Change in flower morphology of Torenia fournieri Lind. induced by forchlorfenuron application

We induced various flower morphologies in torenia (Torenia fournieri Lind.) by the application of forchlorfenuron (CPPU). Those morphologies were the combination of four basic morphological changes, the development of serrate petals, incised petals, a paracorolla, and an increased number of floral organs. These morphological changes occurred systematically depending on the floral stage at the time of CPPU application. Serrate petals were induced when CPPU was applied during the stages of corolla development, whereas application at younger stages induced petal incision. The serrate petal margin resulted from preferential proliferation of cells around the vascular bundles, whereas petal incision likely resulted from the lateral outgrowths of petal. A paracorolla was induced at the adaxial petal face when CPPU was applied between the sepal development stage and early corolla development. The paracorolla appears to have arisen from the lateral outgrowths of the stamen. The numbers of stamens, petals, and sepals increased when CPPU was applied at and before the differentiation of sex organs and the corolla. Enlargement of the floral meristem probably caused this increase. Application of N⁶-benzylaminopurine and zeatin did not induce these morphological changes.     

Production of intraspecific hybrids between wild-type and petaloid-sepal cultivars in Habenaria radiata

Orchids are commercially important plants with flowers that are unique and very specialized in shape and color. The flowers consist mostly of sepals, lateral petals, lip (labellum) and column, and are zygomorphic and resupinate. Whereas most orchid species have petaloid tepals in the first and second whorls, Habenaria radiata has a flower with greenish sepals and white lateral petals and lip. ‘Hishou’, one of the cultivars of H. radiata, is a floral homeotic mutant and has a petaloid median sepal and lip-like lateral sepals in the first whorl. Additionally, this cultivar often has non-resupinate flowers whereas wild-type H. radiata flowers are resupinate. In the present study, we investigated the genetic inheritance of these characters in the ‘Hishou’ cultivar by crossing it with wild-type plants. Some intraspecific hybrids, which were confirmed by PCR-RFLP analysis, had flowers with a petaloid median sepal and lip-like lateral sepals in the first whorl, indicating that these were dominant characters. Since the remainder of the intraspecific hybrids had wild-type flowers, these characters must be heterozygous in ‘Hishou’ plants. Although ‘Hishou’ plants had non-resupinate flowers, intraspecific hybrid flowers were resupinate, even though they had the petaloid median sepal and lip-like lateral sepals. This result indicates that non-resupination must be a recessive character. Since sepal-petalization and triple lip characters of ‘Hishou’ inherited dominantly, these characters can be utilized for the breeding of Habenaria species by intra- and interspecific crosses.     

Effect of the expression level of an AGAMOUS-like gene on the petaloidy of stamens in the double-flowered lily, ‘Elodie’

Double-flowered lilies, in which stamens are converted to petaloid organs, are valuable for horticulturists. ‘Elodie’ is a double-flowered lily cultivar in which stamens are homeotically converted into petaloid organs in whorl 3. The ‘Elodie’ cultivar shows individual variation in stamen structure and it was therefore classified into the following three types according to the strength of petaloidy of the stamens: weak (type-I), intermediate (type-II), and strong (type-III) phenotypes. The AGAMOUS (AG) gene is a class C floral identity gene in Arabidopsis thaliana that is involved in the formation of stamens and carpels. An AG-like gene was isolated from ‘Elodie’ (LelAG1) and its expression was compared between flower types. The LelAG1 gene was expressed in whorls 3 and 4, but not in whorls 1 and 2 in all flower types. In type-I flowers, LelAG1 was expressed strongly in whorls 3 and 4, while its expression was significantly decreased in whorl 3 in type-III flowers. In type-II intermediate phenotype flowers, the expression level of LelAG1 in whorl 3 was reduced by 60%. These results suggest that the expression level of AG-like genes is correlated with the degree of petaloidy of the stamens.     

Initiation and development of pistillate flowers in Actinidia chinensis

Initiation and development of pistillate flowers in Actinidia chinensis Planch, cultivar ‘Hayward’ (kiwifruit, Chinese gooseberry) was followed using light and scanning electron microscopy. Results indicate that dormant buds contain undifferentiated primordia in the leaf axils. These primordia remain undifferentiated until shortly before bud break, approximately two months before full bloom, when the primordia become trilobed as bracts and lateral flower primordia are initiated. The lateral flowers often abort in this cultivar. Acropetal development of the terminal flower proceeds rapidly. Five to seven sepals are initiated, followed by a whorl of five to seven petals. Stamen initiation is centripetal and the anthers develop to produce inviable pollen. The central portion of the floral apex is converted into a large compound pistil with numerous hollow styles, each terminated by an open stigma.     

