十字花科10属种与油菜萝卜胞质不育系杂交的花粉萌发情况观察

对１０属种十字花科植物与油菜萝卜胞质不育系杂交时花粉在柱头上粘全、萌发、花粉管伸长等情况进行了观察。结果表明：（１）海甘蓝花粉粒粘合较难;（２）４８ｈ内无瓣焊菜（Ｒｏｒｉｐｐａ ｄｕｂｉａ）、毛果诸葛菜（Ｏｒｙｃｈｏｐｈｒａｇｎｕｓ ｖｉｏｌａｃｅｕｓ）、桂竹香（Ｃｈｅｉｒａｎｔｈｕｓ ｃｈｅｉｒｉ）、海甘蓝（Ｃ花粉管的伸长受阻 于分萌发启动之明,花粉壁内形成胼胝质塞;播蒿、紫罗兰、莘菜花粉管伸长     

早发生胚水稻小孢子发生及花粉的萌发生长

实验结果表明,早发生胚水稻（PDER）品系小孢子的发生发育与常规水稻品种相同,常规I-KI镜检显示其成熟花粉育性达87．4％．开花后,少量花粉在柱头上能正常萌发,并以短管形式进入柱头．大部分花粉在柱头上发生了异常行为：不萌发花粉管,但排放出大量内容物;花粉管细小或畸形;在枝头内或柱头外花粉管前端破裂;花粉管在柱头上绕行不进入柱头;花粉管在柱头内逆行生长;花粉管进入柱头后又穿出柱头;花粉管壁上粘有颗粒或被有一层膜等．文中就PDER的来源讨论了这些现象,并提出“萌败”这一新概念．     

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。     

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…     

拟南芥授粉前后花粉与乳突细胞的超微结构

利用透射电子显微镜技术,对自交亲和植物拟南芥授粉前后花粉和乳突细胞的超微结构进行了观察。发现花粉和柱头乳突细胞一些未经报道的超微结构特征,可能与拟南芥花粉和乳突细胞的识别及花粉管生长相关:(1)成熟花粉中,电子透明的、体积较大的小液泡(直径200～1000nm)呈均匀分布。部分小液泡内含有多层膜状结构物质,推测可能是膜的一种储存形式,与花粉萌发时大量出现的小囊泡有关。(2)花粉萌发时,小液泡由均匀分布变为不均匀分布。(3)授粉前后的乳突细胞顶端和侧端的内壁上有明显的壁内突结构,粘附的花粉开始萌发时的乳突细胞壁内突处可观察到直径50～100nm的小泡存在,表明拟南芥乳突细胞具有一定的分泌功能。     

百合远缘杂交花粉萌发及花粉管生长过程观察

利用荧光显微镜对百合远缘杂交组合Bernini×Pollyanna花粉萌发及花粉管生长过程进行观察研究,结果显示,授粉后3~30 h内花粉萌发形成花粉管,且花粉管生长速度由快到慢,48~51 h内花粉管停止生长,花粉管最后深入到花柱的1/3处,并观察到一些异常的花粉管形态;花粉管生长过程中还伴随着一系列的胼胝质反应,出现的部位依次是乳突细胞、花粉管、花柱通道细胞、胚珠中的胚囊.结果表明该杂交组合不亲和.研究认为Berni-ni柱头乳突细胞是阻碍Pollyanna花粉管生长的第一道屏障,花柱通道细胞是抑制花粉管在花柱内生长的第二道屏障.     

