玉米种质和新品种对腐霉茎腐病和镰孢穗腐病的抗性分析

玉米是我国最重要的农作物之一,腐霉茎腐病和镰孢穗腐病是玉米生产上的重要病害。2006-2012年期间,对1647份玉米种质进行了抗肿囊腐霉茎腐病和拟轮枝镰孢穗腐病鉴定,筛选出高抗茎腐病和穗腐病的种质分别为564份和27份,占鉴定总材料的34.2%和1.6%,抗性材料分别为209份和352份,占比为12.7%和21.4%,表明高抗肿囊腐霉茎腐病的资源较为丰富,高抗镰孢穗腐病的种质相对匮乏。其中,13份种质对2种病害均表现高抗,207份种质对2种病害均表现抗性或对其中一种表现高抗而另一种表现抗性。自交系中对肿囊腐霉茎腐病和拟轮枝镰孢穗腐病表现抗性以上(含HR和R)的种质分别占总鉴定种质的56.5%和23.6%,在农家种中分别为21.2%和21.4%,表明玉米自交系中的抗性资源较农家种丰富。2009-2013年期间参加国家玉米区试的品种中,对腐霉茎腐病表现高抗、抗性、中抗、感病和高感的品种分别占11.5%、11.9%、40.1%、17.6%和18.9%。2009-2011年间,中抗以上的育成品种所占比例呈现明显上升趋势,但2012-2013年间,中抗以上的品种所占比例呈下降趋势。     

腐霉属的一个新种和二个新记录

本文报告作者1982—1983年在北京和广东一些地区土壤中用已知方法(余永年,1975)分离到的几种腐霉,其中1个新种(Pythium borealis sp.nov.)、2个国内未报道的种(P.oligandrum和P.myriotylum)和1个已知种的变异株(P.ultimum variant)。文中对以上各菌进行了形态学描述。     

NaCl溶液对贵阳腐霉菌丝生长、孢子囊产生及灭蚊能力的影响

研究不同浓度NaCl溶液对贵阳腐霉菌丝生长、产孢能力及灭蚊能力的影响,探讨贵阳腐霉对NaCl溶液的耐受性,为其在含盐水体中控制蚊虫种群的应用提供理论依据。结果表明：低浓度NaCl溶液可以促进贵阳腐霉菌丝生长及孢子囊形成,高浓度NaCl溶液则抑制菌丝生长及孢子囊形成。于0.01%浓度NaCl溶液中培养24h菌丝生长速度最快,产孢子囊数量最多,与对照相比差异显著。随着NaCl浓度升高,菌丝及孢子囊形成均受影响。菌丝生长速度降低,孢子囊形成数量减少。在0.75% NaCl溶液中贵阳腐霉的菌丝生长严重受抑制,且产孢子囊能力为零。灭蚊实验表明,0.01% NaCl溶液中贵阳腐霉的灭蚊能力在72–96h时均比蒸馏水对照组强,但二者未有显著差异,120h蒸馏水对照组灭蚊能力均明显高于各浓度NaCl溶液处理组;蚊虫总感染率蒸馏水对照组均显著高于NaCl溶液处理组。     

云南的腐霉

本文报道迄今为止在我国云南省发现的腐霉属真菌19个种,其中1个新种,3个中国新记录,5个云南新记录。新种为下雄腐霉Pythium hypoandrum Yu ＆ Y.L.Wang sp.nov.; 云南新记录为:旋柄腐霉P.helicoides、长井腐霉P.nagaii、周雄腐霉P.periilum、喙腐霉P.rostratum和钟器腐霉P.vexans,前3者还是中国新记录。有分种检索表,对其中12个种进行了描述并附形态图。     

大白菜腐霉根腐病的病原

在山东青岛发现一种新的大白菜根腐病,主根下部腐烂,根部维管束变褐变黑,地上部生长缓慢,矮小,甚至死亡。通过组织分离法和单菌丝分离法获得纯化菌株HMQAU170164。经柯赫氏法则验证,综合该病原菌形态学特征、生物学特性、ITS和coxⅠ序列分析,界定其为芸薹腐霉Pythium brassicum。该菌引起的大白菜腐霉根腐病为首次报道。     

