植物病原菌的生物控制

植物病害的生物防治,对保证充分利用各种防治方法具有广泛的意义。生物防治策略包括三项关键措施,即控制害虫种群数量、排除害虫及作物的自身防御。这些措施为植保工作者进行生物防治研究提供了重要的理论依据。植物、昆虫与微生物之间相互联系的生态学,是生物防治的一个重要领域,更深刻地理解这些生物的生态学有助于发现更实际的生物控制因子。     

番茄内生细菌的分离及拮抗菌株的筛选

生物防治以其安全、高效及无污染等特点已经成为植物病害防治的重要途径。植物内生细菌在植物体内具有稳定的生存空间、不易受外界环境的影响等特点,近年来受到广泛关注[1]。番茄灰霉病和叶霉病是番茄重要病害,多年来一直依赖化学药剂防治。据报道,这两种病害的生防菌株主要是从土壤中分离的,与植物内生细菌相比,这些“外来”微生物在与植物根际土壤中大量习居微生物的竞争中难以占居优势,田间防治效果大多不明显甚至无效。作者从健康番茄植株体内分离内生细菌,筛选出对灰霉病菌和叶霉病菌有拮抗作用的菌株,以期探索新的生物防治途径。1材料…     

用重寄生菌防治植物病害

本文对国内外已发现的重寄生菌和种类及其寄生于靶标植物病原真菌的类群作了简要概述，分析了利用重寄生菌进行植物病害生物防治方面存在的问题，并提出了解决途径，最后展望了植物病害生物防治中应用重寄生菌的前景。     

绿僵菌与植物的多重关系及其在植物保护中的应用潜力

绿僵菌是广为知晓的昆虫病原真菌,被用作生物杀虫剂防治多种农林植物害虫。近年发现它也是根际微生物群落的一员,且有证据表明它内生于一些植物的根组织中,具有促进植物生长、拮抗植物病原菌、诱导植物抗性等作用。本文着重综述绿僵菌根际作用和植物内生性研究进展,从对植物的直接作用角度,了解其田间生态适应性及与植物的互作关系,以拓展昆虫病原真菌作为植物保护剂的认识,有助于根据生态学特点制定未来的生物防治应用策略。     

烟草青枯病内生拮抗菌的筛选、鉴定及其防效测定

 植物体内的大量微生物,在进化的过程中,由于长期生活在植物特定部位,因而与植物形成了一种特殊的关系,这些微生物在植物体内大量繁殖和扩散,有望成为生物防治有潜力的微生物。内生细菌是植物体内大量存在的微生物之一,具有在植株体内分布广、定殖能力强、防效好以及增殖和扩散快等优点,因而成为发展前景很好的植物病害生防菌。     

木霉在植物病害生物防治中的应用及作用机制

木霉是植物病害生物防治中应用和研究非常广泛的一类生防真菌。本文阐述了木霉在多种植物病害防治上的应用及防治效果，并概括了木霉在生防过程中对植物病原物的生防机制，包括竞争、重寄生、抗生作用等，以及木霉与植物互作中对植物促生和诱导植物抗性的机制。目前，世界上含木霉的商品化制剂已超过250种，在不同国家地区都取得了良好的防治效果，更多的优秀生防木霉菌株也在通过野生菌株筛选或遗传改良等方式开发。木霉生物防治及机制研究对推广生物防治和减少化学农药有重要意义。     

多粘类芽胞杆菌WY110对西瓜枯萎病的控制作用

西瓜枯萎病是由尖孢镰刀菌西瓜专化型引起的西瓜毁灭性土传病害,生产上主要采用药剂防治。由于病原菌的抗药性不断增强,利用拮抗菌对植物病害的生物防治越来越受到重视。目前,已有很多多粘类芽胞杆菌Paenibacillus polymyxa菌株用于植物病害的生物防治。     

角毛壳菌生物防治相关基因的筛选

采用环保的生物防治技术取代传统的化学防治技术已经在植物病害防治领域中达成共识。角毛壳菌（Chaetomium cupreum）属于子囊菌亚门毛壳菌属，是一种有效的生物防治菌，对一些常见的植物病原菌的防治效果好，例如：粉红镰刀菌（Fusarium roseum）、苹果黑星菌（Venturia inequalis）、稻梨孢（Pyricularia oryzae）、灰葡萄孢（Botrytis cinerea）等。     

真菌病毒减弱寄主致病性机理及其生防应用

真菌病毒是在真菌体内复制和增殖的病毒,在真菌中广泛存在。农业生产中70%~80%的植物病害由病原真菌侵染导致,真菌病毒能够减弱植物病原真菌的致病性,还可以将其转换为内生真菌从而促进植物生长和抗病,因此真菌病毒是一类重要的生防资源。本文综述了真菌病毒减弱寄主致病性机理及其在病害防治中的应用,同时提出了真菌病毒用于生物防治的前景和面临的问题,为植物真菌病害的生物防治提供参考。     

