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The genetic diversity and population structure of 38 commercial accessions of double-flowered amaryllis (Hippeastrum hybridum) from the Netherlands and South Africa were evaluated using sequence-related amplified polymorphism (SRAP) markers. Thirty SRAP primer pairs produced 294 loci, of which 263 (89.16%) were polymorphic. A relatively high level of genetic diversity was observed, with estimates of Nei’s diversity index (H) and the Shannon information index (I) of 0.2719 and 0.4158, respectively. Additional genetic distance- and STRUCTURE-based analyses clustered all accessions into two or four subgroups based mostly on origin or color. The genetic differentiation between/among countries and inferred groups was significant, with Fst values ranging from 0.083-0.194%. Accessions from the Netherlands showed higher genetic variation than those from South Africa. Several accessions, such as Aphrodite, are recommended for future programs employing selective hybridization with the goal of expanding the color range. The results of the present study provide appropriate information applicable to designing effective breeding programs for double-flowered amaryllis.

Garden stock (Matthiola incana R. Br.) is a commercially important horticultural crop owing to its ornamental effect. There are different stock cultivars varied in color and shape, especially flowered phenotype is an essential index evaluating its commercial value, because double flowered cultivars have more brilliant flowers compared to single flowered one. The present work aimed: (1) to make superior cultivars with different colors, high fertility, being capable of early selecting only double flowered seedlings by leaf color and to investigate morphological characteristics and (2) to select RAPD and ISSR primers for the cultivar certification and identification to culture and produce good commercial stock cultivars. Here we obtained new double flowered stock cultivars with different colors including pink, pale pink and white, through outcrossing between “white” cultivar (high fertile but unable to select double flower phenotype) and “pink” cultivar (vice. versa). Among newly obtained stock cultivars, single and double flower seedlings are distinguishable from each other by leaf color, having about 70% of fertility. Moreover RAPD and ISSR markers selected in this study can be applied to identify different stock cultivars in seed production, culture and to establish cultivar certification system.

The analysis of herbaceous peony (Paeonia lactiflora Pall.) floral bud initiation and differentiation from autumn to early spring is important because flower formation is strictly correlated with flowering in late spring. A clear understanding of peony flower development would allow management practices to be optimized for stable annual production and supply of cut flowers. The aim of this research was to study the time-sensitive characteristics underlying flower development in peony cultivar ‘Dafugui’. Flower bud differentiation was assessed by paraffin and hand-made slices, as well as stereomicroscopy. Both methods have strengths and weaknesses. Our observations are not entirely consistent with those of previous studies. Flower bud differentiation in ‘Dafugui’, which starts from late September to mid-April of the following year, is divided into differentiation of the lower parts (separate differentiation periods for the bracts, sepals, petals, stamens, and pistillodes) and upper parts (separate differentiation periods for the petals, stamens, and pistil), and is closely related to annual changes in ambient temperature. Differentiation of lower flower buds takes place before winter dormancy, whereas that of upper parts starts early in the following spring, and finally forms a double-flowered type. The three methods used in this article can be used to study P. lactiflora flower bud differentiation and can contribute to an understanding of this process in the future.

Summary The history of cultivated white, pink and double flowered variants of the polymorphic species Wisteria floribunda (Willd.) DC. is discussed in order to preserve and standardise current usage of cultivar names within W. floribunda worldwide. The new combination Wisteria floribunda (Willd.) DC. f. microphylla (Makino) J. Compton is made here for a plant with very small leaflets.

Complex flowers containing large numbers of petals are especially prized as ornamental plants. Double-flowered Tricyrtis macranthopsis , in which stamens and carpels are converted to petaloid organs, is related to AGAMOUS ( AG ) gene expression. So we isolated AGAMOUS gene from T. macranthopsis , named as TrimAG . Since TrimAG expression was limited to whorls 3 and 4 and ectopic expression of TrimAG in Arabidopsis thaliana caused the same phenotype as overexpression of other AG orthologs in transgenic Arabidopsis , this gene has similar function as its AG orthologs. In the double-flowered T. macranthopsis cultivar, the level of TrimAG expression was reduced in the two inner reproductive whorls (stamens and carpels) and caused reproductive organ replacement with petaloid tepals and floral indeterminacy. Southern blot analysis of genomic DNA indicated that there were no significant differences between the double-flowered cultivar and wild-type plants. Analysis of promoter and AG intron II sequences did not identify any critically mutated sequences in the doubled-flowered cultivar. These results suggest that reduced TrimAG expression in whorls 3 and 4 might be caused by mutation in one of the genes in regulatory network which controls AGAMOUS expression or transcriptional silencing by methylation of TrimAG promoter/intron sequences.

