Yellow Petals Research Articles

(283) Petal Color Changes in Carnation Plants Transformed with an Antisense DFR and a CHI Gene

To produce transgenic carnation plants expressing modified flower colors, cultivars of red-flowering carnation (`Desio' and `Garnet') were transformed with a antisense DFR gene encoding dihydroflavonol-4-reductase, and yellow-flowering carnations (`Pallas' and `Keumbyul') were introduced with a CHI gene encoding chalcone synthease isomerase. Explants of leaves, stems, and shoot tips were inoculated with Agrobacterium and grown overnight in induction broth supplemented with 0.2 mm acetosyringone. The cocultures of carnation explants were maintained in the light at 24 °C on one-half strength MS medium solidified with 0.3% Gelite and supplemented with 1.0 mg·L-1 BA for 10 days, and then were transferred to a selection medium containing 250 mg·L-1 cefotaxime/carbenicillin, 500 mg·L-1 kanamycin. They were subcultured every 2 weeks for over six times and regenerated. In `Garnet' and `Desio' carnation cultivars, a total of 146 plants was transformed with anti-sense DFR gene in pGA748/LBA4404. In yellow flowering cultivars `Pallas' and `Keumbyul', transformed with CHI gene in pGA748/LBA4404, 20 putative transformants obtained. The introduction of the transgenes were confirmed through PCR and flower color changes. Rates of phenotypic expression of the transgene, antisense DFR gene, vary among the transformants such as lighter pigmentation or chimeric discoloration, more prominently in outer petals of the flowers. Transgenic plants of chi gene bloomed flowers of lighter yellow petals in general. The most prominent phenotypic changes were discoloration of red strips on petals, which are typical characteristics of the cultivars.

A new species of Haplophyllum A. Juss. (Rutaceae) from the Iberian Peninsula: evidence from morphological, karyological and molecular analyses.

The discovery of a new species, Haplophyllum bastetanum F.B. Navarro, V.N. Suárez-Santiago & Blanca sp. nov., in the south-east of Spain has prompted the comparative study of species of the Iberian Peninsula, and others related, through morphological, cytogenetic, molecular, distributional and ecological characterization. The morphological study involved a quantitative analysis of the species present in the Iberian Peninsula and a comparative analysis of the morphological characteristics between H. bastetanum and other related species. Mitotic analyses were made with root meristems taken from germinating seeds. Phylogenetic analyses of the internal transcribed spacer sequences of nuclear ribosomal DNA were performed using neighbour-joining (NJ) and maximum-parsimony methods. Haplophyllum bastetanum is a diploid species (2n = 18) distinguished primarily for its non-trifoliate glabrous leaves, lanceolate sepals, dark-green petals with a dorsal band of hairs, and a highly hairy ovary with round-apex locules. The other two Iberian species (H. linifolium and H. rosmarinifolium) are tetraploid (2n = 36) and have yellow petals. Both phylogenetic methods generated a well-supported clade grouping H. linifolium with H. rosmarinifolium. In the NJ tree, the H. linifolium-H. rosmarinifolium clade is a sister group to H. bastetanum, while in the parsimony analysis this occurred only when the gaps were coded as a fifth base and the characters were reweighted according to the rescaled consistency index. This latter group is supported by the sequence divergence among taxa. The phylogenies established from DNA sequences together with morphological and cytogenetic analyses support the separation of H. bastetanum as a new species. The results suggest that the change in the number of chromosomes may be the key mechanism of speciation of the genus Haplophyllum in the Iberian Peninsula. An evolutionary scheme for them is propounded.