一个矮牵牛花器官发育突变体aps的表型鉴定及遗传分析

在利用矮牵牛W138株系构建突变体库的过程中,获得了一种花器官发育突变体,该突变体主要表现为花萼和花瓣发育异常,命名为aps(abnormal petals and sepals)。与正常W138植株相比,aps突变体最明显的表型是花冠开裂,通常为3裂,同时5个花萼中有2个出现部分瓣化。扫描电镜观察结果显示,突变体瓣化花萼的表皮细胞表现为正常花瓣的细胞形态。通过突变体自交、与正常姊妹株和矮牵牛W115株系杂交以及F1自交和回交等遗传分析发现,aps突变性状为单基因控制的隐性性状。q PCR分析结果表明,在突变体花萼中,3个B类基因(FBP1、PMADS1和PMADS2)和部分E类基因(FBP2、FBP4和FBP5)出现异位表达或表达量显著升高,而所有A类基因(FBP26、FBP29、PFG、AP2A、AP2B和AP2C)的表达量均明显下降,E类基因FBP9和FBP23的表达量也下调;突变体花瓣中,A类基因除FBP29不表达外,其他所有基因的表达量均显著增加,B类基因FBP1和PMADS2,E类基因FBP2、FBP5、FBP23和PMADS12的表达量上调;C类和D类基因的表达在突变体花萼和花瓣中没有明显变化,但在雄蕊和花柱中C类基因表达量明显下降,D类基因FBP7在子房中显著下调。aps突变体为研究矮牵牛花器官发育的调控机制及相关基因之间的调控关系提供了良好的材料。     

草原龙胆( Eustoma grandiflorum )单、重瓣花器官分化的形态学观察

 本篇论文主要研究了草原龙胆单重瓣花器官的发育特征。取花部发生的第1个和第2个花芽为试材, 直接用于实体解剖观察。结果表明: 1. 单瓣花和重瓣花花芽分化过程均可分形态分化前期、萼片原基分化期、花瓣原基分化期、雄蕊原基分化期、雌蕊原基分化期5个时期, 各轮花器官按照向心顺序发育。2. 到雌蕊原基形成为止, 单瓣花花器官各原基的分化过程大约需要12 d, 重瓣花的整个分化过程大约需要15 d。3. 单瓣花和重瓣花都包含5枚萼片、5枚雄蕊和1枚雌蕊, 而单瓣花花瓣是5枚, 重瓣花约是15枚。     

Senescence of Dendrobium `Pompadour' flowers following pollination

Summary

Flowers of Dendrobium `Pompadour' developed premature petal and sepal senescence following pollination. Pollination induced an ethylene climacteric accompanied by a small respiratory climacteric, epinasty and increased flower or inflorescence fresh weight and water uptake. Pollination did not alter petal and sepal anthocyanin content and ion leakage, and lip, petal and sepal fresh weight and dry weight. The fresh weight and dry weight of stigmas (columns) together with pedicels increased significantly after pollination. Ovary growth of pollinated orchid flowers with petals and sepals intact was greater than that of pollinated orchid flowers without petals and sepals, while their water uptake was not significantly different.     

月季Rh-ADF1基因在花瓣扩展中响应乙烯的表达特性分析

 为探讨肌动蛋白解聚因子（actin depolymerizing factor,ADF）是否参与乙烯对月季花瓣细胞扩展的调节,以切花月季‘Samantha’为试材,从花瓣中分离到响应乙烯的ADF基因,并将其命名为Rh-ADF1,在GenBank中的登录号为JN048105。推定的氨基酸序列分析表明,Rh-ADF1的开放阅读框长度为423 bp,编码140个氨基酸。半定量RT-PCR分析结果表明,Rh-ADF1在花朵的各个器官中均有表达,在花瓣中略高于其他器官;该基因表达能够被乙烯处理强烈诱导升高,被乙烯作用抑制剂1-MCP（1-Methylcyclopropene）处理明显降低。在洋葱表皮细胞中进行的瞬时表达分析表明,Rh-ADF1蛋白分布在整个细胞中,主要与actin组成的微丝网络结合。据此推测,Rh-ADF1基因在转录水平上参与乙烯对花瓣扩展的调节,乙烯可能通过Rh-ADF1基因调控了花瓣细胞骨架的动态变化,进而影响花瓣细胞扩展和形态变化。     

Early flower initiation allows ample manipulation of flowering time in cherimoya (Annona cherimola Mill.)

