Population structure of the butternut canker fungus,Ophiognomonia clavigignenti‐juglandacearum,in North American forests

The occurrence of multiple introduction events, or sudden emergence from a host jump, of forest pathogens may be an important factor in successful establishment in a novel environment or on a new host; however, few studies have focused on the introduction and emergence of fungal pathogens in forest ecosystems. While Ophiognomonia clavigignenti‐juglandacearum (Oc‐j), the butternut canker fungus, has caused range‐wide mortality of butternut trees in North America since its first observation in 1967, the history of its emergence and spread across the United States and Canada remains unresolved. Using 17 single nucleotide polymorphic loci, we investigated the genetic population structure of 101 isolates of Oc‐j from across North America. Clustering analysis revealed that the Oc‐j population in North America is made up of three differentiated genetic clusters of isolates, and these genetic clusters were found to have a strong clonal structure. These results, in combination with the geographic distribution of the populations, suggest that Oc‐j was introduced or has emerged in North America on more than one occasion, and these clonal lineages have since proliferated across much of the range of butternut. No evidence of genetic recombination was observed in the linkage analysis, and conservation of the distinct genetic clusters in regions where isolates from two or more genetic clusters are present, would indicate a very minimal or non‐existent role of sexual recombination in populations of Oc‐j in North America.     

拟南芥新型脂转移蛋白AtDHyPRP1的亚细胞定位及其对灰霉菌的抗性

通过遗传转化技术研究了拟南芥脂转移蛋白AtDHyPRP1在细胞中的定位及其对真菌病原体的抗性。采用PCR方法从拟南芥Ws生态型克隆了AtDHyPRP1基因,构建产生pRI101-AN-AtDHyPRP1植物双元表达载体和pCAMBIA1302-AtDHyPRP1-GFP融合表达载体,经农杆菌介导的叶盘和浸花法得到烟草和拟南芥转基因植株。AtDHyPRP1基因能够明显增加烟草对灰霉菌的抗性,转AtDHyPRP1烟草叶片的被侵染部位有大量H2O2积累,激光共聚焦显微观察发现AtDHyPRP1蛋白定位于细胞表面。说明AtDHyPRP1蛋白在合成后被分泌到细胞外执行特殊的功能,与植物抗病防御机制有关。     

Identification and characterisation of structural maintenance of chromosome 1 (smc1) mutants of Coprinopsis cinerea

A Coprinopsis cinerea homokaryotic fruiting strain was mutagenised, identifying a mutant that exhibited a hyphal growth temperature sensitive defect and hyphal knot development defect at an early fruiting stage, even at the hyphal growth permissive temperature. Microscopic observation suggested that the mutant nuclei exhibited defects in the metaphase to anaphase transition at the restrictive temperature. The gene in which the mutation occurred was cloned, sequenced and determined to be homologous to smc1. Sequence analyses of the mutant revealed deletion of 28 base pairs in the 19th intron of the Cc.smc1 gene, resulting in complete failure of splicing of that intron and in insertion of 14 amino acids in the C-terminal region of the Cc.Smc1 protein. We isolated eight hyphal growth revertants and identified four intragenic suppressors. All were the result of amino acid substitutions in the C-terminal region. Three of the suppressors caused reversion of the arrest in an early fruiting stage. One of the suppressors exhibited cold sensitivity and failed to suppress the fruiting defect, suggesting that flexibility of a lobe in the C-terminal region is important for proper function of Cc.Smc1.     

苍鹭孵化及育雏习性研究

1999、2000年3～6月,对辽宁省朝阳县树俩型苍鹭孵化习性和育雏习性进行观察。苍鹭孵化以雌鸟为主,两性轮流孵化,孵化期24～27天,平均孵化率93．5％;雏鸟为晚成鸟,育雏期40～50天左右,育雏过程分育雏初期、中期、末期三阶段;雏鸟的食物以鱼类、蚌类为主。     

