苹果花脸病田间病情发展及ASSVd在组培条件下的传播

为了明确苹果锈果类病毒（apple scar skin viroid，ASSVd）引起的苹果花脸病在田间的病情发展情况以及ASSVd在组培条件下的传播方式，2012—2015年对河北省顺平南神南村3个果园进行持续调查和检测。结果显示，果园A、B、C的显症率分别从3.00%、19.35%和10.00%上升至10.00%、34.41%和22.00%，带毒率分别从11.00%、20.43%和14.00%上升至23.00%、37.63%和30.00%，带毒率和显症率都逐年增加，而且带毒率大于显症率，即有些带毒果树不显症。发病果树田间分布有明显的发病中心。通过高通量测序发现显症果树ASSVd vsiRNA reads数是带毒未显症reads数的4.08倍，同时实时荧光定量PCR检测发现显症树ASSVd病毒积累量显著高于带毒未显症树。以携带ASSVd的组培苗和无毒组培苗为试材，利用RT-PCR检测明确了ASSVd可通过伤口沾染带毒汁液、组培剪污染、含毒培养基、根系接触进行传播，其中根系接触传染率较高。     

金融经营者不当销售行为的法律规制——以信义义务为进路

一些金融经营者在金融商品交易过程中存在不当销售行为，给金融消费者带来财产损失。然而依据我国现行的有关法律规则，消费者通常难以获得有效的法律救济。在英美法国家，法院通过信义关系理论将金融经营者与金融消费者之间的关系认定为一种信义关系，并在此基础上对经营者设定信义义务的约束，相关原理和规则值得我国立法借鉴。我国立法宜应明确以适当性原则以及说明义务为主要内容的信义义务规则，确立违反信义义务的民事责任，从而为消费者提供可以援引的私法规则。     

河北保定地区苹果锈果类病毒分离物的序列分析

以采自河北保定的苹果锈果类病毒(apple skin scar viroid,ASSVd)样本为试材,采用用RT-PCR方法对样本中的ASSVd全基因组序列进行扩增,然后利用生物学软件MEGA 6.0对该分离物与已发表的其它分离物序列构建系统发育树,对系统进化关系进行分析。结果表明:ASSVd保定分离物基因组全长332nt,将序列提交到GenBank,登录号为KR264032。该分离物与已发表的其它13个来自不同寄主、不同国家的ASSVd分离物间进化关系极近,核苷酸相似性为92%~99%。与加拿大苹果上的X71599株系亲缘关系最近,相似性为99%,仅在第221位有一个碱基差异,与新疆梨上的JX861259株系亲缘关系最远。系统发育分析表明,不同地区的ASSVd分离物聚类没有规律性,说明ASSVd不存在地区专化性。新疆梨、桃、杏、苹果不在同一分支,说明ASSVd可能存在一定的寄主特异性。二级结构预测表明,该分离物的中央保守区与末端保守区与ASSVd其它序列相同。     

Inhibitory efficacy of calcium cyanamide on the pathogens of replant diseases in strawberry

Replant diseases in strawberry caused by Rhizoctonia solani, Fusarium oxysporum and Verticillium dahliae are serious problems for its sustainable production under continuous cropping. This research studied the inhibitory effect of calcium cyanamide on pathogenic fungi in Petri dishes and on sterilized soil. Results indicated that calcium cyanamide had an obvious inhibitory effect on three pathogens on potato dextrose agar (PDA) plates. Among them, the inhibitory effect on Rhizoctonia solani was the highest. As the concentrations of calcium cyanamide was increased from 0.1 to 10 mg/mL, the inhibition rate on mycelial growth increased from −1.43% to 100%. Inhibitory effects on Fusarium oxysporum and Verticillium dahliae also existed on Petri dishes but to a lesser extent. Similar results were also observed in sterilized soil. When the concentration of calcium cyanamide in sterilized soil was 0.1%, the inhibitory effect on Fusarium oxysporum and Verticillium dahliae was 68.46% and 54.46%, respectively. The inhibitive effect of calcium cyanamide on Fusarium oxysporum and Verticillium dahliae increased quickly as the soil moisture changed from 10% to 40% for Verticillium dahliae and from 10% to 60% for Fusarium oxysporum. This indicated that the inhibitive effect of calcium cyanamide could be influenced greatly by the moisture content in the soil.     

有机硅助剂在苹果炭疽叶枯病化学防控中的减药增效作用评价

有机硅助剂具有低毒、易降解的特性,可提高农药的药液展布性和渗透性。本研究分别采用室内离体叶片法和田间试验评价了2种有机硅助剂对吡唑醚菌酯和代森锰锌防治苹果炭疽叶枯病的减药增效作用。室内离体试验结果表明,杀菌剂浓度减半的处理以及模拟雨水冲刷处理均导致吡唑醚菌酯和代森锰锌的防效显著下降;而添加了有机硅助剂后,2种处理的防效显著提高,并且恢复到与正常施药量相同的水平。田间试验结果表明,正常情况下杀菌剂浓度减半后防效显著下降;而施用有机硅助剂后,浓度减半的吡唑醚菌酯和代森锰锌的防效显著高于不施用有机硅的处理。本研究结果表明,施用有机硅助剂可以在减少化学农药实际用量的情况下,保持较高的防效,这对于化学农药的减施增效具有重要意义。     

