Detection of Ralstonia solanacearum (biovar 2A) in stems of symptomless plants before harvest of the potato crop using post-enrichment DAS-ELISA

The detection of Ralstonia solanacearum (biovar 2A) in stems of symptomless plants before harvest of the potato crop, instead of tubers, would not only save highly valued planting material but would be less time-consuming and would also enhance farmers' market decisions. Although pathogen detection in stems has been proven efficient for ring rot, this has never been investigated for bacterial wilt (BW). Therefore the possibility of detecting BW latent infection in stem pieces about three weeks before harvest was assessed in 57 fields of the Andean highlands of Peru. Two sensitive, specific and user-friendly serological methods were used to detect the pathogen in latently infected tubers and stems: double-antibody sandwich (DAS)-ELISA and indirect ELISA on nitrocellulose membrane (NCM) after enrichment of the plant extracts in a semi-specific broth. Optimum sample sizes of stems and tubers were evaluated for 37 potato crops showing between 0 and 0·1% BW incidence using a binomial distribution model to calculate the detection probabilities. Although results of detection using the two serological techniques had 100% concordance, detection probabilities were higher using DAS-ELISA, whatever the plant part tested. BW detection probabilities were higher for tubers than for stems; a 99% detection probability was obtained by analysing 400 stems sections or 250 tubers using DAS-ELISA. Detection of BW infection in symptomless plants 20 days before harvest using post-enrichment DAS-ELISA is a reliable and user-friendly technique that can easily be used by national plant protection services and seed programmes in developing countries.     

Insights into the role of ethylene perception in tomato resistance to vascular infection by Verticillium dahliae

A Tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) system was employed to investigate the role of the tomato ethylene receptor ETR4. By comparing wilting symptoms of verticillium wilt in wild-type, ethylene-insensitive Never ripe ( Nr ) mutant tomato plants and ETR4 -silenced plants, it was demonstrated that disease severity in the Nr and ETR4 -silenced plants was statistically reduced compared to wild-type plants. Disease incidence and severity were reduced by 11 and 20%, respectively, in the Nr plants compared to the wild-type plants, at 33 days post-inoculation (d.p.i.). In the ETR4 -silenced plants, disease incidence and severity were reduced by 14 and 15%, respectively, compared to the TRV -only-inoculated plants, at 37 d.p.i. Quantification of Verticillium dahliae by qPCR revealed that the reduction in symptom severity in the Nr plants was associated with significant reduction of growth of the pathogen in the vascular tissues of the Nr plants compared to that in the wild-type plants, suggesting that impaired perception of ethylene via the Never-ripe receptor results in increased disease resistance. Fungal reduction was evident at each sampling day in the Nr plants, ranging from 1·5 to 1·75 times less than that in the wild-type plants. Fungal quantification in the ETR4- silenced and TRV -only-inoculated plants showed similar levels of fungal biomass.     

万寿菊根提取物对西瓜枯萎病菌的抑菌活性成分及作用机理研究

本文研究了万寿菊根提取物中西瓜枯萎病菌的抑菌活性成分及其抑菌作用机理。结果表明,在4类主要化学物质中,精油类含量最高(59.8%),且抑菌效果最佳;10mg/mL精油提取物的抑制率在24、36和48h分别为62.83%,58.31%和56.30%。在西瓜枯萎病的3个主要发病期(苗期、伸蔓开花期和座果期)施用精油提取液,能有效抑制西瓜枯萎病菌,促进植株生长,同时提高西瓜植株的POD和SOD酶活性,并维持CAT活性,有效减轻了西瓜枯萎病菌对植株的毒害作用。     

大丽轮枝菌拮抗细菌枯草芽孢杆菌8-28菌株产芽孢条件优化

为提高大丽轮枝菌(Verticillium dahilae Kleb)拮抗细菌枯草芽孢杆菌(Bacillus subtilis)8-28菌株的芽孢形成率及芽孢数量,在摇瓶发酵基础上对影响菌株芽孢形成主要因素进行研究.通过单因素试验确定最佳碳源麦芽糊精、氮源黄豆饼粉、无机盐K2HPO4和MuSO4·H2O;采用正交试验对发酵培养基进行优化,摇瓶发酵生产芽孢的最佳条件为:麦芽糊精2.0%、黄豆饼粉2.0%、K2HPO40.05%和MnSO4·H2O0.01%、培养液初始pH值为7.0、种龄18 h、装瓶量50mL·(250mL)-1.在此优化条件下,发酵液中8-28茸株的芽孢微量迭到2.67×1 08个·mL-1.芽孢形成率迭到90%.     

