双抗虫基因三倍体毛白杨对舞毒蛾幼虫的抗性研究

用室内群体饲养舞毒蛾幼虫的方法,对15个双抗基因三倍体毛白杨株系进行饲虫试验。结果表明:校正死亡率划分了高抗、中抗、低抗虫植株,舞毒蛾校正死亡率在95以上为高抗株系;40～75为中抗株系,30以下为低抗株系。舞毒蛾的发育历期、蜕皮指数和毒效反映的规律相一致。     

Iron and zinc accumulation in winter wheat regulated by NICOTIANAMINE SYNTHASE responded to increasing nitrogen levels

Nitrogen (N) is critical for micronutrient biofortification in wheat grain and is essential for a series of nitrogenous compounds biosynthesis. This study aims to assess the role of improved N supply in iron (Fe) and zinc (Zn) enrichment and expression of genes related to Zn and Fe chelation and transport in winter wheat. Potting and hydroponic culture experiments were conducted to study the effect of increasing N application on Zn and Fe uptake and translocation from roots to leaves and the temporal and spatial gene expression profiles of the NICOTIANAMINE SYNTHASE (NAS) genes in wheat. Plants were grown with low, medium and high N supply levels. The results showed that higher N application increased Fe and Zn content in leaves, and decreased Fe and Zn content in root compared with the lower N supply. High N application also increased the distribution of Fe and Zn from roots to leaves. Expression analysis showed that increased N application resulted in up-regulation of two wheat NAS genes, TaNAS1 and TaNAS2. Highly positive response between NAS genes and increasing N application indicated that abundance nicotianamine (NA) resulted from highly expressed NAS genes might involve in the chelation of Fe and Zn in the phloem and favor Fe and Zn uptake and accumulation in wheat leaves.     

野生稻抗病虫基因的挖掘和利用

本文综合国内外文献,简要介绍了野生稻抗病虫基因发掘、定位、克隆及育种应用研究的进展,讨论了野生稻优异抗病虫基因在水稻育种中的应用前景。     

Occurrence of a new leaf spot disease ofMusa sp. incited byThanatephorus cucumeris

A new leaf spot disease of banana(Musa sp.) cv. ‘Rasthali’ (syn. Silk) was observed in Tamil Nadu, in 1987. The causal organism was isolated in pure culture and identified asRhizoctonia solarii Kühn. The teleomorphic stage,Thanatephorus cucumeris (Frank) Donk, has also been induced artificially. This is the first record of this pathogen causing leaf spot disease onMusa sp. The pathogenicity of basidiospores on several other important crops was also tested.     

蜡蚧轮枝菌防治植物病虫害研究进展

蜡蚧轮枝菌在蔬菜病虫害防治中有很大开发潜力。就蜡蚧轮枝菌的致病性、环境条件对其生长的影响、储藏期存活率及在生产中应用的概况的研究进展进行了综述。研究进展表明,该种真菌既可以防治粉虱、蚜虫、蓟马等蔬菜害虫,又可以防治蔬菜的白粉病、锈病等。     

异源微孢子虫对两种蝗虫致病性的观察

以异源微孢子虫对两种蝗虫进行了室内致病性试验。结果表明，有4种微孢子虫可感染东亚飞蝗，其中以杂拟谷盗微粒子虫感染率最高，达96．7％，玉米螟微粒子虫也较高，为92．3％，欧洲玉米螟微粒子虫和斜纹夜蛾微粒子虫对东亚飞蝗的感染率较低，分别为69．2％、43．5％；处理后30d，杂拟谷盗微粒子虫、玉米螟微粒子虫、欧洲玉米螟微粒子虫和斜纹夜蛾微粒子虫对东亚飞蝗的累计致死率分别为77．4％、92．3％、57．7％、47．8％。对黄脊竹蝗仅有杂拟谷盗微粒子虫和玉米螟微粒子虫可感染，其感染率分别为100％、14．3％，但致死率较低。     

Phytogeny and Cross-infectivity of Powdery Mildew Isolates (Podosphaera fuliginea s. lat.) on Cosmos and Cucumber

To clarify the relationship between the phylogeny and infectivity of isolates of Podosphaera fuliginea s. lat. (= Sphaerotheca fuliginea s. lat.) from cosmos and cucumber, more than 50 powdery mildew isolates from these two plants were subjected to nucleotide sequencing or PCR-RFLP analysis of the rDNA internal transcribed spacer (ITS) region and cross-inoculation tests. The isolates from both cosmos and cucumber are genetically monotypic, and there are six nucleotide substitutions in the rDNA ITS region between isolates from cosmos and cucumber. Cross-inoculation tests of these isolates revealed that isolates from cosmos are not pathogenic on cucumber. Although isolates from cucumber produced conidia on leaves of cosmos in the laboratory, the conidial density was much lower than that from isolates from cosmos. This result, as well as the fact that the cucumber strain was not isolated from cosmos in fields, suggests that isolates from cucumber do not infect cosmos in the field. Therefore, powdery mildews on cosmos and cucumber can be regarded to have become specialized for their hosts both genetically and pathogenically. The present study reconfirms the close relationship between phylogeny and infectivity of powdery mildew fungi. Host specialization may be a trigger that causes genetic divergence of powdery mildew fungi. Received 28 June 2000/ Accepted in revised form 4 September 2000