THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. VIII. THE EFFECT OF INHIBITORS OF PROTEIN AND RNA SYNTHESIS ON DEVELOPMENTAL CHANGES OF ANTHOCYANINS IN CULTURED PETALS OF IMPATIENS BALSAMINA

If inhibitors of protein or RNA synthesis are administered to flower petals of the red genotype (HHHP^rP^r) of Impatiens balsamina at a very early stage of development, an alteration in the normal pattern of anthocyanin pigmentation results. Whereas control petals are mainly pigmented with acyl pelargonidin-3,5-diglucoside and pelargonidin-3,5-diglucoside, petals cultured in the presence of inhibitors are mainly pigmented with pelargonidin-3-monoglucoside. The complete absence of the more highly substituted forms of pelargonidin in treated petals suggests that the biochemical reactions required for the addition of glucosyl and hydroxycinnamoyl residues to pelargonidin-3-monoglucoside have been prevented. The ability to block the normal developmental pattern of pigmentation with these inhibitors suggests that de novo synthesis of active enzymes is required, and as indicated by the effectiveness of actinomycin D, specific RNA synthesis is a necessary prerequisite for the synthesis of the normal anthocyanin complement in this tissue. The ability of the white flowered genotype (llhhpp) to metabolize exogenously supplied pelargonidin-3-monoglucoside was found to be prevented by prior culture of immature petals in the presence of DL-ethionine. The data indicate that the enzymes required for this ability are not products of induction by the substrate but rather their presence is a normal feature of petal development. Treatment with inhibitors has failed to produce any inhibition in the formation of specific anthocyanins found in the flower petals of some other genotypes of I. balsamina.     

STUDIES IN THE FLORAL ANATOMY OF CLAYTONIA (PORTULACACEAE)

Claytonia virginica has a regular flower with two sepals, five petals with an equal number of stamens in positions opposite the petals and a many-seeded tricarpellate gynoecium with basal placentation. The flower has been interpreted as uniseriate, the putative sepals as bracts and the corolla as modified calyx lobes. Anatomical and developmental studies were undertaken to find evidence for the existence of vestigial or rudimentary parts whose existence would illuminate the true nature of the flower. Vascular and epidermal anatomy of sepals are both similar to that of leaves. Corolla and androecium develop basipetally and petals and stamens share common vascular traces in the lower part of the receptacle. Thus, in terms of both anatomy and development, evidence supports the conclusion that the perianth is essentially biseriate. Vestigial or rudimentary parts are not present which would alter the manifest design of the mature flower.     

Study on Degradation of Flavonols in Mutants of PoppyPapaver somniferumL.

We studied flavonol-degrading activity of cell-free extracts from petals of the flower color and structure mutants. The relationship between degradation of flavonols (kaempferol, quercetin, and myricetin) and biosynthesis of anthocyanins has been revealed. The white-flower mutant proved to have the highest flavonol-degrading activity toward all substrates, particularly quercetin. The mutations inhibiting synthesis of pelargonidin, an anthocyanin, provide for synthesis of various amounts of cyanidin in the petals. The flavonol-degrading activity considerably increases proportionally to the content of cyanidin. A similar relationship has been revealed in the mutants synthesizing both cyanidin and pelargonidin. The plants accumulating considerable amounts of pelargonidin in their petals have accordingly higher flavonol-degrading activity and predominantly hydrolyze kaempferol. The plants forming additional pods in their flower (pistillody) have higher flavonol-degrading activity as compared to the anther-in-petal and doubleness mutants     

POST-POLLINATION PHENOMENA IN ORCHID FLOWERS. VII. PHOSPHATE MOVEMENT AMONG FLORAL SEGMENTS

Radioactive phosphate applied to labella (lips, median petals), dorsal (median) sepals or stigmas of Cymbidium cv Jungfrau is transported to all parts of the flower. Transport levels vary depending on the sites of application or accumulation. Pollination or application of NAA to the stigma cause accumulation of ³²P in gynostemia (columns) and ovaries. Translocation characteristics correlate with vascular anatomy of Cymbidium flowers.     

