生物源农药在苹果蠹蛾防治中的应用

苹果蠹蛾是世界性检疫害虫,对我国苹果优势产区构成了巨大威胁。长期依赖化学防治使该虫抗性问题变得十分严峻。为了保障食品安全,以环境友好的生物源农药替代化学农药已成为当前苹果蠹蛾防治的热点。本文对国内外现有的生物源农药,如寄生蜂、不育昆虫、颗粒体病毒、病原线虫、Bt、病原真菌、微孢子虫、性信息素、斑蝥素、多杀菌素等,在苹果蠹蛾防治中的最新应用及其存在的问题进行论述,讨论了生物源农药凭借其种类多、来源广且在用药时期上选择性强等特点,在该虫综合治理中的重要地位及面临的挑战。     

免疫学讲座（五）：—传染与抗传染免疫

传染与抗传染免疫是同时存在于机体生命过程中的一对矛盾的两个方面。它们是彼此联系又相互作用的。病原微生物在一定条件下侵入机体、克服机体的防御机能,在一定部位生长繁殖并引起病理生理过程的,称为传染。机体阻止病原微生物的侵入,消灭已入侵的病原微生物并消除其毒害的能力称为抗传染免疫。     

生物源蛋白激发子的研究进展

生物源蛋白激发子是一类能诱导植物产生防卫反应的特殊化合物,主要来源于病原微生物、其他微生物及寄主植物或由寄主-病原物互作后产生。病原微生物或其他微生物产生的激发子包括真菌的β-葡聚糖、糖蛋白、脂类物质和其他细胞壁组分;由寄主植物产生的激发子主要是细胞壁组分中的寡糖物质,如寡聚半乳糖醛酸和木聚糖片段;寄主-病原物互作后产生的激发子主要是互作过程中酶对寄主和病原物细胞组分修饰后产生的。生物源蛋白激发子与寄主植物作用后,通过一系列信号传导,诱导寄主植物产生乙烯、植保素、水杨酸、茉莉酸、病程相关蛋白等,导致植物中多种防卫反应的发生,从而可以控制病害的发展和传播,在农业生产上能够起到减少病虫危害达到增产的目的。近年来,人们对激发子的研究非常广泛,生物源蛋白激发子在生物防治中的作用也日益受到学者们的重视。该文就生物源蛋白激发子的种类:Harpin蛋白、Nep1-like蛋白家族、RXLR蛋白家族、Elicitins及其各类型激发子的功能、信号传导和作用机制的研究进展情况和在农业中的应用进行了综述,并提出了生物源蛋白激发子将来在农业生产中对病害防治方面的展望。     

叶片病原真菌对植物物种共存的影响:进展与挑战

群落内物种如何共存是群落生态学研究中最具争议的核心问题之一。根据当代物种共存理论框架,维持物种共存的机制可以分为稳定化和均等化机制。尽管植物叶片病原真菌在自然界中大量存在,但是目前尚不完全清楚叶片病原真菌如何通过稳定化和均等化机制影响物种共存。本文首先介绍了叶片病原真菌驱动同种负密度制约(稳定化机制)和“生长–防御”权衡(均等化机制)促进物种共存的证据,并阐述了在群落水平抑制叶片病原真菌后物种丰富度的变化。随后,本文归纳了该领域研究中的主要挑战:叶片病原真菌在驱动物种共存过程中相较于环境因子的可能重要性更低、部分叶片病原真菌较弱的宿主专一性无法起到维持物种共存的作用,以及控制叶片病原真菌过程中各种方法均有一定局限性等问题。最后,本文论述了该研究领域未来的主要方向:不同土壤养分/气候变化条件下叶片病原真菌如何影响物种共存、叶片病原真菌与其他高营养层次生物类群的交互作用及其对物种共存的贡献、基于系统发育推断叶片病原真菌对植物群落构建的影响、将叶片病原真菌生活史类型纳入病原真菌影响植物物种共存的相关研究中。     

藓类提取物对植物病原真菌的抑菌性研究

以立枯丝核菌(Rhizoctonia)、尖孢镰孢菌(Fusarium oxysporum)、苹果轮纹病菌(Macrophoma kawatsukai)、梨黑星病菌(Fusicladium pirina)、草莓灰霉菌(Botrytis cinerea)等七种植物病原真菌为供试菌,通过生长速率法测定了24种藓类的乙醇提取物对病原真菌的抑制作用.结果表明,在提取物浓度为1.2mg干样/mL,大镰刀藓提取物对立枯丝核菌的抑制作用最强,抑菌率为67.8%.藓类提取物不仅对植物病原真菌有抑菌活性,而且还有多种藓类提取物对病原真菌菌丝有促进生长活性,如锐尖匍灯藓对立枯丝核菌菌丝生长的促进率为95.1%.选出大镰刀藓、扁灰藓、紫萼藓、山地水灰藓、疣小金发藓、橙色净口藓、锐尖匍灯藓和羊角藓对立枯丝核菌和灰霉菌的抑菌性或菌丝生长促进性进行了进一步研究,藓类提取物对病原菌的抑菌性或菌丝生长促进性在一定范围内随浓度的增加而增强,并且抑菌性随时间的延长呈下降趋势.     

