Yield and fruit quality losses caused by ToMV in pepino (Solanum muricatum L.) and search for sources of resistance

Tomato mosaic virus (ToMV) is a limiting factor for the success of pepino (Solarium muricatum) as a new crop. The effects of ToMV infection on total and marketable yield, fruit weight, length/width ratio and soluble solids content (SSC) have been studied in two commercial clones (`Sweet Long' and `Sweet Round'). ToMV infection depressed total yield in infected plants of `Sweet Long' (43.1%), while it had no effect on this trait in `Sweet Round' . Marketable yield was dramatically reduced by ToMV infection in both clones, 94% in `Sweet Long' and 100% in `Sweet Round'. Infected plants of clone `Sweet Long' had a lower weight than healthy plants. Although no differences in fruit weight were detected in `Sweet Round' between ToMV infected and healthy plants, many fruits from infected plants showed deformities. Changes in fruit length/width ratio and SSC as a result of ToMV infection were not relevant, but fruit quality was lower in infected fruits, most of which had corky-like flesh. Forty-two clones from cultivated (S. muricatum), wild (S. caripense and S. tabanoense) and interspecific hybrids were tested for ToMV resistance. All but seven clones (four from S. muricatum and three from interspecific hybrids S. muricatum × S. caripense) were susceptible. Non-susceptible clones showed variable degrees of resistance and developed hypersensitive local lesions. Among these clones the most promising as sources of variation for resistance to ToMV are those belonging to the cultivated species. Although no immunity was found, plants from these clones remained asymptomatic and absorbance values resulting from the DAS-ELISA tests in these plants were always lower than those of the susceptible control (cv. `Sweet Round'). These sources of resistance may be of great utility in developing commercial clones resistant to this severe disease affecting pepino. This revised version was published online in July 2006 with corrections to the Cover Date.     

Resistance to potato late blight (Phytophthora infestans (Mont.) de Bary) in Solanum nigrum,S. villosum and their sexual hybrids with S. tuberosum and S. demissum

Summary Solanum nigrum and S. villosum, and their sexual hybrids with S. tuberosum and S. demissum respectively, were inoculated with a complex race of Phytophthora infestans. No visible reaction was seen on S. villosum and one genotype of S. nigrum. Another genotype of S. nigrum and the hybrids showed a hypersensitive response on most inoculated leaves. In one experiment, some sporulation was observed on detached leaves of a hybrid derived from S. nigrum. Microscopical examination of infections in S. nigrum and in a hybrid from S. nigrum, showed that penetration of epidermal cells and subsequent intercellular growth of the pathogen into the spongy mesophyll occurred, but without the formation of haustoria, and that invaded and neighbouring cells became necrotic. Callose appositions were found in epidermis and mesophyll cells of all inoculated genotypes, and also in epidermal cells of the unrelated nonhost species Brassica campestris.     

油茶皂素鱼毒制剂对常见淡水鱼虾的毒性研究

采用水箱养殖方式,研究油茶皂素鱼毒制剂对常见淡水鱼虾的毒性作用。结果显示,油茶皂素鱼毒制剂对闽江流域常见淡水鱼类具有较强的毒性,并呈现出良好的剂量-药效和时间-药效关系。在投药浓度为2.5mg/L时,该制剂在24 h内即可将实验鱼全部杀死,LD50为1.60~1.75 mg/L,对泥鳅的LD50为3.0 mg/L。但是该制剂对南美白对虾和河蟹却很安全,在投药浓度达50 mg/L时,南美白对虾48 h存活率可达100%,河蟹48 h存活率可达90%以上。研究结果表明,油茶皂素鱼毒制剂对闽江流域常见淡水鱼类具有显著的的毒杀能力。     

薇菜白粉病的化学防治药剂筛选试验

采用15％粉锈宁可湿性粉剂、45％结晶石硫合剂、50％代森锰锌等9种常规农药,对薇菜白粉病的分生孢子进行毒力测定和对薇菜白粉病进行防治试验。结果表明:15％粉锈宁可湿性粉剂1500倍液、45％结晶石硫合剂179倍液(0.2°Be)和扑菌特可湿性粉剂1500倍液3种药剂对薇菜白粉病防效良好。3种药剂可在生产上交替使用。     

小麦Ta-hir2基因克隆及转Ta-hir2基因小麦的获得

通过基因枪介导法将小麦过敏性诱导反应蛋白2基因Ta-hir2转入小麦胚性愈伤组织中,经分化筛选后获得转基因小麦植株,为验证该基因的功能奠定基础.以接种非亲和叶锈菌小种05-19-43②的小麦‘TcLr15,为材料,采用同源克隆的策略克隆了小麦Ta-hir2基因;将该基因的编码区与植物表达载体pAHC-25相连,成功构建...     