植物病害生防因子的作用机制及应用进展

应用植物病害生防因子是解决化学农药3R问题、促进农业绿色发展的有效途径。本文概述了拮抗微生物、抗生素、植物诱导子等生防因子控制植物病害的作用机制和应用研究进展,分析了生防因子应用存在的问题,并对植物病害生物防治的未来发展方向进行了展望。     

Ecology of Bacillus and Paenibacillus spp. in Agricultural Systems

ABSTRACT Diverse populations of aerobic endospore-forming bacteria occur in agricultural fields and may directly and indirectly contribute to crop productivity. This paper describes recent advances in our understanding of the ecology of Bacillus and Paenibacillus spp. and how different subpopulations of these two genera can promote crop health. The abundance, diversity, and distribution of native populations and inoculant strains in agricultural fields have been characterized using a variety of methods. While native populations of these two genera occur abundantly in most agricultural soils, plant tissues are differentially colonized by distinct subpopulations. Multiple Bacillus and Paenibacillus spp. can promote crop health in a variety of ways. Some populations suppress plant pathogens and pests by producing antibiotic metabolites, while others may directly stimulate plant host defenses prior to infection. Some strains can also stimulate nutrient uptake by plants, either by promoting rhizobial and mycorrhizal symbioses or by fixing atmospheric nitrogen directly. Despite a wealth of new information on the genetics and physiology of Bacillus and related species, a better understanding of the microbial ecology of these two genera must be developed. To this end, several important, but unanswered, questions related to the ecological significance and potential for managing the beneficial activities of these bacteria are discussed.     

油茶炭疽菌侵染对油茶叶片内生细菌群落结构的影响

植物内生菌与植物长期共存,二者协同进化,互惠互利。在胁迫因素的影响下,内生菌群落组成会发生相应的变化并对植物起到重要的保护作用。然而,关于病原菌胁迫对油茶树叶片内生细菌群落结构的影响尚缺乏系统的研究。为了解云南油茶受炭疽病菌侵染后,叶片内生微生物群落如何参与植物防御,本文基于高通量测序技术,对炭疽菌生物胁迫下云南油茶病、健叶片内生菌群的群落组成和多样性进行分析;基于Bugbase软件对菌群的表型进行预测。结果表明,炭疽菌侵染后显著提高了Chao1、ACE丰富度指数,而多样性指数Simpson、Shannon则无显著变化。门水平上,病、健叶片上相对丰度大于1%的种类相同,但所有门的丰度都表现为病叶高于健叶。属水平上,病叶片中Methylobacterium(1.91%)属相对丰度最高,健康叶片中Pontibacter(1.41%)相对丰度最高。感病叶片中有5个特有属,健康叶片中有3个特有属。Bugbase菌群功能预测表明,云南油茶感病叶片内生菌菌群生物膜形成能力和氧化胁迫耐受增强;革兰氏阳性菌的相对丰度增加,革兰氏阴性菌相对丰度降低。可见,油茶炭疽病的发生改变了油茶树叶片内生细菌的群落结构,使少数抗病相关物种优势生长。研究结果为油茶炭疽病的生物防治提供了信息。     

昆虫病原线虫共生细菌对植物病原菌的抑制作用

昆虫病原线虫共生细菌能够产生多种次生代谢产物,如抑菌物质、杀虫蛋白和胞外酶等。其中产生抗生素是共生细菌的普遍特征,并且其代谢产物对多种植物病原菌具有抑制作用,特别是对疫霉具有较好的拮抗作用。对共生细菌的有效抑菌成分进行分离提取,有助于发现新的抗生素。本文综述了昆虫病原线虫共生细菌对植物病原菌的抑制作用以及抑菌作用活性物质的种类、致病机理、产生条件等方面的研究进展。     

植物病原细菌的VBNC状态研究进展

 有活力但不可培养状态（Viable But Non-Culturable,VBNC）被认为是细菌对不良环境条件的一种抗逆反应,包括5种植物病原细菌在内的数十种细菌已报道具有VBNC状态。这种特定的生理状态已经导致细菌学研究中一些方法的探索和改进,对基于分离培养的植物病原细菌学研究产生了重大影响。本文对已经报道VBNC状态的植物病原细菌进行了综述,介绍了VBNC状态细菌的诱导因素、恢复条件、致病性、检测方法等方面的研究进展,对未来植物病原细菌的VBNC研究提出了展望。     

光合细菌的农用微生物功能解读

光合细菌是能利用细菌叶绿素进行光合自养型生长的一类微生物总称,也是植物表面与土壤微生物群落的一个重要组成部分。光合细菌通过自身的特征代谢活动,参与植物的养分摄取、生长发育、抵御逆境等过程,是农田生态系统中与植物以及其他微生物关系密切的有益微生物。本文介绍了光合细菌在农业上植物营养、促生、抗逆、病害防控等方面的功能,阐述了光合细菌通过生物固氮、磷酸盐溶解、重金属固定、植物激素与生长调节剂合成、抗生物质合成、植物免疫诱导等方式维护植物与土壤健康。作为一类代谢功能多样、分布广泛、环境适应能力强,且与植物生长密切相关的微生物,光合细菌将是新型多功能微生物肥料与微生物农药开发的重要菌种资源。     

