欧报春二型花柱的繁育特性研究

二型花柱植物通常具有自交不亲和性,在不同植物中所表现的可育性不同。欧报春(Primula vulgaris)是典型的二型花柱植物,为了探究欧报春的繁育特性,通过温室栽培,对欧报春的长花柱和短花柱的花部特征、花粉和花柱形态、花粉活力、柱头可授性、花粉/胚珠比、杂交指数、杂交亲和性、花粉管观察进行研究。结果表明,(1)长花柱和短花柱的花冠直径、花冠筒长度、柱头高度、花药高度和花筒中部直径均表现出两型性;(2)花粉和柱头观察发现花粉极轴长、花粉赤道轴长、花柱直径、柱头乳突细胞和花粉数量均有差异;(3)长花柱的花粉/胚珠比为384.20,短花柱为369.70,属于兼性异交类型;长花柱和短花柱的花粉活力和柱头可授性能在较长时间内维持较高活力;(4)长花柱杂交指数值为5,短花柱为4,表明繁育系统类型为异交,部分自交亲和,需要传粉者;6种授粉组合均能结实,异型花间授粉的结实数明显高于同型自花授粉和异株同型授粉;短花柱为母本的异型花间授粉组合亲和性优于其他组合;欧报春存在自交不亲和性,长花柱的自交不亲和性低于短花柱。     

小报春与岩生报春种间杂交亲和性研究

以报春花属报春花组的小报春(Primula forbesii)和指叶报春组的岩生报春(Primula saxatilis)为亲本,对种间杂交的结实性及花粉管行为进行了观察。结果表明:小报春与岩生报春种间杂交表现为不亲和,正反交组合正常结实率为0,但正交、反交组合花粉在柱头表面的萌发和花粉管伸长过程有明显差异,小报春花粉授粉4h后可以在岩生报春柱头表面萌发,但花粉管伸长的速度明显比对照组[岩生报春(P)×岩生报春(T)、岩生报春(T)×岩生报春(P)]慢,并且花粉管生长弯曲,授粉192h后花粉管仍未到达子房;岩生报春的花粉可以在小报春柱头上正常萌发,授粉48h后花粉管到达子房;4个对照授粉组合均分别于24h(短花柱为母本)、48h(长花柱为母本)时完成受精过程。研究表明,岩生报春×小报春杂交存在受精前障碍,小报春×岩生报春杂交亲和性较好,并可通过幼胚拯救的方法获得组间杂种后代;花柱长度可能是影响种间杂交结实能力的因素之一。     

芥菜型油菜与白菜正反杂交的胚胎学研究

利用荧光技术对芥菜型油菜（Brassica juncea）与白菜（B．pekinesis）种间正反杂交后花粉萌发和花粉管生长过程进行了观察。结果显示：芥菜型油菜与白菜正交授粉后,花粉在柱头上能正常萌发,多数花粉管沿花柱到达胚珠完成受精,且受精方式有珠孔受精、合点受精和中部受精,少量花粉管生长不正常,出现花粉管顶端膨大扭曲,花粉管分支等异常现象;反交授粉后,花粉在柱头上萌发时柱头乳突细胞产生强烈胼胝质反应,影响花粉管生长,只有少量花粉管通过花柱到达胚珠完成受精。用石蜡切片技术观察了正反杂交后杂种的胚胎发育,正交杂种胚胎发育较早,胚和胚乳生长较正常,杂种胚一般均能发育至成熟;反交杂种胚发育至心型期便不能继续发育,胚乳也停滞在游离核阶段并最终败育。综合分析表明,芥菜型油菜与白菜正反杂交都存在一定程度的受精不亲和性。     

