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关键词： medicinal plant   endangered species   ecology   conservation biology   Eastern Himalaya  

摘要： Medicinal plants are a valuable resource for regional economic development in the tropics, and the Eastern Himalaya in particular harbours many such species. Extensive deforestation and over-exploitation in this region have brought several species to the brink of extinction, and Coptis teeta is such an endangered species;yet scientific information for its conservation is lacking. Investigations on the distribution range, demography, ecology, cytology, reproductive biology and population genetic structure of C. teeta were carried out;it was found to be endemic to a small area, to occupy a very narrow habitat and to be highly dispersed with very small population sizes. Edaphic factors were found to have played a vital role in ecological preference, natural distribution and evolutionary divergence of the species. The species exhibits a 'K' strategy, high male sterility, low reproductive success and efficiency, inadequate seed dispersal, and little genetic variability. A combination of these genetic hurdles and external threats in the form of habitat disturbance and over-exploitation for commercial purposes could result in its extinction. The species was found to have highly specific microsite requirements that cannot be met in other habitats. It is argued that in situ conservation measures would be the best strategy for the continued survival of this species. For effective management of the species it is recommended that its habitat be declared a protected area with the active cooperation of local inhabitants including the sharing of benefits of conservation.

关键词： Cactaceae   Opuntia spinosissima   pollen tube   apomixis   polyploidy  

摘要： Opuntia spinosissima (Martyn) Mill. (Cactaceae) is an extremely rare taxon with a single remaining wild population of 13 plants located on Little Torch Key, Florida. The plants rarely set viable seeds and most ovaries abscise without initiation of fruits. Pollination and breeding system were examined in Little Torch Key and in plant accessions located at Fairchild Tropical Garden. Four pollination treatments were carried out to test for apomixis, self-pollination, outcrossing, and autogamy;a control treatment was also monitored. Additionally, pollen viability, pollinators, and seed set and viability were investigated. On selfed, crossed, and open (control) stigmas pollen grains germinated, but the tubes usually did not reach the base of the style. This suggests that O. spinosissima has pre-zygotic self-incompatibility. None of the pairwise crosses set seed, so the extant plants were apparently not inter-compatible. Out of 173 manipulated and control flowers, only one set fruit. Although this flower was outcrossed, no pollen tubes germinated on the stigma;this suggests agamospermy, a process common in the Cactaceae. In those flowers where pollen tubes did reach the ovary they failed to penetrate ovules. suggesting ovarian inhibition or that this taxon has lost the ability to be fertilized. Most field-collected seeds were viable, but there is no seedling recruitment under natural conditions, and vegetative reproduction is common. Based on these findings, I hypothesize that O. spin osissima is a sterile polyploid and that the 13 extant plants are asexually derived from a single lineage.

关键词： 植物系统   进化   同工酶分析   核酸分析  

摘要： 在植物系统与进化研究中，为了揭示真实本质，必须从分子水平进行研究。植物分子系统学的研究包括两大方面，一是蛋白质与酶，二是核酸。酶电泳是分子水平上研究植物分子遗传学最经济有效的方法，可以有效地揭示自然居群中遗传结构、基因流动、变化系统、选择作用和系统发育等问题。植物核酸系统学的研究倍受青睐，因为核酸分子是最基本的进化单元，几乎不受主观因素影响。相关的核酸分析技术主要有：ＤＮＡ杂交、ＤＮＡ限制酶谱分析、ＲＦＬＰ分析、ＤＮＡ指纹图技术、ＲＡＰＤ分析和核酸序列分析。在植物系统学和进化研究中，结合各方面的生物学证据，才能显示植物分子系统学的独特优势。

关键词： 濒危植物   保护生物学   遗传多样性   生殖生物学   国家自然科学基金委员会   生物学特性   中国科学院   濒危物种   种群动态模型   传粉生物学  

摘要： 国家自然科学基金“八五”重大项目“中国主要濒危植物的保护生物学研究”，由中国科学院洪德元院士主持，中国科学院植物研究所、发育生物学研究所、成都生物研究所、武汉大学、北京大学、东北林业大学、江苏省植物研究所、哈尔滨师范大学、云南大学等单位共同承担。经过...