A SCANNING ELECTRON MICROSCOPIC STUDY ON THE INITIATION AND DEVELOPMENT OF FLORAL ORGANS OF BRASSICA NAPUS (CV. WESTAR)

The initiation and development of the floral organs of Brassica napus L. (cv. Westar) were examined using the scanning electron microscope. After transition of the vegetative apex into an inflorescence apex, flower primordia were initiated in a helical phyllotactic pattern. The sequence of initiation of the floral organs in a flower bud was that of sepals, stamens, petals and gynoecium. Of the four sepal primordia, the abaxial was initiated first, followed by the two lateral and finally the adaxial primordium. The four long stamens were initiated simultaneously in positions alternating with the sepals. The two short stamens were initiated basipetal to and outside the long stamens, and opposite the lateral sepals. The petals arose on either side of the two short stamens and the gynoecium was produced from the remainder of the apex. During development, the sepal primordia curved sharply at the tips and tightly enclosed the other organs. Stamen primordia developed tetralobed anthers at an early stage while filament elongation occurred just prior to anthesis. A unique pattern of bulbous cells was present on the abaxial surface of the anther. Growth of petal primordia lagged relative to the other floral organs but expansion was rapid prior to anthesis. The gynoecium primordium was characterized by an invagination early in development. At maturity, there was differentiation of a papillate stigma, an elongated style and a long ovary marked externally by sutures and divided internally by a septum. Distinct patterns of cuticular thickenings were observed on the abaxial and adaxial surfaces of the petals and stamens and on the surface of the style. The patterns were less obvious on the sepals and ovary. Stomata were present on both surfaces of the mature sepals, on the style and restricted areas on the abaxial surface of the anthers and nectaries but were absent from the petals, the adaxial surface of the stamens and the ovary. No hairs were present on any of the floral organs.     

Continuous petal variation in Epimedium tianmenshanense (Berberidaceae), a taxon endemic to western Hunan,China

In the protologue, Epimedium tianmenshanense (Berberidaceae), a species endemic to western Hunan, China, was described as ‘flower small, 0.2–0.4 cm diam., inner sepals white, petals as long as inner sepals or a little shorter than the latter, spur very short, ca 5.0 mm’. However, both morphological characteristics and molecular evidence suggest that E. tianmenshanense is closely related to E. baojingense, a taxon with a long spur, thus suggesting that the size of the floral parts is not as reliable as previously believed. When investigating the variability of E. tianmenshanense in more detail, in the field as well as in cultivation, we found that the petals were are highly variable in morphology (both shape and size), being cucullate, subulate, short to long spurred, and with various transitions. The flowers size varied from small to large accordingly. The flowers with cucullate and subulate petals, which were a little shorter than the inner sepals or almost as long as the latter, were small (about 0.8 cm in diameter). The flowers with long spurs, which were much longer than the inner sepals, were also large (about 2.5–3.5 cm in diameter). Finally, the flowers with short spurs, which were a little longer than the inner sepals, were medium-sized (about 1.0–1.2 cm in diameter). In addition, the color of inner sepals was revised from ‘white, occasionally light mulberry-purple’ to yellowish green or yellowish white. Epimedium tianmenshanense is a perfect example of natural petal evolution, which could be used for further taxonomic and evolutionary studies. The reason for the variation and the taxonomic treatment of the species still need further study.     

FLORAL ANATOMY OF KRAMERIA LANCEOLATA

The anatomy of each of the series of floral organs of Krameria lanceolata was examined. The sepals are characterized by three main veins each, an undifferentiated mesophyll, and stomata on the upper epidermis. The fleshy petals are distinguished by their numerous veins as well as by palisade-like epidermal cells on the outer surface. The three partially united petals have each a single vein and long, narrow epidermal cells similar to those on other floral organs. The stamens are united at their bases and bear tetra-sporangiate, conical anthers. The gynoecium includes a sterile and a fertile carpel. In the receptacle the veins to the sepals and petals are separated by a wide gap; those to the petals and stamens, by a narrow gap. Anatomical characteristics of the flower dissociate Krameriaceae from the legumes with which they have frequently been thought to be allied.     

THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. III. METABOLISM OF SOME EXOGENOUS ANTHOCYANINS BY DETACHED PETALS OF IMPATIENS BALSAMINA

The anthocyanins of mature petals of Impatiens balsamina L. are distinct from the pigments found in vegetative tissue. In the red genotype (llHHP^rP^r) a sequential elaboration of the characteristic anthocyanins has been previously demonstrated through the examination of buds at successive stages of development. The metabolism of anthocyanins, especially pelargonidin-3-mono-glucoside, was examined by infiltration into developing petals of a genetically white strain. This anthocyanin appears to play a central role in the biochemical sequences involved and it has been observed that the genetically white flowers possess the enzymatic potential to metabolize this substrate, producing the same final products which are produced in the red genotype. There is a pattern of change in the relative amounts of each anthocyanin during the incubation period which follows closely the pattern which occurs during normal development of the colored genotypes. This indicates that the enzymes which are normally produced in the colored flowers are also produced in flowers which never produce anthocyanins. The metabolic capabilities of several other genetic strains and the influence of light and puromycin have been examined.     

Spatial fragrance patterns within the flowers ofRanunculus acris (Ranunculaceae)

Floral scents emitted from different flower parts ofRanunculus acris were investigated by trapping headspace volatiles onto Porapak Q followed by solvent desorption and GC-MS analysis. Isoprenoids, strongly dominated bytrans--ocimene, constituted the principal class of volatiles in all flower parts except pollen; sesquiterpenes were especially diverse. Odors collected separately from petals, stamens, and sepals + gynoecium comprised the same volatiles, but these were present in disparate proportions among the flower parts, thereby creating subtle contrasts within the flower. The main sources of volatiles were the petals and stamens, which made equal contributions to the whole-flower fragrance. Emissions from the petals differed quantitatively between the apical and basal petal regions, thereby paralleling optical nectar-guide patterns. Pollen odor was markedly unlike that of other flower parts, with only few volatiles, a high representation of 5-methylene-2(5H)-furanone (protoanemonin), and no detectabletrans--ocimene. The distinctiveness of the pollen's volatile profile suggests that it may serve a signalling role to pollen-feeding insects.     

COMPARATIVE REPRODUCTIVE BIOLOGY OF HERMAPHRODITIC AND MALE-STERILE IRIS DOUGLASIANA HERB. (IRIDACEAE)

A comparative study of the reproductive biology of male-sterile and hermaphroditic plants in a gynodioecious population of Iris douglasiana Herb. (Iridaceae) was conducted at the University of California's Marine Laboratory at Bodega Bay, California, between 1976–1979. Each year of the study, there were 11.1% male-sterile plants in the population, some of which began blooming at the same time as the earliest blooming hermaphrodites. Male-sterile flowers made up between 7–21% of the flowers produced during the male-sterile flowering period. Male-sterile flowers had smaller sepals and petals than hermaphrodites, there were fewer of them per square meter, and they had fewer pollinated stigmas than did hermaphroditic flowers. In a test to determine pollinator preference, intact hermaphroditic flowers tended to have more pollinated stigmas than did hermaphrodites with their stamens removed or those flowers with shortened sepals made to resemble the smaller male-sterile flowers. Floral phenology and nectar-flow patterns were similar in both types of flowers as were the kinds of amino acids and sugar rewards in the nectar. Male-sterile flowers, however, produced much less nectar per flower. There were no significant differences in the number of ovules per flower or the number of seeds produced per capsule between the two flower types, but the loss of seeds through larval predation was much greater in capsules from hermaphroditic flowers. Early flowering and setting of seed by plants with male-sterile flowers could give them a reproductive advantage over plants with hermaphroditic flowers which experience higher levels of larval predation later in the growing season.     