桦木科植物花柱适应风媒传粉的特征

植物体为适应自己的传粉系统, 表现出高度的适应特征。风媒花植物为适应风传播花粉, 要形成特殊的结构, 以扩大接受花粉粒的面积。利用扫描电镜观察了桦木科(Betulaceae)6属18种植物花柱的形态及花粉粒在花柱上的萌发过程, 探讨了桦木科植物花柱适应风媒传粉的特征。结果表明, 桦木科植物的二心皮(铁木、云南鹅耳枥稀为三心皮)雌蕊具柱状花柱, 柱头不发达, 花柱表皮细胞长条状, 纵向排列紧密。传粉时, 花柱表皮细胞能执行柱头的功能, 接受花粉粒, 为花粉粒萌发提供场所和萌发条件。桦木科植物花柱有2种类型: 一种是花柱表皮细胞能形成乳突, 花粉管经乳突细胞进入花柱; 另一种是花柱表皮细胞不形成乳突, 花粉管经过花柱表皮细胞或胞间隙进入花柱。无论花柱表皮细胞是否形成乳突, 乳突的形态、大小以及花粉管和乳突的结合方式等在族间、属间、属内种间存在差异。与基部被子植物相比, 桦木科植物的花柱呈现适应风媒传粉的进化特征。桦木科植物花柱表皮细胞形成的乳突与基部被子植物柱头乳突功能相同, 是桦木科植物风媒传粉的适应策略。     

柚雌蕊不同部位抽提液对自交不亲和阻抑效果的研究

以‘土柚’（Citrus grandis ‘Tuyou’）作对照,采用荧光显微技术对‘琯溪蜜柚’（Citrus grandis‘Guanxi-miyou’）、‘度尾蜜柚’（Citrus grandis ‘Duweimiyou’）两个品种花粉在本品种和异品种雌蕊不同部位抽提液中花粉萌发和花粉管伸长状态进行了观察。结果表明：‘琯溪蜜柚’和‘度尾蜜柚’子房抽提液对自身花粉管伸长阻抑最明显,并产生严重的弯曲;柱头抽提液对自身花粉管伸长稍有影响,出现中度弯曲;花柱抽提液中自身花粉管伸长正常,仅有轻微弯曲。然而,对于异品种的花粉以及自交亲和的‘土柚’,其子房、花柱和柱头抽提液对花粉管伸长没有这种阻抑效应。     

高温对苹果花粉在花柱内萌发和生长的影响

以‘长富2号’红富士苹果为母本,‘红星’苹果为父本,研究35℃高温对苹果花粉在花柱内萌发和生长的影响。结果表明：温度影响花粉在柱头和花柱内的萌发及生长,与对照相比,高温促进花粉在柱头表面快速萌发,并加速花粉管在花柱内的伸长生长,但是在授粉72hN,高温处理下培养的花粉管形态出现花粉管变粗、弯曲并有瘤状小结的异化现象,同时,花柱发生褐变,并产生胼胝质,最终导致花粉管不能进入胚珠完成受精。     

青篱柴通过促进亲和花粉生长而提高传粉精确性

异型花柱植物的适应意义在于提高亲和花粉的传递, 从而促进异交, 但是有不少研究发现柱头上落置了大量不亲和花粉。目前, 很少有人研究柱头是否有利于亲和花粉的萌发和花粉管伸长, 以及通过去雄处理排除花内和植株内不亲和花粉干扰从而验证二型花柱植物是否可以促进异交。本研究以亚麻科青篱柴属(Tirpitzia)的二型花柱植物青篱柴(T. sinensis)为研究对象, 分居群调查了青篱柴长、短柱型的植株数量, 测量不同柱型的花粉与柱头大小以及观察其表面纹饰, 测定不同开花时间长、短柱型的柱头活性与花粉活力, 统计自然状态下柱头上落置的不同表型花粉比例, 进一步统计花内、株内去雄和自然对照下柱头上落置的不同表型花粉比例, 计算型间、型内和混合授粉花粉管长度和花粉萌发率, 人工授粉检测其是否型内异交不亲和与自交不亲和。结果表明, 自然居群中长、短柱型青篱柴植株数量没有显著性差异; 短柱型青篱柴花粉体积显著大于长柱型, 且二者花粉表面纹饰不同, 但不同柱型的柱头表面积与表面纹饰无差异; 青篱柴开花第一天的花粉活力显著高于开花第二天, 而柱头活性在开花前两天无显著性差异; 自然状态下柱头上落置的不亲和花粉比例显著高于亲和花粉; 在长柱型青篱柴中, 花内和株内去雄显著提高了柱头上亲和花粉的落置比例; 柱头上授型内花粉, 其花粉萌发率和花粉管的长度都显著低于授型间花粉; 授粉结果表明青篱柴为型内异交不亲和与自交不亲和。二型花柱植物通过促进亲和花粉的萌发和花粉管的伸长而有利于型间授粉, 从而显著提高其传粉精确性。     

