高温诱导黄瓜抗霜霉病机理

研究了高温对黄瓜霜霉病菌致病力的影响以及高温控制霜霉病发生的效果.结果表明,40 ℃高温处理2 h和45 ℃处理1 h对黄瓜霜霉病的诱导抗病性作用最明显,其在接种后4 d时的防效分别为58.40%和45.81%,到接种后6 d时,防效分别下降为39.35%和37.65%.经高温诱导后,过氧化物酶（POD）、苯丙氨酸解氨酶(PAL)、几丁质酶（Cht）、β-1,3-葡聚糖酶（Glu）活性均显著高于对照,与未诱导植株相比,高温诱导后叶片组织的细胞壁表面有大量木质素沉积,表明高温处理后黄瓜表现出对霜霉病的抗病性.     

NO和钙信使系统在草酸诱导黄瓜叶片抗霜霉病中的作用

通过草酸及其与不同抑制剂亚甲基蓝、EGTA、氯丙嗪和Li+组合处理黄瓜叶片,研究了草酸与抑制剂不同处理组合方式对黄瓜叶片POD活性和叶片病情指数的影响,探讨NO、钙信使系统在草酸诱导叶片抗霜霉病中的作用.结果显示,10～70mmol/L草酸均能不同程度诱导黄瓜叶片POD活性的升高,提高叶片对黄瓜霜霉病的抗病性,降低叶片病情指数,并以30mmol/L效果最好.4种抑制剂分别与30mmol/L草酸同时或先于草酸处理,或草酸处理后一定时间再用抑制剂处理,均明显抑制黄瓜叶片POD活性的升高及病情指数的降低.研究表明,NO、Ca2+、钙调素(CaM)和磷酸肌醇均可能参与了草酸诱导黄瓜霜霉病抗性的信号转导过程.     

假霜霉一新种

本文报道寄生在香薷上的一种新的假霜霉,命名为香薷假霜霉(Pseudoperonospora elsh-oltniae Taog sp. Nov.),并作了描述。     

The prevalence of Fasciola hepatica in its snail intermediate host determined by DNA probe assay

Accurate snail intermediate host infection prevalence data have the potential to be extremely useful in determining seasonal transmission dynamics of Fasciola hepatica. Because the microscopic techniques currently used lack the sensitivity and specificity necessary to obtain meaningful infection prevalence data, we developed a highly accurate and efficient DNA probe assay. The assay has a sensitivity of 100%, a specificity of >99%, easily detects a single miracidia and does not cross-hybridize with DNA of Fascioloides magna, Paramphistomum liorchis or Heterobilharzia americana, trematodes that share the same intermediate host and enzootic range as Fasciola hepatica. Using this assay, we determined the prevalence of F. hepatica in its snail intermediate host, Fossaria cubensis, during the second year of a 2-year study on the epizootiology of Fasciola hepatica in Florida. The overall infection prevalence of snails assayed in this study (n = 5246) was 1.5% and ranged from 0.1% to 3.1% for individual cattle ranches. Additionally, infection prevalence differed significantly for successive size groupings of snails, varying from 0% for 1-mm snails to 18.5% for 9- and 10-mm snails. The accuracy and efficiency of the DNA probe assay reported here for determining snail infection prevalence offers an inexpensive alternative to tracer animal studies for determining the epizootiology of F. hepatica.     

A New Species of Antarctoecia Ulmer, 1907 (Trichoptera: Limnephilidae) from Southeastern Brazil

A new species of Antarctoecia Ulmer, 1907 (Trichoptera: Limnephilidae) from south-eastern Brazil, Antarctoecia brasiliensis sp. nov., is described and figured based on adult male and female specimens from Mantiqueira mountain range, Minas Gerais State. This is the first record of the family Limnephilidae from Brazil.     

Pathogenic variability of Pseudoperonospora cubensis in Gangetic Alluvial region of West Bengal,India

Cucurbits are tremendous economically important vegetable crops and extensively cultivated in tropical and subtropical part of the world during both rainy and winter seasons. Biotic stresses are of paramount importance in causing economic losses in cucurbits. Downy mildew, a foliar disease caused by an Oomycetes, Pseudoperonospora cubensis (Berk. & Curt.) Rostow, is one of the most destructive pathogens of cucurbits especially in wet and temperate regions, with worldwide distribution. Isolates of pointed gourd and ivy gourd showed no symptoms with most of the cucurbits hosts except pointed gourd and ivy gourd. P. cubensis isolate of pointed gourd differed from other isolates and may belong to different pathotype. The results of this investigation suggest that high variability of P. cubensis in terms of different pathotypes exists in the Gangetic Alluvial Region of West Bengal. Based on morphological characterisation, nine isolates of P. cubensis are grouped into four clusters by using hierarchical cluster analysis.     

A Study on the Overwintering of Cucumber Downy Mildew Oospores in China

Oospore formation of Pseudoperonospora cubensis was investigated in 10 Chinese locations: Mohe, Harbin, Changchun, Shenyang, Beijing, Liaocheng, Yinchuan, Xining, Yangling and Haikou. Oospores were observed in all but Haikou. Oospore viability was monitored from 10 January to 10 July 2009, in Harbin. Percentages of activated oospores increased from 10 April with a peak in late May (14.0% on 25 May 2009), and then decreased. This is in accordance with the usual time of downy mildew appearance in Harbin, 20–30 May. Inoculation tests using the oospores overwintered in Harbin, whether in the greenhouse or outdoors, showed that these were viable, with a disease occurrence of 26.6–95.0%. Oospores overwintering locally could be primary infection sources of downy mildew in cool temperate northern China.     

黄瓜叶片胞间隙几丁质酶与抗霜霉菌侵染关系的研究

采用高抗霜霉病的‘津春4号’和易感霜霉病的‘长春密刺’黄瓜的温室穴盘幼苗为材料,研究了接种霜霉菌对黄瓜叶片胞间隙几丁质酶累积变化及幼苗生长的影响.结果显示:(1)与易感品种相比,抗病品种叶片胞间隙液蛋白浓度升高快、含量高;同时几丁质酶活性上升的速度快、幅度大,于接种后第2天达到峰值,且高活性维持至第7天;(2) SDS-PAGE电泳分析发现,抗病品种有一种27 kD的酸性几丁质酶在接种后第2天迅速积累,并在接种后第4、7天呈现出较高的表达量;Western blotting的结果也证实了上述胞间隙几丁质酶积累的变化.(3)与未接种对照相比,接种处理后第4、7天,易感黄瓜幼苗鲜重、干物质积累量均出现显著降低,但在接种后第7天抗病品种的上述生长指标要显著高于易感病品种.研究表明,接种霜霉菌后,抗病黄瓜叶片胞间隙几丁质酶迅速累积且活性快速升高,以减轻霜霉病对幼苗生长的侵害,这可能是黄瓜抗霜霉菌侵染的一种防御机制.     

瑞拉菌素产生菌S-5120菌株防治黄瓜霜霉病害的研究初报

经黄瓜霜霉病孢子萌发试验和离体叶片抑菌试验表明,瑞拉菌素产生菌S-5120菌株和瑞拉菌素均对黄瓜霜霉病有较强抑制作用。温室防病试验表明,瑞拉菌素产生菌S-5120发酵液对黄瓜霜霉病有明显的保护和治疗作用。相对保护效果达75．17％;治疗效果达69．69％,且高于农抗-120的相对防效62．65％。