西安和上海两地葡萄根瘤蚜种群周年消长动态观察

 2005 年以来在我国多地发现葡萄根瘤蚜 (Daktulosphaira vitifoliae Fitch.)。为了解其种群年增长动态，对西安和上海两地田间葡萄根瘤蚜种群进行了调查，结果表明，两地的葡萄根瘤蚜为根瘤型，以孤雌生殖为主，在8—10 月出现有性世代更替，田间调查发现少量根瘤蚜有翅型若虫，但未发现有翅型成虫；虫口总量分别在7 月和10 月出现两次高峰。从11 月开始，成虫大量死亡，卵的数量随之减少，种群数量开始下降，逐渐进入越冬休眠状态，1 龄幼虫是其越冬的主要形态。春季当地温上升到13.0 ℃左右时，葡萄根瘤蚜结束休眠，幼虫开始取食，经过几次蜕皮逐渐转变为成虫，进行孤雌生殖产卵。     

Development of an enzyme-linked immunosorbent assay for quantitative determination of cyhalofop-butyl

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for cyhalofop-butyl was developed with a polyclonal antibody produced against a hapten (cyhalofop acid) conjugated with bovine serum albumin (BSA). The ELISA of cyhalofop-butyl showed an IC₅₀ value of 0.067 ± 0.004 mg/l and the limit of detection (LOD, IC₁₀) of 0.0029 ± 0.0001 mg/l at the optimal conditions. No significant cross-reaction to other structure-related compounds suggested high specificity for cyhalofop-butyl of the method. The average recoveries of cyhalofop-butyl from fortified water and soil were in the range of 83.2-119.7% and 80.1-104.0%, respectively. These data indicate that this method is a convenient analytical technique for monitoring cyhalofop-butyl in water and soil without purification steps.     

Inhibitory effects of Schiff analogs of salicylidene aniline on phenoloxidase from Pieris rapae L. (Lepidoptera: Pieridae)

In order to gain insight into the development of insecticides with novel modes of action, the effects of salicylidene aniline (a), salicylidene-4-chloroaniline (b), salicylidene-4-bromoaniline (c), and salicylidene-4-nitroaniline (d) on partially purified phenoloxidase (PO) from Pieris rapae L. were investigated. The results showed that the 4 compounds could inhibit PO activity, and the inhibitor concentrations leading to a loss of 50% activity (IC₅₀) were estimated to be 0.025 mmol L⁻¹, 0.732 mmol L⁻¹, 0.471 mmol L⁻¹, and 0.675 mmol L⁻¹, respectively. Meanwhile, all the inhibitors showed reversible competitive inhibition, except (d), which showed reversible mixed inhibition. The K_I values were determined as 0.106 mmol L⁻¹, 10.059 mmol L⁻¹, 8.390 mmol L⁻¹, and 20.198 mmol L⁻¹ for the four compounds, respectively. The UV-vis spectra of (a) and (d) in the presence of copper ions and the enzyme showed that (a) could directly chelate the copper ions of PO; however, (d) could neither chelate the additional copper ions nor the copper ions of PO.     

The development of a PCR-based method for detecting <Emphasis Type="Italic">Puccinia striiformis</Emphasis> latent infections in wheat leaves

Stripe rust of wheat caused by Puccinia striiformis f. sp. tritici is one of the most important diseases on wheat worldwide, especially in temperate regions with cool moist weather conditions. A rapid and reliable detection of the pathogen in latent infected wheat leaves during overwintering of the fungus in the dormant stage will contribute to determine the initial inoculum potential and thus to predict early outbreak and to improve effective management of the disease. To achieve this aim, a PCR-based method was developed for specific and sensitive detection of P. striiformis. Specific primers were designed according to a genome-specific sequence of P. striiformis. To evaluate the specificity of the primers, seven different isolates and races of P. striiformis as well as six other pathogens of wheat were tested. All isolates of P. striiformis yielded a distinct band of a fragment of 470 bp, while using DNA of the other wheat pathogens as a template no amplification product was detected. The sensitivity of the primers was tested using serial dilutions of total DNA from P. striiformis; the limit of detection was 10 pg of DNA. Using extracts from P. striiformis-infected wheat leaves, the fungus could be determined in the leaves before symptoms appeared. The stripe rust could also be detected in the dormant stage by the PCR assay in samples of wheat leaves taken during the winter season. The application of the PCR assay may be useful for rapid and reliable detection of P. striiformis in latent infected leaves of overwintering wheat plants.     

Induction of systemic resistance in banana (<Emphasis Type="Italic">Musa</Emphasis> spp.) against <Emphasis Type="Italic">Banana bunchy top virus</Emphasis> (BBTV) by combining chitin with root-colonizing <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> strain CHA0

Pseudomonas fluorescens strains CHA0 and Pf1 were investigated for their biocontrol efficacy against Banana bunchy top virus (BBTV) in banana (Musa spp.) alone and in combination with chitin under glasshouse and field conditions. Bioformulation of P. fluorescens strain CHA0 with chitin was effective in reducing the banana bunchy top disease (BBTD) incidence in banana under glasshouse and field conditions. In addition to disease control, the bioformulation increased the economic yield significantly compared to the untreated control. Increased accumulation of oxidative enzymes, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), pathogenesis-related (PR) proteins, chitinase, β-1,3-glucanase and phenolics were observed in CHA0 bioformulation amended with chitin-treated plants challenged with BBTV under glasshouse conditions. Indirect ELISA indicated the reduction in viral antigen concentration in P. fluorescens strain CHA0 with chitin-treated banana plants corresponding to reduced disease ratings. The present study revealed that induction of defence enzymes by P. fluorescens with chitin amendment reduced the BBTD incidence and increased bunch yield in banana.     