乳及乳制品中病原微生物溯源技术研究进展

牛奶营养丰富,素有"白色血液"之称,随着公众对食源性疾病原因和来源问责制的需求增加,准确追踪特定食源性病原微生物在暴发过程中所经过的途径变得越来越重要。微生物溯源研究有助于人们更深入地了解病原微生物种群结构及其多样性的起源和进化,为病原微生物的检验、流行监测、综合防治等研究提供重要的信息资料和科学依据。在牛奶中病原微生物溯源技术研究中,光谱技术、质谱技术、分子方法、全基因组测序等方法均发挥了重要作用。本文根据近年国内外相关文献资料,对检测奶及奶制品中病原微生物常用溯源技术的原理和应用进行了概述。     

细菌铁载体拮抗植物病原真菌及促生作用研究进展

铁载体是微生物在缺铁条件下分泌的小分子有机化合物,以获取铁元素维持其生长。细菌分泌的铁载体在拮抗植物病原菌和促进植物生长方面具有重要作用。本文总结了细菌铁载体拮抗植物病原真菌的营养和生态位竞争、诱导植物诱导性系统抗性、扰乱病原菌铁稳态的机制,以及促进植物生长的作用,以解释细菌分泌的铁载体在多功能微生物菌剂研制中的重要作用。     

菌寄生真菌的研究进展

菌寄生真菌能寄生在其他真菌并抑制其生长这一特性,在防治病原真菌时显示巨大潜力。综述了近年来菌寄生真菌在寄生过程中的识别、信号传导、侵染机制等方面的研究进展,并讨论菌寄生真菌的应用前景。     

林下参内生生防细菌的分离鉴定及定殖能力

【背景】多年生林下参在自然环境下生长多年,其体内存在的内生菌具有更强的适应性和定殖性,可以提高植物自身抗性,抑制病原菌的生长,更好地发挥与植物的互作。【目的】筛选定殖能力强、繁殖能力快且对病原菌具有拮抗作用的优势菌株。【方法】采用常规组织分离方法,从健康林下参根部组织中分离内生菌,通过对峙试验筛选出对人参病原菌有拮抗作用的内生细菌并对其以传统的鉴定方法进行鉴定。【结果】在得到的6株内生细菌中,菌株LXS-N2对人参立枯病病原菌、人参猝倒病病原菌均有明显抑菌性,而且具有定殖性好、繁殖快的特点,通过破坏病原真菌细胞壁和细胞膜以及改变菌丝形态从而抑制病原真菌生长。【结论】经形态学观察、生理生化反应及16S rRNA基因序列分析鉴定内生菌LXS-N2为贝莱斯芽孢杆菌,具有良好的应用开发潜力。     

环介导等温扩增技术在病原微生物快速诊断中的应用

近年来出现的环介导等温扩增技术(LAMP)在等温条件下即可对目的基因高效扩增。因为操作简便、反应快速、特异性好、灵敏性高,尤其是因添加荧光染料而通过肉眼观察就能轻松判断扩增反应是否发生,该法已被广泛应用于细菌、病毒、真菌、寄生虫等病原微生物的检测研究。我们主要对LAMP技术的原理、优缺点,及其在病原微生物快速诊断中的应用做简要综述。     

A physiological study of Saksenaea vasiformis Saksena

Summary The physiological conditions governing growth and sporulation ofSaksenaea vasiformis Saksena, a fungus with outstanding morphological features quite peculiar for Mucorales, were determined. Earlier studies made byTiwari (1955) on a strain of the same species had shown that this fungus is incapable of sporulating on any synthetic medium normally employed for growing fungi.The fungus had been found to have a high tolerance for very low and high pH values. It showed maximum growth at two pH values, one near neutral point, at pH 6, and another at high alkaline pH value, i.e., pH 11. Reason for this behaviour of this fungus has already been discussed. The most suitable temperature for the growth of the fungus was found to be between 30–35° C.Nearly all the carbon, nitrogen and sulphur sources which generally favour growth of fungi were found to support vegetative growth of this fungus as well. However, sporulation in this fungus had peculiar nutritional needs. Only some of the carbon sources, viz., arabinose, rhamnose, sorbose, galactose, lactose and citric acid which supported poor growth, were found to support good or excellent sporulation. But it may be stated that not all carbon sources supporting poor growth could induce sporulation of the organism. Also none of the nitrogen or sulphur sources could induce the fungus to sporulate in presence of glucose as carbon source.     