Flower initiation date and readiness to flowering in buds of different age were studied in ‘Fino de Jete’ cherimoya (Annona cherimola) cultivar in order to establish the limits for the manipulation of its flowering date. Flower initiation was analyzed by light and scanning electron microscopy (SEM) collecting axillary buds from May to the following February, whereas the bud readiness to produce perfect flowers was determined by forcing buds of different age to sprout by means of leaf removal and tipping the new growth. SEM images confirm that cherimoya buds are differentiated into flowers almost a year before blooming. In this regard, axillary buds have already formed the sepals when the subtending leaf has just begun unfolding (week 0), while the petals are clearly visible in 1-week-old buds. Sectioning of paraffin-embedded buds illustrate that cherimoya buds are in fact a bud complex that 1 week after its inception comprises 4–5 buds of different size of which the two largest ones are reproductive, while the 2–3 smallest buds often remain undifferentiated at that time. The high capacity of flowering expressed by young buds that have been forced to grow proves that cherimoya meristems are early competent for flowering. No differences in fertility or in the time needed to reach anthesis after leaf removal were found among buds of different ages. Node position had no effect on bud break and flowering potential. The early flower initiation in cherimoya deduced from this work opens a wide temporal window for the experimental manipulation of flowering and harvest dates in this crop.     

牡丹切花ERF转录因子基因的分离与表达分析

利用已获得的‘洛阳红’牡丹花瓣转录组数据库,筛选得到3个与植物乙烯响应因子ERF蛋白同源性较高的Unigene序列,利用RACE及RT-PCR技术,设计特异性引物对3个ERF基因最大阅读框进行扩增并测序。生物信息学分析表明PsERF1、PsERF2和PsERF3分别含有长为1 158、747和609 bp的开放阅读框,编码383、248和202个氨基酸残基,且均含有1个典型的AP2结构域。进化分析表明3个牡丹ERF转录因子分别属于ERF亚家族的B2组、B1组和B3组。利用实时定量PCR分析了3个ERF基因在牡丹乙烯敏感型品种‘洛阳红’和乙烯不敏感型品种‘雪映桃花’不同花器官（花瓣、雄蕊、雌蕊和萼片）以及不同发育级别切花花瓣中的表达情况。结果表明,PsERF1在2个品种花瓣中的表达量显著高于其他花器官,其表达量在‘洛阳红’切花发育过程中逐渐增加,而在‘雪映桃花’切花发育过程中逐渐降低,推测PsERF1可能对牡丹切花的乙烯响应具有重要的调控作用,PsERF2和PsERF3则可能同时参与了多种信号途径。     

建兰花发育相关B、C和E类MADS-box基因的表达分析

开花植物中B、C和E类MADS-box基因控制花雄蕊和雌蕊的合成。以具有高度进化蕊柱（雄蕊和雌蕊合生）的建兰为材料,从已有转录组中搜索到14个B、C和E类基因,包括GLO、DEF、AG、SEP和AGL6类基因,并进行实时荧光定量表达分析,发现CeDEF1和CeAGL6-1在萼片和花瓣中大量表达,唇瓣中微量表达;CeDEF3、CeDEF4和CeAGL6-3则在唇瓣和蕊柱中大量表达,在萼片和花瓣中几乎不表达;CeAG1和CeAG2主要在蕊柱中表达;而且CeDEF3、CeDEF4、CeAG1、CeAG2和CeAGL6-3在蕊柱突变体‘新品梅’的蕊柱状花瓣中的表达量比‘铁骨素’花瓣中高很多,说明这几个基因在建兰蕊柱的形成过程中可能扮演关键角色。     