FS11.6 Contact dermatitis to Iris in a florist

Objective: To detect a possible allergen in a florist with occupational dermatitis. Patient and methods: a 27‐year‐old atopic female working in a greenhouse since 10 years presented with a 3 months history of severe eczema involving hands, face, eyelids and neck requiring a stop of the work. Tests were performed with European standard series (Trolab®), additional series, plant series, (Chemotechnique Diagnostics®) and flowers. Readings were performed at D2 and D3 according ICDRG criteria. Results: positive patch tests were parabens +/+ nickel sulphate ++/++ cobalt chloride −/++ palladium chloride ++/++ thiomersal ++/++, Iris petal ++/+. Then various colours of Iris were tested and pale blue, yellow and white petals were positive ++/++ but purple blue petal was negative. The proximal yellow part of purple blue petal and orange part of yellow petal were also positive ++/++. The leaf and pistil of Iris were negative. One control with a white Iris petal was negative. Then the patient presented flare up of her dermatitis in the presence of Iris, at home, without handling them, that could make suspect an airborne contact dermatitis. Even after examination by a botanist, the precise identificaton of these Iris was not possible. Positive patch tests to unspecified Iris (petal and leaf) have already been reported in a florist who was allergic to safflower (Van der Willigen A.H. and al, Contact Dermatitis, 1987, 17,184). Conclusion: this case could evoke the responsibility of anthocyans, which play a role in the colours, but essential oils or other components are also possible responsibles.

Nectar guide fluctuating asymmetry does not relate to female fitness in Mimulus luteus

Most studies assessing the importance of developmental instability of floral characters for pollinator visits and plant fitness have focused on the fluctuating asymmetry (FA) of the corolla phenotype. The importance of stability process for nectar guide characters that signal floral reward has not been considered in the literature. In principle, flowers with symmetrical guides should be more successful at attracting pollinators, therefore increasing their reproductive success in comparison to asymmetrical flowers. In this paper we test this hypothesis in a population of 171 individuals of the Andean monkey flower, Mimulus luteus in northern Chile. This species shows a conspicuous red spot in the landing yellow petal, which permits assessment of the functional relationship between nectar guide FA and female fitness. Our results did not reveal a significant linear nor nonlinear relationship between nectar guide FA and fitness. This result was consistent after controlling the level of FA by guide and corolla size. Because the corolla of M. luteus did not show evidence of UV wavelength reflectance, our negative result could not be attributable to a confounding effect of UV guides. Even though we can not rule out that nectar guide FA correlates better with male than female fitness, the low fraction of the variance in female fitness accounted for nectar guide FA, suggests that other components of the floral phenotype as well as environmental factors may be more important to predict pollinator preference and reproductive success in this species.

Cloning and heterologous expression of cDNAs encoding flavonoid glucosyltransferases from Dianthus caryophyllus

Yellow petals of carnations contain chalcone 2′-O-glucoside. The glucosylation occurs after the p-coumaroyl CoA and malonyl-CoA condensation reaction by chalcone synthase (CHS), but the enzyme(s) transferring glucose from UDP-glucose to the 2′-OH position of chalcone has not been identified. The full-length cDNA clones for 18 glucosyltransferase (GT) genes were isolated from petal tissue of carnation (Dianthus caryophyllus) bearing various flower colors. The 18 GTs encoded in the cDNAs were enzymatically characterized in an E. coli expression system using chalcone, flavanone, flavone, flavonol and anthocyanidin as substrates. Three of the 18 were characterized as 3-GT possessing different substrate specificities for flavonoids and anthocyanidin and another two GTs catalyzed the transfer of glucose to the 2′-hydroxyl group of chalcone. In addition, these two enzymes glucosylated flavonol (3-OH and 7-OH), flavanone (7-OH), flavone (7-OH) and anthocyanidin (3-OH and 7-OH).

