蒙药植物蓝盆花的授粉亲和性

利用显微镜观察花粉和柱头形态,采用离体萌发法对花粉活力进行测定,采用压片法对自交授粉后花粉管生长动态进行观察,以探明蓝盆花自交是否存在授粉障碍,为今后蓝盆花人工栽培和杂交育种工作提供理论依据。结果表明:蓝盆花花粉饱满,具有1~3个萌发孔,二裂柱头,花柱细长通直,培养10 h花粉萌发率达86.06%,花粉活力高。授粉后4 h多数花粉萌发后花粉管进入花柱;授粉后10 h花粉管进入花柱中上部;授粉后12 h多条花粉管进入花柱并到达中部;授粉后48 h花粉管到达花柱基部进入子房,但通过观察发现花柱顶端有胼胝质及花柱内的花粉管交叉缠绕停止生长的异常现象,从而花粉管不能进入子房完成受精过程,这可能是导致果实空瘪的一个原因。由此推测,蓝盆花自交授粉存在受精前障碍,属于配子体自交不亲和类型。     

小麦花粉管生长途径及受精过程经历时间的研究

应用常规石蜡切片和荧光显微镜技术对小麦花粉管生长途径及受精过程相应时间进行研究。结果表明，授粉后，花粉随即萌发，2个精子进入花粉管，营养核留在花粉粒内，不久解体。花粉管进入羽毛状柱头分支结构的细胞间隙，继续生长于花柱基部至子房顶部的引导组织的细胞间隙内。随后穿过子房壁，在子房壁与外珠被之间的缝隙中向珠孔方向生长。自花粉萌发至花粉管长入珠孔大约需要1 h。自花粉萌发并到达柱头分支结构中，花粉管均具明显的绿色荧光；但在引导组织区以及子房壁与外珠被之间生长的花粉管几乎看不到荧光。授粉后1 h花粉管经珠孔及珠心表皮细胞间隙进入1个助细胞，并释放精子。授粉后2～6 h精卵融合，授粉后16 h合子第一次分裂。授粉后2～3 h精子与极核融合，授粉后4 h初生胚乳核第一次分裂。授粉后2～16 h，即精卵融合至合子分裂前为花粉管通道法转化合适的时间，采用花柱横切滴加法转入外源DNA。     

高山杜鹃‘XXL’与蓝果杜鹃的杂交亲和性

利用高山杜鹃优异品种与野生种质进行杂交是培育自主观叶新品种的有效途径。本研究开展以高山杜鹃‘XXL’(Rhododendron’XXL’)为母本,蓝果杜鹃(R. cyanocarpum)为父本进行杂交授粉,用荧光显微镜观察授粉花粉萌发及花粉管的生长过程,调查其子房膨大率和结实率。结果显示,在授粉后1～8 d,蓝果杜鹃的花粉萌发率呈缓慢上升趋势,‘XXL’花粉管在花柱中呈显著伸长趋势,期间无受精情况发生;在授粉后11～17 d,花粉管进入‘XXL’子房并发生受精;在授粉后17 d,其花粉萌发率和受精胚珠数达最大值,分别为(31.67±8.50)%和(13.67±3.79)个。在花粉管生长过程中,在柱头细胞、花粉管、花柱、子房和胚珠等多处出现异常胼胝质沉积反应;其杂交子房膨大率为18.75%,结籽率为零。研究表明,高山杜鹃‘XXL’与蓝果杜鹃的杂交不亲和性明显且可能存在较强的杂交障碍。     

高粱受精过程及其经历的时间

应用常规石蜡切片技术, 对高粱花粉管生长途径、双受精过程及其经历的时间进行研究。结果表明, 高粱开花即授粉,花粉随即萌发, 花粉管进入羽状柱头分支结构的细胞间隙,向下生长于花柱至子房顶部引导组织的细胞间隙中;进入子房腔后,在子房壁与外珠被之间的缝隙中向珠孔方向生长;花粉管破坏一个助细胞后, 在卵细胞与中央细胞之间的空隙中释放连续的球状内容物;两个精核分别进入卵细胞和中央细胞分别与卵核和极核融合。受精过程经历的时间为开花后0.5~3 h左右, 花粉管破坏一个助细胞进入胚囊,并释放精子;1~3 h精核与极核融合形成初生胚乳核, 精卵融合形成合子;4 h左右初生胚乳核分裂;14 h左右合子分裂。4~14 h为合子静止期,该期为物理、化学诱变及花粉管通道法转基因技术实施的合适时间。     