蚊幼虫病原真菌贵阳腐霉的生物学研究

为了开发灭蚊真菌贵阳腐霉Pythiumguiyangense用于蚊虫防治,对贵阳腐霉生物学特性进行了研究。采用菌丝生长率、真菌产孢情况以及对致倦库蚊Culexquinquefaciatus1龄幼虫的毒力作为评价的指标。测试了7种人工培养基、7种单糖、7种氮源、真菌生长所需的pH范围和温度范围、以及4种光-暗比的光照程序对真菌的影响。结果证明该真菌生长的适合温度为5℃～35℃,最佳温度为25℃～30℃;适合pH范围是5～12;在pH9～11范围内菌丝和游动孢子生长最好;测试的人工培养基中,按照菌丝生长速度从高到低排列,依次为Czapek’SFE、PYG、KPYG2、SDAY、CMA和PDA。其中从真菌的游动孢子形成量和对蚊幼虫的毒力来看,最佳培养基为SFE;葡萄糖、果糖、乳糖、蔗糖、麦芽糖、甘露糖和可溶性淀粉都是本真菌的合适碳氢营养源;含有机氮的培养基比含无机氮的培养基好;不同的光照程序没有表现明显的影响,但是观察到紫外光对本真菌有明显的抑制作用。     

蚊幼虫病原真菌贵阳腐霉的生物学研究

为了开发灭蚊真菌贵阳腐霉Pythium guiyangense用于蚊虫防治,对贵阳腐霉生物学特性进行了研究。采用菌丝生长率、真菌产孢情况以及对致倦库蚊Culex quinquefaciatus1龄幼虫的毒力作为评价的指标。测试了7种人工培养基、7种单糖、7种氮源、真菌生长所需的pH范围和温度范围、以及4种光-暗比的光照程序对真菌的影响。结果证明该真菌生长的适合温度为5℃～35℃,最佳温度为25℃～30℃;适合pH范围是5～12;在pH 9～11范围内菌丝和游动孢子生长最好;测试的人工培养基中,按照菌丝生长速度从高到低排列,依次为Czapek’SFE、PYG、KPYG₂、SDAY、CMA和PDA。其中从真菌的游动孢子形成量和对蚊幼虫的毒力来看,最佳培养基为SFE;葡萄糖、果糖、乳糖、蔗糖、麦芽糖、甘露糖和可溶性淀粉都是本真菌的合适碳氢营养源;含有机氮的培养基比含无机氮的培养基好;不同的光照程序没有表现明显的影响,但是观察到紫外光对本真菌有明显的抑制作用。     

腐霉属的两个新种

新种镰雄腐霉 Pythium fatciforme sp.nov.和南宁腐霉 P.nanningense sp.nov.分离自中国广西地区土壤。新种提供了拉丁文、中文描述和形态图,并讨论。模式标本保藏于广西大学植物病理教研室(GUPL)。     

特异腐质霉纤维素酶的研究

由腐植土中分离到一株嗜热真菌,经鉴定为特异腐质霉(Humicola insolens Cooney etEmerson)。研究了这株菌纤维素酶的产生条件和一般性质。菌在含麦麸5％、NaNO0.3％的液体培养基(灭菌前pH7.5,灭菌后pH7.2)中,于45℃培养4天,以羧甲基纤维素钠为底物,每ml滤液酶活力为20个单位。酶作用的最适条件为:pH6.0,温度为65—70℃。该纤维素酶是一种耐热酶,热稳定性较强,70℃保温5分钟后,酶活力剩余88％。底物对该酶的热钝化有较强的保护作用,无底物存在条件下,70℃保温6小时后,酶活力仅剩余1％,而在同样的处理温度和时间,在有底物存在条件下,酶活力可剩余30％。该酶在45℃保温15小时的条件下,pH稳定范围为6.0—9.0。     