튤립(Tulipa gesneriana) 꽃의 발달단계에 따른 효소 활성 및 미량요소 함량의 변화

본 실험은 튤립 품종 ‘Apeldoorn’과 ‘Golden Apeldoorn’의 꽃잎 발달 단계에 따른 각종 가수분해 효소 활성의 변화 및 효소 활성의 조절에 관여하는 무기성분들의 함량의 변화를 조사하였다. RNase와 peroxidase, protease의 효소활성은 초기단계로부터 꽃이 발달이 진행될수록 증가하는 경향을 보였다. Polyphenol oxidase의 경우, 꽃이 만개한 5단계에서 활성이 가장 높았으며, 이 효소가 노화가 시작되는 초기 단계에 관여하는 것으로 생각된다. 한편, Protease의 활성은 ‘Apeldoorn’과 ‘Golden Apeldoorn’의 꽃 발달동안 꽃잎 추출물에서 현저한 차이가 관찰되었다 이 결과는 protease는 튤립의 화색의 생합성에 관련성을 시사한다. 조사된 K, Mn, Zn, P의 함량은 꽃 발달 동안 점차적으로 감소하는 경향을 보인 반면, Ca, Mg, Fe의 무기성분은 초기 단계에서 꽃의 노화 단계까지 점차적으로 증가하였으며, RNase와 peroxidase, protease의 효소 활성의 변화와 같은 경향을 보였다. 이는 꽃의 발달단계동안 이들 효소와 무기성분 사이에 서로 결합력이 있다고 추측된다. 본 연구결과는 튤립 꽃의 발달단계에 따른 기초적인 생화학적 변화의 경향을 조사한 결과로서, 절화수명 연장을 위한 기초자료로 유용하게 활용될 수 있을 것이다. This study was carried out to investigate the changes of enzymes and micro inorganic nutrients that is associated with flower senescence during flower development in tulip cultivars, ‘Apeldoorn’ and ‘Golden Apeldoorn’. Ribonuclease, peroxidase and protease activities were gradually increased from the stage of early flowering to later Polyphenol oxidase showed the highest activity at stage 5, which the flower was in full bloom indicating that it acts at an initial stage of flower senescence. The protease activity was different in the petal extracts during flower development between the cultivars ‘Apeldoorn’ (red petal) and ‘Golden Apeldoorn’ (yellow petal). This result suggested that protease might relate to pigment biosynthesis in petal of tulip. In contrast to the decrease of inorganic nutrients K, Mn, Zn and P contents during floral development, Ca, Mg and Fe showed the gradual increasement that is similar with ribonuclease, peroxidase and protease. It suggests that they have some interaction during flower senescence.

Ontogenetic Variation Regarding Hypericin and Hyperforin Levels in Four Accessions of Hypericum perforatum L.

SUMMARY Hypericin and hyperforin contents of isolated flowers and capsules, collected from 4 different Hypericum perforatum accessions at four developmental stages, i.e., (A) the stage of closed buds with yellow petals already visible, (B) the stage of fully opened flowers, (C) the stage of green capsules and (D) the stage of brown capsules, were determined via HPLC. Principally, hypericin contents increased with advancing of the stages, whereas hyperforin decreased. However, genotype specific deviations were observed, e.g., one genotype showing a low and relatively stable hyperforin content throughout all stages of development or another genotype revealing similar hypericin contents in stage (A) and (B).

Effect of genome composition and cytoplasm on petal colour in resynthesized amphidiploids and sesquidiploids derived from crosses between Brassica rapa and Brassica oleracea

AbstractThe effect of genome composition and cytoplasm on petal colour was studied in Brassica. Three accessions of yellow‐petalled B. rapa (2n= 20, AA) were crossed with a white‐petalled B. oleracea var. alboglabra (2n= 18, CC) and with three cream‐yellow‐petalled B. oleracea var. gongylodes (2n= 18, CC) to produce resynthesized B. napus (2n= 38, AACC or CCAA) and sesquidiploids (2n= 29, AAC or CAA). Petal colour was measured with a Hunter automatic colour difference meter. The results revealed that petal colour in Brassica is controlled by nuclear genes and by cytoplasmic factors. Additive and epistatic gene effects were involved in the action of nuclear genes. When crosses were made between yellow‐petalled B. rapa and white‐petalled B. oleracea var. alboglabra, significant additive, epistatic and cytoplasmic effects were found. White petal colour was partially epistatic over yellow petal colour. When crosses were made between yellow‐petalled B. rapa and cream‐yellow‐petalled B. oleracea var. gongylodes, only epistatic effects were detected. Yellow petal colour was epistatic over cream‐yellow.