亚麻受精过程及其经历的时间

应用石蜡制片技术, 观察亚麻的受精过程及其各阶段经历的时间。结果表明, 亚麻开花时落到柱头上的花粉随即萌发, 花粉管在花柱引导组织的细胞间隙中生长, 进入子房后经子房内表面, 沿胎座经珠柄进入珠孔, 进入1个助细胞, 在卵细胞与中央细胞之间释放2个精子;精子脱掉细胞质鞘后,形成精核与细胞质体;2个精核同时分别进入卵细胞和中央细胞, 并与卵核及次生核融合;精核与次生核融合速度稍快;观察到合子中雌、雄性核仁融合的过程。受精各阶段经历的时间为,花粉落到柱头上随即萌发;开花后4.5 h左右, 花粉管长入胚珠的珠孔;4.5~5.5 h,花粉管进入1个助细胞并释放精子;5.5~6.5 h为精卵融合和精核与次生核的融合期;7.5~8.5 h初生胚乳核分裂;12.5 h之后,合子分裂;6.5~12.5 h为合子静止期。     

甘薯与低倍体种间杂种杂交低结实性的克服

通过观察花粉萌发、 花粉管生长、 受精、 胚发育等过程, 发现甘薯与低倍体(3 x, 5 x)种间杂种杂交低结实性的原因： 一是花粉附着量少、 花粉萌发量少、 花粉管生长缓慢导致子房受精不足, 使子房出现第一次大量脱落; 二是胚发育异常导致子房出现第二次大量脱落。 这种胚发育异常对甘薯×5 x杂种来说是受精卵发育缓慢; 对     

甘蓝自交不亲和系柱头和花粉粒不亲 和互作的电镜扫描研究

扫描电镜观察到甘蓝(Brassica oleracea L.)自交不亲和系02-E1柱头上不能萌发的花粉在授粉后18小时内就会萎缩变小直至干瘪。能够萌发的花粉从一个萌发沟萌发后，另外两个萌发沟就自动萎缩，其花粉管有的扭曲不能伸入乳突细胞，仅少量花粉管能伸长进入花柱。经过5%NaCl溶液处理后的甘蓝自交不亲和系的柱头表膜乳突细胞或皱缩或破裂，花粉粒很容易萌发并长出花粉管，然后花粉管穿破乳突细胞壁而伸入花柱完成受精作用。     

关于甘薯属甘薯组中 A 群和 B 群之间可交配性的研究

用对甘薯组 A 群的种 I.tiliacea 和 I.gracilis 与 B 群的种 I.trifida 和 I.littoralis 杂交观察授粉后的胚胎发生的情况,发现授粉后7小时,花粉粒均能在柱头上发芽,花粉管也能通过花柱到达胚珠。在授粉后两天的子房内,可看到已受精、正受精、未受精等受精过程的各个阶段。此时以 B 群 K_(233-1)为母本的卵细胞受精率可达80%     

紫牡丹杂交结实率的差异

紫牡丹是进行栽培牡丹花色改良育种的关键亲本之一。设置紫牡丹与亚组内、亚组间、亚组间杂交后代及芍药组等多个杂交组合,并观察受精前障碍。结果表明:(1)紫牡丹不存在无融合生殖,异株授粉结实率最高,自交结实率最低;(2)紫牡丹作母本的杂交组合亲和性好于作父本,紫牡丹与其杂种后代组合亲和性较好;(3)紫牡丹为母本,栽培品种为父本的杂交组合亲和性高于紫牡丹为父本的组合;(4)紫牡丹×黄牡丹受精前障碍主要表现为花粉粒附着、花粉管萌发慢、到达雌蕊各部分时间延迟,生长方向杂乱、管内出现胼胝质块,形态基本正常且能正常到达子房的花粉数量较少。探究紫牡丹结实特性及不同杂交组合亲和性差异,有助于获得更多杂交种子,提高育种效率。     

桃花粉管通道法转基因技术的初步研究

以曙光为试材,对桃花粉管通道法转基因技术进行探索性研究,结果表明：（1）活体人工授粉后,24h花粉开始在柱头上萌发授粉后48h已有大量的花粉管长至花柱上端;授粉后96h大量的花粉管生长至花柱的中部;授粉后144h大量的花粉管到达花柱基部。（2）确定外源DNA的注射时间为人工授粉后的144h;花柱横切滴加法注射方式不适用于桃;当外源质粒DNA浓度为0.2 mg/l时,发育期内其坐果率都显著高于其它浓度水平。     