Highlight Four double-flowered mutants of dioecious Silene dioica have been characterized; we recount their 400 year history, trace their ancestral genetic relationships, describe their phenotypes, and characterize mutant MADS-box gene alleles., Records of double-flowered Silene dioica date from the late sixteenth century and four named varieties are grown today, as previously, for their horticultural interest. Although double-flowered mutants have been characterized in several plants, their study in dioecious species is of particular interest due to influences of the homeotic mutation on the different floral whorl configurations in males and females. We have analysed four double-flowered varieties of Silene dioica: Flore Pleno and Rosea Plena date back to the seventeenth and nineteenth centuries, Thelma Kay and Firefly were recognized in the latter part of the twentieth and early twenty-first centuries. We have analysed the floral structure of the four varieties, which have distinct floral architectures. Based on Y chromosome-specific PCR analysis we show that Firefly is male and that the other three varieties are female: Random Amplification of Polymorphic DNA (RAPD) analyses suggested a common origin for the three female varieties. The double-flowered phenotype in all four varieties is caused by mutation of the C-function MADS-box transcription factor gene SDM1. We show that Firefly carries a unique 44bp insertion into SDM1, revealing an independent origin for this variety. Comparative analysis of SDM1 cDNA and genomic sequences in Flore Pleno, Rosea Plena and Thelma Kay shows that all three are caused by the same 7bp insertion within SDM1 and therefore share a common origin. The three alleles also differ by several single nucleotide polymorphisms, which represent somatic mutations accumulated over four centuries of asexual propagation.

A comparative study of floral ontogeny in normal and double-flowered phenotype of Syringa vulgaris was conducted using the epi-illumination light microscopy. In the wild phenotype, floral differentiation starts with calyx inception and the formation of four sepals in orthogonal positions (two median and two lateral). The corolla emerges as a continuous ring-like structure leading to the appearance of four petal lobes alternating with the sepals. Androecium was formed by initiation of two stamen primordia in transverse plane and finally the bicarpellate gynoecium emerges in median position. In the case of the double-flowered lilac, there are supernumerary petals in an additional whorl. In double-flowered phenotype, a ring meristem is formed acropetally after the first petal whorl initiates. Stamens and carpels initiated similarly in double-flowered as well as in wild-type plants. However, position of stamens deviates from the typical transverse situation. It seems that the appearing of an extra petal whorl did not exhibit any adverse effect on the initiation of other whorls, in terms of organ identity. Therefore, it would be suggested that the double-flowered phenotype of Syringa represents a case of neoheterotopy, with formation of an extra petal whorl, rather than a case of homoheterotopy with transformation of an ancestral androecium whorl into petals.

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.

International audience; Many double-flowered plants, in which petals replace stamens, are highly valued by the horticultural industry. These mutants exhibit a homeotic conversion of floral organs and frequently also a meristic increase in floral organ number. By gamma irradiation we generated a novel double-flowered mutant, Sl-dfl, in a male genetic background of the dioecious plant white campion (Silene latifolia). This mutant shows a homeotic conversion of stamens to petals, together with uncontrolled growth and division of second and third whorl floral organ primordia, causing a proliferation of petal and chimeric petal-stamen organs. We characterize this mutant developmentally by scanning electron microscopy and demonstrate that the effects of the mutation commence following the formation of a correctly partitioned floral meristem with a wild-type arrangement of organ primordia. We have commenced a molecular investigation of the Sl-dfl mutant by testing the expression and genomic organization of the known while campion putative MADS-box floral. homeotic genes. These si;dies indicate Four MADS-box genes to be unlikely to be mutated in the double-flowered mutant. The possibility that a putative C-function MADS-box gene may cause the mutant phenotype has not currently been excluded, though our morphological studies suggest that a C-funciion mutation is not involved in this case. We conclude that a number of different classes of double-flowered mutation exist, not all of which are currently known from model plant species. This may be indicative of important developmental differences between species and may also emphasize a need for comparative studies of floral development.