凤尾鸡冠茎腐病综合防治研究

本文根据凤尾鸡冠茎腐病的发生条件、规律和症状,进行该病的防治研究,得出一套从苗床土壤消毒、苗期和生长期到盛花期的定期预防、控制浇水时间和浇水量、合理施用氮、磷、钾肥等的有效防治措施,使该病发生率从15.4%降至1.3%,并使凤尾鸡冠的综合性状明显改善,有效地提高了产量和质量。     

Wilt and vascular root rot (<i>Pythium tracheiphilum</i>) of lettuce in Bahía Blanca,Argentina

A new disease of lettuce has been observed in the surroundings of Bahía Blanca, Argentina. The symptoms include dwarfing, general chlorosis, wilting, root rot, and leaf blight, sometimes followed by plant death. Pythium tracheiphilum Matta was found to be consistently associated with those symptoms. The morphological and morphometric characteristics of this oomycete are described. Isolates obtained from field-infected lettuce plants were inoculated to lettuce and caused similar symptoms as those found in natural infections. Seedling emergence was also severely affected following experimental inoculation. Koch’s Postulates were fulfilled by recovering the fungus from inoculated plants. The new disease shows a high destructive potential but currently has a limited prevalence and incidence.     

莴笋炭疽病病原鉴定

【背景】2018年7-8月,甘肃省兰州市永登县武胜驿镇种植的莴笋大面积发生炭疽病,约40%的地块发病,绝收面积达10%。【目的】明确莴笋炭疽病的病原。【方法】采用组织分离法进行病原菌分离;通过Koch’s法则明确分出病菌的致病性;采用形态学和分子生物学方法对病原菌进行种类鉴定。【结果】分离得到形态特征一致的真菌菌株3株。在PDA平板上20°C培养7 d,病菌分生孢子无色,单隔,梭形,(10.44-19.40)μm×(2.61-4.48)μm。代表性菌株Lett-11接种莴笋离体叶片可引起与自然发病相似的症状。BLASTn分析结果显示,菌株Lett-11 (GenBank登录号MK252097)的r DNA-ITS序列与莴苣盘二孢菌Marssonina panattoniana strain CBS 163.25 (GenBank登录号MH854831.1)的序列相似性达99%。【结论】引起莴笋炭疽病的病原菌被鉴定为莴苣盘二孢菌Mar. panattoniana [Synonymy:Microdochium panattonianum],这是莴苣盘二孢菌引起莴笋炭疽病在甘肃的首次报道。     

Biocontrol of Pythium tracheiphilum in Chinese Cabbage by Clonostachys rosea under Field Conditions

Control of leaf and head rot of Chinese cabbage (Brassica campestris L. ssp. pekinensis), caused by Pythium tracheiphilum, was obtained by Clonostachys rosea (isolate IK726) in field trials conducted in 1995 and 1999 on naturally infested land in a commercial crop in Denmark. A significant 2-3-fold disease reduction was obtained at an application rate of 10⁸-10⁹ conidia m^-2 (high application rate) in both years, but not at a 10-fold reduced rate in 1999. Disease reduction by Trichoderma harzianum (Supresivit) was almost significant at the high application rate (1 g product m^-2 corresponding to 7×10⁹ colony forming units (CFUs) m^-2) in both years, but not at a 10-fold reduced rate applied in 1999. In both 1995 and 1999 trials, the percentage of marketable heads increased significantly by 10% following a full application rate of C. rosea. Supresivit applied at the full application rate gave a significant 13% yield improvement in 1995 but not in 1999. No yield improvement was found when the two agents were applied at 10-fold reduced rates. A Danish T. harzianum isolate significantly increased yield by 13% in 1995, but gave no disease control. Plant growth promotion may have been responsible for yield improvements obtained by Supresivit and the Danish isolate of T. harzianum. The 1995 trial also evaluated the products Binab T (T. harzianum+T. polysporum), Mycostop (Streptomyces griseoviridis), Polyversum (P. oligandrum) and Aliette (fosetyl-Al) and Danish isolates of P. oligandrum (2) and T. virens (1), none of which gave disease control or yield effects.     