簇生沿丝伞的生物学特性

文中以对采自山东省的子实体进行组织分离获取的菌株作为试验材料,对其生物学特性进行研究,对温度、pH、碳源、氮源4个因素进行单因素试验。温度组选取15,20,25,30,35℃5个梯度,pH组选取pH5,6,7,8这4个梯度,碳源组选取葡萄糖、蔗糖、麦芽糖、可溶性淀粉、乳糖、果糖6种,氮源组选取酵母膏、蛋白胨、硫酸铵、牛肉膏、黄豆粉、亚硝酸钠6种,进行单因素试验。根据菌丝在培养皿中的日均生长速度和生长势综合比较,分别选取4个因素中最优的3个,温度组选取20,25,30℃;pH组选取pH 5,6,7;碳源组选取葡萄糖、蔗糖和麦芽糖;氮源组选取蛋白胨、牛肉膏、硫酸铵。然后通过4因素3水平的正交试验,结果表明:4种因子对簇生沿丝伞的影响程度为温度>氮源>碳源>pH,各因素之间呈极显著差异,最终得出该菌菌丝生长的最佳培养条件为温度20℃,pH 5,碳源为蔗糖,氮源为牛肉膏。     

Nutritional study on <Emphasis Type="Italic">Embellisia astragali</Emphasis>, a fungal pathogen of milk vetch (<Emphasis Type="Italic">Astragalus adsurgens</Emphasis>)

Embellisia astragali is a strong, virulent pathogen that develops within milk vetch (Astragalus adsurgens). In order to determine nutrient requirements, the fungus was cultured on 9 carbon sources, 9 nitrogen sources, and 13 growth media in the dark at 25°C. Growth rates and sporulation capacity were measured after 4 and 12 weeks. All carbon sources supported growth, but only soluble starch, inulin, and dextrose supported sporulation. In general, better growth was obtained on disaccharides and polysaccharides than on monosaccharides. Compared with no growth on NH₄ ⁺-N and urea, the fungus grew little on all NO₃ ⁻-N, amino-N, and other organic-N such as peptone. There was no sporulation or very sparse conidia on almost all nitrogen sources with supplied dextrose or soluble starch as sole carbon source. The better growth and sporulation on most of the semidefined media than on defined media indicates that some components in plant or animal material may be vital to the fungus. Sporulation was positively correlated with growth rate in N source experiment at 12 weeks and in growth media experiment at 4 and 12 weeks. The fungus favors grow within agar with growth rate less than 1.18 mm day⁻¹.     

草坪草离蠕孢叶枯病菌生物学特性的研究

对草坪离蠕孢叶枯病病原菌进行分离鉴定,并对其生物学特性进行了研究。结果表明:该病害由禾草离蠕孢(Bipolaris sorokiniana)引起。该病原菌的菌丝生长及产孢的最适温度为30℃,孢子萌发最适温度为25℃,菌丝的致死温度为65℃,而孢子的致死温度则为55℃;该菌对酸碱度的适应能力较强,中性偏酸性的条件对菌丝的生长有利,而pH值为8.0时最易产孢;各碳源对菌丝的生长均有促进作用,但不同碳源对产孢量的影响很大,单糖和双糖利于产孢,多糖对产孢的影响不大。氮源对菌丝生长和产孢量非常重要,无机氮效果较好,硝态氮好于氨态氮,有机氮效果最差。花粉、叶面物质和草坪草汁液可促进孢子萌发。     

GROWTH OF PHELLINUS (PORIA) WEIRII ON DIFFERENT VITAMINS AND CARBON AND NITROGEN SOURCES

Mycelial growth of Phellinus weirii (Murr.) Gilb., a root pathogen of conifers in the Pacific Northwest, was studied in defined liquid media with different carbon and nitrogen sources and vitamins. The fungus grew significantly more on glucose, xylose, maltose, or fructose than on other carbon sources. Starch did not support growth. Maximum growth occurred in 4 weeks on all carbon sources except dextrin and sucrose, with which maximum growth occurred in 3 weeks. Of the nitrogen sources, peptone supported the best growth of the fungus; glutamic acid, serine, aspartic acid, alanine, leucine, ammonium sulphate, and urea supported significantly better growth than tyrosine, arginine, methionine, threonine, and glycine. Potassium nitrate, phenylalanine, sodium nitrate, lysine, proline, and cysteine inhibited growth. Thiamine hydrochloride was not absolutely required for growth of P. weirii, but better growth was obtained with its addition. The fungus showed no significant responses to a range of other vitamins.     