Classification of Chinese Kale Cultivars by RAPD Analysis.

The genetic relationship of 20 Chinese kale cultivars (Brassica oleracea L. var. alboglabra L. H. Bailey) was examined by RAPD analysis using 12 dodecamer oligonucleotide primers singly or in combination. The cultivars examined were classified into three groups based on the numerous polymorphisms of DNA fingerprints. The first group consisted of nine cultivars with white petals and wrinkled leaves (8 cultivars), such as 'Large leaf kailaan' and a cultivar with white or yellow petals, 'Nanjing huanghua (huang)'. The second group included six cultivars with yellow petals and dark green leaves (2 cultivars), such as 'Huanghualenye' and those with yellow petals and pale green leaves (4 cultivars), such as 'Huanghuagelin'. The third group included five cultivars with white or yellow petals (1 cultivar), such as 'Nanjing huanghua (bai)', and white petals without wrinkled leaves (4 cultivars), such as 'Hei' and 'Small leaf kailaan'. These results suggest that the Chinese kale cultivars with yellow petals diverged from those with white petals when they were introduced into Taiwan from China.

Relationship between the structural and functional changes of the photosynthetic apparatus during chloroplast-chromoplast transition in flower bud of Lilium longiflorum.

The relationship between the structural and functional changes of the photosynthetic apparatus in the flower bud of Lilium longiflorum during chloroplast-chromoplast transition was examined. Compared with green petals, there was a five-fold increase of the carotenoid content in yellow petals, whereas the chlorophyll content decreased five-fold. Absorption and emission fluorescence spectra of chromoplasts indicated that newly synthesized carotenoids were not associated with photosystem II (PSII) photochemistry. The maximum quantum yield in the remaining PSII reaction centers remained constant during the chromoplast formation, whereas the photosynthetic electron transport beyond PSII became inhibited, as indicated by a marked decrease of the O2 evolution capacity, of the photochemical quenching of chlorophyll-alpha fluorescence and of the operational quantum yield of photosynthetic electron transport. Deconvoluted fluorescence emission spectra indicated a more rapid degradation of photosystem I (PSI) complexes than of PSII during chromoplast formation. Compared with green petals, the spillover between PSII and PSI decreased by approximately 40% in yellow petals. Our results indicate that during chloroplast-chromoplast transition in the flower bud of L. longiflorum, PSII integrity was preserved longer than the rest of the photosynthetic apparatus.

CDNA cloning and expression of carotenogenic genes during flower development in Gentiana lutea.

All cDNAs involved in carotenoid biosynthesis leading to lycopene in yellow petals of Gentiana lutea have been cloned from a cDNA library. They encode a geranylgeranyl pyrophosphate synthase, a phytoene synthase, a phytoene desaturase and a zeta-carotene desaturase. The indicated function of all cDNAs was established by heterologous complementation in Escherichia coli. The amino acid sequences deduced from the cDNAs were between 47.5% and 78.9% identical to those reported for the corresponding enzymes from other higher plants. Southern analysis suggested that the genes for each enzyme probably represent a small multi-gene family. Tissue-specific expression of the genes and expression during flower development was investigated. The expression of the phytoene synthase gene, psy, was enhanced in flowers but transcripts were not detected in stems and leaves by northern blotting. Transcripts of the genes for geranylgeranyl pyrophosphate (ggpps), phytoene desaturase (pds) and zeta-carotene desaturase (zds) were detected in flowers and leaves but not in stems. Analysis of the expression of psy and zds in petals revealed that levels of the transcripts were lowest in young buds and highest in fully open flowers, in parallel with the formation of carotenoids. Obviously, the transcription of these genes control the accumulation of carotenoids during flower development in G. lutea. For pds only a very slight increase of mRNA was found whereas the transcripts of ggpps decreased during flower development.

