一定的相互抑制作用。根据不同时间、顺序对桃树苗木人工接种根癌土壤杆菌(Agrobactium tumefaciens)和摩西球囊霉(Glomus mosseae),结果表明桃树苗木形成AM后可以抑制根癌病的发生,反之苗木感染根癌病后也降低了AM真菌对根的侵染和在根内的扩展,对苗木同时接种Agrobactium tumefaciens和Glomus mossea时,病原菌要优先于AM真菌侵染寄主并形成病害。AM提高了苗木根系内与抗病性相关的过氧化物酶和多酚氧化酶活性。     

荒漠生态系统中丛枝菌根真菌多样性

到目前为止,在全球荒漠生态系统中,共报道了69个科389种丛枝菌根真菌的寄主植物,其中,Compositae,Gramineae和Leguminosae 3个科的植物为荒漠生态系统中丛枝菌根真菌寄主植物的优势类群;共发表了7个属的89种丛枝菌根真菌,其中,Acaulospora和Glomus 属的真菌为荒漠生态系统中的优势类群.在此基础上,分析了荒漠生态系统中AM真菌多样性研究中存在的问题,并探讨了荒漠生态系统中AM真菌的研究方向.     

泡囊——丛枝菌根生态学研究进展

泡囊－－丛枝菌根（ＶＡ菌根）是广泛分布的一类内生菌根，能够促进寄主对土壤中矿质元素的吸收，调节寄主体内的代谢活动，增强植物的抗逆性，有利于植物生长。综合有关研究资料，论述了近年来关于泡囊－－丛枝菌根真菌的有效性，寄主特性及土壤环境条件等生态因子对泡囊－－丛枝菌根效应影响等方面的研究进展和取得的成就，泡囊－－丛枝菌根生态学研究的发展方向为自然及农业大生态和微环境生态。     

极细链格孢蛋白激发子诱导棉花抗病性及相关酶的变化

本研究室从多种病原真菌中分离出的激活蛋白激发子对多种植物具有诱导抗病性、增强抗逆能力、促进植物生长的功能。由大丽轮枝菌（Verticillium dahliae）引起的棉花黄萎病一直是困扰棉花生产的重大病害，常规化学农药难以达到理想的防治效果。本文研究极细链格孢（Alterneria tenuissima）蛋白激发子对苗期棉花黄萎病的诱导抗性作用及抗病相关酶的影响。     

丛枝菌根真菌对接种尖孢镰刀菌后黄瓜 根系次生代谢物的影响

采用灌根法对4周龄的黄瓜幼苗接种尖孢镰刀菌Fusarium oxysporum f.sp.cucumerinum,研究了不同取样时期AM真菌Glomus versiforme对植株根系黄酮和总酚含量及叶片中POD和PPO酶活性的影响.结果表明:菌根化植株可通过生物量的补偿和体内次生代谢物含量的改变来提高抗病性.即接种F.oxysporum f. sp. cucumerinum的第9天,菌根化植株根系和地上部生物量分别比对照高出50%和31.7%,此时,对照发病率达15%,而菌根化植株生长始终正常;在病原菌的侵入初期和后期,菌根化植株根系中黄酮和总酚含量高于对照;在植株发病期,菌根化植株仍可通过根系中含量相对较低的黄酮和总酚来抵御病原菌的侵害;与对照相比,抗病性较强的菌根化植株叶片中POD酶活性变化较为缓和,且PPO酶活性一直较高.     

Regulation of biosynthesis,perception, and functions of strigolactones for promoting arbuscular mycorrhizal symbiosis and managing root parasitic weeds

Strigolactones (SLs) are carotenoid‐derived plant secondary metabolites that play important roles in various aspects of plant growth and development as plant hormones, and in rhizosphere communications with symbiotic microbes and also root parasitic weeds. Therefore, sophisticated regulation of the biosynthesis, perception and functions of SLs is expected to promote symbiosis of beneficial microbes including arbuscular mycorrhizal (AM) fungi and also to retard parasitism by devastating root parasitic weeds. We have developed SL mimics with different skeletons, SL biosynthesis inhibitors acting at different biosynthetic steps, SL perception inhibitors that covalently bind to the SL receptor D14, and SL function inhibitors that bind to the serine residue at the catalytic site. In greenhouse pot tests, TIS108, an azole‐type SL biosynthesis inhibitor effectively reduced numbers of attached root parasites Orobanche minor and Striga hermonthica without affecting their host plants; tomato and rice, respectively. AM colonization resulted in weak but distinctly enhanced plant resistance to pathogens. SL mimics can be used to promote AM symbiosis and to reduce the application rate of systemic‐acquired resistance inducers which are generally phytotoxic to horticultural crops. © 2019 Society of Chemical Industry     