The effect of acetylated xylan and sugar beet pulp on the expression and secretion of enzymes by <Emphasis Type="Italic">Penicillium purpurogenum</Emphasis>

Sugar beet pulp is a natural carbon source composed mainly of pectin and cellulose, which is utilized and degraded by the ascomycete Penicillium purpurogenum. The fungus also grows on and degrades acetylated xylan which lacks cellulose and pectin. Both carbon sources have been used in our laboratory to grow the fungus and to purify different enzymes secreted to the medium. The enzymes involved in the complex process of degradation of these carbon sources by the fungus have been explored previously under non-denaturing conditions; multienzyme complexes were separated and some subunits identified by Western blots and mass spectrometry. In this work, proteomic profiles show that the secretome is composed of numerous proteins varying in pI and molecular weight. Some enzymes are common to both growth conditions, while others are specific for each carbon source. The results show that the carbon sources utilized exert strong regulatory control over the proteins secreted. This is the first secretome study from a lignocellulolytic Penicillium.     

大气二氧化碳浓度升高对植物-昆虫相互关系的影响

综述了CO2浓度升高对植物与昆虫相互关系影响的研究结果。大量研究表明,高浓度CO2对植物生理生化活动有显著的影响,植物营养物质的变化对植食性昆虫亦产生不同程度的影响,高浓度CO2条件对咀嚼式口器昆虫的取食、生长发育和生殖有不同程度的不良影响,昆虫为了获得足够的氮素营养而增加取食强度和时间,从而更易于受到天敌的攻击,这些昆虫的生长率、繁殖和生存率有下降的趋势;而对刺吸韧皮部汁液的昆虫来说,多引起种群数量增加或无显著影响。并对研究中存在的问题进行了分析,提出了今后研究的方向。     

马铃薯干腐病菌硫色镰孢的生物学特性

从碳源、氮源、酸碱度及生长温度等方面对引起马铃薯干腐病的硫色镰孢Fusarium sulphureum的生物学特性进行了研究。结果表明,该病原菌在不同发育阶段对营养和环境条件的要求存在差异。在固体培养基上,菌落生长最佳碳源为葡萄糖、麦芽糖,最佳氮源为蛋白胨,pH8?为最佳;在液体培养基中,菌丝体生长以麦芽糖为最佳碳源,以硝酸钠为最佳氮源,pH6?为最佳;在分生孢子萌发阶段,在以羧甲基纤维素钠、蛋白胨和谷氨酸为碳、氮源的营养液中,分生孢子萌发率最高,最适pH 6–8。该病菌最适生长温度为25℃,分生孢子致死     

黑胶粉虱虫生菌的研究

扁座壳孢(Aschersonia placenta Berk.et Br.)是黑胶粉虱病原真菌,在寄主初龄幼虫期使用孢子悬浮液喷雾,个体容易感病,而且致死力较强。该菌最适生长温度24—26℃,暴发性流行季节气候条件多阴雨,相对湿度在85％以上。病原能在一般培养基上生长繁殖。在自然界以感病致死虫尸为营养载体,粘附在叶面,不断形成分生孢子,产生再次侵染,对控制害虫虫口增长作用显著,是综合防治中不可忽视的生物因素。     

Beginning to understand the role of sugar carriers in Colletotrichum lindemuthianum: the function of the gene mfs1

Fungi of the Colletotrichum genus are among the most prominent phytopathogens that cause diseases with a considerable economic impact, such as anthracnose. The hemibiotrophic fungus Colletotrichum lindemuthianum (teleomorph Glomerella cingulata f. sp. phaseoli) is the causal agent of the anthracnose of the common bean; and similarly to other phytopathogens, it uses multiple strategies to gain access to different carbon sources from its host. In this study, we examine mfs1, a newly identified C. lindemuthianum hexose transporter. The mfs1 gene is expressed only during the necrotrophic phase of the fungus’ interaction within the plant and allows it to utilize the available sugars during this phase. The deletion of mfs1 gene resulted in differential growth of the fungus in a medium that contained glucose, mannose or fructose as the only carbon source. This study is the first to describe a hexose transporter in the hemibiotrophic pathogen C. lindemuthianum and to demonstrate the central role of this protein in capturing carbon sources during the necrotrophic development of the plant/pathogen interaction.