Inheritance of petal colour and its independent segregation from seed colour in Brassica rapa

AbstractThe inheritance of petal (flower) colour and seed colour in Brassica rapa was investigated using two creamy‐white flowered, yellow‐seeded yellow sarson (an ecotype from Indian subcontinent) lines, two yellow‐flowered, partially yellow‐seeded Canadian cultivars and one yellow‐flowered, brown‐seeded rapid cycling accession, and their F1, F2, F3 and backcross populations. A joint segregation of these two characters was examined in the F2 population. Petal colour was found to be under monogenic control, where the yellow petal colour gene is dominant over the creamy‐white petal colour gene. The seed colour was found to be under digenic control and the yellow seed colour (due to a transparent coat) genes of yellow sarson are recessive to the brown/partially yellow seed colour genes of the Canadian B. rapa cvs.‘Candle’ and ‘Tobin’. The genes governing the petal colour and seed colour are inherited independently. A distorted segregation for petal colour was found in the backcross populations of yellow sarson × F1 crosses, but not in the reciprocal backcrosses, i.e. F1× yellow sarson. The possible reason is discussed in the light of genetic diversity of the parental genotypes.

Purification and Characterization of Precarthamin Decarboxylase from the Yellow Petals of Carthamus tinctorius L

Carthamin, a red quinochalcone pigment in safflower (Carthamus tinctorius L.), is enzymatically converted from a yellow precursor, precarthamin. The enzyme, which catalyzes the oxidative decarboxylation of precarthamin to carthamin, was purified to apparent homogeneity from yellow petals of safflower and named precarthamin decarboxylase. The molecular mass of the denatured enzyme was estimated as 33 kDa by SDS–PAGE. The molecular mass of the native enzyme was determined by gel filtration chromatography to be 24 kDa; thus, the native enzyme is a monomer. The optimum pH of the enzyme was 5.0. The enzyme activity was inhibited by Mn2+, Fe2+, and Cu2+ and sharply decreased at temperatures higher than 50°C for 10 min. The activation energy and the Arrhenius frequency factor of the enzyme reaction were 19.7 kcal mol−1 and 9.94 × 1011 s−1, respectively. The saturation curve of precarthamin showed that the enzyme follows Michaelis–Menten kinetics. The Km and Vmax of the enzyme were calculated as 164 μM and 29.2 nmol/min, respectively. The turnover number (kcat) of the enzyme was calculated as 1.42 × 102 s−1. The enzyme activity was severely inhibited by reducing agents such as glutathione and DTT at pH 5.0, suggesting that a disulfide bond may play an important role in enzyme function.

Enzymatic conversion of precarthamin to carthamin by a purified enzyme from the yellow petals of safflower.

Precarthamin, a yellow precursor of carthamin, was efficiently isolated from the yellow petals of safflower (Carthamus tinctorius L. ) with Sephadex LH-20 column chromatography and preparative HPLC, and identified with UV-vis and NMR spectrometry. The UV-vis spectrum of precarthamin showed lambda(max) of 238 and 406 nm in MeOH. The molar extinction coefficients of precarthamin at 406 nm in MeOH and 50 mM citrate buffer (pH 5.0) were 59 000 M(-)(1) cm(-)(1) and 45 400 M(-)(1) cm(-)(1), respectively. The isolated and structurally identified precarthamin was converted to a red pigment by a homogeneously purified enzyme from the immature petals of safflower in 50 mM citrate buffer (pH 5.0). The enzymatically converted red pigment was identified as carthamin, a red pigment of safflower by TLC, HPLC, and UV-vis spectral analysis.