Soilborne Plant Diseases Caused by Pythium spp.: Ecology,Epidemiology, and Prospects for Biological Control

Soilborne root diseases caused by plant pathogenic Pythium species cause serious losses in a number of agricultural production systems, which has led to a considerable effort devoted to the development of biological agents for disease control. In this article we review information on the ecology and biological control of these pathogens with the premise that a clear understanding of the ecology of the pathogen will assist in the development of efficacious biocontrol agents. The lifecycles of the pathogens and etiology of host infection also are reviewed, as are epidemiological concepts of inoculum-disease relationships and the influence of environmental factors on pathogen aggressiveness and host susceptibility. A number of fungal and bacterial biocontrol agents are discussed and parallels between their ecology and that of the target pathogens highlighted. The mechanisms by which these microbial agents suppress diseases caused by Pythium spp., such as interference with pathogen survival, disruption of the process of plant infection, and induced host resistance, are evaluated. The possibilities for enhancement of efficacy of specific biological control agents by genetic manipulation or deployment tactics are discussed, as are conceptual suggestions for consideration when developing screening programs for antagonists.     

Biocontrol activity of the extract prepared from Zingiber zerumbet for the management of rhizome rot in Zingiber officinale caused by Pythium myriotylum

Zingiber zerumbet Smith or wild ginger is remarkable for its inherent resistance to Pythium spp., which cause soft rot disease in Zingiber officinale Rosc. In the present study, various concentrations of extract prepared from Z. zerumbet were screened for its activity against Pythium myriotylum. Microscopic observation of P. myriotylum in presence of Z. zerumbet extract has confirmed the complete lysis of pathogen within 10 h. However, the same treatment with Z. officinale extract was found to have partial antifungal effect even after 24 h due to inability of its metabolites to prevent the growth of P. myriotylum. Due to the antifungal activity, extract from Z. zerumbet was subjected to GC–MS and LC-QTOF-MS which has identified Zerumbone with m/z 219 as the major compound. Further, in vivo study and the subsequent microscopic analysis have confirmed the applicability of extract from Z. zerumbet as a phytomedicine to control rhizome rot in ginger.     

The role of strigolactones and ethylene in disease caused by Pythium irregulare

Plant hormones play key roles in defence against pathogen attack. Recent work has begun to extend this role to encompass not just the traditional disease/stress hormones, such as ethylene, but also growth‐promoting hormones. Strigolactones (SLs) are the most recently defined group of plant hormones with important roles in plant–microbe interactions, as well as aspects of plant growth and development, although the knowledge of their role in plant–pathogen interactions is extremely limited. The oomycete Pythium irregulare is a poorly controlled pathogen of many crops. Previous work has indicated an important role for ethylene in defence against this oomycete. We examined the role of ethylene and SLs in response to this pathogen in pea (Pisum sativum L.) at the molecular and whole‐plant levels using a set of well‐characterized hormone mutants, including an ethylene‐insensitive ein2 mutant and SL‐deficient and insensitive mutants. We identified a key role for ethylene signalling in specific cell types that reduces pathogen invasion, extending the work carried out in other species. However, we found no evidence that SL biosynthesis or response influences the interaction of pea with P. irregulare or that synthetic SL influences the growth or hyphal branching of the oomycete in vitro. Future work should seek to extend our understanding of the role of SLs in other plant interactions, including with other fungal, bacterial and viral pathogens, nematodes and insect pests.     

Some New Taxa of Chara from Guangxi and Gansu,China

In order to get a thorough understanding of the Characeae, the specimens collected from Guangxi and Gansu were identified. The result shows that the two provinces, especially Guangxi, are abundant in this family. In this paper, however, reported are only new species, new varieties and new records of Chara in China. They are Chara vernicosa sp. nov. C. globularis var. inflata var. nov. and C. howe-ana var. subgymnophylla var. nov., C. brionica stapf and C. calveraensis comb. nov.     

