怎样判别组成雌蕊的心皮数目

在多年的植物学教学实践过程中 ,发现学生在书写植物花程式时 ,感到最困难 ,最容易出错的地方就是对组成雌蕊的基本单位——心皮数目的判别上。为此 ,笔者经过不断探索 ,总结出一套较为有效的判别组成雌蕊的心皮数目的方法。具体作法如下 :1　确定雌蕊的类型在 1朵花中 ,依据雌蕊的数目及组成每个雌蕊的心皮数目的多少 ,将雌蕊分为单雌蕊、离生单雌蕊和复雌蕊等 3种类型。1)在具体观察 1朵花时 ,如花中有两个或两个以上雌蕊时 ,该雌蕊类型为离生单雌蕊 ;如花中只有 1个雌蕊时 ,则要判断该雌蕊是属于单雌蕊还是复雌蕊。2 )如在 1朵花中只有 1…     

漫谈植物的心皮

在显花植物中,花内着生胚珠的器官叫做心皮.心皮又称为大孢子叶,它是构成雌蕊群的基本单位,是一原始的伸长的变态叶.心皮在茎上的着生位置、排列,维管束的联系、解剖和个体发育均同叶与茎的关系一样.组成雌蕊群的心皮数目,因植物种类不同而异,有的雌蕊群由一个心皮组成,如大豆等;有的由二个或二个以上的心皮组成,如油菜、柑橘等.如果一朵花中有两个或两个以上的心皮,它们可以是彼此分离的,形成离生心皮雌蕊,如毛茛、八角茴香等;也可以是相互连合的,形成合生心皮雌蕊,如梨、苹果等.     

一种新型无花瓣油菜突变不育系花器官的形态解剖研究

在自育的甘蓝型油菜(Brassica napus)无花瓣品系AP197中, 发现并育成由4对隐性核基因控制的无花瓣油菜突变不育系AMS971。AMS是一种雄蕊心皮化为不结实的假性雌蕊而引起的新的雄性不育类型, 不育性非常彻底, 其植株形态特征与AP197相同。比较花器官发现, AMS971除一个正常的雌蕊外,还有6个梭形的心皮化假性雌蕊。假心皮化雌蕊上部变成近似倒U形的柱头结构区, 下部是完全突变的半开裂心皮, 其上着生4~14个不等的裸露的幼小胚珠; 蜜腺比正常油菜小, 数目为0~4个, 这与AP197没有差异。AMS971的四轮花器官由于突变造成了大小和重量的重新分配。推断AMS为类似拟南芥属B功能缺失的突变体。     

一种新型无花瓣油菜突变不育系花器官的形态解剖研究

在自育的甘蓝型油菜(Brassica napus)无花瓣品系AP197中,发现并育成由4对隐性核基因控制的无花瓣油菜突变不育系AMS971.AMS是一种雄蕊心皮化为不结实的假性雌蕊而引起的新的雄性不育类型,不育性非常彻底,其植株形态特征与AP197相同.比较花器官发现,AMS971除一个正常的雌蕊外,还有6个梭形的心皮化假性雌蕊.假心皮化雌蕊上部变成近似倒U形的柱头结构区,下部是完全突变的半开裂心皮,其上着生4～14个不等的裸露的幼小胚珠;蜜腺比正常油菜小,数目为0～4个,这与AP197没有差异.AMS971的四轮花器官由于突变造成了大小和重量的重新分配.推断AMS为类似拟南芥属B功能缺失的突变体.     

一种新型矮牵牛花发育突变体的研究

报道了新发现的一种矮牵牛(Petunia hybrida L.)花发育突变体,命名为efficient(eff),并对这一突变体进行了形态学和遗传学分析。eff突变体主要表现为雌蕊心皮数目的增加和雄蕊上长出花瓣状结构,同时,雄蕊、花瓣和萼片数亦有增多,但营养器官无变化。心皮数目的增加导致雌蕊柱头和子房体积的显著增大,并形成较大的果实。雄蕊上花瓣的形成对花粉的产生无明显影响。扫描电镜观察发现,eff突变体在花器官原基形成时发生了相应数目的增加及特征的变化。遗传学分析表明,突变的表现型符合孟德尔单基因遗传规律。     