植物内生真菌及其展望

内生真菌在自然界广泛存在,有些内生真菌可以促进植物营养吸收、提高植物抗生物逆境和非生物逆境的能力、刺激植物产生活性物质等。因此,内生真菌是植物病虫害生物防治领域的重要研究内容之一。本文就内生真菌与寄主共生的分子基础、内生真菌对植物影响机制、内生真菌与寄主特异性相互作用、特殊的内生真菌--植物病原真菌、内生真菌形成的分子机制和内生真菌研究展望等6个方面对内生真菌进行了叙述,期望为科学地利用内生真菌资源提供一些参考。     

Parasitic plant infection is partially controlled through symbiotic pathways

Legumes are unique in interacting with Rhizobium , arbuscular mycorrhizal (AM) fungi, and parasitic plants. To dissect common parts of these three plant–organism interactions, infection by Orobanche crenata was studied in mutants with altered symbiotic phenotypes of Medicago truncatula and Pisum sativum . Orobanche crenata inoculation of mutant lines carrying defective mutation in the genes dmi2 / sym19 and dmi3 resulted in an increase in O. crenata establishment. Similarly, inoculation of mutants carrying mutation in the gene sunn / sym29 that controls the autoregulation mechanism of the symbiosis, also lead to a significant increase in haustoria formation. Altogether, our results suggest that parasitic plant infection is partly controlled by both the conserved symbiotic pathway that mediates symbiont recognition and establishment and the autoregulation mechanism that regulates the extent of colonisation by Rhizobium and AM fungi.     

Role of methyl jasmonate in the expression of mycorrhizal induced resistance against Fusarium oxysporum in tomato plants

Arbuscular mycorrhiza (AM) colonization led to a decrease in the severity of fusarium wilt disease caused by Fusarium oxysporum f. sp. lycopersici in tomato plants. The involvement of two plant defense hormones, namely methyl jasmonate (MeJA) and salicylic acid (SA), in the expression of mycorrhiza induced resistance (MIR) against this vascular pathogen was studied in the AM colonized and non-colonized (controls) plants. Activity of lipoxygenase (LOX), which plays a role in jasmonic acid (JA) biosynthesis, as well as levels of methyl jasmonate (MeJA) increased in AM colonized plants as compared to controls, but did not show any further changes in response to F. oxysporum inoculation. On the other hand, activity of phenylalanine ammonia lyase (PAL), which is an enzyme from salicylic acid (SA) biosynthetic pathway, as well as SA levels, increased in both controls and AM colonized plants in response to application of F. oxysporum spores. Hence the JA and not the SA signalling pathway appeared to play a role in the expression of MIR against this vascular pathogen. The resistance observed in AM colonized plants was completely compromised when plants were treated with the JA biosynthesis inhibitor salicylhydroxamic acid (SHAM). This confirmed that the AM-induced increase in JA levels was involved in the expression of resistance toward F. oxysporum. The SA response gene pathogenesis-related 1 (PR1) showed an increased expression in response to F. oxysporum infection in SHAM treated AM colonized plants as compared to plants that were not treated with this JA inhibitor. This suggested the possibility that JA inhibited SA responses, at least in the roots. AM colonization therefore appeared to prime plants for improved tolerance against the vascular pathogen F. oxysporum, which was mediated through the JA signalling pathway.     

