植物内生菌及其次生代谢活性物质多样性的研究进展

植物内生菌是一种新型的微生物资源,具有重大的研究意义和潜在的应用价值,近年来已成为微生物资源研究的热点之一.对植物内生菌及其次生代谢活性物质多样性的研究进展进行了综述.     

植物内生菌的研究进展

植物内生菌是一种新型的微生物资源,具有重大的研究意义和潜在的应用价值,近年来成为微生物资源研究的热点之一。对植物内生菌的研究进展和生物学作用进行了综述,以期更好地了解和研究植物内生菌。     

植物内生菌在环境污染修复中的应用研究进展

植物内生细菌作为微生物学同植物微生态学的重要交叉点,近年来备受关注。国内外学者针对植物内生菌这一宝贵的微生物资源库进行了多方面的研究和探索。本文主要介绍植物内生菌的概念和特点,并重点阐述了植物内生菌在环境污染的生物修复中的应用研究动态。旨在为植物内生菌的实际应用提供新的思路。     

植物内生真菌农药活性的研究进展

植物内生真菌是一类可开发生物农药的新兴微生物资源，综述了国内外近20多年来从植物内生真菌中发现的具有抗病抗虫作用的菌株及其活性化合物，讨论了利用植物内生菌防治植物病虫害的途径、存在问题和前景展望。     

内生微生物和其在作物管理中的潜在应用

<正>1介绍1.1植物内生菌内生菌寄居在植物组织中,不引起植物病害(一般为真菌和细菌)。所有或大部分植物具有内生菌,在大多数情况下它们通过种子迁移,从植物种子发芽开始就能促进植物生长和健康。其他内生菌可能来自土壤,但对植物具有相似的有益作用。内生微生物是植物重要的部分,以以下方式影响植物:(1)使植物获得的营养增加;(2)保护植物免受病原菌和昆虫的危害;(3)增加植物对胁迫的耐受性;(4)调节     

镉污染土壤的微生物-植物协同修复研究进展

土壤重金属镉(Cd)污染是我国亟待解决的环境问题之一。植物-微生物协同修复因其原位、环保、费用低等特点在修复Cd污染土壤方面展现出较好的应用潜力。微生物通过促进重金属胁迫条件下的植物生长,提高植物对土壤Cd污染的修复效率。本文在阐述修复机理的基础上,对近年来国内外学者采用丛枝菌根真菌、根瘤菌和植物内生菌与植物协同的方法修复土壤Cd污染进行的研究进行了综述,并对今后的发展方向进行了探讨。     

亚马逊雨林发现能隆角塑料的真菌

据报道,塑料包装和塑料产品严重威胁着生命赖以生存的许多生态系统,这可能使人类陷入最大的人为环境灾难中。研究人员发现了一种可以降解塑料的真菌,从而有望帮助人类消除这个威胁。康涅狄格州耶鲁大学的一个学生科研小组在亚马逊雨林中发现一种真菌,它能降解普通的聚氨酯塑料,这是一种应用最为广泛的材料。数据显示,2007年全球消费了1200多万t聚氨酯原材料,其使用率平均每年增长约5％。研究人员在厄瓜多尔雨林搜寻植物,然后分离出内生菌。研究了这些有机体降解聚氨酯的能力,最后确认几种有机体,例如小孢拟盘多毛孢的两种不同的分离菌,它们不仅具有很强的降解能力,还可在缺氧情况下生长时以聚氨酯为唯一碳源。内生菌是生活在植物内部组织的微生物,不会使它们的宿主表现出任何明显的疾病症状。它们在植物死后发生的降解过程中常扮演关键角色。耶鲁大学研究人员表示,随着对内生菌特性研究的深入,他们会发现更多具有降解其它塑料潜力的真菌。     

微生物联合植物修复土壤重金属研究现状

经济快速发展的今天，重金属对土壤的污染已成为大家关注的焦点。高效、安全、投入低的微生物联合修复方法，是目前修复土壤重金属污染的主要方式。通过归纳总结微生物联合植物的重金属抗性机制，并对其在修复重金属污染土壤方面的应用进行了综述。现阶段对PGPR技术的研究已经较为全面，但是对于内生菌通过辅助植物修复重金属污染土壤的机制尚不明确，但是具备开发的潜力。     