活性氧和一氧化氮在植物-病原体互作反应中的作用

植物被病原体感染后,植物体内活性氧产量急剧增加,这一现象被称为氧爆。活性氧族包括如单线态氧^1O2、超氧阴离子自由基O2^-、氢过氧自由基HO2·、过氧化氢H2O2、羟自由基·OH等。与ROS关系密切的一氧化氮,属于活性氮族。ROS和NO参与植物生长发育调控和对环境胁迫的应答反应,特别是在对抗外来病原体的入侵的防卫过程中发挥了重要作用。本文主要讨论ROS和NO在植物与病原体相互作用中发挥的作用。     

亚麻立枯病病原菌鉴定及药剂筛选

根据亚麻立枯病病原菌形态特征和致病性等特点,亚麻立枯病病原菌为Rhizoctonia solani kuehn,属于半知菌亚门,丝核菌属.供试的12种杀菌剂对病原菌菌丝的抑制效果试验表明,对亚麻立枯病病原菌菌丝生长有较强抑制效果的杀菌剂有立枯净、多菌灵、代森锰锌,其抑菌率分别为96.3%、92.5%、88.8%,其次,甲基托布津抑菌率为83.8%,甲霜灵,抑菌率为77.5%.     

不同药剂处理对无花果根腐病的影响

以2～3a生"布兰瑞克"无花果为试材,研究4种组合药剂对无花果根部病害的防治效果。结果表明:从防治效果和成本看,福美砷+五氯硝基苯+多菌灵或福美砷+根病清+甲霜灵锰锌10～15g的300倍液为最佳组合药剂。     

药剂种类和浓度对杨木强化改性效果的影响

以杨木板材为研究对象,选择不同浓度的酚醛树脂胶粘剂、异氰酸酯胶粘剂、硅溶胶／苯丙乳液试剂为浸渍药剂,利用真空压力装置,对杨木板材进行加压浸渍强化改性,并利用扫描电镜分析木材的微观结构。研究表明,浓度35％的酚醛树脂（PF）、浓度25％的异氰酸酯（PAPI）及浓度25％的苯丙乳液配比方案较优;3种药剂处理后的杨木强化效果优异程度为：异氰酸酯（PAPI）〉酚醛树脂（PF）〉硅溶胶／苯丙乳液。     

激发子PB90诱导不结球白菜过敏性细胞死亡早期上调表达基因片段的分析

【目的】从基因组水平筛选不结球白菜中受激发子PB90诱导过敏性细胞死亡早期上调表达的基因。【方法】采用抑制性差减杂交的方法筛选疫霉菌激发子PB90注射处理不结球白菜叶片5 h内上调表达的基因。【结果】测定分析了200个上调表达的cDNA片段,生物信息学分析表明它们包含70个上调表达的基因片段,共分为9类：基本能量或代谢产物;蛋白质合成分解;细胞信号传导;细胞凋亡;转录;运输相关和编码未知功能的蛋白等。进一步用半定量RT-PCR分析了候选基因beclin,thioredoxin,HLA-B,MAP3K,SPT1, SPT2和AGO1,表明这7个基因在PB90诱导不结球白菜过敏性细胞死亡早期上调表达。【结论】构建了疫霉菌激发子PB90诱导不结球白菜过敏性细胞死亡早期抑制性差减杂交cDNA文库,获得了70个上调表达的基因,并对其中7个基因的可能功能进行预测分析,认为这些基因可能与疫霉菌激发子PB90诱导不结球白菜过敏性细胞死亡有关。这些基因的挖掘为进一步阐明过敏性细胞死亡的分子机制提供了素材。