A semiaxenic phototrophic system to study interactions between arbuscular mycorrhizal and pathogenic fungi in woody plants

Among other benefits, arbuscular mycorrhizal (AM) fungi may increase plant tolerance to root diseases. The research on the underlying mechanisms requires growth conditions that are both controlled and realistic. To study these interactions, a semiaxenic phototrophic system was developed in which the roots grow in a controlled environment and can be inoculated with both pathogenic and symbiotic fungi. Micropropagated fig plantlets were grown in containers having shoots in the outside and roots in a growth medium without sugar, inoculated or not with the AM fungus Rhizophagus irregularis and the pathogenic fungus Armillaria mellea. Dual inoculated plants developed the mycorrhizal association and pathogen infection symptoms. Mycorrhizal inoculation lowered disease index and increased plant growth. Colonization of A. mellea in fig roots was quantified by real-time PCR, showing that R. irregularis did not significantly lower the quantity of Armillaria, suggesting that other mechanisms were involved in increased tolerance to the pathogen. The results show that the system proposed is suitable to study the triple interaction involving plant, AM and root pathogenic fungi.     

接种丛枝菌根对玉米生长与抗旱性的影响

采用盆栽试验,研究了水分胁迫下接种丛枝菌根真菌对玉米生长及其抗旱性的影响。结果表明:玉米与丛枝菌根可形成良好的共生关系,接种丛枝菌根显著提高了玉米生物量、株高、地径。与未接菌相比,接菌提高了植株水分利用效率,水分胁迫和正常供水条件下,较对照分别提高117%和24.6%。接菌后玉米叶片SPAD值和可溶性蛋白含量增加,叶片过氧化氢酶活性增强。同时,接种菌根显著降低了植株叶片脯氨酸、丙二醛含量,干旱胁迫和正常供水条件下,较未接菌处理分别降低了14.1%、18.9%和59%、69%。由此可见,接种丛枝菌根真菌能够促进玉米的生长,缓解干旱胁迫对玉米生长造成的不利影响,提高了玉米的抗旱性。     

Arbuscular mycorrhizal fungal colonization of Glycyrrhiza glabra roots enhances plant biomass,phosphorus uptake and concentration of root secondary metabolites

Arbuscular mycorrhizal(AM)fungi penetrate the cortical cells of the roots of vascular plants,and are widely distributed in soil.The formation of these symbiotic bodies accelerates the absorption and utilization of mineral elements,enhances plant resistance to stress,boosts the growth of plants,and increases the survival rate of transplanted seedlings.We studied the effects of various arbuscular mycorrhizae fungi on the growth and development of licorice(Glycyrrhiza glabra).Several species of AM,such as Glomus mosseae,Glomus intraradices,and a mixture of fungi(G.mosseae,G.intraradices,G.cladoideum,G.microagregatum,G.caledonium and G.etunicatum)were used in our study.Licorice growth rates were determined by measuring the colonization rate of the plants by the fungi,plant dry biomass,phosphorus concentration and concentration of secondary metabolites.We established two cloned strains of licorice,clone 3(C3)and clone 6(C6)to exclude the effect of genotypic variations.Our results showed that the AM fungi could in fact increase the leaf and root biomass,as well as the phosphorus concentration in each clone.Furthermore,AM fungi significantly increased the yield of certain secondary metabolites in clone 3.Our study clearly demonstrated that AM fungi play an important role in the enhancement of growth and development of licorice plants.There was also a significant improvement in the secondary metabolite content and yield of medicinal compounds from the roots.     

Costs and trade-offs associated with induced resistance

Plants resist attack by pathogens and herbivorous insects through constitutive and inducible defences. Based on differences in signalling pathways and spectra of effectiveness, different types of induced resistance have been defined. Systemic acquired resistance (SAR) occurs in distal plant parts following localized infection by a necrotizing pathogen. It is controlled by a signalling pathway that depends upon the accumulation of salicylic acid (SA) and the regulatory protein NPR1. In contrast, induced systemic resistance (ISR) is induced by selected strains of non-pathogenic plant growth promoting bacteria (PGPR). ISR functions independently of SA, but requires NPR1 and is regulated by jasmonic acid (JA) and ethylene (ET). It is generally believed that induced resistance evolved to save energy under pathogen or insect-free conditions, although costs still arise when defences are activated following attack. Costs can arise from the allocation of resources to defence and away from plant growth and development, and there are also ecological costs which result from trade-offs between induced resistance and the plant's interaction with beneficial organisms e.g. mycorrhizal fungi. To date, few studies have examined the costs and trade-offs associated with induced resistance to pathogens. There is a clear need for long-term studies of costs and trade-offs associated with induced resistance in crops under commercial conditions. Without such information, the potential offered by induced resistance is unlikely to be realized.