野菊与菊花杂交中花粉活力和柱头可授性及胚胎发育研究

应用石蜡制片、活体压片、光学显微镜及扫描电子显微镜观察等方法,研究了四倍体河南云台山野菊(Dendranthema indicum)与栽培菊花'钟山金山'(D.grandiflorum 'Zhongshanjinshan')种间杂交中父本花粉活力、花粉在柱头萌发、花粉管生长及胚胎发育情况等.结果发现,父本云台山野菊的花粉活力在授粉时为12%左右.人工授粉后的不同时间,在柱头上都观察到正常萌发的花粉粒,且花粉管都能进入柱头,其中,在授粉后0.5 h时,平均每柱头有5.9粒花粉萌发;12 h时,为59.9粒;而24和48 h时,则分别降为47.1和35.7粒.此外,在授粉后8、10、12和15 d时,分别在49.1%、40.8%、39.7%和38.5%子房内观察到正常发育的胚胎,最终杂交结实率为44.8%,而母本自然开放结实率为52.3%.研究表明,授粉前其多数母本雌蕊发育良好、授粉后多数花粉能在柱头正常萌发和花粉管正常生长,在受精后大部分胚胎发育正常是野菊与栽培菊种间杂交较高结实率的重要保证,而授粉前父本较低的花粉活力对杂交结实率影响不大.     

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。     

艳丽耳草的二型花柱及异型自交不亲和系统

异型花柱是一种受遗传因素控制的花型多态性现象,包括二型花柱和三型花柱两种类型.本文以茜草科艳丽耳草(Hedyotis pulcherrima)为实验材料,通过对其野外居群的花型、花部形态及花粉特征等观察,发现艳丽耳草野外居群同时存在长花柱型花和短花柱型花,长/短花柱型花的数量比例为1∶1.两型花具有精确的交互式雌雄异位特征,并且该特征与花冠长度相关性显著.长/短花柱型花的柱头裂片长度、花粉大小及淀粉含量等具有二型性.花粉体外培养时花粉萌发率及花粉管生长速率无显著性差异.人工授粉后,艳丽耳草长/短花柱型花型间异交花粉管生长形态正常,授粉24 h后花粉管均已进入子房.而长/短花柱型花在自交及型内异交下均表现为不亲和,花粉管生长停止于柱头,花粉管顶端累积胼胝质并膨大.艳丽耳草没有无融合生殖现象,型间人工辅助异交授粉结实率为100％,显著高于自然结实率.本研究结果表明,艳丽耳草是典型的二型花柱植物,并具有异型自交不亲和系统.     

露珠杜鹃繁育系统及杂交亲和性

为种质资源保护和乡土园林树种推广提供技术支持,对野生露珠杜鹃（Rhododendron irroratum）繁育系统和杂交亲和性进行研究,试验包括开花生物学特性,繁育系统特性,与高山杜鹃优良园艺品种杂交授粉,荧光显微镜观察授粉花粉萌发及花粉管生长过程,以及坐果率和结实率统计。结果表明（：1）露珠杜鹃开花时间为4月下旬到5月下旬,花粉活力与柱头可授粉性随开花时间的延长逐渐下降。（2）杂交指数（OCI）为3,P/O值为343.47。（3）主要传粉者为膜翅目中华蜜蜂（Apis cerana）,繁育系统为兼性异交型,自交亲和,需要传粉者,属虫媒花。（4）人工控制授粉发现不存在无融合生殖,能自动自花授粉,异株异花、同株异花、自花授粉坐果率分别为46.96%、45.03%、37.16%,人工授粉平均坐果率与自然传粉坐果率基本一致。（5）露珠杜鹃作为亲本进行人工杂交授粉表现出杂交不亲和,母本花粉管中存在胼胝质栓塞,导致花粉管不能延伸至子房。通过观察发现,露珠杜鹃杂交亲和难点在于花粉管生长过程。     

小报春不同授粉组合亲和性研究

利用小报春‘红星’、‘紫霞’、‘罗兰香’3个品种分别设置8种授粉组合,统计了不同授粉组合的结实情况和单果种子数量,并对‘红星’品种部分授粉组合的花粉萌发与花粉管伸长过程进行荧光显微观察。结果显示:(1)3个品种的结实率和单果种子数量均表现为异型植株授粉>长花柱同型异株授粉、长花柱自交>短花柱同型异株授粉、短花柱自交,不同授粉组合间单果种子数量差异极显著,异型植株授粉类型结实率均达到100%,单果种子数量为44～181粒,显著高于自交组合和同型异株杂交组合;以异型致死花粉作为蒙导对短花柱同型异株授粉组合的结实有一定促进作用,但对长花柱同型异株授粉组合的结实没有一致的促进作用;3个品种中‘红星’的结实率和单果种子数量最高。(2)荧光显微观察表明,异型授粉组合花粉在柱头上大量萌发并在花柱中伸长,授粉144h后花粉管开始进入子房;同型授粉组合授粉12h后花粉开始萌发,但直到授粉后144h花粉管还没有进入花柱;自交授粉组合授粉后144h仍无花粉萌发。实验结果说明,小报春存在明显的自交不亲和性,且短花柱类型的自交不亲和性比长花柱类型强。     

