贵州省烟草黑胫病菌对烯酰吗啉的敏感性

为了明确烟草黑胫病菌对烯酰吗啉的敏感性现状,从贵州省各地采集了47株烟草黑胫病菌株,分别测定了菌丝生长和游动孢子囊形成对烯酰吗啉的敏感性.结果表明,烯酰吗啉对烟草黑胫病菌菌丝生长和孢子囊形成的抑制基本一致,对菌丝EC50范围为0.792 6～4.232 7μg/mL,平均为2.476 8μg/mL;对孢子囊的抑制作用略强,EC50范围为0.394 5～4.625 3μg/mL,平均值为2.040 0 μg/mL.统计分析表明,烟草黑胫病菌47个菌株菌丝生长和孢子萌发对烯酰吗啉的敏感性符合正态分布,不同菌株对烯酰吗啉的敏感性有显著差异,而且菌株对烯酰吗啉的敏感性与其地理来源有一定的相关性.     

安徽省烟草黑胫病菌的交配型及其地理分布研究

 Total 69 isolates of Phytophthora nicotianae var. nicotianae were isolated and identified from tobacco black shank samples collected from different areas of Anhui province, and mating types of the oomycete were investigated by the method of partnership culture in vitro on L-tryptophan medium with β-sitosterol. The results showed that A2 mating type was the predominant in isolates of P. nicotianae var. nicotianae, next was A₀ mating type, A₁ and other mating types were not observed. It was suggested that sexual reproduction of P. nicotianae var. nicotianae might not take place frequently, and Anhui province might not be the original center of P. nicotianae var. nicotianae. The results indicated further that mating type geographical distribution of P. nicotianae var. nicotianae in Anhui province was in line with that in China. In addition, the significance of the test results and the possible reason for A₁ mating type being absent were discussed.     

Root rot of lavender caused by Phytophthora nicotianae

Lavender (Lavandula angustifolia) plants with rotted roots and discoloured vascular systems consistently yielded cultures of fungi that were identified as Phytophthora nicotianae van Breda de Haan (= P. parasitica). Inoculation experiments using either zoospore suspensions or mycelial fragments were successful in reproducing symptoms originally observed on wilting and dying plants. Lavender is a new host for P. nicotianae.     

烟草黑胫病菌培养特性的研究

研究了云南烟草黑胫病菌在不同培养基、不同温度的生长情况及不同菌龄与不同诱导时间孢子囊的产生数量。结果表明,菌株在8种供试培养基中,以燕麦培养基和选择性培养基上菌落生长最好,其次为胡萝卜培养基,在番茄汁和马铃薯培养基上生长最差。同一菌株在不同培养基上产孢量不同、产生的孢子囊大小亦有所不同。05P226菌株在玉米培养基上产孢量最高;05P55菌株在燕麦培养基上产孢量最高,在番茄汁培养基上产生的孢子囊最大,而05P62菌株在燕麦培养基上产孢量最高,在烟叶汁培养基上产生的孢子囊最大。在30℃菌丝生长速率最高,其次为28℃,以35℃生长最差。供试3个菌株间生长差异显著,以05P226生长最好,05P55菌株次之,05P62生长最差。05P226、05P55菌株皆以培养14d、诱导72h产孢量最高,最适宜试验中产孢培养。     

长春花疫病的发生危害与防治

进口F₁代长春花上疫病 (Phytophthora nicotianae)是普遍发生的一种病害 ,危害较重。经对其发生规律、发病条件、药剂筛选及防治等方面研究 ,结果表明 ,该病的发生与长春花生育期及湿度等密切相关 ,RH>80%时病害迅速发展。现蕾期至初花期为病害易发期 ,克露等3种药剂对其防效达90%以上     

Root rot of tree lucerne caused by Phytophthora nicotianae

Phytophthora nicotianae Breda de Haan was consistently isolated from rotted roots and discoloured vascular tissues of tree lucerne ( Chamaecytisus palmensis ). It was identified with the aid of total DNA restriction fragment length polymorphisms and morphological characters. Pathogenicity was demonstrated by inoculation. This is the first record of P. nicotianae on tree lucerne in South Africa.     