Biological characteristics of strain F603 of Epicoccom sp., an antagonistic fungus for controlling Phytophthora infestans

Factors influencing vegetative growth and spore germination of strain F603 of Epicoccom sp., an antagonistic fungus for Phytophthora infestans (Mont) de Bary, were studied. Among the different growth media tested, Rye agar was the best medium for its vegetative growth. The range of temperature and pH value for mycelial growth was 5–35°C and 2–12, respectively, with the optimum 25°C and 6–9, respectively. The fungus grew better in Czapek medium with maltose and dextrose as carbon sources and peptone, KNO₃, and NaNO₃ as nitrogen sources. The range of temperature for spore germination of strain F603 was 5–35°C, the optimum was 20°C. The range of temperature for sporulation was 10–30°C, and the optimum was 15–18°C.     

Infection of cucumber seedling roots by Pseudomonas amygdali pv. lachrymans following artificial substrate inoculation

European Journal of Plant Pathology - There are few studies of cucumber roots at the seedling stage infected by Pseudomonas amygdali pv. lachrymans (Pal). We used growth chamber assays to determine...     

10种化学杀菌剂对苹果树腐烂病的防效评价

本试验通过采用抑制菌丝生长、促进伤口愈合以及在离体枝条上的保护和治疗试验,对市售的10种化学药剂进行了防治苹果树腐烂病效果的评价.这些药剂分别为甲硫·萘乙酸、腐植酸·铜、菌毒清、丙环唑、代森铵、丁香菌酯、噻霉酮、辛菌胺·醋酸盐、甲基硫菌灵(山西北方种业)和甲基硫菌灵(日本曹达).试验结果表明,不同的测试方法得到不同的排序.在抑菌试验中,抑菌作用最强的药剂是甲基硫菌灵(山西北方种业)和腐植酸·铜,抑菌带均为5.00 cm,其次为菌毒清、丙环唑和甲硫·萘乙酸.在伤口愈合试验中,甲基硫菌灵(日本曹达)和甲硫·萘乙酸对伤口的愈合作用最好,其愈伤组织宽度分别比对照宽2.00 mm和0.92 mm.在离体枝条保护作用试验中,甲硫·蕃乙酸、腐植酸·铜、甲基硫菌灵(日本曹达)处理均未发病.在离体枝条治疗作用试验中,甲硫·萘乙酸、菌毒清、代森铵、甲基硫菌灵(山西北方种业)、腐植酸·铜的病斑平均扩展面积均小于50 mm2,其中甲硫·萘乙酸和菌毒清的防效均为87.5％,病斑面积仅为对照的1.6％和2.2％.综合排序和分析认为,甲硫·萘乙酸是治疗腐烂病效果最好的药剂.     

利用内标为基础的苹果锈果类病毒RT-PCR检测技术

为开发准确、灵敏的苹果锈果类病毒(Apple scar skin viroid,ASSVd)RT-PCR检测方法,以田间染病苹果组织为试材,提取高质量总RNA为模板,在常规RT-PCR检测体系中引入苹果线粒体nad5基因作为内标基因,对RT-PCR反应体系和程序进行优化,并测定其灵敏度和稳定性,最后利用优化的检测体系确定苹果果实着色期最佳检测部位。结果表明:以RNA提取改良法提取总RNA为模板合成cDNA后,进行PCR扩增,优化后的PCR体系(25μL)中cDNA模板2μL、ASSVd(20pmol/μL)正反向引物各1.0μL,nad5(20pmol/μL)正反向引物各0.1μL;扩增程序中退火温度为60.9℃,循环次数为35次;检测灵敏度为37.5ng新鲜样本;果实着色期,染病植株的幼嫩叶片、1a生枝的韧皮部和木质部、果实及部分种子样本均能检测到病毒,最佳检测部位为幼嫩韧皮部。研究结果可以为ASSVd高效、快速、准确的检测提供可靠方法,并为田间病害诊断及无毒苗木繁育提供依据和借鉴。     

黄瓜绿斑驳病毒河北分离物基因组克隆及序列分析

为揭示河北省黄瓜绿斑驳病毒(Cucumber green mottle mosaic virus,CGMMV)分类地位及系统进化情况,通过分子克隆测定了来自河北省西瓜产区分离获得的分离物CGMMV-chb的近全基因组序列,分析其基因组结构特征;并依据近全基因组核苷酸序列及外壳蛋白氨基酸序列进行了系统进化关系分析。结果表明,CGMMV-chb近全基因组大小为6 383 nts,Gen Bank登录号为KJ658958,含4个开放阅读框,编码4种蛋白;与Gen Bank库中的其它12个CGMMV分离物的核苷酸相似性为92%~100%,氨基酸相似性为98%~100%。CGMMV-chb与韩国分离物CGMMV-KW基因序列相似性最高,为98%~100%,与以色列分离物CGMMV isolate Ec基因序列相似性最低,为92%~99%;系统进化关系中CGMMV-chb与其它中国分离物、日韩分离物亲缘关系较近,处于同一亚组的不同分支中,与以色列分离物亲缘关系相对较远。