Homeotic, Meristic and Cytological Floral Mutants of Thryptomene calycina (family Myrtaceae)

Twenty plants with various phenotypic abnormalities to the flowerswere selected from very large populations of Thryptomene calycinain the Grampian and Black Ranges. Most of these had impairedreproductive function. Normal flowers were epigynous with fivesepals, five petals, five anthers, a single style and two anatropousovules. The mutants were two partially male sterile, tetraploidplants with large flowers, one of which occasionally producedadditional flowers from the leaf axils with peduncles as wellas pedicels; one plant which produced a proportion of hexapetaloidflowers with six stamens; three gross mutants with fleshy, bracteoidpointed petals and sepals, no stamens, vestigial styles andstigmas, exposed ovules and no inferior ovary; one plant withfleshly, bracteoid pointed sepals, vestigial style and stigmabut with exposed ovular structures replaced by four to fivesterile ovules generally inside an abnormal ovary; two plantswith reduced ovary diameter and sterile ovules, shortened style,five reduced sepals and petals and five to eight anthers; threeanthocyanin-free plants; three plants with pink sepals; twoplants with half-sized flowers which produced a proportion offasciated stems; one plant which occasionally produced flowerswithout pedicels which virtually resulted in organs which wereleaf-flower composites; two plants which produced sepals andpetals which contained chlorophyll and prematurely senesced,and had partial substitution of petals by anthers.Copyright1993, 1999 Academic Press Thryptomene calycina, Myrtaceae, Victorian lace flower, floral mutations, mutants, homeotic, meristic, tetraploid, fasciation, male sterility, cut flowers     

ONTOGENY AND ANATOMY OF THE FLOWER OF LIMNOCHARIS FLAVA (BUTOMACEAE)

The flowers of Limnocharis flava (L.) Buch. are borne in an indeterminate umbel and each consists of three sepals, three yellow petals, and about 18 carpels surrounded by numerous stamens and staminodia. The androecium is centrifugally developed, and the last-formed members are staminodial; it is supplied by branching vascular systems. Carpels arise almost simultaneously, and a prominent residual floral apex remains. The carpels are partially conduplicately closed and are also primitive in possessing laminar placentation and in lacking differentiation of a style. The gynoecium is essentially apocarpous, but there are slight fusions of adjacent carpels near their ventral margins where they are attached to the receptacle. It is suggested that the Limnocharis flower is the most primitive in the family.     

ORGANOGENESIS IN THE CARPELLATE FLOWER OF DRIMYS LANCEOLATA

This study of floral development in Drimys lanceolata in Section Tasmannia provides a basis for comparison with D. winteri, a member of the section Wintera, which has been described previously. The carpellate flowers of D. lanceolata have 2 sepals, 4–6 petals, and a solitary carpel, which form in acropetal succession. In symmetry the flower and its apical meristem are bilateral rather than radial, as in the flower of Drimys winteri. The floral apex of D. lanceolata is zonate while that of D. winteri is organized as a mantle and core. Preceding carpel initiation the floral apex of D. lanceolata is narrowly wedge-shaped, while that of D. winteri is low-convex. The entire apex is utilized in carpel initiation in D. lanceolata, involving many subsurface cell divisions over the entire summit. No apical residuum remains, and the carpel is terminal. In this feature the contrast with D. winteri is particularly marked, since in the latter, carpels are initiated laterally around the floral apex, which c an be recognized as an apical residuum after all appendages have formed.     