蝴蝶兰PhSVP的克隆及其在花发育过程中的表达分析

从蝴蝶兰杂交品种‘大辣椒’中克隆到SVP同源MADS-box基因PhSVP，使用RACE方法获得PhSVP全长，其开放阅读框为687 bp，编码228个氨基酸。蛋白序列多重比对表明PhSVP蛋白包含一个高度保守的MEF2-like MADS结构域和一个中度保守的K-box结构域，且与兰科的SVP/AGL24同源蛋白相似度高，进化树分析也表明PhSVP蛋白与其他兰科植物的SVP/AGL24同源蛋白亲缘关系最近。PhSVP的空间表达模式表明其在营养器官表达量高，在萼片、侧瓣和唇瓣等生殖器官表达量低。进一步对PhSVP在成花转换和花发育过程中花序顶端的表达进行分析，表明PhSVP的转录水平在营养分生组织向花序分生组织过渡的过程中无显著变化，仅在花序分生组织阶段有少量上升，但在花发育早期花分生组织阶段中的表达水平显著升高，而在花发育后期的萼片原基、花瓣原基和合蕊柱原基阶段持续下降。此外还发现A类基因PhAP1在花发育过程中的花序顶端的表达模式与PhSVP相似，而B类基因PhPI和C类基因PhAG在花瓣原基和合蕊柱原基阶段的表达量最高。检测了PhSVP在抽葶期、花蕾期和盛花期的根、叶和花葶中的转录水平，结果表明PhSVP在花蕾期的根中的表达量稍高于其他时期，在不同阶段的叶中的表达水平无显著差异，而在抽葶期花葶中的表达量显著高于花蕾期和盛花期。试验结果暗示蝴蝶兰PhSVP可能起到调控花分生组织状态的维持、避免花器官原基过早分化的作用。     

A petal breakstrength meter for Arabidopsis abscission studies

Background  

Abscission is the regulated dropping of plant organs, such as leaves or flower petals. This process involves a break down of the cell wall between layers of cells in the abscission zone, causing the organ to become detached. The model plant Arabidopsis thaliana undergoes floral organ abscission. Various experimental methods have been used to study Arabidopsis floral organ abscission, including measuring the petal breakstrength, or the amount of force required to pull a petal from the receptacle. Petal breakstrength provides a quantitative insight into the physical integrity of the petal abscission zone.     

Regulation of flower development in Dendrobium crumenatum by changes in carbohydrate contents,water status and cell wall metabolism

The involvement of carbohydrates, water potential, cell wall components and cell wall-based enzymes in regulating flower development in Dendrobium crumenatum was investigated. Plants were subjected to cold treatment to release floral buds from dormancy, and the various parameters were investigated from young floral bud stage till flower senescence. Development of floral buds was accompanied by progressive decrease in concentrations of fructans and starch. Upon full flower opening, concentration of soluble sugars was maximum, accompanied by a more negative water potential. High pectin methylesterase activity was observed during early bud development and decreased thereafter. Significant increase in activities of β-galactosidase, β-mannosidase and β-xylosidase was also observed during floral bud development. The cell walls of sepals and petals were modified extensively during floral bud and flower development, as observed by changes in the amounts of celluloses, hemicelluloses and total pectin. Pectin solubilisation was also observed to commence during early floral bud development. These results indicated that carbohydrate hydrolysis, osmotic changes and cell wall dissolution that began early in young floral buds, all regulated flower development in this sympodial orchid. Possible applications of the findings in the horticultural industry are discussed.     

托桂花型菊花花发育的组织结构观察

采用石蜡切片技术对托桂型菊花和非托桂型菊花的花发育过程以及花瓣的组织机构进行观察。结果表明：菊花的花芽分化可分为花序分化和小花分化两个阶段,托桂和非托桂型菊花的花芽分化过程在小花花冠伸长期开始出现差异,桂瓣的发育过程中组织结构的变化更类似于舌状花;成熟的桂瓣和舌状花一样,其花瓣结构均由上下表皮细胞和内部多层叶肉细胞构成,而非托桂花型菊花管状花花瓣仅有上下表皮细胞。桂瓣内层细胞旺盛的分裂能力以及发达的维管束组织可能是菊花形成托桂花型的重要原因。     

Physiological and biochemical studies during flower development in two rose species

The present investigation was aimed to study the changes in various physio-chemical attributes in petals of two different rose species, Rosa damascena Mill and Rosa bourboniana Desport differing in flowering behaviour from small bud (stage 1) till full bloom (stage 8). In both rose species fresh weight, dry weight and moisture content were maximum during full bloom. Electrical conductivity of the petal diffusates reached maximum at full bloom with significantly higher values in R. damascena. In both the species, starch content declined as the flower reached its full bloom stage with maximum reducing sugar content during this period. With progressive increase in petal growth, total protein and RNA declined. The results showed that in both the species peroxidase (POX) and catalase (CAT) activity were lower during full bloom with high activity of invertase and lipoxygenase (LOX) at this period. The present study indicates that lipid peroxidation induced membrane permeability could partly be the result of higher lipoxygenase activity during full bloom. The possible significance of these findings is discussed in relation to flower development in the two diverse rose species.