STERILITY BARRIERS OF SOME ARTIFICIAL F1 ORCHID HYBRIDS: MALE STERILITY. I. MICROSPOROGENESIS AND POLLEN GERMINATION

Microsporogenesis, pollen germination and fertility of males gametes were studied in 24 artificial intergeneric and interspecific F₁ hybrids of orchids. Although parental species had the same chromosome number (2n = 40), microsporogenesis of the hybrids was irregular due to the lack of homology of the chromosomes of the parental species. This led to formation of tetrads of microspores without micronuclei, tetrads with 1–8 micronuclei, triads, dyads with and without micronuclei, and monads. Chromosomes numbers found in haploid microsporocytes ranged from 7 to 40; in micronuclei the chromosome number varied between 1 and 5. In terms of pollen germination, three situations were observed: 1) hybrids whose pollen grains did not germinate in the stigma; 2) hybrids in which the pollen tubes grew down in the style, but did not penetrate into the ovary; 3) hybrids in which the pollen tubes grew down normally through the ovary, reaching the ovules. When the pollen tubes did not penetrate the ovary no fruit was formed. Therefore germination tests carried out in vitro may not indicate pollen fertility, because pollen tube growth in the style of the flower may be insufficient to induce fruit formation or to accomplish fertilization.     

莴苣授粉前后柱头与花柱中钙的分布变化

莴苣柱头呈两裂片状,有接受花粉的接受面和非接受面之分。授粉前后,柱头接受面乳突细胞的细胞壁中贮存丰富的细小钙颗粒,而非接受面的表皮细胞壁中的钙颗：粒很少。在花柱组织中钙的分布具有明显特征,在同一水平上,钙主要分布在引导组织的质外体中,如细胞壁和细胞间隙中,而在引导组织外的薄壁组织中钙主要分布在的细胞内液泡和细胞壁中以及维管束导管内。在花柱不同水平上,花柱中的钙呈现出梯度分布,顶端各组织中的钙颗粒较少,基部各组织中的钙颗粒较多。授粉后1h花柱基部组织的钙颗粒增多,钙梯度分布现象增强。花柱引导组织中的钙梯度分布很可能是吸引花粉管向下生长的原因。讨论了莴苣花柱引导组织中钙梯度分布特征和花粉管在其体内生长的关系。     

莴苣授粉前后柱头与花柱中钙的分布变化

莴苣柱头呈两裂片状,有接受花粉的接受面和非接受面之分。授粉前后,柱头接受面乳突细胞的细胞壁中贮存丰富的细小钙颗粒,而非接受面的表皮细胞壁中的钙颗粒很少。在花柱组织中钙的分布具有明显特征,在同一水平上,钙主要分布在引导组织的质外体中,如细胞壁和细胞间隙中,而在引导组织外的薄壁组织中钙主要分布在的细胞内液炮和细胞壁中以及维管束导管内。在花柱不同水平上,花柱中的钙呈现出梯度分布,顶端各组织中的钙颗粒较少,基部各组织中的钙颗粒较多。授粉后1h花柱基部组织的钙颗粒增多,钙梯度分布现象增强。花柱引导组织中的钙梯度分布很可能是吸引花粉管向下生长的原因。讨论了莴苣花柱引导组织中钙梯度分布特征和花粉管在其体内生长的关系。     