芥菜型油菜与白菜正反杂交的胚胎学研究

利用荧光技术对芥菜型油菜(Brassica juncea)与白菜(B. pekinesis)种间正反杂交后花粉萌发和花粉管生长过程进行了观察。结果显示: 芥菜型油菜与白菜正交授粉后, 花粉在柱头上能正常萌发, 多数花粉管沿花柱到达胚珠完成受精, 且受精方式有珠孔受精、合点受精和中部受精, 少量花粉管生长不正常, 出现花粉管顶端膨大扭曲, 花粉管分支等异常现象; 反交授粉后, 花粉在柱头上萌发时柱头乳突细胞产生强烈胼胝质反应, 影响花粉管生长, 只有少量花粉管通过花柱到达胚珠完成受精。用石蜡切片技术观察了正反杂交后杂种的胚胎发育, 正交杂种胚胎发育较早, 胚和胚乳生长较正常, 杂种胚一般均能发育至成熟; 反交杂种胚发育至心型期便不能继续发育, 胚乳也停滞在游离核阶段并最终败育。综合分析 表明, 芥菜型油菜与白菜正反杂交都存在一定程度的受精不亲和性。     

渐危植物鹅掌揪的授粉率及花粉管生长

对鹅掌揪Ｌｉｒｉｏｄｅｎｄｒｏｎｃｈｉｎｅｎｓｅ３个自然居群连续３个直接统计落置柱头上的花粉量,其中结实率在６－８倍,鹅掌揪结实率低的主要原因可能不是由于花粉的限制,落置柱头的花粉几乎均可萌发,少数花粉管穿过花柱道,经珠孔端进入胚囊,暗示花粉间存在的强烈的竞争,授粉率和柱头上的平均花粉量与结实率呈正相关（Ｒ＝０．７７,Ｒ＝０．６９）在柱头上人工授同株和异株的花粉,花粉管生长速率看不出明显差异,到达     

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。     

厚朴基原植物及其4个近缘种的花粉鉴定

采用扫描电镜对2种厚朴基原植物(厚朴Magnolia officinalis Rehd.et Wils.、凹叶厚朴M.officinalis Rehd.et Wils.var.biloba Rehd.et Wils.)及4种近缘植物(玉兰M.denudata Desr.、紫玉兰M.liliiflora Desr.、望春玉兰M.biondii Pampan.、荷花玉兰M.grandiflora L.)的花粉形态、表面纹饰和大小进行了观察研究。结果显示:(1)6种植物的花粉粒均为单粒,具远极单萌发沟,沟长,直达两端,左右对称,异极;侧面观均为舟形,两端较尖,赤道面观为椭圆形或近椭圆形,极面观均为近圆形;外壁均具小穴状或网状纹饰。(2)厚朴的小穴状纹饰小而浅,不明显;凹叶厚朴的小穴状纹饰小但较深,也不甚明显;相比之下,紫玉兰、玉兰、望春玉兰和荷花玉兰的花粉粒表面密布不规则隆起及深穴点,明显。(3)6种植物花粉粒由大至小依次为:荷花玉兰凹叶厚朴厚朴玉兰紫玉兰望春玉兰。3种不同的花粉处理方法中,自然干燥法能清晰地观察到花粉的扫描电镜特征,此方法优于戊二醛固定法和叔丁醇真空冷冻干燥法。本研究结果为厚朴中药资源的基原植物及其近缘种鉴定提供了新的证据,也为现代植物从种及亚种级水平分类提供了参考。     

POLLEN TUBE ATTRITION IN ERYTHRONIUM GRANDIFLORUM

Seed set after selfing in E. grandiflorum is often reduced relative to seed set after crossing; however, the compatibility patterns seen are not due to genes of major effect (i.e., S alleles). There is quantitative variation in the proportion of pollen tubes reaching the base of the style after both self- and cross-pollinations. Pollen tubes require between 24 and 72 hr to reach the ovary, but pollen tube growth ceases after 72 hr. When styles were removed from the ovaries 5 days after pollination, between 10 and 80% of the pollen tubes in the stigma had not reached the base of the style. The number of pollen tubes at the base of the style is a much better predictor of seed set than is the number of pollen tubes in the stigma. Pollen tube attrition is not affected by the age of the recipient flower or by the number of pollen donors contributing to the stigmatic pollen pool. The number of pollen tubes reaching the base of the style is dependent upon the source of the pollen and appears to be a decelerating function of the number of pollen tubes present in the stigma.     