Interrelationship between the Different Flower Parts during Emasculation-Induced Senescence in Cymbidium Flowers

In Cymbidium flowers emasculation by removal of the anther capand the pollinia, led to rapid colouration of the lip and advancedwilting of the petals and sepals. The ethylene production ofwhole flowers showed an emasculation-induced early peak in ethyleneevolution followed some days later by a second increase concomitantwith the wilting of the flower. In non-emasculated flowers theethylene production increased later and simultaneously withcolouration of the lip and wilting of the petals and sepals.At all stages of senescence, the contribution of the lip, petals,and sepals to the total amount of ethylene produced was negligible. Parallel to the increase in ethylene production of whole flowers,an increase in 1-aminocyclopropane-l-carboxylic acid (ACC) andmalonyl-ACC (MACC) in the central column and, to a lesser extent,in the ovary was observed. Also an increase in internal ethyleneconcentration was demonstrated and this, in contrast, was apparentin all the different flower parts. The activity of the ethylene-formingenzyme in lips, petals, and sepals showed an increase afteremasculation and such an effect could also be induced by treatmentof isolated lips with low concentrations of ethylene. The data indicate that senescence in Cymbidium flowers is regulatedby the central column and perhaps the ovary and that both ACCand ethylene may play a signalling role in inter-organ communication. Key words: 1-aminocyclopropane-l-carboxylic acid, ethylene, Cymbidium, senescence     

春兰CgSEP3基因的克隆和表达分析

该研究采用RT-PCR和RACE技术从春兰(Cymbidium goeringii)中分离到1个SEPALLATA3(SEP3)基因。序列分析表明,该基因含有1个732bp的开放阅读框(ORF),共编码243个氨基酸。系统进化树分析显示,该基因是MADS-box基因家族AP1/AGL9组SEP的同源基因,其编码蛋白与其它植物SEP3类蛋白具有较高的一致性,命名为CgSEP3(登录号为KF924272)。实时荧光定量分析表明,CgSEP3在春兰花器官中均有表达,其中在唇瓣、侧瓣和萼片中的表达量较高,在子房和蕊柱中的表达量较低;而且CgSEP3在花发育各个时期都有表达,在1~2cm的花芽中表达量最高,在盛开的花中的表达量最低。研究认为,CgSEP3基因可能在春兰花瓣和萼片的形成过程中具有重要作用。     

Impatiens pingxiangensis sp. nov. (Balsaminaceae) from the limestone areas in Guangxi,China

Impatiens pingxiangensis H. Y. Bi & S. X. Yu (Balsaminaceae), a new species from the limestone areas in Guangxi, China, is described and illustrated. The new species is similar to I. obesa in having succulent stems, subsessile peduncle, tufted pedicel and the lower petal in each pair of lateral united petals being connate, but differs from the latter by having perennial stems, leaf blades with 7–9 pairs of lateral veins, 1–2‐flowered racemes, ovate inner lateral sepals, and elliptic capsule. Moreover, the pollen and seed coat characters also support the recognition of the new species.     

Genes directing flower development in Arabidopsis.

We describe the effects of four recessive homeotic mutations that specifically disrupt the development of flowers in Arabidopsis thaliana. Each of the recessive mutations affects the outcome of organ development, but not the location of organ primordia. Homeotic transformations observed are as follows. In agamous-1, stamens to petals; in apetala2-1, sepals to leaves and petals to staminoid petals; in apetala3-1, petals to sepals and stamens to carpels; in pistillata-1, petals to sepals. In addition, two of these mutations (ap2-1 and pi-1) result in loss of organs, and ag-1 causes the cells that would ordinarily form the gynoecium to differentiate as a flower. Two of the mutations are temperature-sensitive. Temperature shift experiments indicate that the wild-type AP2 gene product acts at the time of primordium initiation; the AP3 product is active later. It seems that the wild-type alleles of these four genes allow cells to determine their place in the developing flower and thus to differentiate appropriately. We propose that these genes may be involved in setting up or responding to concentric, overlapping fields within the flower primordium.     