樱桃番茄植株内源物质对甲基硫菌灵降解影响

[目的]甲基硫菌灵为一种广谱性内吸苯并咪唑类杀菌剂,能防治多种作物病害,具有内吸、预防和治疗作用,为了进一步了解其在植物体内的代谢降解过程。[方法]以樱桃番茄植株为载体,研究其体内微生物、常见氧化酶和生物碱3类不同物质对甲基硫菌灵降解代谢的影响。[结果]植物内生菌对甲基硫菌灵有缓慢的降解作用;过氧化物酶、过氧化氢酶和超氧化物歧化酶处理的试验中甲基硫菌灵分别降解了35.55%、23.20%、27.43%。葫芦巴碱也可显著加速甲基硫菌灵的降解。[结论]植物对农药有其自身的代谢解毒过程。     

敌草隆内生降解真菌筛选

[目的]筛选可降解敌草隆菌株,并研究其降解特性,为微生物降解敌草隆提供新途径。[方法]采用平板涂布法从植物体内分离内生真菌,并通过摇瓶富集法筛选有降解作用的菌株;通过形态学特征和ITS鉴定菌株;采用高效液相色谱法检测分离的内生菌对敌草隆的降解效果,并研究其降解的最适温度、pH值、营养源和降解动力学特性。通过标准品比对鉴定降解产物。[结果]从牛筋草中分离得到一株具有降解除草剂敌草隆能力的真菌,命名为D12,鉴定为镰刀菌属(Fusarium Lk.ex Fr.)。降解条件优化试验结果表明,该菌的最佳营养源为淀粉,在35℃和pH值6的条件下对敌草隆具有良好降解作用。以敌草隆50 mg/L为起始质量浓度进行研究,经过7 d培养,降解率达57.42%,半衰期为7.30 d。鉴定其降解产物为1-(3,4-dichlorophenyl)methylurea。[结论]镰刀菌属D12具有降解敌草隆得能力,在微生物降解除草剂领域具有良好的应用前景。     

葛根内生菌的分离及其发酵产物抗氧化活性的初步研究

从健康葛根植株的根、茎、叶中分离到11株内生菌,通过聚酰胺薄层层析检测到其中有两株内生菌（S1和S2）的乙醇提取液分别有2条和1条层析带与葛根乙醇提取物的层析带比移值相当,并以总还原力等体外抗氧化模型分别测定了内生菌S1和S2乙醇提取液的抗氧化性,得出结果：内生菌S1的抗氧化性较S2强。     

Isolate-Specific Effect of Entomopathogenic Endophytic Fungi on Population Growth of Two-Spotted Spider Mite (Tetranychus urticae Koch) and Levels of Steroidal Glycoalkaloids in Tomato

Journal of Chemical Ecology - Entomopathogenic fungi (EPF) can be experimentally established in several plant species as endophytes. Ecological effects of EPF inoculations on plant growth and...     

Different Levels of Protective Alkaloids in Grasses with Stroma-forming and Seed-transmitted Epichloë/Neotyphodium Endophytes

The three alkaloid groups—lolines, ergopeptides, and peramine— are typically associated with endophyte infection of grasses, with the main function to protect hosts against herbivores. We determined levels of N-formylloline, N-acetylloline, ergovaline, and peramine in 18 European grasses naturally infected with seed-transmitted Neotyphodium endophytes or sexual Epichloë species. Peramine was the most common alkaloid, whereas lolines and ergovaline were only detected in Festuca hosts infected with E. festucae, N. coenophialum, or N. uncinatum. Only ten of the grass species analyzed contained detectable amounts of one or more of these alkaloids. There was a clear tendency for plants associated with stroma-forming Epichloë species to be free of alkaloids, and those that did produce alkaloids contained only small levels of peramine. In contrast, plants infected with seed-transmitted Neotyphodium endophytes often contained extremely high levels of lolines. Lolines enhance host survival through increased protection from herbivores and, thus, may be particularly favored in asexual endophytes that depend on host seed-production for their dispersal.     

Symptomless Endophytic Fungi Suppress Endogenous Levels of Salicylic Acid and Interact With the Jasmonate-Dependent Indirect Defense Traits of Their Host,Lima Bean (Phaseolus lunatus)