心皮的辨别

心皮相当于大孢子叶,由原始叶变化而来,包被胚珠,之后变成果皮,包被种子,起保护或传播种子的作用。有一些愈合不完全的畸变的心皮,可以清楚地看到这种原始叶的叶形、叶脉、叶缘及卷曲状态。心皮缝合处称之为腹缝线,这里是胚珠着生的地方,主脉部分称之为背缝线。心皮是构成雌蕊的单位,由一个心皮构成的称为单雌蕊,由2个以上心皮构成的称为复雌蕊。单雌蕊(图C)在发育过程中,当愈合正常时,它的柱头、花柱一般都是不分裂的,由     

如何判别雌蕊的心皮数

植物花程式是将组成花的各部分,用符号和数字列成的公式。如何准确地写出各种植物的花程式,是学生学习植物分类学必须掌握的基本技能之一。有关花萼、花冠和雄蕊的组成特点,均可通过肉眼观察便能基本掌握,而惟独雌蕊的组成特点,特别是组成雌蕊的基本单位——心皮的数目,则需     

不结球白菜雄蕊心皮化雄性不育系HGMSⅡ特性研究

对不结球白菜雄蕊心皮化雄性不育系HGMS和HGMSⅡ进行花器形态比较、同功酶分析及结实性研究.结果表明:HGMSⅡ较好地保留了HGMS花瓣萼片化、雄蕊心皮化鲜明特征,而且花瓣EST和POD同功酶酶带与萼片酶带基本相同,心皮化器官EST和POD同功酶酶带与雌蕊酶带相同.与完全雄蕊心皮化的HGMS相比,HGMSⅡ雄蕊心皮化突变主要发生在花药部位,导致花药丧失了产生花粉的能力,从而保留了HGMS不育性稳定、彻底的优良特性.与HGMS相比,HGMSⅡ开花习性明显改善,柱头表面花粉明显增多,雌蕊发育基本正常,单株平均籽粒产量达到8.96 g,较HGMS增加了7.17 g,增幅达401%,结实性得到了显著提高.     

商陆科植物的子房结构观察

商陆科植物几种雌蕊类型的发育和结构进行了观察,结果表明,商陆科植物的心皮发生后,首先形成一个开放的心皮,开口在心皮的腹侧,开口的封闭都是由心皮边缘的：表皮细胞及表皮下的几层细胞的分裂和生长完成。单心皮雌蕊在子房封闭后不留任何痕迹,而多心皮雌蕊的心皮封闭后留下明显的封闭线。封闭线由栅栏组织状组织构成。栅栏组织状组织一直延伸到珠柄,在珠柄基部形成毛刷状结构。离生心皮的隔在子房的生长过程中生长很少,心皮的大部分是分离的;合生心皮的隔在心皮的生长过程中与心皮同步生长,心皮始终是合生的。成熟子房的结构基本相同,子房壁为薄壁细胞,除表皮以外其他细胞均无太：大区别。在子房外侧壁中均匀地分布有3～5个维管束,隔中有一个维管束。胚珠生于子房的基部腹侧。     

马蹄香雌蕊形态及传粉生物学研究

通过对马蹄香(Asarum henryi Oliv.)雌蕊不同发育阶段的整体发育形态观察和组织切片显微结构观察,结果表明,马蹄香雌蕊心皮离生,不分化为柱头、花柱和子房三部分,开花前在心皮腹缝线上部1／2～2／3处分化出数列多细胞表皮毛,构成鸡冠状柱头,表现出原始的雌蕊结构特征。开花习性、传粉试验观察,杂交指数(OCI)及花粉-胚珠比(P／O)测定结果表明,马蹄香植物为兼性自花传粉繁育系统。     

黄瓜雄花形成过程中心皮的发育

黄瓜(Cucumis sativus L.)为重要的经济作物,雌雄同株异花,是研究植物性别分化的经典材料。人们对黄瓜性别分化进行了广泛的研究。Astmon和Galun、任吉君和王艳对黄瓜性别分化的形态特征和器官发生进行了初步研究,表明黄瓜单性花分化和发育过程中经历了无性期、两性期和单性期,最终只有一种性别的性器官原基发育成有功能的性器官,从而形成单性花,而对单性花中未形成有功能器官的相反性别原基的研究报道甚少。我们对雄花发育过程进行了连续的形态学分析,并对不同时期雄花中的心皮进行了细胞计数和同工酶电泳分析,以期从性器官发育的角度探讨黄瓜性别表现的机理。     

黄瓜雄花形成过程中心皮的发育

黄瓜(Cucumis sativus L)为重要的经济作物,雌雄同株异花,是研究植物性别分化的经典材料。人们对黄瓜性别分化进行了广泛的研究。Astmon和Galun,任吉君和王艳对黄瓜性别分化的形态特征和器官发生进行了初步研究,表明黄瓜单性花分化和发育过程中经历了无性期、两性期和单性期,最     