AtROP1 negatively regulates potato resistance to Phytophthora infestans via NADPH oxidase-mediated accumulation of H2O2

Background

The characteristics of pollen tube growth are not constant, but display distinct patterns of growth within the different tissues of the pistil. In the stigma, the growth rate is slow and autotrophic, whereas in the style, it is rapid and heterotrophic. Very little is known about the interactions between these distinct maternal tissues and the traversing pollen tube and the role of this interaction on the observed metabolism. In this work we characterise pollen tube growth in the apple flower and look for differences in glycoprotein epitope localization between two different maternal tissues, the stigma and the style.

Results

While immunocytochemically-detected arabinogalactan proteins were present at high levels in the stigma, they were not detected in the transmitting tissue of the style, where extensins were abundant. Whereas extensins remained at high levels in unpollinated pistils, they were no longer present in the style following pollen tube passage. Similarily, while abundant in unpollinated styles, insoluble polysaccharides such as β-glucans, were depleted in pollinated pistils.

Conclusions

The switch from autotropic to heterotrophic pollen tube growth correlates spatially with a change of glycoprotein epitopes between the stigma and the style. The depletion of extensins and polysaccharides following pollen tube passage in the style suggest a possible contribution to the acceleration of heterotrophic pollen tube growth, which would imply an active contribution of female tissues on prezygotic male–female crosstalk.     

Pollen tube competition as a mechanism of prezygotic reproductive isolation between Mimulus nasutus and its presumed progenitor M. guttatus

This paper considers the extent to which differences in pollen tube growth rates can provide prezygotic reproductive isolation between Mimulus nasutus and its presumed progenitor, Mimulus guttatus . Mimulus nasutus is partially cleistogamous, but its larger chasmogamous flowers offer appreciable opportunity for outcrossing. Mimulus nasutus was found to have smaller pollen grains and shorter styles than M. guttatus . No differences were observed in pollen grain germination on conspecific and heterospecific stigmas. However, pollen tube growth rates of M. nasutus were found to be much slower than those of M. guttatus in the styles of that species. Consequently, any M. nasutus pollen transferred to an M. guttatus stigma was found to be competitively disadvantaged in an M. gutattus style. By contrast, no difference in pollen tube growth rate was detected between the species when growing in M. nasutus styles, possibly because M. nasutus styles are unable to support fast pollen tube growth. We tested the prediction from the pollen tube studies that a 50:50 mix of M. guttatus and M. nasutus pollen would produce 50% hybrid seeds when M. nasutus was the maternal parent, and near to 0% hybrid seed when M. guttatus was the maternal parent. The results were found to support this prediction. We conclude that pollen–pistil interactions can effect strong reproductive isolation between these species, as M. guttatus pollen tubes have a competitive advantage over those of M. nasutus in an M. guttatus style, but not in an M. nasutus style.     

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.     

Fluorescence and scanning electron microscopic study on self-incompatibility in distylous Averrhoa carambola L.

Various combinations of intermorph, selfing and intramorph pollinations were carried out in Averrhoa carambola and the pollinated pistils were observed under fluorescence and scanning electron microscopes in time-course experiments. In both compatible and incompatible pollinations, similar behavior of pollen germination and penetration was observed in the first 4 h after pollination. In compatible intermorph pollination, pollen tubes were found at the base of the transmitting tract of the style at 8 h and 24 h after pollination in both the pin and thrum morphs. With thrum flowers, selfing resulted in pollen tubes being uniformly arrested at the junction between the stigmatic and stylar tissues. Penetration of pollen tubes into the upper portion of style was observed in thrum intramorph pollination and, when the second member was treated as the gynoecial tissue under the same pollination, penetration of tubes was further enhanced. Pin flowers, on selfing, resulted in pollen tube penetration farther down the style than was the case with thrum selfing. Intramorph pollination of pin morph behaved in a similar manner to selfing and was not affected by genotypes. Beside the stamen-style dimorphism, the receptive surface of the cob stigma was larger in pin than thrum flowers. While pin pollen was round, thrum pollen was oblong in shape with pin to thrum ratio on the polar axis being 1.2 and on the equatorial axis 0.8. The stigma of pin morph belonged to the dry type, while that of the thrum resembled the wet type.     