Evaluation of two self-incompatibility alleles in three summer rape (Brassica napus L.) cultivars by UV fluorescence microscopy, seed set and outcrossing rates

S-alleles W1 and T2 and an incompletely dominant white petal character were introgressed into the self-compatible (SC) summer rape (Brassica napus L. ssp. oleifera {Metzg.}) cultivars Global, Topas and Westar. The derived self-incompatible (SI) lines were evaluated for strength of incompatibility by ultraviolet fluorescence of pollen tubes, and by seed set. Pollen tube and seed set analyses showed the W1 and T2 alleles were strongly, moderately and weakly expressed in Topas, Global and Westar, respectively. Seed set data showed a significant difference between SI lines, but not between S-alleles, or between homozygous or heterozygous lines from the same SI cultivar. SI cultivar yellow petal (wild type) lines were field pollinated with SC white petal lines. Seed collected from the SI cultivars were evaluated for proportion of outcrossed progeny by recording the frequency of yellow petal and cream petal plants, which were the result of self- and cross-pollination, respectively. The proportion of outcrossed progeny (i.e., outcrossing rates) ranged from 23% to 79%. Topas SI lines had significantly higher outcrossing rates than Global SI lines, which corresponded to SI line seed set data. Environment, S-allele selection and genotype significantly affected outcrossing rates. Key words: Brassica napus, sporophytic incompatibility, S-allele, outcrossing rate

Lepidostemon (Brassicaceae) Is No Longer Monotypic

Previously monotypic Lepidostemon is expanded to include five species, of which L. everestianus and L. gouldii are herein described as new. The new combinations L. rosularis and L. glaricola are proposed. The genus is reported for the first time from China. Chrysobraya is reduced to synonymy of Lepidostemon. Lepidostemon has been recognized as monotypic since the original description of L. pedunculosus J. D. Hooker & Thomson as the generic type (Hooker & Thomson, 1861). Except for the treatments by Hayek (1911) and Schulz (1936), the genus was never studied in context with other Himalayan genera in Brassicaceae (Cruciferae). As shown below, of the five species of Lepidostemon, one was described in the monotypic genus Chrysobraya H. Hara (as C. glaricola H. Hara) and another in Christolea Cambessades (as C. rosularis K. C. Kuan & Z. X. An). However, neither of these two species was compared with L pedunculosus. In his original description of Chrysobraya, Hara (1974) indicated that the genus is most closely allied to Braya Sternberg & Hoppe and listed several similarities, including aspects of their nectar glands, cotyledonary position, ebracteate racemes, and branched trichomes. Although the trichomes in Chrysobraya are branched, they are almost exclusively dendritic, whereas in Braya these trichomes are simple and unbranched, and are only forked. Furthermore, the persistence of all floral parts well after fruit dehiscence in Chrysobraya in contrast to their abscission immediately after anthesis in Braya does not support any close affiliation. Chrysobraya is morphologically similar to Lepidostemon, with which it shares trichome aspect, persistent floral parts, toothed nectaries, coarsely toothed leaves, yellow petals, and solitary early flowers. However, Chrysobraya differs from Lepidostemon in having cotyledons incumbent instead of accumbent and staminal filaments toothless and wingless instead of winged and toothed. Several genera of the Brassicaceae (e.g., Alyssum L., Dontostemon Andrzejowski ex C. A. Meyer) include species with both toothed or toothless and winged or wingless staminal filaments (Al-Shehbaz, 1987; Al-Shehbaz & Ohba, 2000), and the cotyledonary position has often been shown to be an unreliable generic character. Therefore, Chrysobraya is reduced to synonymy of Lepidostemon. As delimited herein, Lepidostemon consists of five, exclusively Himalayan species distributed in Bhutan, China (Xizang), Nepal, and Sikkim. It is characterized by having branched trichomes sometimes mixed with simple ones (but at least some are dendritic), floral parts (sepals, petals, and stamens) persisting well after fruit maturity, winged and often toothed median staminal filaments, as well as linear or linear-oblong, often torulose fruits. It should be noted that one species, L. glaricola, has slender, toothless filaments, and another, L. gouldii, has floral parts that fall off shortly after anthesis. However, these two species show such remarkable morphological similarities in other characters to L. pedunculosus that they may reliably be included in Lepidostemon. From both Streptoloma Bunge (2 species, central Asia) and Braya, Lepidostemon is readily distinguished by having toothed and/or winged median staminal filaments, persistent floral parts, and often some dendritic trichomes. Both Braya and Streptoloma have wingless and toothless median staminal filaments, readily deciduous floral parts, and no dendritic trichomes. Braya has simple a d/or forked stalked trichomes, whereas Streptoloma has almost exclusively malpighiaceous ones. Lepidostemon J. D. Hooker & Thomson, J. Linn. Soc., Bot. 5: 131. 1861. TYPE: Lepidostemon pedunculosus J. D. Hooker & Thomson. Chrysobraya H. Hara, J. Jap. Bot. 49: 193. 1974. TYPE: Chrysobraya glaricola H. Hara. Herbs annual or caespitose perennial. Trichomes dendritic, forked and stalked, submalpighiaceous, or simple, often more than one kind present. Stems erect, simple from rosettes, leafy or leafless. Basal leaves petiolate, rosulate, simple, entire or dentate. Cauline leaves similar to basal, sometimes pinnatifid, rarely absent. Racemes few to many flowered, ebracteate or rarely bracteate throughout, elongated or not elongated in fruit, sometimes flowers solitary on long pedicels originating from axils of rosette leaves. Fruiting pedicels slender, divaricate or recurved. Sepals oblong, persistent or rarely caduNovoN 10: 329-333. 2000. This content downloaded from 157.55.39.192 on Wed, 24 Aug 2016 03:53:19 UTC All use subject to http://about.jstor.org/terms