Plantacyanin plays a role in reproduction in Arabidopsis

Plantacyanins belong to the phytocyanin family of blue copper proteins. In the Arabidopsis (Arabidopsis thaliana) genome, only one gene encodes plantacyanin. The T-DNA-tagged mutant is a knockdown mutant that shows no visible phenotype. We used both promoter-beta-glucuronidase transgenic plants and immunolocalization to show that Arabidopsis plantacyanin is expressed most highly in the inflorescence and, specifically, in the transmitting tract of the pistil. Protein levels show a steep gradient in expression from the stigma into the style and ovary. Overexpression plants were generated using cauliflower mosaic virus 35S, and protein levels in the pistil were examined as well as the pollination process. Seed set in these plants is highly reduced mainly due to a lack of anther dehiscence, which is caused by degeneration of the endothecium. Callose deposits occur on the pollen walls in plants that overexpress plantacyanin, and a small percentage of these pollen grains germinate in the closed anthers. When wild-type pollen was used on the overexpression stigma, seed set was still decreased compared to the control pollinations. We detected an increase in plantacyanin levels in the overexpression pistil, including the transmitting tract. Guidance of the wild-type pollen tube on the overexpression stigma is disrupted as evidenced by the growth behavior of pollen tubes after they penetrate the papillar cell. Normally, pollen tubes travel down the papilla cell and into the style. Wild-type pollen tubes on the overexpression stigma made numerous turns around the papilla cell before growing toward the style. In some rare cases, pollen tubes circled up the papilla cell away from the style and were arrested there. We propose that when plantacyanin levels in the stigma are increased, pollen tube guidance into the style is disrupted.     

梨远缘花粉原位萌发及生长特性

应用荧光标记方法对梨远缘花粉在‘丰水’和‘噢嗄二十世纪’柱头上萌发及花粉管生长特性进行观察,结果表明:(1)梨远缘花粉均能在柱头上萌发,但其萌发率不同,授粉后24 h,在‘丰水’柱头上‘红叶桃’花粉萌发率最高,达62.8%,而‘盖县大李’花粉萌发率仅为12.0%,各种远缘花粉在‘丰水’柱头萌发率均高于‘噢嗄二十世纪’柱头。(2)各种远缘花粉管在梨柱头或花柱内生长情况也有差异,‘红叶桃’等核果类花粉管在梨柱头上均表现为扭曲、盘绕等现象,不能穿过柱头;‘红星’和‘红富士’花粉管虽然有少量穿过柱头,但不能进一步在花柱内生长,表现为扭曲变形、先端膨大等不亲和性现象。因此,梨与远缘果树杂交不亲和在柱头上就已发生,这与梨自交不亲和反应发生在花柱内的现象不同。     

Maize pollen coat xylanase facilitates pollen tube penetration into silk during sexual reproduction

Cell wall hydrolases are well documented to be present on pollen, but their roles on the stigma during sexual reproduction have not been previously demonstrated. We explored the function of the tapetum-synthesized xylanase, ZmXYN1, on maize (Zea mays L.) pollen. Transgenic lines (xyl-less) containing little or no xylanase in the pollen coat were generated with use of an antisense construct of the xylanase gene-coding region driven by the XYN1 gene promoter. Xyl-less and wild-type plants had similar vegetative growth. Electron microscopy revealed no appreciable morphological difference in anther cells and pollen between xyl-less lines and the wild type, whereas immunofluorescence microscopy and biochemical analyses indicated an absence of xylanase on xyl-less pollen. Xyl-less pollen germinated as efficiently as wild-type pollen in vitro in a liquid medium but less so on gel media of increasing solidity or on silk, which is indicative of partial impaired water uptake. Once germinated in vitro or on silk, the xyl-less and wild-type pollen tubes elongated at comparable rates. Tubes of germinated xyl-less pollen on silk did not penetrate into the silk as efficiently as tubes of wild-type pollen, and this lower efficiency could be overcome by the addition of xylanase to the silk. For wild-type pollen, coat xylanase activity on oat spelled xylan in vitro and tube penetration into silk were inhibited by xylose but not glucose. The overall findings indicate that maize pollen coat xylanase facilitates pollen tube penetration into silk via enzymatic xylan hydrolysis.     