Quantitative trait locus analysis in crosses between outbred lines with dominance and inbreeding

In an effort to determine the genetic basis of exceptionally large tomato fruits, QTL analysis was performed on a population derived from a cross between the wild species Lycopersicon pimpinellifolium (average fruit weight, 1 g) and the L. esculentum cultivar var. Giant Heirloom, which bears fruit in excess of 1000 g. QTL analysis revealed that the majority (67%) of phenotypic variation in fruit size could be attributed to six major loci localized on chromosomes 1-3 and 11. None of the QTL map to novel regions of the genome-all have been reported in previous studies involving moderately sized tomatoes. This result suggests that no major QTL beyond those already reported were involved in the evolution of extremely large fruit. However, this is the first time that all six QTL have emerged in a single population, suggesting that exceptionally large-fruited varieties, such as Giant Heirloom, are the result of a novel combination of preexisting QTL alleles. One of the detected QTL, fw2.2, has been cloned and exerts its effect on fruit size through global control of cell division early in carpel/fruit development. However, the most significant QTL detected in this study (fw11.3, lcn11.1) maps to the bottom of chromosome 11 and seems to exert its effect on fruit size through control of carpel/locule number. A second major locus, also affecting carpel number (and hence fruit size), was mapped to chromosome 2 (fw2.1, lcn2.1). We propose that these two carpel number QTL correspond to the loci described by early classical geneticists as fasciated (f) and locule number (lc), respectively.     

Morphology ofCoptis japonica and its meaning in phylogeny

In the genusCoptis, some interesting features are found which are considered important phylogenetically. The median bundles of petiole and petiolule, and the midrib of lamina are double. They seem to represent a transitional situation between a dichotomy and a single median bundle found in usual angiospermous venation. The double bundle is either derived from 2 independent leaf trace bundles or formed by dichotomy of a leaf trace bundle, and it does not seem so important whether the number of trace bundles is even or odd. The nodal structure is trilacunar or pentalacunar with 3, 4, 6 or 8 trace bundles. The upper part of the carpel does not produce ovules and is open from the initiation of the carpel. It is suggested that the carpel becomes open secondarily concomitant with the reduction of ovules. This shows that the closure of the carpel is not perfectly established.     

A TEST OF SEVERAL HYPOTHESES FOR THE DETERMINATION OF SEED NUMBER IN AMELANCHIER ARBOREA,USING SIMULATED PROBABILITY DISTRIBUTIONS TO EVALUATE DATA

The number of seeds per fruit is variable within Amelanchier arborea trees. Because A. arborea flowers are five-carpellate and each carpel contains two ovules, we were able to use the pattern of seed maturation within fruits to test whether the failure of some ovules to develop into seeds is determined by mechanisms operating at the level of carpels, such as stigma-clogging, or by mechanisms operating at the level of ovules, such as ovule infertility. The presence of one-, two-, and zero-seeded carpels demonstrated that the number of ovules developing into seeds was not due entirely to carpel-level phenomena. In order to test the hypothesis of carpel independent seed development, without the assumption that all ovules have the same probability of developing into seeds, it was necessary to use simulation, since no conventional statistical models were appropriate. Analysis of this simulation allowed us to reject carpel independent processes as the only determinant of seed number. A mixed model of seed development, in which some carpels fail entirely and ovules in the remaining carpels develop equiprobably, was shown to be consistent with the data.     

Within-carpel and among-carpel competition during seed development, and selection on carpel number, in the apocarpous perennial herb Helleborus foetidus L. (Ranunculaceae)

Apocarpous flowers share opportunities for post-fertilization ovule selection among more functional levels than syncarpous flowers, because the occurrence of a variable number of unfused carpels adds a new source of variation to the likelihood of successful female reproduction. The extent to which post-fertilization events might differ among these unfused carpels may promote variations in the reproductive strategies of plants. We report a study of the variation, within and among carpels and flowers, in seed production and mass in the apocarpous Helleborus foetidus (Ranunculaceae), in relation to the number of carpels per flower. Differences within and among carpels in female reproductive success were affected by carpel number and pollination environment. When analysing whole flowers as functional units we also found that the magnitude of the differences related to carpel number and pollination treatment actually depended on the “distribution” of pollen types within flowers. Thus, variable within-flower pollination environments, more likely to occur in apocarpous than in syncarpous flowers, may affect the strategies of resource allocation for fruit development at different stages of the reproductive process. Regarding seed production, we found that producing more flowers with four carpels was under directional; however, when mean diaspore mass was considered as a measure of fitness, directional selection was found on producing flowers with two and three carpels (the modal carpel number found in wild populations). We discuss ecological and developmental reasons which could explain the observed pattern, and conclude that selection on an optimum carpel number may be very variable across the species range, as the discussed reasons may impose constraints on eventual evolutionary response, thus contributing to the maintenance of the intra-individual variability in carpel number.     