Production and cytogenetics of intergeneric hybrids between the three cultivated Brassica diploids and Orychophragmusviolaceus

It has been proposed that both complete and partial separation of the parental genomes during mitosis and meiosis occurs in the intergeneric hybrids between Orychophragmus violaceus (2n=24) and the three cultivated Brassica tetraploids (B. napus, B. carinata and B. juncea). The hypothesis has been that this and the variations in chromosome numbers of these hybrids and their progenies result from the different roles of the A, B and C genomes originating from Brassica. To test this hypothesis, we produced hybrids between O. violaceus and the cultivated Brassica diploids. The hybrids with B. oleracea (2n=18, CC) had an intermediate morphology, but their petals were purple like those of O. violaceus. They were sterile and had the expected chromosome number (2n=21) in their mitotic and meiotic cells. The hybrid with B. campestris (2n=20, AA) was morphologically intermediate, except for its partial fertility and its yellow petals, which were similar to those of B. campestris. It was mixoploid (2n=23-42), and cells with 2n=34 were most frequent. Partial separation of parental genomes during mitosis, leading to the addition of O. violaceus chromosomes to the B. campestris complement, was proposed to explain the findings in the mitotic and meiotic cells of the hybrid and its progeny. In crosses with B. nigra (2n=16, BB), the majority of the F(1) plants were of the maternal type (2n=16), a small fraction had B. nigra morphology but were mixoploids (2n=16-18), predominantly with 2n=16 cells and three plants, each with a specific morphology, were mixoploids consisting of cells with varying ranges of chromosome numbers (2n=17-26, 11-17 and 14-17). The origin of these different types of plants was inferred to be a result of the complete and partial separation of parental genomes and the loss of O. violaceus chromosomes. Our findings in the three crosses suggest that the A genome was more influential than the C genome with respect to complete genome separation during mitosis and meiosis of the hybrids with B. napus. Possible complete and partial genome separation during mitotic divisions of the hybrids with B. carinata was mainly attributed to the role of the B genome. The combined roles of the A and B genomes would thus contribute to the most variable chromosome numbers of mitotic and meiotic cells in the hybrids with B. juncea and their progenies. The possible cytological mechanisms pertaining to these hybrids and the potential of genome separation in the production of Brassica aneuploids and homozygous plants are discussed.