The double-flowered variety of Hibiscus rosa-sinensis L. (Malvaceae) displays a divergent floral morphology that appears to fit the criteria for homeosis. A comprehensive definition defines homeosis as the complete or partial replacement of one part of an organism with another part. The corolla of the single flower is pentamerous. The mature flower has a staminal tube bearing 60 – 70 stamens that surrounds an exserted synstylous gynoecium with five fused stigmas. In double flowers, the outermost whorl of petals is similar in appearance to that of the single flower. The remaining floral appendages have a morphology that is intermediate between petals and stamens, to varying degrees. No two double flowers are exactly the same, even on the same plant. As with other members of the Malvaceae, floral development in both floral types is unusual: once the calyx has been initiated, a ring meristem is formed from which both petal and stamen primordia are initiated. In the single flower, petal primordia are initiated on the flank of the ring, and then stamen primordia arise in five distinct and orderly clusters. In the double flower, petal primordia are also initated on the abaxial flank, but the remainder of the ring initiates primordia that form a mixture of petals, petal – stamen intermediates, and stamens. A common ring meristem that has two different developmental pathways provides a novel opportunity to study homeosis from the perspective of comparative developmental morphology. Keywords: homeosis, Hibiscus rosa-sinensis, androecium, intermediates, ring meristem, floral development.

In the model plant Arabidopsis thaliana , a core eudicot, the floral homeotic C-class gene AGAMOUS ( AG ) has a dual role specifying reproductive organ identity and floral meristem determinacy. We conduct a functional analysis of the putative AG ortholog ThtAG1 from the ranunculid Thalictrum thalictroides , a representative of the sister lineage to all other eudicots. Down-regulation of ThtAG1 by virus-induced gene silencing resulted in homeotic conversion of stamens and carpels into sepaloid organs and loss of flower determinacy. Moreover, flowers exhibiting strong silencing of ThtAG1 phenocopied the double-flower ornamental cultivar T. thalictroides ‘Double White.’ Molecular analysis of ‘Double White’ ThtAG1 alleles revealed the insertion of a retrotransposon causing either nonsense-mediated decay of transcripts or alternative splicing that results in mutant proteins with K-domain deletions. Biochemical analysis demonstrated that the mutation abolishes protein–protein interactions with the putative E-class protein ThtSEP3. C- and E-class protein heterodimerization is predicted by the floral quartet model, but evidence for the functional importance of this interaction is scarce outside the core eudicots. Our findings therefore corroborate the importance and conservation of the interactions between C- and E-class proteins. This study provides a functional description of a full C-class mutant in a noncore (“basal”) eudicot, an ornamental double flower, affecting both organ identity and meristem determinacy. Using complementary forward and reverse genetic approaches, this study demonstrates deep conservation of the dual C-class gene function and of the interactions between C- and E-class proteins predicted by the floral quartet model.