Pollen tube growth and fertilization after different in vitro pollination techniques of Aechmea fasciata

The effect of cut style and placental pollination on fertilization efficiency was studied for compatible Aechmea fasciata plants. These alternative in vitro pollination techniques resulted in lower penetration rates of the ovules by pollen tubes in comparison to pollination on the stigma. An explanation was found in the intervention of the normal pollination process,through which less pollen-pistil interactions were built up. After cut style pollination the percentage of ovule penetration by pollen tubes increased when a longer style part was left at the ovary. Probably fewer factors that control pollen tube growth are present in the lower style part. Pollen germinated on the ovules after placental pollination but only rarely penetration of the micropyle by a pollen tube occurred. Activation of the ovary, induced by in vivo prepollination for 6 hours, and pollination two days after anthesis did not increase the fertilization percentage. Grafting a style with active growing pollen tubes to ovules on the placenta (placental grafted style pollination) resulted in a higher fertilization percentage. Pollen tube growth through the style was essential for pollen tube guidance to the ovules and penetration of the micropyle. This revised version was published online in August 2006 with corrections to the Cover Date.     

Prefertilization barriers to interspecific hybridization involving Gossypium hirsutum and four diploid wild species

Interspecific hybridization among species of cotton has lead to improvement in productivity, earliness, fibre quality and resistance to pests and diseases. However, wide crosses is often limited by the operation of either pre‐ or/and post‐fertilization barriers. An investigation on pollen tube behaviour of four wild species in the pistils of Gossypium hirsutum was taken up. Pollen germination was normal in crosses involving Gossypium triphyllum and Gossypium armourianum and markedly inhibited in the crosses involving Gossypium davidsonii and Gossypium thurberi. Pollen tubes reached the pistils and fertilization was accomplished within 8 h after pollination (HAP) in control cross. Even though delay in pollen tube was a common phenomenon in all the four crosses successful fertilization was observed in crosses involving G. triphyllum and G. armourianum, as they reached the ovary at 24 HAP. In crosses with G. davidsonii and G. thurberi, pollen tubes failed to reach the ovary even at 24 HAP indicating the presence of strong stylar and ovarian incompatibility. Measures to overcome such barriers to interspecific hybridization in the incompatible crosses are discussed.     

Factors affecting haploid production in wheat using the Hordeum bulbosum system. 1. Genotypic and environmental effects on pollen grain germination,pollen tube growth and the frequency of fertilization

Summary A quantitative examination of pollen grain germination and pollen tube growth within the overy wall was made in selected wheat × tetraploid H. bulbosum hybridizations, to investigate the effect of the wheat and the H. bulbosum genotype on these characters. As expected, variation at the known crossability loci had no effect on pollen grain germination. The frequency of pollen tube penetration of the ovary wall was, however, severely reduced when the dominant alleles were present. Pollen tube penetration was nevertheless observed in 3 of the 110 ovaries examined of the non-crossable cultivar Highbury. The H. bulbosum genotype had a much smaller effect on these characters, but significant differences between the clones were observed in the numbers of pollen tubes initially penetrating the ovary wall. Although two H. bulbosum genotypes showed no significant differences in the number of ovaries with pollen tubes at the base of the ovule, significant differences in the frequency of fertilization were observed. The possible cause of this discrepancy is discussed.The frequency of fertilization in crossable wheat × H. bulbosum hybridizations was improved by the application of gibberellic acid within 10 minutes of pollination, and reduced by an increase in the ambient temperature from 20°C to 26°C. Fertilization following the pollination of non-crossable wheat genotypes was not affected by either of these factors.     

Self-pollination vs. cross-pollination in almond: pollen tube growth, fruit set and fruit characteristics

Pollen tubes reaching the ovary, fruit set and the main fruit characteristics of six self‐compatible genotypes (‘Marta’, ‘Antoñeta’, ‘Guara’, ‘Lauranne’, ‘S2332’ and ‘S4017’) of almond were studied after self‐ or cross‐pollination. No significant differences after self‐ or cross‐pollination were found in the number of pollen tubes reaching the ovary, the percentage of ovaries finally penetrated, fruit set and fruit characteristics. The results showed the possibility of obtaining suitable fertilization, yields and quality of fruits by self‐pollination of self‐compatible almond cultivars in a single cultivar orchard.     