温度制御条件下におけるカイラン（Ｂｒａｓｓｉｃａ ｏｌｅｒａｃｅａ Ｌ． ｖａｒ． ａｌｂｏｇｌａｂｒａ Ｌ． Ｈ． Ｂａｉｌｅｙ）の花芽形成

The effects of growing temperature on flower bud formation were investigated in Chinese kale (Brassica oleracea L. var. alboglabra L. H. Bailey) cultivars with white petals of 'Hakushin', 'Kairan-T', 'Kairan-M', 'Chugoku-kairan', 'Shirobana-kuroba' and 'Kairan-K', cultivars with yellow petals of 'Chugoku-kairan (Y) ' and 'Kibana-kakurin'.The developmental process of flower bud in Chinese kale was divided into eight stages.Cultivars with white petals or yellow petals were grown in a phytotron. Flower bud formation of cultivars with white petal occurred earlier and at higher temperatures than that of cultivars with yellow petals. The number of nodes from cotyledon to flower decreased with exposure to low temperatures.When cultivars with white petals held 3.2-4.1 unfolding leaves, they were transferred to the phytotron rooms. 'Hakushin', 'Kairan-T' and 'Kairan-M' formed flower buds at temperatures below 30°C, 'Chugoku-kairan', 'Shirobana-kuroba' and 'Kairan' formed buds at temperatures below 25°C. The number of nodes from cotyledon to flower decreased with exposure of low temperatures.These results indicated that cultivars with white petals have a quantitative cold requirement for flower bud initiation in response to low temperatures.

The Yellow-Flowered Species of Cuphea (Lythraceae), Including Three New Taxa

Among the predominantly purple- and red-flowered species of the genusCuphea, only seven yellow floral tube and/or yellow-petaled members in three sections were known. We add here two new species and one new variety.Cuphea congesta from Venezuela andC. splendida var.viridiflava from Bolivia are new to sect.Melvilla.Cuphea xanthopetala from Brazil is described in sect.Euandra and expands the presence of this feature to a fourth section of the genus. A key is provided to allCuphea with yellow floral tubes and/or yellow petals to expedite determinations when these exceptional character states are present.

DNA Fingerprinting of Trout Lilies: A High School Student Project

IN May 1996, six high school students and two instructors participated in a three-week course (six hours per day) on applications of DNA fingerprinting to permit students to experience the entire scientific process directly (from designing and conducting original research to presentation and submission of the findings). The specific project involved using DNA fingerprinting to assess the level of genetic variability in a species of trout lily, Erythronium americanum, and determining how the total diversity was subdivided within and among populations of individuals. Individual leaf samples were collected from plants in five populations and nucleic acids were isolated from each. The Polymerase Chain Reaction (PCR) was used with random primers to amplify genetic loci in RAPD (Random Amplified Polymorphic DNA) analyses (Williams et al. 1990; Demeke & Adams 1994). The banding patterns of the amplified products on agarose gels were analyzed for genetic relationships among individuals and populations. Trout lilies are ephemerals, wildflowers that are found only in early spring. They usually grow in dense populations in temperate zone forests (Hughes 1992). E. americanum has yellow petals and is one of two species of trout lilies found in Indiana (E. albidium has white petals) (Gleason & Cronquist 1991). These species belong to the family Liliaceae, a large group of highly variable herbaceous monocotyledons that have underground bulbs (Walters & Keil 1977). Thus, it is believed that they may reproduce sexually or asexually. Hypothetically, the greater the geographical distance that separates populations of E. americanum, the more genetic variation expected among them. In addition, the total genetic variability within this species might be low, reflecting a high degree of vegetative reproduction. On the other hand, frequent sexual