西瓜枯萎病菌毒素培养滤液对西瓜幼苗可溶性蛋白含量的影响

以不同抗性西瓜苗品种为材料,研究了西瓜苗期感染枯萎病菌(Fusarium oxysporumf.sp.niveum)病原菌毒素粗提液处理后在生长的不同时期、不同生长部位植株体内可溶性蛋白含量的变化情况,并分析了这些变化与植物抗病性的相互关系。结果表明,经毒素粗提液处理后,与对照相比,不同部位间可溶性蛋白含量存在明显差异。但是从总体上看,叶部可溶性蛋白含量最高、茎部次之、根部最低;一般情况下,在同一部位抗病品种的可溶性蛋白含量大于感病品种。     

广西粉蕉生产存在的问题及发展对策

介绍了广西粉蕉的生产概况,指出广西粉蕉生产存在尖孢镰刀菌枯萎病发生严重,易遭根结线虫、象鼻虫、红蜘蛛、蓟马和烟霉病等病虫危害,品种少,种植技术不完善等问题;提出开展对香蕉枯萎病的发病、传播机理和化学防治的基础研究,开展粉蕉种植技术集成、试验、示范及品种选育研究等对策。     

我国棉花抗黄萎病遗传育种研究综述

介绍了棉花黄萎病的危害,综述了我国棉花抗黄萎病的遗传研究和抗黄萎病育种现状和存在的问题,并针对如何解决我国棉花抗病遗传和育种中存在的问题提出了一些建议。     

Selection for verticillium wilt resistance in potato breeding populations derived from four cross types

Verticillium wilt (VW) is one of the important yield-limiting diseases for potato production. To develop resistant clones, the potential for early generation selection was studied using three basic selection methods, individual, family, and within family selection, for two clonal generations. A total of 152 clones were derived from four cross types (2x × 2x, 2x × 4x, 4x × 2x and 4x × 4x). Clones were evaluated for maturity, symptom expression, yield and stem colonization in replicated trials. Heritability and selection response for the traits were estimated for each selection method. Direct selection in the second clonal generation and individual selection showed more gain than that from other methods. Both 2x × 2x and 4x × 2x families were higher yielding and had lower stem colonization scores than 2x × 4x and 4x × 4x crosses. Therefore, 2x × 2x or 4x × 2x crosses between carefully chosen parents with high yield and VW resistance may produce offspring with superior performance.     

棉花抗枯黄萎病品种耐低磷种质筛选

 采用蛭石栽培和营养液浇灌的方法,研究棉花品种耐低磷筛选指标,利用这些指标对88份棉花抗枯、黄萎病品种进行磷素利用率极端基因型的筛选。结果表明,株高和根冠比在不同品种和不同磷浓度处理之间无显著差异,而棉苗干物重、地上部鲜重、总叶面积、叶绿素含量、地上部干物重及磷利用率在不同磷浓度处理和不同品种之间均存在显著差异,可以作为棉花苗期耐低磷能力的评价指标。利用这些指标对棉花抗枯、黄萎病品种进行了分析。聚类结果将88个品种主要分为耐低磷基因型和非耐低磷基因型两大类,分别包括25个和55个品种。其中,中棉所21、中99和陕棉11属于耐低磷的极端基因型。     

朱砂根枯萎病的发生特点与防治技术

朱砂根近几年作为观果花卉连年设施栽培,导致枯萎病发生日益严重。经作者多年试验探讨,总结了朱砂根枯萎病发生的症状、病原菌、病害发生规律及其影响因素,并提出相应的综合防治措施。这是我国南方对朱砂根枯萎病的首次报道。