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关键词： 药用植物种子   长命种子   隔年  

关键词： Aegiceras   allozyme   genetic structure   ISSR mangrove   outcrossing rate  

摘要： Mangroves consist of a group of taxonomically diverse species representing about 20 families of angiosperms. However, little is known about their reproductive biology, genetic structure, and the ecological and genetic factors affecting this structure. Comparative studies of various mangrove species are needed to fill such gaps in our knowledge. The pollination biology outcrossing rate, and genetic diversity of Aegiceras corniculatum were investigated in this study. Pollination experiments suggested that the species is predominantly pollinator-dependent in fruit setting. A quantitative analysis of the mating system was performed using progeny arrays assayed for intersimple sequence repeat (ISSR) markers. The multilocus outcrossing rate (t(m)) was estimated to be 0.653 in a wild population. Both allozyme and ISSR were used to investigate genetic variation within and among populations. The combined effects of founder events and enhanced local gene now through seedling dispersal by ocean currents apparently played an important role in shaping the population genetic structure in this mangrove species. Both allozyme variation (P = 4.76%, A = 1.05, H-E= 0.024) and ISSR diversity (P = 16.18%, A = 1.061, H-E = 0.039) were very low at the species level, in comparison with other woody plants with mixed-mating or outcrossing systems. Gene differentiation among populations was also low: allozyme G(ST) = 0.106 and ISSR G(ST) = 0.178. The unusually high genetic identities (0.997 for allozyme and 0.992 for ISSR loci), however, suggest that these populations are probably all descended from a common ancestral population with low polymorphism.

关键词： Angiosperms/classification   Angiosperms/classification   DNA, Plant   DNA, Ribosomal   Genes, Plant   Phylogeny   Phylogeny   Plant Proteins/genetics   Plastids/genetics   Ribulose-Bisphosphate Carboxylase   Ribulose-Bisphosphate Carboxylase   RNA, Ribosomal, 18S/genetics  

摘要： Comparative biology requires a firm phylogenetic foundation to uncover and understand patterns of diversification and evaluate hypotheses of the processes responsible for these patterns. In the angiosperms, studies of diversification in floral form(1,2), stamen organization(3), reproductive biology(4), photosynthetic pathway(5), nitrogen-fixing symbioses(6) and life histories(7) have relied on either explicit or implied phylogenetic trees, Furthermore, to understand the evolution of specific genes and gene families, evaluate the extent of conservation of plant genomes and make proper sense of the huge volume of molecular genetic data available for model organisms(8) such as Arabidopsis, Antirrhinum, maize, rice and wheat, a phylogenetic perspective is necessary. Here we report the results of parsimony analyses of DNA sequences of the plastid genes rbcL and atpB and the nuclear 18S rDNA for 560 species of angiosperms and seven non-flowering seed plants and show a well-resolved and well-supported phylogenetic tree for the angiosperms for use in comparative biology.

关键词： 植物学:生物学   高等学校   教材   生物学:植物学   高等学校   教材  

关键词： 桔梗科-植物保护   研究   植物保护-桔梗科   研究  

关键词： 保护生物学   木根麦冬   种群生态   濒危植物   百合科  

摘要： 从种群生态、生殖生物学特性和遗传结构与多样性等方面对濒危植物木根麦冬(Ophiopogon xylorrhizusu)进行了研究。从不同的侧面阐明了木根麦冬的生物学特性,分析了这些特性与其濒危状况之间的关系,介绍了木根麦冬的现状与有关的研究方法以及取得的重要结果,分析了木根麦冬可能致濒危因素,提出了保护策略与具体措施。

关键词： 干旱胁迫   生物学机理   基因工程  

摘要： 本文介绍了干旱胁迫对植物的伤害。

关键词： 离子通道   生理功能   调节   分子生物学   植物  

摘要： 本文对植物离子通道的特征、生理功能。

关键词： Bone Transplantation  

摘要： The terminology of bone transplantation is complicated by the various histologic types of bone grafts. A graft moved from one site to another within the same individual is an autograft;the corresponding adjective is autologous or autogenous. An allograft (adjective, allogeneic) is tissue transferred between two genetically different individuals of the same species. A xenograft (adjective, xenogeneic) is tissue from one species implanted into a member of a different species.

关键词： chemical-mediated induced resistance   elicitor-mediated resistance   gold cytochemistry   microbial-mediated induced resistance   soil-borne pathogens   ultrastructure  

摘要： During the course of their co-evolution, plants and pathogens have evolved an intricate relationship resulting from a continuous exchange of molecular information. Pathogens have developed an array of offensive strategies to parasitize plants and, in rum, plants have deployed a wide range of defence mechanisms similar in some respects to the immune defences produced in animals. The recent advances in molecular biology and plant transformation have provided evidence that sensitizing a plant to respond more rapidly to infection could confer increased protection against virulent pathogens. One important facet in ascertaining the significance of defence molecules in plant disease resistance is the exact knowledge of their spatio-temporal distribution in stressed plant: tissues. In an effort to understand the process associated with the induction of plant disease resistance, the effect of microbial and chemical elicitors on the plant cell response during attack by fungal pathogens was investigated and the mechanisms underlying the expression of resistance to bacteria and nematodes studied by both histo- and cytochemistry. Evidence is provided that the disease-resistance response correlates with changes in cell biochemistry and physiology that are accompanied by structural modifications including the formation of callose-enriched wall appositions and the infiltration of phenolic compounds at sites of potential pathogen penetration. Activation of the phenylpropanoid pathway is a crucial phenomenon involved in pathogen growth restriction and host cell survival under stress conditions. Ultrastructural and cytochemical approaches have the potential to significantly improve our knowledge of how plants defend themselves and how plant disease resistance is expressed at the cell level. (C) 1999 Editions scientifiques et medicales Elsevier SAS.