Symptomless ‘type II’ fungal endophytes colonize their plant host horizontally and exert diverse effects on its resistance phenotype. Here, we used wild Lima bean (Phaseolus lunatus) plants that were experimentally colonized with one of three strains of natural endophytes (Bartalinia pondoensis, Fusarium sp., or Cochliobolus lunatus) to investigate the effects of fungal colonization on the endogenous levels of salicylic acid (SA) and jasmonic acid (JA) and on two JA-dependent indirect defense traits. Colonization with Fusarium sp. enhanced JA levels in intact leaves, whereas B. pondoensis suppressed the induction of endogenous JA in mechanically damaged leaves. Endogenous SA levels in intact leaves were significantly decreased by all strains and B. pondoensis and Fusarium sp. decreased SA levels after mechanical damage. Colonization with Fusarium sp. or C. lunatus enhanced the number of detectable volatile organic compounds (VOCs) emitted from intact leaves, and all three strains enhanced the relative amount of several VOCs emitted from intact leaves as well as the number of detectable VOCs emitted from slightly damaged leaves. All three strains completely suppressed the induced secretion of extrafloral nectar (EFN) after the exogenous application of JA. Symptomless endophytes interact in complex and strain-specific ways with the endogenous levels of SA and JA and with the defense traits that are controlled by these hormones. These interactions can occur both upstream and downstream of the defense hormones.     

Influence of different P sources on the efficiency of several tropical endomycorrhizal fungi in promoting the growth ofZea mays L.

The effect of inoculation with fourteen endomycorrhizal species belonging to the generaGigaspora, Scutellospora, Glomus, Acaulospora andEntrophospora on the growth of maize (Zea mays L.) was evaluated under glasshouse conditions in an unsterilized tropical virgin soil using two P sources with different solubility. In both P treatments the population of indigenous mycorrhiza species was not affected and growth of maize was enhanced. Introducing VAM species additionally modified the growth pattern of maize. Using a low-grade rock phosphate (Patos de Minas) from Brazil all endophytes with exception ofGigaspora margarita, Scutellospora verrucosa, Scutellospora gregaria, Entrophospora colombiana andGlomus pallidum improved shoot dry weight. In the treatment with single superphosphate, dry matter production was not significantly enhanced byGigaspora margarita, Gigaspora gigantea, Scutellospora verrucosa, Scutellospora reticulata, Scutellospora gilmorei andGlomus manihotis. When rock phosphate was added root fresh weights were enhanced only by three endophytes (Gigaspora margarita, Gigaspora gigantea andAcaulospora rehmii); with single superphosphate none had a significant effect. The percentage of P in shoots was almost equal in non-inoculated and inoculated plants and yield responses did not always follow the pattern of P uptake. Mycorrhizal root infection was always highest in the treatment with single superphosphate and in most cases a correlation with plant growth was found. The present results show that introduced vesicular arbuscular mycorrhiza species differently promote growth of maize according to their adaptability to the P source and to their capability to compete with native VAM endophytes.     

Bioactive Alkaloids from Plants Poisonous to Livestock in North America

Plants produce a multiplicity of chemical compounds which have a variety of uses including flavors, fragrances, insecticides, dyes, poisons, and pharmaceutical agents. In this review, we focus on plant alkaloids from the genera Delphinium, Lupinus, Conium, Nicotiana, Veratrum, and selected plant endophyte derived alkaloids. Alkaloids discussed include norditerpenoid alkaloids which act as antagonists to block the ligand binding sites of nicotinic acetylcholine receptors and cause acute toxicosis in adult animals which can result in death. The inhibition of fetal movement and resulting fetal defects caused by quinolizidine and piperidine alkaloids, the inhibition of the hedgehog (Hh) signaling pathway by Veratrum alkaloids, and compounds derived from fungal endophytes that form symbioses with plant hosts will be also be discussed. The bioactivity of these alkaloids makes them useful tools for research and in human and veterinary medicine or potentially harmful toxins.     

Putative LysM Effectors Contribute to Fungal Lifestyle

Fungal LysM effector proteins can dampen plant host–defence responses, protecting hyphae from plant chitinases, but little is known on these effectors from nonpathogenic fungal endophytes. We found four putative LysM effectors in the genome of the endophytic nematophagous fungus Pochonia chlamydosporia (Pc123). All four genes encoding putative LysM effectors are expressed constitutively by the fungus. Additionally, the gene encoding Lys1—the smallest one—is the most expressed in banana roots colonised by the fungus. Pc123 Lys1, 2 and 4 display high homology with those of other strains of the fungus and phylogenetically close entomopathogenic fungi. However, Pc123 Lys3 displays low homology with other fungi, but some similarities are found in saprophytes. This suggests evolutionary divergence in Pc123 LysM effectors. Additionally, molecular docking shows that the NAcGl binding sites of Pc123 Lys 2, 3 and 4 are adjacent to an alpha helix. Putative LysM effectors from fungal endophytes, such as Pc123, differ from those of plant pathogenic fungi. LysM motifs from endophytic fungi show clear conservation of cysteines in Positions 13, 51 and 63, unlike those of plant pathogens. LysM effectors could therefore be associated with the lifestyle of a fungus and give us a clue of how organisms could behave in different environments.