细菌耐药拮抗剂的研究

本文介绍了具有拮抗细菌耐药性作用的物质的研究进展情况，包括灭活酶抑制剂、药物渗透促进剂、外输泵抑制剂、细菌生物被膜抑制剂、抗菌药物增强剂、耐药质粒消除剂等。     

The effect of populations of Xanthomonas campestris pv. phaseoli in bean reproductive tissues on seed infection of resistant and susceptible bean genotypes

Surface and internal populations of Xanthomonas campestris pv. phaseoli, causal agent of common bacterial blight of bean, on and in flower buds, blossoms and pods of seven bean (Phaseolus vulgaris) genotypes were studied. Bean plants were grown in the field and artificially inoculated at the seedling stage (18 days old). The pathogen was recovered in high numbers from flower buds, blossoms, pods and seed of both resistant and susceptible bean genotypes. Significant differences (P = 0.05) in population levels of X. c. pv. phaseoli between stages of reproductive tissue development were observed. Infected seed from resistant bean genotypes had no visible symptoms. Such seed may play an important role in the epidemiology of common bacterial blight because they are difficult to detect and may occur at low frequency in seed lots, as was the case in the current study.     

疫霉菌对霜脲氰抗性遗传及对霜脲氰和甲霜灵的交互抗性

就疫霉菌对霜脲氰抗性的产生和遗传，以及疫霉菌对霜脲氰和甲霜灵的交互抗性进行了研究。结果表明，苎麻疫霉容易对霜脲氰产生抗药性突变，但抗性在连续３代单游动孢子分离过程中逐渐丧失。大雄疫霉对霜脲氰不易产生抗性突变，恶疫霉、大雄疫霉和苎麻疫霉对甲霜灵和霜脲氰不存在交互抗性     

世界葡萄抗寒育种的成就与展望

近2个世纪,通过选种和杂交育种,世界葡萄抗寒育种在抗寒性与果实优质性状的结合方面取得了突破,育成许多抗寒性极强(耐-30～-40℃低温)、品质优良的鲜食、酿酒和制汁品种。由于葡萄的抗寒性是受多基因控制的数量性状,杂交后代的抗寒性基本呈以亲中值为峰顶的正态分布,所以我国应积极引进这些品种,在华北、西北等葡萄主产区试验、推广露地越冬栽培的同时,利用它们与现有抗寒性较弱的主栽品种(抗寒性-15～-18℃)杂交,培育适合我国冬季气候条件的抗寒品种(抗寒性在-25℃左右),迅速提高我国葡萄抗寒育种水平。     

甘蓝多酚氧化酶的生物化学性质及其杀虫剂的诱导作用

采用时间动力学法,在研究了甘蓝多酚氧化酶的最适反应条件的基础上,对有机溶剂和杀虫剂对多酚氧化酶活性的影响进行了研究。结果表明:甘蓝多酚氧化酶反应的最适pH值为6.4,最适反应温度为55℃;丙酮和乙醇对多酚氧化酶活性有明显的激活作用;高效氯氰菊酯、灭多威和辛硫磷以及小菜蛾和桃蚜取食的胁迫会对多酚氧化酶的活性产生影响。     

Evaluation of Olive Cultivars for Resistance to Verticillium dahliae

Resistance of 23 important olive cultivars to Verticillium dahliae has been evaluated in four experiments under controlled conditions. Nine-month-old nursery olive plants were inoculated with a cotton non-defoliating (ND) (V4) or a cotton defoliating (D) (V117) isolate of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves. The percentage of plants killed and of those which recovered from the disease were used as additional parameters for including a particular cultivar into a defined category. Most of the evaluated cultivars were susceptible, although at different levels, to both isolates of V. dahliae. All cultivars were more susceptible to the D pathotype than to the ND one. A group of 11 cultivars, including several important Spanish cultivars, were susceptible or extremely susceptible to both pathotypes of V. dahliae. A second group showed differences of resistance depending on the pathotype used. They were susceptible or extremely susceptible to the D pathotype but resistant or moderately susceptible to the ND one. Finally, 'Frantoio', 'Oblonga' and 'Empeltre' were moderately susceptible to the D isolate of V. dahliae and resistant to the ND one. The resistance of 'Empeltre' was evident by the plant ability to recover from infection with either isolates. 'Empeltre' is considered to be a valuable cultivar for inclusion in breeding programmes for resistance to Verticillium wilt.     