关键词： 南川升麻   传粉生物学   濒危植物  

摘要： 南川升麻（ＣｉｍｉｃｉｆｕｇａｎａｎｃｈｕａｎｅｎｓｉｓＨｓｉｓｏ）的繁育系统以异交为主，传粉昆虫主要为蝇类，盛花时的访花频率平均每花每天１１次，雄蕊脱落后约０６次；单穗升麻（Ｃ．ｓｉｍｐｌｅｘＷｏｒｍｓｋ）以虫媒为主，风也可以帮助其花粉在近距离传播。单穗升麻的传粉昆虫有蝇类和蜂类，盛花时的访花频率蝇类为１．４次，蜂类为１．２次。南川升麻和单穗升麻都是靠大的花序和气味来吸引传粉昆虫，报酬是退化雄蕊基部分泌的蜜液。自然条件下南川升麻每个柱头上平均有４枚花粉，结籽率平均为６４％，而单穗升麻每个柱头上平均有１７枚花粉，结籽率平均为４５９％。南川升麻有性生殖中传粉的限制是其致濒的重要因素之一。

关键词： freeze avoidance   inoculation   thermal limits   chill coma   heat stupor   acclimation  

摘要： During May 1997 thermal tolerance, supercooling point (SCP), low and high temperature survival, and desiccation resistance were examined in field-fresh Embryonopsis halticella Eaten larvae from Marion Island. SCPs were also examined in acclimated larvae, larvae starved for seven days, larvae within their leaf mines, and in larvae exposed to ice crystals. Field-fresh larvae had a critical minimum temperature (CTMin) and critical maximum temperature (CTMax) of 39.7 degrees C and 39.7 degrees C, respectively. Mean SCP of field-fresh caterpillars was -20.5 degrees C and this did not change with starvation. Field-fresh larvae did not survive freezing and their lower lethal temperatures (70% mortality below -21 degrees C) and survival of exposure to constant low temperatures (100% mortality after 12 hrs at -19 degrees C) indicated that they are moderately chill tolerant. SCP frequency distributions were unimodal for field-fresh larvae, but became bimodal at higher acclimation temperatures. Contact with ice-crystals caused an increase in SCP (-6.5 degrees C), but contact with the host plant had less of an effect at higher subzero temperatures. It appears that the remarkable desiccation resistance of the larvae is selected for by the absence of a boundary layer surrounding their host plant, caused by constant high winds. This suggests that the low SCPs of E. halticella larvae may have evolved as a consequence of pronounced desiccation resistance. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： 花卉   根结线虫   天敌   真菌  

摘要： 在调查包头市花卉植物线虫病时,发现寄生麦秆菊的根结线虫中少数雌虫已被真菌所捕食,仅剩下带有线虫轮廓的粗菌丝束.在CMA平板上采用直接分离法进行分离和纯化,经对线虫捕食性的测定,得到2个菌株,分别编号为BM1和BM2.依据产孢结构的特征,分生孢子形成方式及Saccardo孢子类群,在10×40倍镜检记录菌丝、分生孢子梗及分生孢子的各项分类性状进行鉴定,并对其部分生物学特性进行初步研究.结果认为:BM1菌株为少孢节丛孢Arthobotrys oligospora Fres,***.171:18.1852,其形态特征为在CMA平板上25℃培养14d,菌落白色,菌丝稀疏,絮状.菌丝有隔,分枝,厚垣孢子产生于菌丝中间,单生或串生,球形,直径14.5～21.2μm;分生孢子梗直立,不分枝,单生,有4～6个瘤节,大小为158～369μm×3.2～5.0μm;分生孢子梨形至倒卵形,1隔,生于瘤状突起的小齿梗上,大小为16.0～29.5(24.4)μm×7.8～15.2(13.6)μm.形成三维菌网.BM2菌株为宽环单顶孢霉 Manacrosporium lysipaga(Drechsler)Subramanian,***.90C.42:293,1963,其形态特征为在CMA平板上25℃培养14d,菌落白色,菌丝稀疏.菌丝无色、有隔、分枝.分生孢子梗直立、无色、少见分枝,大小为32～115μm×2.0～4.5μm,具3～4隔,基部宽于顶部.分生孢子单生于梗顶端.纺锤形。

关键词： 植物   生殖   花   雄性不育   S位点特异蛋白   离体受精  

摘要： 简介了成花的网状系统模型的建立、花器官分化的基因控制模型、基因工程方法构建雄性不育、自交不亲和的Ｓ位点编码产物的性质、性细胞研究及离体显微操作等方面的研究动态和进展。

关键词： 植物受精   有性繁殖   被子植物   双受精   受精生物学  

摘要： 今年是被子植物双受精现象发现一百周年。一百年前的这个重大发现,早已在大学和中学的生物学课本中成为普及知识了。它的意义,在于双受精是植物界进化到被子植物这一最高层次所出现的独特现象,而在生物界的其它所有类群中均只有卵的受精而无中央细胞的受精;还在于双受精的第二产物胚乳对胚胎发育、种子形成与后代有重要作用,加之人类赖以生存的粮食也主要来源于胚乳。

关键词： 永瓣藤   卫矛科   珍稀特有植物   生物学特性  

摘要： 本文研究了我国珍稀特有植物永瓣藤（Ｍｏｎｉｍｏｐｅｔａｌｕｍｃｈｉｎｅｎｓｅ）的自然环境、地理分布、群落学特点、外部形态、内部结构特征、生长发育及其开花结实特性，为其种质保存和保护生物学研究提供基础资料。