The breeding system of rubber (Hevea brasiliensis): an evaluation of controlled hand pollination methods

Summary Controlled hand pollinated pistils of rubber were observed using fluorescence microscopy to assess the efficiency of the universally-employed method for the production of progeny for plant breeding. The controlled hand pollination method conducted in the morning resulted in the deposition of a mean of 15.6 pollen grains on the stigma, with no stray pollination observed. Over 36% of the pistils had the potential to set fruit.Pollinations conducted in the afternoon at the normal time of anthesis, had double the fruit set potential of morning pollinations as measured by penetration of ovules by pollen tubes. Pollinator efficiency also varied, with excessive damage to stigmas resulting in reduced pollen germination and tube growth. There were differences between clones in both female and male fertility, in the proportion of pistils with more than three carpels and in the production of small abnormal stigmas. There was no difference in pollen tube growth following self- or cross-pollination, indicating that the self-sterility mechanism of rubber operates in the ovary. Pollen could be stored for 5 days at 5°C and 75% RH with a 22% loss of fertility.     

The progamic phase in Cichorium intybus L. Pollen tube growth in the style,incompatibility reaction and gametophytic competition

Summary Pollen germination and tube growth were studied following compatible, incompatible and pseudo-compatible pollinations in chicory. Pollen germination begins 3 minutes after compatible pollinations. The earliest pollen tubes reach the ovary 17 minutes later. Many of the later germinating pollen tubes are arrested and burst at the stigma papillae. In the transmitting tissue inhibitional effects due to negative interactions between pollen tubes are frequently observed. Complete self-incompatibility results in total inhibition of germination. In case of pseudo-self-compatibility, some pollen germinate but germination and stigma penetration are delayed and often result in pollen bursting. There is no self-incompatibility reaction in the transmitting tract but if the pollen tubes reaching this tissue are relatively numerous, negative interactions between them occur as after compatible pollinations. An hypothesis is presented which attributes the negative interactions between pollen tubes to the diffusion of a substance from the growing pollen tubes. This substance would also provoke pollen bursting on the stigma.     

Pollen germination and pollen tube growth following self-pollination and intra- and interspecific pollination of Medicago species

Summary Pollen germination and pollen tube growth after self- and intra- and interspecific pollinations of annual [M. scutellata (L.) Mill., M. disciformis DC., and M. rigidula (L.) All.] and perennial (M. sativa L.) Medicago species were studied using a Carl Zeiss microscope with a fluorescence filter attachment.Self-pollination of self-fertile annual and intraspecific pollination of cross-fertile perennials were characterized by high pollen germination and rapid normal pollen tube growth. In contrast pollen germination percentages were very low and many pollen tube growth abnormalities occurred following interspecific pollination and self-pollination of self-sterile plants. The time period from pollination to fertilization for interspecific crosses was about double that following self-pollination of the annual species. However, fertilization occurred frequently following interspecific pollinations. Much of the sterility was due to factor(s) operating after fertilization.Cooperative investigations of the Kansas Agricultural Experiment Station, Dept. of Agronomy and the U.S. Department of Agriculture, Agricultural Research Service. Contribution No. 82-582-J- Mention of a trademark name or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture, and does not imply its approval over other products that also may be suitable.     

Germination of pollen of weed rye (Secale segetale L.) on wheat (Triticum aestivum L.) stigmas and the growth of the pollen tubes

Summary Two gene pairs have been found regulating the crossability of wheat and rye. It is concluded from our work that the same genes regulate crossability between wheat and weed rye. The crossing barrier was not observed in the stigma, style or ovary wall because pollen tubes of weed rye were seen in these tissues irrespective of the wheat variety used as the female parent.Pollen grains germinated within 6 min after pollination. The tubes reached the region of the micropyle after about 40 min.     

美国梾木(Cornus spp.)花粉活力及萌发特性

为了了解美国梾木花粉活力及萌发特性,采用扫描电镜技术对13个美国梾木无性系花粉形态进行观测与方差分析,并采用荧光显微技术和TTC染色法对无性系2号花粉萌发特性及花粉活力进行观察。结果显示:(1)不同无性系间花粉大小差异不显著,但外壁纹饰差异较大,极面沟距的变异系数最高且遗传最为稳定。(2)花序开花率为75%时花粉活力最高,整花4℃条件下短期保存花粉活力较高。(3)授粉后,多数花粉可在柱头上正常萌发,72 h后花粉管即可进入子房。研究认为,花粉外壁及极面沟距可作为鉴定美国梾木无性系的形态指标,美国梾木花粉活力及萌发特性是抗逆及丰产杂交组合的重要保证。