雌蕊胞外基质在花粉管生长中的作用

雌蕊胞外基质对雌蕊与花粉的识别以及花粉管的定向生长有着重要的作用,是近年来植物生殖生物学的研究热点之一。与花粉萌发和花粉管生长相关的雌蕊胞外基质种类主要包括阿拉伯半乳糖蛋白、类伸展素糖蛋白、富含脯氨酸糖蛋白、钙调素、S—糖蛋白、果胶以及子房的特异性物质等。本文着重介绍这些雌蕊胞外基质的生理功能及其研究进展。     

甘蓝油菜雌蕊中花粉管生长途径的钙离子定位

用焦锑酸钾定位 Ca~(2 )的技术,证明了甘蓝油菜(Brassica napus)柱头乳突细胞的少量分泌物、柱头表皮下的引导组织细胞间隙、花柱引导组织细胞壁外表面和胞间隙的分泌物以及子房假隔膜分泌区的表皮细胞外和内部引导组织细胞壁外表面和胞间隙的分泌物中均有 Ca~(2 )沉淀存在,而花柱皮层薄壁细胞无此种现象。花粉管生长的整个途径中 Ca~(2 )的存在与花粉管在雌蕊中的定向生长有关。     

烟草雌蕊的花粉管生长途径中几种植物激素的免疫金电镜观察

用免疫金电镜法观察了大叶国花柱、珠孔及助细胞内玉米素（ｔ－Ｚ）、吲哚乙酸（ＩＡＡ）、赤霉素（ＧＡ７一ＧＡ４）和脱落酸〖（＋）ＡＢＡ〗的分布。刚授粉地的花柱引导组织细胞内与胞间基质中ｔ－Ｚ较多、ＩＡＡ、ＧＡ７／４、（＋）ＡＢＡ较少;授粉后２４ｈ（此时花粉管已穿过花柱中部）,该部位ｔ－Ｚ显著减少,ＩＡＡ略增加,ＧＡ７／４显著增加,而（＋）ＡＢＡ仍较少。授粉后２４ｈ,花柱中段薄壁组织细胞与胞间基质中ＩＡ     

肌动蛋白在丝瓜花粉管顶端生长中的作用

用非固定荧光标记的鬼笔环肽作为肌动蛋白探针观察并证明了丝瓜未萌发的花粉粒和不同生长时期花粉管中肌动蛋白纤丝的分布及其形态变化。又用细胞松弛素Ｂ（ＣＢ）、氯丙嗪（ＣＰＺ）及Ｎ－乙酰马来酰胺（ＮＥＭ）证明了丝瓜花粉管伸长与肌动蛋白暨有密切的关系，也受Ｃａ＾２＋的调节。     

花粉-雌蕊的相互作用机制

就近年来有关被子植物有性生殖过程中,雌蕊对花粉萌发、花粉管生长以及生长方向的作用和传粉对雌蕊发育的影响的研究进展作了介绍。     

小毛茛雌蕊群的授粉率及花粉管生长途径

为探讨毛茛属中是否具有与慈姑属中类似的花粉管再分配现象,对小毛茛开花后不同时期柱头的授粉率和花粉量进行了统计,并采用荧光显微术观察了其花粉在雌蕊群中的萌发及花粉管生长过程。该种的每朵花中含有39.2±9.9个离生心皮,开花过程常持续4~6d,开花2d后,柱头授粉率就可达到100%,平均每柱头的花粉量在3d后达到17.0±2.4粒。虽然开花的当天即有少数柱头落置有花粉粒,但花粉萌发常自开花的次日开始。花粉管先沿各雌蕊之向心一侧的组织中穿行至子房基部后部分花粉管转向胚珠,由珠孔进入珠心。从花粉粒落置于柱头到花粉管进入珠心大约需要24h。尽管毛茛属有着与慈姑属类似的多心皮雌蕊群,但大量的荧光显微观察表明,与慈姑属植物中不同的是,小毛茛的花粉管生长均局限于每一雌蕊中而不能穿过子房向其他雌蕊生长。雌蕊群的比较解剖发现野慈姑的子房基部有一条通向花托表面的孔道,这正是花粉管由一个雌蕊到另一个雌蕊的通路,但小毛茛的子房基部不存在此孔道。     

陆地棉雌蕊的花粉管生长途径中钙分布的超微细胞化学定位

用焦锑酸盐沉淀法对陆地棉(Gossypium hirsutum L.)授粉前后的柱头、花柱、珠孔与珠心组织中的钙进行了超微细胞化学定位。X射线波谱与能谱分析证明所定位的沉淀确系焦锑酸钙。观察结果表明:在整个花粉管生长途径中的雌蕊组织,钙分布均较其它相邻组织密集;钙主要分布在细胞壁与胞间基质等质外体系统中。在雌蕊中生长的花粉管,其尖端细胞器区也有丰富的钙。     