耐药性木霉菌株的筛选及其对灰霉病的防治

兽籁当莨8咖耋楹∞102025323840455055培养时间（h）Time（h）图1ELll2单细胞生长曲线Fig．13heC（Kllx3eofthecells’samountsofELll2510152530354050培养时间Time（h）图2不同发酵时间的酶活Fig．23hed~stolyticactivityoffem~ent’8processing异。许多研冗表明,微生物营乔和代掰荚型与共生长蚧境碉着很大的关系。所以在采样时选择肉类加为了提高生物菌剂对植物病害的防治效果和稳定性,达到生物农药和化学农药综合防治的目的,采用了紫外诱变处理与药物培养基驯化培养相结合的方法,分离筛选出对化学杀菌剂速克灵有显著抗性的突变型木霉菌株T-4。该菌株与亲本菌株相比其抑菌能力及耐受性均优于亲本木霉菌株。经菌和药的协同作用研究发现,木霉菌剂与速克灵配比为8：2条件下,协同抑菌率达84．3％;活体拮抗性测定防治效果达到81％。这表明综合利用生物与化学防治,不仅可以降低农药使用量,减轻对环境的污染。而且,对植物病害的防效均高于单独使用木霉菌剂和速克灵的防治效果。     

Control of preharvest and postharvest fruit rot in Strawberry by Metschnikowia fructicola

The yeast Metschnikowia fructicola was tested as a preharvest treatment to control preharvest and postharvest rots of strawberry fruit in Turkey and Israel. In greenhouse trials, the efficacy of the yeast antagonist against preharvest rots was equal to that of a chemical control (fenhexamid) in two growing seasons. In an open-field experiment, the yeast reduced the incidence of rot to commercially acceptable levels. M. fructicola reduced the incidence of fruit rot by 56-69% in greenhouses, open-field culture, and in low plastic tunnels. The yeast suppressed postharvest incidence of fruit rot significantly better than fenhexamid. Among fruit from greenhouses, open-field culture, or tunnels, M. fructicola treatment reduced the incidence of fruit rot during postharvest storage by 70, 64, and 72%, respectively. When applied weekly in the greenhouse or in the field, the population density of M. fructicola was about 1×10⁵ cfu/fruit. Similar population density of the antagonist was also observed during storage of the fruit at 0° C.     

Biological Control of Botrytis cinerea Pers. ex Fr. in Strawberry by Paenibacillus polymyxa (Isolate 18191)

Isolate 18191, obtained from mature strawberry fruit and determined as Paenibacillus polymyxa has shown an antagonistic potential against Botrytis cinerea , the causal agent of grey mould in strawberries. Germ tube growth of conidia of B. cinerea was strongly inhibited by the culture suspension of the antagonist in aqueous strawberry fruit pulp suspension (1%) but germination rate of conidia was not affected. The application of the culture suspension and the washed cells on detached strawberry leaf discs reduced conidiophore density of B. cinerea by 67 and 84%, respectively. The treatment of detached leaf discs with culture suspensions of different cell densities (1 × 10⁶, 1 × 10⁷, 1 × 10⁸) showed that the lowest density already reduced incidence of B. cinerea by 68% after 8 days incubation period. Investigating the influence of the temperature on the effectiveness of P. polymyxa it was observed that the antagonist was highly effective already at 10°C and reduced incidence and conidiophore density of B. cinerea by 53 and 58%, respectively. In 3-year field trials the effectiveness of P. polymyxa was in a range of 24–36% as compared to the water control.     

Fate of transformed Trichoderma harzianum in the phylloplane of tomato plants

A propiconazole-resistant Trichoderma harzianum strain with high phylloplane survival capability was transformed with the E. coli hygromycin B phosphotransferase gene (hph), coding for hygromycin B resistance. Four transformants were analysed for survival ability on the phylloplane of tomato plants grown under glasshouse conditions in comparison with their prototype and a yellow, hygromycin B-sensitive mutant. Over 2 weeks, the four transformants showed higher survival rates in comparison with the wild-type strain. The yellow mutant TF3/973 did not significantly differ in survival from the transformants. Both hygromycin B resistance and mitotic stability of transformants were evaluated during growth in vitro and after reisolation from tomato phylloplane. Hybridization patterns with the complete plasmid indicated that all four transformants were mitotically stable after several rounds of vegetative growth without selective pressure and during 2 weeks on tomato plants. None of the transformants had lost the ability to grow in the presence of both propiconazole and hygromycin B after growth under the same conditions. The results are discussed in relation to risk assessment of the release of transgenic fungi.