Pathogenicity and virulence factors of Pseudomonas syringae

In 1994, Oku reported that plant pathogens, mainly fungal pathogens, require three essential abilities to infect plants: to enter plants, to overcome host resistance, and to evoke disease. Because the infectious process of phytopathogenic bacteria differs from that of fungal pathogens, we have attempted to characterize pathogenicity, the ability of a pathogen to cause disease, using the phytopathogenic bacterium Pseudomonas syringae as a representative pathogen. To establish infection and incite disease development, bacteria first have to enter a plant. This process requires flagella- and type IV pili-mediated motility, and active taxis is probably necessary for effective infection. After bacteria enter a plant’s apoplastic spaces, they need to overcome host plant resistance. To do this, they secrete a wide variety of hypersensitive response and pathogenicity (Hrp) effector proteins into the plant cytoplasm to interfere with pathogen/microbe-associated molecular pattern- and effector-triggered immunity, produce phytohormones and/or phytotoxins to suppress plant defense responses and extracellular polysaccharides to prevent access by antibiotics and to chelate Ca²⁺, and activate the multidrug resistance efflux pump to extrude antimicrobial compounds for successful colonization. Furthermore, to evoke disease, bacteria produce toxins and Hrp effectors that compromise a plant’s homeostasis and injure plant cells. The expression of these virulence factors depends on the infection processes and environmental conditions. Thus, the expression and function of virulence factors interact with each other, creating complex networks in the regulation of bacterial virulence-related genes.     

Induced Systemic Resistance by Fluorescent Pseudomonas spp

ABSTRACT Fluorescent Pseudomonas spp. have been studied for decades for their plant growth-promoting effects through effective suppression of soilborne plant diseases. The modes of action that play a role in disease suppression by these bacteria include siderophore-mediated competition for iron, antibiosis, production of lytic enzymes, and induced systemic resistance (ISR). The involvement of ISR is typically studied in systems in which the Pseudomonas bacteria and the pathogen are inoculated and remain spatially separated on the plant, e.g., the bacteria on the root and the pathogen on the leaf, or by use of split root systems. Since no direct interactions are possible between the two populations, suppression of disease development has to be plant-mediated. In this review, bacterial traits involved in Pseudomonas-mediated ISR will be discussed.     

Identification and sensitive endophytic detection of the fire blight pathogen Erwinia amylovora with 23S ribosomal DNA sequences and the polymerase chain reaction

Two short sequences, situated in the bacterial 23S rDNA gene, were used as primers for the PCR detection of Erwinia amylovora bacteria. All 34 E. amylovora strains tested, coming from different geographical and host plant origins and of different virulence, produced a 565-bp PCR fragment. The E. amylovora bacteria could be discriminated from all other phytobacteria with which no PCR product was observed. Only Escherichia coli bacteria were cross-recognized by the production of a weaker PCR band of similar size to E. amylovora . In a fast PCR protocol, where two temperatures were cycled, E. amylovora in pure culture could be detected on gel at concentrations as low as 3 × 10² cfu mL^–1. This corresponds to a detection limit of 1.5 bacteria per PCR. However, reliable PCR detection in woody host plant tissue was only obtained with PVP/PVPP-treated sample extracts. Using E. amylovora -spiked plant extracts and extracts of fruit tree shoots artificially infected with E. amylovora , the PCR detection sensitivity was determined to be 6.6 × 10² cfu mL^–1 of extract. Starting from the plant samples, the PCR detection results were visualized on gels within 5 h.     

TLC-生物自显影检测26种植物中的抗细菌和抗氧化活性物质

我国华南地区植物资源丰富,为快速筛选和检测具有抗菌和抗氧化活性的植物资源,本研究采用甲醇冷浸提取法制备植物提取物,并采用TLC-生物自显影法快速检测其抗细菌和抗氧化活性。活性测定的结果表明,豺皮樟和桂木的抗细菌活性最强,对所有供试细菌均表现出抑制活性,且抑菌斑的最大直径均大于10 mm。红果仔、锡叶藤和山油柑也对所有供试细菌表现出抑制活性,但其活性弱于豺皮樟和桂木。粪箕笃、海金沙和小蜡未表现出任何抗细菌活性,其他供试植物对部分供试细菌表现出抑制活性。白花酸藤子、海南杜英、黄牛木、山油柑和基及树表现出较好的抗氧化活性,抗氧化斑的R_f值范围为0.0～1.0,说明具有较多的活性化合物。TLC-生物自显影法能够快速、有效地筛选和检测具有抗细菌和抗氧化活性的植物提取物,本研究结果为植物资源的开发和利用提供重要的理论依据。