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关键词： metabolic engineering   gene regulation   secondary metabolism   signal transduction   subcellular compartmentation  

摘要： Recent advances in the cell, developmental, and molecular biology of alkaloid biosynthesis have heightened our appreciation for the complexity and importance of plant secondary pathways. Several biosynthetic genes involved in the formation of tropane, benzylisoquinoline, and terpenoid indole alkaloids have now been isolated. The early events of signal perception, the pathways of signal transduction, and the function of gene promoters have been studied in relation to the regulation of alkaloid metabolism. Enzymes involved in alkaloid biosynthesis are associated with diverse subcellular compartments including the cytosol, vacuole, tonoplast membrane, endoplasmic reticulum, chloroplast stroma, thylakoid membranes, and perhaps unique "biosynthetic" or transport vesicles. Localization studies have shown that sequential alkaloid biosynthetic enzymes can also occur in distinct cell types, suggesting the intercellular transport of pathway intermediates. Isolated genes have also been used to genetically alter the accumulation of specific alkaloids and other plant secondary metabolites. Metabolic modifications include increased indole alkaloid levels, altered tropane alkaloid accumulation, elevated serotonin synthesis, reduced indole glucosinolate production, redirected shikimate metabolism, and increased cell wall-bound tyramine formation. This review discusses the biochemistry, cell biology, molecular regulation, and metabolic engineering of alkaloid biosynthesis in plants.

ISBN: (纸本)7109068226

关键词： 新疆,葱属,种质资源,分类,叶表皮形态,花粉形态, 种皮微形态,核型  

摘要： 本文对新疆葱属部分植物的叶表皮形态学、花粉形态学、种皮微形 态学以及细胞学几个方面进行了研究。结果如下： 1．对18种植物叶的上、下表皮进行形态学观察，发现叶表皮形态 在种间及组间差异较大，可将其形态特征分为两大类、共7小类，葱组 和洋葱组属Ⅰ型，其余3个组属Ⅱ型，其中，根茎组包括①、②、③、 ④类，单生组包括①、②、③、⑤类，均较为复杂； 2．对23种植物、共24个居群的花粉进行形态学观察，发现种间在 花粉形态上差异不大，但外壁纹饰上有一定差异，可分为两大类：条纹 状和网状纹饰，细分为5小类：浅条纹状、深条纹状、穴网状、细穿孔 网状和粗穿孔网状纹饰等。其中，根茎组、单生组和葱组的外壁纹饰既 包括原始类型，也包括进化类型，洋葱组属较进化类型，多籽组属较原 始类型； 3．对18种植物种皮进行微形态学观察，发现种间及组间差异较大， 可分为两大类、共6小类。其中，根茎组中既有原始类型，也有衍生类 型，葱组、洋葱组和单生组属较原始类型，多籽组属衍生类型； 4．对19种植物细胞学研究的结果为：染色体数目为2n=16、20、32 或48，基数为X=8或10，倍性水平为二倍体、四倍体或六倍体，核型 属1A、2A或2B型，对称性较高，随体染色体属Ⅰ、Ⅱ或Ⅵ型，结果 显示，该属植物核型较原始。其中，石生韭、旱生韭、灰皮葱、新疆蒜 和健韭为首次报道。 根据野外及资源圃田间观察，结合以上研究结果，认为本文所观察 的4个方面特征在该属植物的分类上具有一定的意义，并初步认为根茎 组和单生组的划分是不自然的，还有待于进一步研究商榷。由于该属植 物具有种类繁多、差异较大等特点，因此，对其进行更为全面的生物学 特性研究不仅可为该属植物的分类及系统研究、还可为该属资源的开发 利用提供重要的理论依据。

关键词： 新疆   郁金香属   物候学   大孢子发生   雌配子体发育  

摘要： 本文综述了郁金香属的研究历史及我国野生郁金香属的研究概况，针对新疆郁金香属存在的问题，对该属植物中3组共11种及少数种的不同居群进行了物候学观测及资源评价、对8个种的大孢子发生及雌配子体发育的比较胚胎学及具有较大育种价值的准噶尔郁金香（*** ）传粉生物学等方面进行了研究。结果如下： 1.物候学特点：该属所观察的11种植物具有萌动早、年生长期短、抗寒性强等特点。毛蕊组（Sect. Eriostemones）、长柱组（Sect. Orithyia）及无毛组（ Sect. Leiostemones）3组组间物候节律不同，组内种间具一定相似性，但无毛组（ Sect. Leiostemones）组内种间、甚至是同种植物的不同居群在同一生境下物候期相差相对较大。从物候节律来看，毛蕊组（Sect. Eriostemones）较进化，无毛组（ Sect. Leiostemones）较原始。 2.该属3组中8种郁金香共具有5种胚囊类型，即毛蕊型(Eriostemones type)、贝母型(Fritillaria type)、五福花型(Adoxa type)、德鲁撒型(Drusa type)及四叶郁金香型(T. tetraphylla type)。除毛蕊郁金香（T. dasystemon）和异叶郁金香(T. heterophylla)外，其它6个种的胚囊发育类型均为首次报导，且发现长柱组（Sect. Orithyia）的异叶郁金香(T. heterophylla)和异瓣郁金香(T. heteropetala)不止1种胚囊发育类型。从比较胚囊学角度，初步探讨了郁金香属植物胚囊类型在分类学上的意义。 3.准噶尔郁金香（T. schrenkii ）自花授粉有少量结实，但以异花传粉为主，且为虫媒传粉，有效传粉昆虫主要是西方蜜蜂（Apis mellifera L.），其授粉方式为腹面接触式，访花频率平均为4.20次／15min。 4.资源评价结果：通过对11种及少数种的不同居群的园艺性状的观测，发现每个种及少数种的不同居群都有其特点，在育种工作中可以根据实际需要将其作为杂交育种的基因材料。

关键词： biennial   demography   facultative biennial   Geranium robertanium   herb Robert   life cycle   life history   self-pollination  

摘要： For nine years I studied the life cycle, demography, and reproductive biology of a woodland herb, Geranium robertianum, in central Massachusetts. These plants are facultative biennials that typically flower in the year after germination. Of 408 seeds experimentally sown in natural habitat, 26% gave rise to seedlings within six years. Of 1352 marked, naturally occurring seedlings, 53% survived to the end of their first growing season, 13% of plants alive at the end of their first growing season survived to year two, and 54% of these flowered. Plants germinating in early spring were more likely to survive to the end of year one and to flower than those germinating later in the year. Low summer rainfall appeared to reduce summer survival and low winter temperatures combined with little snow cover seemed to reduce winter survival. Floral structure and development, pollen-ovule ratios, and pollinator activity all suggest that plants of this species are highly self-pollinated. Herb Robert is one of only a few biennials that occupy undisturbed forest habitat.

关键词： similarity measures   equilibrium theory   Lake Erie Archipelago   flora   conservation biology   island biogeography  

摘要： Using a compiled list of the vascular flora for 21 islands in the western basin of Lake Erie, Preston's resemblance measure and Connor and Simberloff's Null Hypothesis I were applied to native and alien species subsets in order to examine how these findings fit within the equilibrium theory. Based on Preston's measure, it was found that the similarity of species between island pairs was more likely to fit with MacArthur and Wilson's equilibrium theory when native species were considered than when alien species were considered. Native species have restricted distributions - especially those found on the smaller islands and appear to be less randomly distributed about the islands. This study also found that a large component of the alien flora is widespread in its distribution, and appears to be randomly distributed among most of the islands.