The Effect of Inoculation Treatment and Long-term Application of Moisture on Fusarium Head Blight Symptoms and Deoxynivalenol Contamination in Wheat Grains

Fusarium head blight (FHB) is an important disease of wheat, which can result in the contamination of grains with mycotoxins such as deoxynivalenol (DON). Artificial inoculation of flowering ears with conidial suspensions is widely used to study FHB diseases. Our goal was to compare four inoculation treatments in which a conidial suspension was sprayed on flowering ears and to study the effect of the application of moisture during kernel setting and filling with a mist-irrigation system. Ten wheat genotypes were inoculated with a DON-producing Fusarium culmorum strain. Inoculation treatments varied in time of application of the inoculum (morning or evening) and in the method of controlling humidity during inoculation (bagging or mist irrigation). A wet season was simulated with a mist-irrigation system, keeping the crop canopy wet for at least 26 days after flowering. The severity of FHB symptoms (area under disease progress curve (AUDPC)), yield loss and DON contamination in the grains were determined. AUDPC data obtained with the different inoculation treatments were highly correlated (r=0.85–0.95). Mist irrigation after inoculation resulted in a higher mean disease severity, but in a overall lower toxin contamination as compared to the non-irrigated treatments. Genotypic differences in DON accumulation were present: for one wheat line toxin contamination significantly increased when irrigated, while two genotypes accumulated significantly less toxin. The closest relationships (r=0.73–0.89) between the visual symptoms and the DON content were obtained under moderate mean infection pressure. This relation between visual symptoms and the DON content deteriorated at higher infection levels.     

小麦矮化腥黑穗病菌侵染能力的研究

中美专家合作在美国犹他州对小麦矮化腥黑穗病菌的侵染能力进行了研究。试验采用不含抗病基因的小麦品种Cheyanne,播种前用溴甲烷对试验小区进行了熏蒸。接种物为含有多种致病型的冬孢子悬浮液,采用土壤表面喷洒冬孢子悬浮液的方法进行接种,接种密度为每cm20、0.88、8.84、88.45、884.49、8844.89、88449个孢子。结果表明,接种密度为每cm20.88个孢子时即可产生0.21％的穗发病率。对试验数据进行分析后表明,小麦矮化腥黑穗病菌的侵染规律符合侵染概率理论,在本试验条件下,单个孢子的侵染概率为0.0002。     

Characterisation of a Quantitative Resistance to Vector Transmission of Tomato yellow leaf curl virus in Lycopersicon pimpinellifolium

Two wild genotypes from the same species Lycopersicon pimpinellifolium, WVA106 (susceptible) and INRA-Hirsute (so-called ‘resistant’), were compared with respect to their reaction to Tomato yellow leaf curl virus isolate Réunion (TYLCV-Mld[RE]), using both whitefly-mediated inoculation and graft inoculation. Disease incidence and symptom severity were scored. Presence and quantification of viral DNA were assessed by dot blot hybridisation. Upon insect inoculation, accession INRA-Hirsute showed a moderate resistance against TYLCV that was overcome by a high inoculation pressure obtained by increasing the cumulative number of inoculative whiteflies. Temporal analyses of the disease progress in relation to this criterion exhibited that the protection was quantitative, mainly reducing the TYLCV-Mld[RE] incidence by at maximum 50% at low inoculation pressure. When graft inoculated, the final TYLCV-Mld[RE] disease incidence was 100% in both susceptible and resistant genotypes with severe symptoms, suggesting a reduction of virus transmission by a vector resistance as a possible mechanism. Implications of using such type of resistance in breeding programmes are discussed.     

黑龙江省水稻穗颈瘟人工接种技术研究

为建立水稻穗颈瘟准确的鉴定技术,在黑龙江省人工气候室完成发病条件鉴定试验,结合田间病圃完成接种条件鉴定试验.结果显示,在人工气候室内,自然光源下、环境温度26℃、相对湿度≥90％、水稻孕穗末期用5号或6号针头注射接种的鉴定效果最佳,供试水稻品种平均发病率为92.22％.在人工控制环境条件的前提下,试验点田间接种的效果也...     