Chaotic Floral Phyllotaxis and Reduced Perianth in Achlys (Berberidaceae)

Among the 16 genera of the Berberidaceae Achlys is the only one with a reduced perianth, an irregular floral phyllotaxis, and variable stamen number. Early floral stages show an unstable (chaotic) arrangement of the organ primordia. Only the single carpel of the gynoecium has a more fixed position in that the placenta is formed in the adaxial half of the flower. The irregularities in the androecium may be caused by the lack of influence of a perianth on floral symmetry. On the other hand, the regular orientation of the carpel is perhaps due to the early polarity of the flower, whereby the abaxial half of the flower is larger (with further developed stamen primordia) at the time when carpel polarity is established.     

Gynoecium evolution in angiosperms: Monomery,pseudomonomery, and mixomery

The presence of a gynoecium composed of carpels is a key feature of angiosperms. The carpel is often regarded as a homologue of the gymnosperm megasporophyll (that is, an ovule-bearing leaf), but higher complexity of the morphological nature of carpel cannot be ruled out. Angiosperm carpels can fuse to form a syncarpous gynoecium. A syncarpous gynoecium usually includes a well-developed compitum, an area where the pollen tube transmitting tracts of individual carpels unite to enable the transition of pollen tubes from one carpel to another. This phenomenon is a precondition to the emergence of carpel dimorphism manifested as the absence of a functional stigma or fertile ovules in part of the carpels. Pseudomonomery, which is characterized by the presence of a fertile ovule (or ovules) in one carpel only, is a specific case of carpel dimorphism. A pseudomonomerous gynoecium usually has a single plane of symmetry and is likely to share certain features of the regulation of morphogenesis with the monosymmetric perianth and androecium. A genuine monomerous gynoecium consists of a single carpel. Syncarpous gynoecia can be abruptly transformed into monomerous gynoecia in the course of evolution or undergo sterilization and gradual reduction of some carpels. Partial or nearly complete loss of carpel individuality that precludes the assignment of an ovule (or ovules) to an individual carpel is observed in a specific group of gynoecia. We termed this phenomenon mixomery, since it should be distinguished from pseudomonomery.     

COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE. I. PRUNOIDEAE: PRUNUS

A study of the carpel in 27 species of Prunus has shown certain notable structural relationships associated with the extent of closure of the carpellary margins. These relationships involve the degree of fusion of the 2 integuments, the number of vegetative bundles in the base of the carpel, the extent of fusion of the ovular bundles with one another and with the wing bundles, the relative size of the ovular bundles, and the relative development of the central vascular plexus. The comparative evidence strongly supports a primitively separate state of ovular and vegetative bundles. The significance of this finding is discussed.     

Overexpression of TAPETUM DETERMINANT1 alters the cell fates in the Arabidopsis carpel and tapetum via genetic interaction with excess microsporocytes1/extra sporogenous cells

Previously, we reported that the TAPETUM DETERMINANT1 (TPD1) gene is required for specialization of tapetal cells in the Arabidopsis (Arabidopsis thaliana) anther. The tpd1 mutant is phenotypically identical to the excess microsporocytes1 (ems1)/extra sporogenous cells (exs) mutant. The TPD1 and EMS1/EXS genes may function in the same developmental pathway in the Arabidopsis anther. Here, we further report that overexpression of TPD1 alters the cell fates in the Arabidopsis carpel and tapetum. When TPD1 was expressed ectopically in the wild-type Arabidopsis carpel, the number of cells in the carpel increased significantly, showing that the ectopic expression of TPD1 protein could activate the cell division in the carpel. Furthermore, the genetic analysis showed that the activation of cell division in the transgenic carpel by TPD1 was dependent on EMS1/EXS, as it did not happen in the ems1/exs mutant. This result further suggests that TPD1 regulates cell fates in coordination with EMS1/EXS. Moreover, overexpression of TPD1 in tapetal cells also delayed the degeneration of tapetum. The TPD1 may function not only in the specialization of tapetal cells but also in the maintenance of tapetal cell fate.