有花植物触敏柱头的闭合行为及其适应意义

有花植物触敏柱头的闭合行为一直是传粉生态学和进化生物学研究的热点问题之一。植物花的多裂片柱头在传粉者接触后迅速闭合的现象主要存在于玄参目的一些类群中。早在上个世纪初,植物学家就对花的柱头闭合现象进行过初步的研究,认为柱头闭合主要是由于花粉在柱头上萌发时吸收水分导致柱头细胞膨压降低而引起的;并对柱头闭合的适应性提出了一些假说。近年来,许多学者研究证实柱头闭合能促进花粉萌发及花粉管伸长,或减少花粉散出与柱头接受花粉间的相互干扰,提高传粉者访问过程中花粉的散播量,并且柱头的状态会直接影响传粉者的取食行为。到目前为止,对柱头闭合的机制及其避免自交的假说还存在许多争议。关于触敏柱头的闭合行为,尤其是其适应机制及其生态学意义还有待更加系统和深入的研究。本文概述了触敏柱头的研究进展,并对研究中尚存在的一些问题进行了讨论。     

The joint evolution of mating system and pollen performance: Predictions regarding male gametophytic evolution in selfers vs. outcrossers

Studies of sexual selection in plants historically have focused on pollinator attraction, pollen transfer, gametophytic competition, and post-fertilization discrimination by maternal plants. Pollen performance (the speeds of germination and pollen tube growth) in particular is thought to be strongly subject to intrasexual selection, but the effect of mating system on this process has not been rigorously evaluated. Here we propose four predictions derived from the logic that pollen performance should evolve with mating system as an adaptive response to: (1) the competitive environment among pollen genotypes and (2) variation among female genotypes regularly encountered by a given pollen genotype. First, as previously predicted, due to the higher potential for intense selection among diverse pollen genotypes in outcrossing relative to selfing taxa, pollen should evolve to germinate and/or to grow more rapidly in outcrossers than in selfers. Second, due to stronger selection on pollen performance in outcrossing than in selfing taxa, heritable variation in pollen tube growth rate is more likely to be purged in outcrossers. In selfers, by contrast, genetic variation in pollen tube growth rates may readily accumulate because selfing reduces the number of genetically distinct male gametophytes likely to be deposited on any given stigma, thereby relaxing selection on male gametophytic traits. A summary of published studies presented here provides preliminary support for this prediction. Third, due to the high probability that the pollen of outcrossing individuals will be exposed to multiple pistil genotypes, we predict that the pollen of habitually outcrossing taxa will evolve to perform more consistently across female genotypes than the pollen of selfing taxa. Fourth, we predict that epistatic interactions between pollen and pistil genotypes are more likely to evolve in selfers than in outcrossers. We suggest several empirical approaches that may be used to test these predictions.     

The breeding system of Fumana ericifolia: first evidence of autogamy in woody Cistaceae

Fumana ericifolia belongs to the family Cistaceae, in which all perennial species previously studied have been reported to be self-incompatible and xenogamous. Here we show that F. ericifolia is self-compatible and autogamous. Its flowers last only four to eight hours and produce a small amount of pollen and ovules. Self-pollination depends on changes in the relative position of the stigma and the anthers, triggered by the abscission of the petals; this in turn causes closing of the sepals, which push the anthers onto the stigma. Pollen remains highly viable and germinable, and the stigma keeps its receptivity several hours after the loss of the petals. Hand pollination treatments revealed that fruits are produced both in selfed and crossed flowers. The germination of pollen grains on the stigma, the rate of pollen tube growth along the style, and the penetration into the ovules were similar in self-and cross-pollinations; also, there were no significant differences in fruit set, seed set and weight of seeds. Thus, we report the first evidence of autogamy in a woody Cistaceae and suggest that selfing may ensure reproductive success when pollinators are limited.