Isolation of Pythium Acanthicum,P. oligandrum,and P. periplocum from Soil and Evaluation of Their Mycoparasitic Activity and Biocontrol Efficacy Against Selected Phytopathogenic Pythium Species

Mycoparasitic Pythium species with spiny oogonia were surveyed in 50 Palestinian agricultural fields subject to different cropping practices using the Sclerotia Bait Technique (SBT) and the Surface-Soil-Dilution-Plate method (SSDP) with the selective VP3 medium. The mycoparasitic Pythium species were obtained from 21 (42%) soils using the SSDP method and from 37 (74%) soils using SBT. Pythium acanthicum and P. oligandrum were isolated by both methods, whereas P. periplocum was isolated only by the SBT. Using a newly modified dual plate culture method (MDPCM), the three mycoparasites showed varying antagonistic performance against several Pythium host species under a range of in vitro conditions. However, P. periplocum and P. oligandrum were found to be active biocontrol agents against P. ultimum, the damping-off organism of cucumber. This pathogen was antagonized, on thin films of water agar, by the three mycoparasites, and was moderately susceptible to P. periplocum while slightly susceptible to P. acanthicum and P. oligandrum. In direct application method in which antagonistic mycoparasites were incorporated into peat/sand mixture artificially infested with P. ultimum under growthroom conditions, Pythium oligandrum and P. periplocum (at 500 CFUg⁻¹) significantly improved seedling emergence and protected seedlings from damping-off. In the seed coating method, biocontrol by two types of seed dressing (homogenate- or oospore coated seeds), was comparable to that achieved by direct application. This revised version was published online in June 2006 with corrections to the Cover Date.     

不同光照时间红蓝LED光对生菜生长和品质的影响

生菜(Lactuca sativa var. ramosa Hort.)富含维生素、花青素和胡萝卜素等营养成分,且具有抗衰老和抗癌功能[1] ,是可控环境下主栽蔬菜种类之一. 光照时间能调控植物开花、花性分化、发育进程及光合生长[2-3]. 夜间补光和低光量子通量密度条件下延长光照时间可以提高生菜的生物量和品质[4-5]. 全人工光照条件下,红蓝光是培育植物的适宜光谱[6-7].     

寡雄腐霉发酵液的动物安全性及其对黄瓜的防病促生效应

【目的】生物农药安全无害,环境友好。为了评价寡雄腐霉发酵液(Pythium oligandrum broth,POB)的动物安全性和防病促生效应,研制高效、无害的生物农药。【方法】试验利用自主分离的寡雄腐霉生防菌株(P.oligandrum CQ2010)制备POB,通过动物试验、拮抗试验、盆栽和生产试验,研究了POB的动物毒性,对黄瓜蔓枯病的防治作用,以及对黄瓜生长、产量和品质的影响。【结果】用大剂量的POB灌胃给药对小鼠体重增长无显著影响,其外观和行为均无异常,组织器官也未见病理改变。POB对甜瓜球腔菌的抑制率为51.95%,药效介于1∶800的百菌清溶液和1∶200的甲基托布津溶液之间。在黄瓜幼苗接种甜瓜球腔菌前后喷施POB,叶片丙二醛含量下降,过氧化物酶和超氧化物歧化酶活性增强,发病率和病情指数均显著降低,相对防治效果达到54.8%–64.1%,故POB能减轻病原菌对细胞膜的伤害,激发防御性生理反应,增强黄瓜植株的抗病能力。此外,POB处理提高叶绿素含量,增强根系活力,增加植株氮、磷、钾吸收量,促进黄瓜植株生长,生物量和果实产量分别提高81.10%和11.58%。POB还使黄瓜果实Vc和可溶性糖提高,硝酸盐含量降低。【结论】寡雄腐霉发酵液对动物安全无毒,能有效防治黄瓜蔓枯病,促进黄瓜生长,提高产量品质。