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关键词： Euphorbia esula   Euphorbia cyparissias   Aphthona cyparissiae   Aphthona flava   Aphthona nigriscutis   Aphthona czwalinai   Aphthona lacertosa   Chrysomelidae   life history   host range   leafy spurge   weeds   biological control  

摘要： Leafy spurge (Euphorbia esula) is an herbaceous perennial of European origin that was accidentally introduced into North America where it has become a serious weed in pastures and rangelands. Five species of root-feeding chrysomelid beetles in the genus Aphthona have been released in North America for the biological control of leafy spurge. They originate from central and eastern Europe and occur in different habitats. The brown species, Aphthona cyparissiae, Aphthona flava, and Aphthona nigriscutis, occur predominantly in open dry habitats, and the black species, Aphthona czwalinai and Aphthona lacertosa, prefer moister habitats. All five species are univoltine and overwinter as larvae. The host range of these five Aphthona species is restricted to species in the subgenus Esula. (C) 1996 Academic Press,Inc.

关键词： Plants   Epidemiology   Ustilago   Disease transmission   Infections   Teliospores   Ecological genetics   Parkways   Fungal diseases   Medical genetics  

摘要： In the southeastern United States, anther-smut disease (Ustilago violacea) was observed on the native fire pink (Silene virginica), and on the introduced white campion (Silene alba). Fungal isolates from the two host species showed fixed differences at allozyme loci, and isolates from S. alba were similar to isolates from S. alba in Europe. Fungal isolates from S. virginica did not produce disease on S. alba;crosses between fungal isolates from the two hosts showed reduced inoculation success on S. alba. Teliospores from hybrids between the isolates showed abnormal sporidial development. We conclude that the anthersmuts from each of the host species are genetically distinct and partially reproductively isolated ''host-races.'' Ustilago violacea occurs on S. virginica throughout its range, and far beyond the range of diseased S. alba. Rates of infection of healthy flowering individuals in natural populations of S. virginica were very low but a large fraction of plants were already diseased when they first flowered, suggesting disease is transmitted by spares that fall on seedlings or rosettes. There was substantial heterogeneity in disease incidence even among local populations in the same vicinity, but evidence suggests that the disease was not rapidly spreading in S. virginica.

关键词： 决明属   根瘤菌   生物学特性  

摘要： 调查了广东地区10种Cassia植物结瘤状况,仅山扁豆(***)和圆叶决明(***)结瘤,从山扁豆和圆叶决明各分离到1株根瘤菌并鉴定为慢生型。在所试的10种Cassia植物中,2株Cassia植物根瘤菌除了与山扁豆和圆叶决明结瘤外,均不与其余8种Cassia植物结瘤;同样,3株蝶形花科植物根瘤菌和3株含羞草科植物根瘤菌除了与山扁豆和圆叶决明结瘤外,也均不与其余8种Cassia植物结瘤。此外,2株Cassia植物根瘤菌均能与所试5种蝶形花科和4种含羞草科植物结瘤。2株Cassia植物根瘤菌在碳源利用、耐盐性、耐酸碱度及5种酶的活性等特性方面,与3株蝶形花科植物根瘤菌和3株含羞草科植物根瘤菌极为相似。

关键词： 低温   分子生物学   植物  

关键词： very long chain fatty acid elongation   glossy   elongase   condensing enzyme   cuticular lipids  

摘要： The aerial surfaces of plants are covered with a wax layer that is primarily a waterproof barrier but that also provides protection against environmental stresses. The ubiquitous presence of cuticular wax is testimony to its essential function. Genetic and environmental factors influence wax quantity and composition, which suggests that it is an actively regulated process. The basic biochemistry of wax production has been elucidated over the past three decades;however, we still know very little about its regulation. This review presents a discussion along with new perspectives on the regulatory aspects of wax biosynthesis. Among the topics discussed are the partitioning of fatty acid precursors into wax biosynthesis and the elongation of fatty acids with particular emphasis on the nature of the acyl primer, and the role of ATP in fatty acid elongation. The recent cloning of wax biosynthetic genes and the transport of wax to plant surfaces are also discussed.

关键词： 单穗升麻   南川升麻   生殖生物学   频危植物  

摘要： 南川升麻是中国特有的毛茛科多年生草本植物,分布范围局限,个体数量稀少,处于濒危状态.为了探讨致濒的原因,该文地南川升麻及其对照种单穗升麻的生殖生物学特性进行了研究.

关键词： 土壤微生物学   高等学校   教材  

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关键词： Bacteria/metabolism   Carrier Proteins/genetics   Carrier Proteins/metabolism   Fungal Proteins/genetics   Fungal Proteins/metabolism   Fungi/genetics   Fungi/metabolism   Ion Channels/metabolism   Membrane Proteins/genetics   Membrane Proteins/metabolism   Patch-Clamp Techniques   Patch-Clamp Techniques   Phosphate-Binding Proteins   Phosphates/metabolism   Phosphates/metabolism   Plant Roots/metabolism   Plant Roots/microbiology   Quaternary Ammonium Compounds/metabolism   Quaternary Ammonium Compounds/metabolism   Symbiosis