FLORAL DEVELOPMENT IN CAESALPINIA (LEGUMINOSAE)

Utilizing scanning electron microscopy, we studied the early floral ontogeny of three species of Caesalpinia (Leguminosae: Caesalpinioideae): C. cassioides, C. pulcherrima, and C. vesicaria. Interspecific differences among the three are minor at early and middle stages of floral development. Members of the calyx, corolla, first stamen whorl, and second stamen whorl appear in acropetal order, except that the carpel is present before appearance of the last three inner stamens. Sepals are formed in generally unidirectional succession, beginning with one on the abaxial side next to the subtending bracts, followed by the two lateral sepals and adaxial sepal, then lastly the other adaxial sepal. In one flower of C. vesicaria, sepals were helically initiated. In the calyx, the first-initiated sepal maintains a size advantage over the other four sepals and eventually becomes cucullate, enveloping the remaining parts of the flower. The cucullate abaxial sepal is found in the majority of species of the genus Caesalpinia. Petals, outer stamens, and inner stamens are formed unidirectionally in each whorl from the abaxial to the adaxial sides of the flower. Abaxial stamens are present before the last petals are visible as mounds on the adaxial side, so that the floral apex is engaged in initiation of different categories of floral organs at the same time.     

Secondary metabolites during ontogenetic phase of reproductive structures in Hypericum maculatum

The distribution patterns of flavonoids hyperoside, isoquercitrin, quercitrin, quercetin, I3,II8-biapigenin and naphtodianthrones hypericin and pseudohypericin were studied in reproductive structures during ontogenetic phase of flowering in Hypericum maculatum Crantz. Considerable differences in the content of these secondary metabolites, in the particular flower parts were found. The content of all the metabolites studied is stable during the whole period of flowering in green flower parts (sepals). In petals, stamens and pistils their content undergoes considerable change associated with the biological functions of particular metabolites. The most conspicuous changes during ontogenetic phase of flowering were the decrease of hyperoside and isoquercitrin content in petals (average content in buds 1.589 mg g⁻¹ dry weight, average content in overblown flowers 0.891 mg g⁻¹ dry weight), the decrease of the I3,II8-biapigenin content in stamens (in buds 1.189 mg g⁻¹ dry weight, in overblown flowers 0.319 mg g⁻¹ dry weight), and the increase of hypericin and pseudohypericin content in both petals (total average content of hypericins in the buds 0.547 mg g⁻¹ dry weight; in overblown flowers 0.792 mg g⁻¹ dry weight) and stamens (in buds 0.189 mg g⁻¹ dry weight; in overblown flowers 0.431 mg g⁻¹ dry weight). Hypericins are absent in the pistil. The flavonoids hyperoside and isoquercitrin, the content of which decreased during ontogenetic phase of flowering, reach the highest contents in the pistil.     

蒙农红豆草不同花色表型及色素成分特征分析

蒙农红豆草不仅是良好的饲草作物,还可以用作庭院观赏及蜜源植物。该研究以蒙农红豆草浅色花瓣突变体与对照群体中的粉红色、紫红色花瓣为试验材料,通过对花瓣颜色的表型和色素种类及含量的综合分析,明确影响花色形成的主要物质。结果表明:(1)蒙农红豆草浅色花突变体与对照的粉红色花和紫红色花为3种不同的色系,根据黄度(b*)和色相角(h°)将浅色花突变体的花色定义为黄白色花。(2)在3种花色中共检测到10种类黄酮和5种花青素,其中6种山奈酚衍生物、2种矮牵牛素衍生物、2种飞燕草素衍生物和1种锦葵素衍生物为首次在蒙农红豆草中报道;同时还发现山奈酚-3-芸香苷、山奈酚-3-葡萄糖苷和飞燕草素-3-羧基修饰芸香苷在3种花色中含量(36%~50%、21%~35%和27%~65%)最多。研究推测:芦丁、山奈酚-3-芸香苷-5-鼠李糖苷和山奈酚-3-p-香豆酰葡萄糖苷为影响蒙农红豆草花色变化的主要成分。