稻瘟菌拮抗细菌的筛选与鉴定

从不同水稻根际土壤样品中分离纯化了486株细菌。采用平板测定法和微培养离体测定试验获得12株对稻瘟菌有不同程度抑制作用的拮抗细菌。结果表明:B4,B8,B18,B31,B34,B73和B74等菌株对稻瘟菌菌丝生长抑制率均在80%以上,其培养液100%抑制稻瘟菌孢子萌发;同时对水稻纹枯病菌、油菜菌核病菌、小麦赤霉病菌、草莓炭疽病菌和黄瓜枯萎病菌等多种病原真菌有较好抑制作用,经鉴定该组拮抗细菌为枯草芽孢杆菌。B1,B43和B44菌株对稻瘟菌菌丝生长和孢子萌发有较好抑制作用,对水稻纹枯病菌具有一定的抑制作用,经鉴定为短小芽孢杆菌。B48和B59为链霉菌,对稻瘟菌的抑菌带明显,但对稻瘟菌孢子萌发和附着胞的形成抑制作用不明显。     

烟草疫霉的快速分子检测

 根据烟草疫霉与其他疫霉菌ITS序列的差异设计了1对寡聚核苷酸引物，用于烟草疫霉的PCR检测。结果表明，在优化的反应体系与扩增条件下，该对引物表现出强特异性，只在烟草疫霉为模板的扩增体系中具有1条660bp的条带。利用此特异性引物可稳定地从含有烟草疫霉的土壤及其发病组织中检测出病原菌。本实验提供并完善了一套快速检测烟草疫霉的方法和技术，特别对土传病害的准确诊断与快速检测在实践和理论上具有重要意义。     

云南烟草赤星病菌及近似种rDNA ITS序列分析

 为了进一步研究云南省烟草赤星病病原的系统发育关系，提取28份供试菌株的菌丝基因组DNA，进行rDNA ITS序列及两侧ITS序列扩增。28个供试菌株与GenBank中登录的链格孢属7个种（包括5个小孢子种Alternaria citri，A．alternata，A．longipes，A．mali，A．gaisen和2个大孢子种A．porri，A．solani）14个菌株的序列进行聚类分析：42个菌株明显地分成两支，供试菌株与5个小孢子种聚为一个分支，序列同源性高达99％～100％，没有明显的地域性差异；但另2个大孢子种聚为单独的一支，明显地与供试菌株和其他5个小孢子种区分开。rDNA ITSl 58S ITS2序列在相对保守的基础上又存在一定变异，在一些菌物属的研究中可作为分类鉴定、分子标记、系统发育的重要依据，但通过对世界各地Alternaria菌株序列的分析发现，rDNA ITS1 58S ITS2仅能将大孢子种和小孢子种分开，还不能作为区分不同地域不同来源菌株的标准。     

马铃薯疮痂病菌拮抗菌ZWQ-1的鉴定及防效测定

为探明马铃薯疮痂病菌拮抗菌ZWQ-1的生物学分类地位和防病效果,结合其生物学特性和16SrDNA序列特征对菌株ZWQ-1进行了鉴定,利用纸碟法和温室盆栽接种试验测定了该菌的抑菌活性及其对马铃薯疮痂病的防效。结果表明,该菌的形态和生理生化特征与枯草芽孢杆菌一致,其16SrDNA序列与枯草芽孢杆菌菌株JQ398853、JN399219的同源性高达99%,因此,将其鉴定为枯草芽孢杆菌(Bacillus subtilis)。盆栽接种防病测试结果表明,拮抗菌ZWQ-1可显著降低马铃薯疮痂病的发病程度,对病原菌CPS-1、SHXHZ-3、CPS-3、CPS-2和NM-10的防治效果较为明显,防效分别为79.09%、78.85%、77.44%、54.68%和49.68%,说明拮抗菌株ZWQ-1对马铃薯疮痂病具有较好的防治作用。此外,该菌对其他18种植物病原菌也有一定的抑菌作用,说明菌株ZWQ-1是一株较具开发潜力的生防菌株。     

烟夜蛾滞育期间日失重、含水量及呼吸速率的变化

为探明烟夜蛾的滞育机制,测定了烟夜蛾滞育蛹和非滞育蛹日失重、含水量及呼吸速率的变化。结果表明,滞育蛹鲜质量、含水量均显著低于非滞育蛹;滞育蛹日失重变化比较平缓,没有明显的失重高峰,其平均值为3.19mg/头,而非滞育蛹的体质量变化较大,4日龄时达高峰,日失重高达13.67mg/头;滞育蛹和非滞育蛹的CO2呼出量无显著差异,但滞育蛹的呼吸速率相对平稳,非滞育蛹的呼吸速率变化较大,呈上下波动的曲线。这可能与滞育蛹滞育期间较弱的生理代谢水平和较高的抗寒性有关。