类整合素在烟草花粉萌发和花粉管生长中的作用

本文研究了动物整合素VnR抗血清及动物整合素专一性抑制剂含RGD的多肽对体外及半体内培养条件下烟草花粉萌发及花粉管生长的影响。结果表明在体外培养条件下,VnR抗血清及GRGDSP肽对花粉的萌发及花粉管的生长没有明显的抑制作用,但可抑制钙调素促进的花粉萌发和花粉管的生长;两者对柱头上进行的花粉萌发及在花柱里进行的花粉管生长也有一定程度的抑制。对类整合素在花粉萌发及花粉管生长中的作用进行了讨论。     

肌动蛋白在丝瓜花粉管顶端生长中的作用

用非固定荧光标记的鬼笔环肽作为肌动蛋白探针观察并证明了丝瓜未萌发的花粉粒和不同生长时期花粉管中肌动蛋白纤丝的分布及其形态变化。又用细胞松弛素B（CB）、氯两嗪（CPZ）及N-乙酰马来酰胺（NEM）证明了丝瓜花粉管伸长与肌动蛋白既有密切的关系,也受Ca2 的调节。     

类整合素在烟草花粉萌发和花粉管生长中的作用

The effects of antiserum against human VnR integrin and integrin antagonist GRGDSP peptides on Nicotiana tabacum pollen germination and tube growth both in in vitro and in semi-vivo conditions were studied. No obvious inhibitory effects on pollen germination and tube growth in vitro were observed when anti-VnR serum or GRGDSP peptides was added to BK culture medium, but the enhancement of pollen germination and tube growth in vitro promoted by calmodulin was depressed by adding anti-VnR serum or GRGDSP peptides to BK culture medium. In addition to that, pollen germination and tube growth on stigma, as well as tube growth in styles were also inhibited at some extent by treating stigma and microinjecting GRGDSP peptides or anti-VnR serum into styles. The role of integrin-like proteins in regulation of pollen germination and tube growth in situ was discussed.     

Pistil Exudate Production and Pollen Tube Growth in Lilium longiflorum Thunb.

Exudate production in the pistil of Lilium longiflorum was studiedin relation to pollen tube growth, using scanning electron microscopy(SEM), transmission electron microscopy and light microscopy.In contrast with conventional fixation for SEM, during whichthe exudate of L. longiflorum largely washes away, the exudateremains present through freezing in case of cryo-SEM. Usingthe latter method we observed that exudate production on thestigma and in the style started before anthesis. Just underneaththe stigma the exudate was first accumulated at the top of eachsecretory cell, followed by a merging of those accumulationsas exudate production proceeded. Exudate is also produced bythe placenta. It was however not possible to determine whetherany of this fluid originated from the micropyle. Apart fromthe cell shape and the cuticle present in between the secretorycells, the ultrastructure of the secretory cells covering theplacenta was comparable to those of the stylar canal. The transferwall of the secretory cells of the placenta originated fromfusing Golgi vesicles but the endoplasmic reticulum seemed tohave an important role as well. After pollination the pollen tubes grew across the stigma andentered the style through one of the slits in the three stigmalobes. The pollen tubes grew straight downward through the styleand were covered by exudate. As the pollen tubes approachedthe ovary their growth was restricted to the areas with secretorycells. In the cavity the pollen tubes formed a bundle and theybent from this bundle in between the ovules towards the micropylarside. There they bent again to stay close to the secretory cells.After bud pollination the pollen tube growth was retarded. Laterarriving pollen tubes had a tendency to grow close to the secretorycells of the style, which resulted in a growth between thesecells and preceding pollen tubes. If there was still a littleexudate produced, it resulted in a lifting up of the pollentubes, out of the exudate. The relationship between exudateproduction and pollen tube growth is discussed. Both the speedand the guidance of the pollen tube seemed determined by theproperties of the exudate.Copyright 1994, 1999 Academic Press Cryo-scanning electron microscopy, exudate, Lilium longiflorum, lily, ovary, pollination, pollen tube growth, secretory cell, stigma, style     