Protection of Citrus Rootstocks Against Phytophthora spp. with a Hypovirulent Isolate of Phytophthora nicotianae

ABSTRACT Phytophthora root rot of citrus in Florida is caused by Phytophthora nicotianae and P. palmivora. A naturally occurring isolate of P. nicotianae (Pn117) was characterized as hypovirulent on citrus roots. Pn117 infected and colonized fibrous roots, but caused significantly less disease than the virulent isolates P. nicotianae Pn198 and P. palmivora Pp99. Coincident inoculation of rootstock seedlings of Cleopatra mandarin (Citrus reticulata) or Swingle citrumelo (C. paradisi x Poncirus trifoliata) with the hypovirulent Pn117 and the virulent isolates Pn198 and Pp99 did not reduce the severity of disease caused by the virulent Phytophthora spp. When either rootstock was inoculated with the hypovirulent Pn117 for 3 days prior to inoculation with virulent isolates, preinoculated seedlings had significantly less disease and greater root weight compared with seedlings inoculated with the virulent isolates alone. Recovery of the different colony types of Phytophthora spp. from roots of sweet orange (C. sinensis) or Swingle citrumelo was evaluated on semiselective medium after sequential inoculations with the hypovirulent Pn117 and virulent Pp99. Pn117 was isolated from roots at the same level as the Pp99 at 3 days post inoculation. Preinoculation of Pn117 for 3 days followed by inoculation with Pp99 resulted in greater recovery of the hypovirulent isolate and lower recovery of the virulent compared with coincident inoculation.     

化学合成寡糖诱导烟草抗黑胫病的初步研究

 抑菌测定和盆栽试验表明:化学合成的Lewis^x和Lewis^a寡糖对烟草黑胫病病原菌菌丝生长无明显影响;Lewis^x五糖和七糖处理烟草,可使烟草植株产生对黑胫病菌(Phytophthora nicotianae)的抗性,在处理浓度0~10μg/m L内,随着浓度增高诱导效果增强,当浓度达10 μg/m L时,诱导防病效果达90%以上。Lewisx七糖处理,可导致烟草叶片过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸裂解酶(PAL)等防卫酶活性不同程度地提高,PPO、POD及PAL分别在处理后第4d、第6d和第8d达到最大值,比对照分别增加了70.7%、150.0%和142.8%。     

Specific and Sensitive Detection of Phytophthora nicotianae By Simple and Nested-PCR

Phytophthora nicotianae Breda de Haan is one of the most important soil-borne plant pathogens. The identification of this pathogen based on morphological or physiological characters is time-consuming and labour-intensive and requires comprehensive knowledge of fungi. Molecular analysis of the internal transcribed spacer (ITS) regions of rDNA is a novel and very effective method of species determination. Based on this concept, conventional and single closed tube nested-PCRs were developed for the specific and sensitive detection of P. nicotianae. Two new specific primers, designed from the spacer regions ITS1 and ITS2, internal to the nucleotide sequence flanked by universal primers ITS4 and ITS6, were used. To evaluate the specificity of the method, 36 morphologically characterized isolates were tested. A positive reaction, characterized by an amplification product of 737 bp, was shown by all P. nicotianae isolates and two P. nicotianae/cactorum hybrids. No amplification product was observed when other Phytophthora species and genera were assayed. The sensitivity of this method was analysed by serial dilutions of a defined amount of fungal DNA in a healthy root extract. Nested-PCR was at least 1000 times more sensitive than conventional PCR. In addition, samples from different infection sites, origins and crops, samples from nutrient solution, water and the rockwool used in hydroponic cultures, were analysed to validate this method.     

四种作物根系分泌物对烟草疫霉的抑菌活性分析

通过分析玉米、大蒜、茴香和油菜4种作物根系分泌物对烟草疫霉的抑菌活性,发现这4种作物根系表现出很强的化感作用,根系分泌物能在短时间内迅速地杀死烟草疫霉的游动孢子,抑制其萌发。其中,玉米根系分泌物在最高浓度2.59mg/mL时,对疫霉休止孢萌发的抑制率高达100%;大蒜根系分泌物浓度为0.1 mg/mL时,20min内能完全抑制游动孢子的游动。分析4种作物根系对游动孢子的趋化作用发现,茴香、油菜对疫霉游动孢子的吸引活性最强,T0最高分别为76.3、68.7,玉米、大蒜次之。以上结果为建立"以生物多样性为基础,克服烟草土传病害连作障碍"的病害防治新模式提供有力的理论支撑。     