Assessment of inoculation methods for screening black alder resistance to Phytophthora ×alni

Identification of resistance to Phytophthora ×alni could provide the basis for a management strategy against alder decline in riparian ecosystems in Europe. This study aimed to test methods to evaluate the resistance of riparian alders to the disease, and to screen alder genotypes for resistance. Phytophthora ×alni isolates were compared for their aggressiveness (lesion length on stem) and sporulation capacity (sporangia). While no difference in lesion lengths was found between isolates, sporangia production was dependent on isolate, highlighting the need for careful selection of isolates used for zoospore inoculation methods. Inoculation tests carried out at different periods of the year revealed a seasonal change in susceptibility to the disease, with the period from June to September being the most efficient for inoculation tests. Stem‐wounded inoculations, carried out on excised shoots, were unreliable for evaluating the level of resistance of alder genotypes to P. ×alni infection, with divergent results between two successive years or between two inoculation periods during the same year. In contrast, a method that mimics the natural conditions of infection, based on flooding of rooted cuttings in artificially infected river water, was found promising. Another method, based on the inoculation of foliated terminal shoots with zoospore suspensions, was found to be repeatable and could be used for high‐throughput analyses. Altogether, the results show a continuous resistance response from highly susceptible to moderately resistant genotypes. This suggests that breeding might be a useful strategy to manage alder decline caused by P. ×alni.     

龟纹瓢虫幼虫人工饲料的研究

以蝇蛆和黄粉虫蛹作为外源动物蛋白配制龟纹瓢虫幼虫人工饲料,从初孵幼虫开始饲喂,以幼虫历期、幼虫存活率、蛹历期、羽化率、成虫体重、成虫获得率作为评价指标,对外源动物蛋白的添加形式进行筛选,蝇蛆及黄粉虫蛹脱脂粉饲喂效果均优于其他蛋白形式;在上述结论配方的基础上,以脱脂粉、酵母抽提物、蔗糖和橄榄油为主成分进行L9(34)正交试验,经Duncan's新复极差检验分析,得出两组优化配方:(1)蝇蛆脱脂粉0.50g、酵母抽提物0.25g、蔗糖0.30g、橄榄油0.01g;(2)黄粉虫蛹脱脂粉0.50g、酵母抽提物0.35g、蔗糖0.30g、橄榄油0.02g.验证饲养表明,两组理论优化配方均符合实际.     

用转基因方法进行抗线虫农作物育种的研究进展

在许多农作物中,植物寄生线虫引起重大损失。有幸的是,某些植物对线虫有抗性,而且存在于栽培种和其近亲野生种中的抗性基因,可以用分子标记方法建立图谱。标记辅助的选择方法已广泛应用于育种工作中,两种抗线虫的基因已经通过定位克隆技术分离出来,并成功地在栽培作物中得到表达。建立线虫抗性的另一个方法是将具有杀线剂效应的基因导入植物中,该方法也已取得了一些进展。     

应用赤眼蜂蛹人工饲养尼氏钝绥螨的研究初报

本文首次报导应用赤眼蜂蛹作为替代食料人工饲养尼氏钝绥螨。日食蛹量,幼螨为0.18头,产卵前期成螨达1.18头,而产卵期成螨则为0.95头左右。在25℃饲养条件下,每雌产卵达45粒,卵历期48小时,孵化率近92％,幼螨存活率88％,成螨雌性占55％,雌成螨寿命25天。用赤眼蜂蛹连代饲养的尼氏钝绥螨在桔园释放,对柑桔全爪螨具有明显的控制作用。     

金耳有效原种的配方和品种筛选

将生产中用到的两个金耳品种作为研究对象,将不同配方培养基中的菌丝、子实体生长状况进行对比,挑选出更适宜大规模生产的金耳品种,并探究麦麸在金耳有效原种制备中的必要性。研究结果显示,金耳1号菌丝较金耳2号更粗壮,长势更好,菌丝满瓶速度更快,子实体形态更好,更适合作为大规模生产的品种进行推广,且添加麦麸的配方更适合金耳1号原种生长。     

氨基脲人工抗原的合成及其多克隆抗体的制备

目的合成氨基脲人工抗原并制备其多克隆抗体。方法以氨基脲(SEM)和对醛基苯甲酸(CP)为原料合成半抗原(CP-SEM),并采用碳化二亚胺法和混合酸酐法将其分别与牛血清白蛋白(BSA)和鸡卵清蛋白(OVA)偶联,合成氨基脲人工抗原。以氨基脲人工抗原(CPSEM-BSA)为免疫原免疫Balb/c小鼠,利用间接ELISA法测定其抗体效价。结果经薄层层析、红外光谱和元素分析等方法鉴定合成半抗原即为CP-SEM。紫外扫描、聚丙烯酰胺凝胶电泳结果表明人工抗原合成成功。免疫获得抗氨基脲的多克隆抗体,其抗体效价为1:64000。结论氨基脲人工抗原合成成功,并获得抗氨基脲的多克隆抗体。