The Pollen Tube Pathway in the Pistil of Lycopersicon peruvianum

The pollen tube pathway has been studied in unpollinated andpollinated pistils of Lycopersicon peruvianum using histochemicalstains for detection of proteins, lipids and arabinogalactansby bright-field microscopy, and decolourized aniline blue fordetection of pollen tubes by epifluoresence microscopy. Thepollen tube pathway is a continuous tract of mucilage from thestigma surface to the ovule micropyles, and is associated witha continuous tract of specialized, protein-rich transmittingcells comprising the stigmatic papillae, vertical files of stylartransmitting cells and the placental epithelium within the ovary.The superficial exudate of the stigma is hydrophobic and richin lipids. The mucilage of the style and ovary is hydrophilicand rich in arabinogalactans but low in proteins. Pollen tubesgrow between cells through the mucilage of the stigma and stylartransmitting tract, and across the surface of the placenta inthe ovarian mucilage. The structure of the junction of the stylartransmitting tract with the top of the ovary placenta assistseffective distribution of pollen tubes within the ovary. Lycopersicon, solanaceae, fertilization, pistil, pollen tube, pollination     

花柱和花粉胞外钙调素对花粉萌发和花粉管伸长的影响

以烟草为材料,通过半体内实验,就花柱和花粉胞外钙调素对花粉萌发和花粉管伸长的影响进行了观察。发现用EGTA及钙调素抗血清处理柱头或花粉均可抑制花粉在柱头上的萌发;向花柱引导组织中显微注射纯化钙调素可促进花粉管束伸长,而注射钙调素抗血清可抑制花粉管束伸长;同时证实玉米花柱和花粉细胞壁中均存在钙调素及钙调素结合蛋白,而且花粉和花柱细胞壁中钙调素结合蛋白的种类有差异。结果表明存在于花粉和花柱细胞外的钙调素对花粉萌发和花粉管伸长均有促进作用。     

Strategic Endothelial Cell Tube Formation Assay: Comparing Extracellular Matrix and Growth Factor Reduced Extracellular Matrix

Malignant tumors require a blood supply in order to survive and spread. These tumors obtain their needed blood from the patient''s blood stream by hijacking the process of angiogenesis, in which new blood vessels are formed from existing blood vessels. The CXCR2 (chemokine (C-X-C motif) receptor 2) receptor is a transmembrane G-protein-linked molecule found in many cells that is closely associated with angiogenesis¹. Specific blockade of the CXCR2 receptor inhibits angiogenesis, as measured by several assays such as the endothelial tube formation assay. The tube formation assay is useful for studying angiogenesis because it is an excellent method of studying the effects that any given compound or environmental condition may have on angiogenesis. It is a simple and quick in vitro assay that generates quantifiable data and requires relatively few components. Unlike in vivo assays, it does not require animals and can be carried out in less than two days. This protocol describes a variation of the extracellular matrix supporting endothelial tube formation assay, which tests the CXCR2 receptor.     

Pistil Receptivity and Pollen Tube Growth in Relation to the Breeding System of Eucalyptus woodwardii (Symphyomyrtus: Myrtaceae)

Pistil structure, stigma receptivity and pollen tube growthwere investigated in relation to seed set of Eucalyptus woodwardii.Self-pollination resulted in reduced capsule retention and seeddevelopment as compared with cross-pollination. The pistil consistedof an ovary with five locules, a long style with a canal extendingfor two-thirds of its length, and a papillate stigma. Therewas no change in style length with time after anthesis, butboth stigma secretion and ability to support pollen germinationand tube growth increased to reach a peak at 7 d. Pollen germinatedon the stigma surface and in the stylar canal, but most tubegrowth occurred intercellularly in the transmitting tissue surroundingthe canal. At the base of the style the pollen tubes split intofive groups following the transmitting tissue strands to theovary. Each group grew through a septum dividing two loculesand entered the placenta. The tubes then emerged from the placentato penetrate the ovules at between 10 and 20 d after pollination.Fewer ovules were penetrated following self- than cross-pollination. Eucalyptus woodwardii Maiden, Lemon-flowered gum, Pistil receptivity, Pollen tube growth, Breeding system, Self-incompatibility     

肌醇磷脂信号途径参与胞外钙调素启动花粉萌发和花粉管伸长

高等植物有性生殖是植物发育生物学研究的重要内容之一,而作为雄配子体的花粉在雌蕊柱头上萌发及花粉管在花柱内的持续生长是有性生殖实现的关键。已有许多研究表明Ca2 在花粉萌发和花粉管生长过程中起重要作用。最近,我室在多年细胞外钙调素（calinodulin,CaM）存在。性质及生物学功能研究（孙大业等1995;Sun等1994,1995;Tang等1996）的基础上,通过不过膜的大分子CaM拈抗剂或抗体并结合恢复实验证实细胞外CaM对花粉的萌发和花粉管的伸长具有启动作用（马力耕和孙大业1996）,并发现G蛋白、质膜Caz”通道及胞内依赖Caz”的蛋白…