深绿木霉T2菌株对百合疫霉拮抗作用及机制

本文采用对峙培养、抗生物质测定、对扣培养、圆盘滤膜法、酶活性测定等方法,研究了深绿木霉对百合疫霉病菌的拮抗作用及机制。结果表明,深绿木霉T2菌株具有较强的营养竞争与重寄生作用;并发现其有抗生物质和溶菌酶类产生,对峙培养60 h时,深绿木霉生长速率是百合疫霉的3.68倍,能够与其竞争营养,抑制了百合疫霉的生长与扩展,深绿木霉寄生在百合疫霉菌丝上生长,导致百合疫霉菌丝降解;其代谢产物能够抑制百合疫霉的生长,48 h时难挥发性和易挥发性代谢产物对百合疫霉的抑菌率分别为85.07%和79.10%;深绿木霉T2菌株的发酵液有较高的β 1,3 葡聚糖酶活性,并在第5天达到峰值,为18.54U;深绿木霉发酵液对百合疫霉菌丝有降解作用。     

Molecular Characterization of Natural Hybrids of Phytophthora nicotianae and P. cactorum

ABSTRACT Hybrid isolates of Phytophthora nicotianae x P. cactorum from five different hosts (Cyclamen, Lavandula, Lewisia, Primula, and Spathiphyllum spp.) were identified by their atypical morphology and their well-defined heterozygous isozyme patterns. The hybrid nature of these isolates was tested by restriction fragment length polymorphism analysis of the internal transcribed spacer (ITS) region of rDNA, generating fragments typical for both P. nicotianae and P. cactorum. In hybrid isolates, polymerase chain reactions (PCR) with primers derived from unique parts of the ITS region (ITS-PCR) of both species yielded a combination of unique amplicons typical of both parental species. Eleven hybrid isolates, three isolates of each parental species and two atypical isolates from Rhododendron and Idesia spp. close to P. cactorum, were analyzed for amplified fragment length polymorphisms (AFLP). Consistent differences in AFLP patterns existed among the hybrid isolates, strongly indicating that these hybrids have arisen from independent hybridization events between P. nicotianae and P. cactorum. The two atypical isolates morphologically resembling P. cactorum were identical to the latter species in ITS-restriction fragment length polymorphism and response to the specific PCR primers but were intermediate between P. nicotianae x P. cactorum and P. cactorum in isozyme profiles and AFLP patterns. Since the introduction of hydroponic systems in greenhouses in the Netherlands, outbreaks of Phytophthora diseases are occurring in previously unaffected host species. This may be due to interspecific hybridization events resulting in novel pathogenic behavior.     

贵州省烟草黑胫病菌对甲霜灵的抗药性

为了明确贵州地区烟草黑胫病菌对甲霜灵的抗药性水平, 从贵州省12个市、县采集黑胫病病株, 经分离纯化鉴定, 获得98株黑胫病菌株, 采用生长速率法测定其对甲霜灵的敏感性。结果表明, 采自不同地区的菌株对甲霜灵的敏感性差异较大, 各供试菌株的EC50 值分布范围为0.419 2～20.486 1 μg/mL; 各地区平均EC50 在0.551 9～10.986 0 μg/mL之间; 最低抗药性水平为1.00, 最高抗药性水平为48.87, 相差48.87倍, 各地区平均抗药性水平在1.32～26.21之间。遵义、兴仁、贵定、赫章和兴义有抗甲霜灵菌株出现, 除遵义部分菌株的抗性水平表现为高抗外, 其余菌株对甲霜灵产生的抗性均处于中抗水平。     

贵州省烟草黑胫病菌遗传多样性分析

运用RAPD分子标记技术分析了采自贵州各个地区的38个烟草黑胫病菌株的遗传多样性,探索了贵州省主要烟草种植区间的烟草黑胫病病菌的遗传分化关系.结果表明,受试38个菌株共产生65条谱带.其中多态性为59条,占90.7％.说明贵州省主要烟草种植区的烟草黑胫病病菌具有丰富的遗传多样性,不同地点烟草黑胫病病菌的遗传结构之间都有一定的差异.根据引物扩增的指纹图谱,运用UPGMA分析法,以遗传相似系数0.74,将供试38个菌株划分为9个基因型,发现除少数地区的菌株被划分为同一基因型外,其他不同地理区域的菌株基因型的划分与地理来源没有直接的相关性.