Variation and distribution of virulence phenotypes of Bremia lactucae in natural populations of Lactuca serriola

During 1997–2000 the virulence variation and distribution of virulence phenotypes of Bremia lactucae (lettuce downy mildew) in natural populations of Lactuca serriola (prickly lettuce) were studied. Altogether 139 isolates of B. lactucae originating from the Czech Republic, France and Germany were examined for the presence of 27 virulence factors (v-factors) and their combinations. In the Czech population, 37 different v-phenotypes (P1–P37) of B. lactucae were found to occur on L. serriola . Most v-phenotypes were characterized by v-factors that match resistance ( Dm genes/R-factors) carried by L. serriola . A wide diversity of v-phenotypes was recorded every year, but most were rare and did not reappear in other populations of B. lactucae . The three v-phenotypes P21, P28 and P29 were most frequent and widely distributed. There was variation both between spatially isolated populations and within populations of the pathogen. Geographic differences in virulence were found for the southern parts of Moravia, where the phenotypic composition of pathogen populations was completely different from the remaining part of the area investigated. However, some populations had v-phenotypes similar to those of spatially distant populations in Moravia.     

土壤pH值对极小种群毛枝五针松生理特性的影响

幼苗建成期是毛枝五针松(Pinus wangii)天然更新的关键阶段,为找出影响毛枝五针松幼苗存活的关键生态因子,采用植物生理学方法,研究在7个酸碱度土壤培育下,毛枝五针松松针超氧化物歧化酶(SOD)、过氧化物酶活性(POD)活性和脯氨酸、可溶性糖质量分数及丙二醛(MDA)摩尔质量浓度的变化。结果表明:毛枝五针松在弱碱土壤中抗逆性更强,形态观察得知其在弱碱性土壤中生长更好;生理指标测定结果表明,土壤在p H=7.69~8.42时最适宜毛枝五针松幼苗的生长发育。     

Comparative bioactivity of selected seed extracts from Brazilian Annona species and an acetogenin-based commercial bioinsecticide against Trichoplusia ni and Myzus persicae

The acute and chronic toxicity of ethanolic seed extracts from selected Brazilian Annona species (Annona montana Macfadyen, Annona mucosa Jacquin, Annona muricata Linnaeus, and Annona sylvatica A. St.-Hil) and an acetogenin-based commercial bioinsecticide (Anosom^®) were investigated against the cabbage looper Trichoplusia ni Hübner (Lepidoptera: Noctuidae) and the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae). In the laboratory, extracts of A. mucosa and A. sylvatica as well as Anosom^® were especially active through oral and topical administration. A greenhouse trial showed that a formulated A. mucosa extract and Anosom^® were highly effective (>98% mortality) against third instar T. ni larvae, and comparable to a pyrethrin-based commercial insecticide (Insect Spray^®) used as a positive control. Similar to results with T. ni, A. mucosa extract showed the greatest aphicidal activity followed by A. sylvatica extract and Anosom^®. In another greenhouse trial, aphid population reduction from the formulated A. mucosa extract was superior to that provided by other treatments including the positive control. Though inferior to the A. mucosa extract, the acetogenin-based commercial insecticide (Anosom^®) and A. sylvatica extract also reduced aphid populations in a manner comparable to the positive control. Botanical insecticides based on these Annonaceae derivatives could be useful in the framework of Brassica IPM in Brazil and elsewhere, especially for organic production.