Heterostyly inPrimula. 2. Sites of pollen inhibition,and effects of pistil constituents on compatible and incompatible pollen-tube growth

Summary In incompatible (intramorph) pollinations of the heterostylousPrimula vulgaris, pollen germination or tube growth may be partially inhibited in several sites associated with the stigma or style. Blockage may occur, a) on the stigma surface through the failure of germination or of pollen tube penetration after germination, b) in the stigma head during the passage of the tube through the specialized transmitting tissue of the head, or c) in the transmitting tract of the style. None of the barriers is complete, and the prohibition of selfing or intramorph crossing depends upon the cumulative screening effect of one following upon the other. In both morphs, the germination of incompatible pollen on the stigma is enhanced in high ambient relative humidity, but many tubes still fail to penetrate the stigma. Those that do are retarded or blocked in their growth in the transmitting tissues of the stigma head and style. Crude extracts from the tissues of the stigma head and style show some differential effect on the growth of pollen tubesin vitro, and dialysates of extracts containing high molecular weight fractions show a consistent differential effect, those from thrum tissues retarding thrum tubes while having a lesser effect on pin tubes, and those from pin tissues retarding pin tubes while having lesser effect on thrum. It is suggested that the factors influencing tube growth are present in the intercellular secretions of the transmitting tract.     

菊花自交不亲和性初步研究

以菊花品种杂交为对照,通过自交亲和指数、受精作用及自交有性过程荧光显微镜观察,对菊花自交不亲和性进行了研究。结果表明:菊花自交难以结实,具不亲和性;菊花自交不亲和的反应部位在雌蕊柱头,表现为花粉粒粘附少、萌发率低及诱导胼胝质生成,花粉管在柱头上出现各种异常现象而难以进入花柱。     

沙田柚花柱蛋白对花粉管生长的影响

本文以沙田柚及其授粉树种酸柚为材料,对其花粉在不同培养介质中的萌发率进行测定,筛选了０２～０４ｍｏｌ／Ｌ聚乙二醇－４００（ＰＥＧ－４００）＋００１％硼酸作为花粉萌发介质。用授粉后３ｄ的花柱提取液进行沙田柚、酸柚花粉萌发抑制实验,花柱提取液对自交花粉萌发无抑制作用,明显地抑制花粉管的生长。其中以花柱提取液的３５％饱和度硫酸铵级分对花粉管伸长的抑制最明显。模拟了花粉在雌蕊中的生长方式,进行花粉萌发生长,能收集到较多的花粉管,为研究花粉管的Ｓ－糖蛋白提供了材料。     

甘蓝型油菜雌性不育突变体FS-M1乳突细胞的细胞学观察

雌性不育突变体FS-M1是从甘蓝型油菜(Brassica napus)品种宁油10号中发现的.为了从细胞学角度研究FS-M1的雌性不育机理,利用荧光显微镜、扫描和透射电子显微镜观察分析了FS-M1柱头乳突细胞的授粉行为和超微结构.结果表明:花粉粒能在FS-M1乳突细胞上附着和萌发形成花粉管,但花粉管无法穿越柱头乳突细胞;开花后的FS-M1乳突细胞迅速衰退而呈干瘪萎蔫状,在衰退过程中,FS-M1柱头乳突细胞的细胞器数量减少,细胞液泡化明显,高尔基体、内质网和线粒体等一些细胞器结构被逐渐破坏.因此,推测FS-M1的雌性不育性是由于柱头乳突细胞发育异常造成的.