BACKGROUND AND AIMS Homeotic transitions are usually dismissed by population geneticists as credible modes of evolution due to their assumed negative impact on fitness. However, several lines of evidence suggest that such changes in organ identity have played an important role during the origin and subsequent evolution of the angiosperm flower. Better understanding of the performance of wild populations of floral homeotic varieties should help to clarify the evolutionary potential of homeotic mutants. Wild populations of plants with changes in floral symmetry, or with reproductive organs replacing perianth organs or sepals replacing petals have already been documented. However, although double-flowered varieties are quite popular as ornamental and garden plants, they are rarely found in the wild and, if they are, usually occur only as rare mutant individuals, probably because of their low fitness relative to the wild-type. We therefore investigated a double-flowered variety of lesser periwinkle, Vinca minor flore pleno (fl. pl.), that is reported to have existed in the wild for at least 160 years. To assess the merits of this plant as a new model system for investigations on the evolutionary potential of double-flowered varieties we explored the morphological details and distribution of the mutant phenotype. METHODS The floral morphology of the double-flowered variety and of a nearby population of wild-type plants was investigated by means of visual inspection and light microscopy of flowers, the latter involving dissected or sectioned floral organs. KEY RESULTS The double-flowered variety was found in several patches covering dozens of square metres in a forest within the city limits of Jena (Germany). It appears to produce fewer flowers than the wild-type, and its flowers are purple rather than blue. Most sepals in the first floral whorl resemble those in the wild-type, although occasionally one sepal is broadened and twisted. The structure of second-whorl petals is very similar to that of the wild-type, but their number per flower is more variable. The double-flowered character is due to partial or complete transformation of stamens in the third whorl into petaloid organs. Occasionally, 'flowers within flowers' also develop on elongated pedicels in the double-flowered variety. CONCLUSIONS The flowers of V. minor fl. pl. show meristic as well as homeotic changes, and occasionally other developmental abnormalities such as mis-shaped sepals or loss of floral determinacy. V. minor fl. pl. thus adds to a growing list of natural floral homeotic varieties that have established persistent populations in the wild. Our case study documents that even mutant varieties that have reproductive organs partially transformed into perianth organs can persist in the wild for centuries. This finding makes it at least conceivable that even double-flowered varieties have the potential to establish new evolutionary lineages, and hence may contribute to macroevolutionary transitions and cladogenesis.

The double marsh marigold, Caltha palustris ‘Plena’ was introduced to cultivation by Clusius in Vienna from a meadow near Salzburg in the late sixteenth century. The plant entered cultivation in gardens in Austria and in southern Germany. It became a valued garden plant in collections of connaisseurs in Austria, Switzerland, Germany, England, Holland and Flanders. There it was noted by Jan Brueghel I, who painted it in many of his flower paintings. Several artists who worked in Antwerp used the plant as well, probably following Brueghel. Besides ‘Plena’ the cultivar Monstruosa was possibly known in the early seventeenth century. Further development of cultivated forms of Caltha palustris occurred around 1900 and more recently in England from about 1985 onwards. Double marsh marigolds are valued but minor plants in present day horticulture; their days of glory were in early seventeenth century flower painting.

Periwinkle [Catharanthus roseus (L.) G. Don.], a member of the Apocynaceae family, is endemic to Madagascar. This herbaceous plant grows to 80 cm high and blooms continuously year-round with pink, purple, or white flowers (Hogan, 2003). A program to conserve and protect this species has been established, because it produces secondary metabolites such as terpenoid indole alkaloids that may be used to treat cardiac diseases and certain tumors in mammals (Favali et al., 2004). Catharanthus roseus has become pantropical by escaping from cultivation and naturalizing in many other regions (Levy, 1981). The flower is functionally close to cleistogamous with pollination limited by the foraging behavior of insects, and thus seed production is expensive (Miyajima, 2004). Breeding efforts have resulted in many new forms and cultivars, making them valued as bedding plants and flowering potted plants (Armitage, 2001). However, few double-flowered periwinkle cultivars are available on the markets. Flower doubleness may increase the horticultural value of the plant. ‘Taoyuan No. 1 Rose Girl’ was selected from a cross between a double-flowered mutant identified from a self-pollinated ‘Pacifica Polka Dot’ population and a line derived from selfing ‘Titan Burgundy’. The horticultural traits of this newly released cultivar are described below.

A comparative study of floral ontogeny in single- and double-flowered Alcea rosea L. was conducted using epi-illumination light microscopy. In both floral types, floral differentiation starts with the appearance of three epicalyx lobes, which subsequently subdivide to produce a 7–10-parted epicalyx. Five sepals appear then in a unidirectional or possibly spiral sequence. In single flowers, a corolla-androecium common primordium is formed and subsequently differentiated into five androecial sectors (= primary androecial primordia). Petals are developed at the base of the androecial sectors and secondary androecial primordia are initiated centrifugally in two rows on each sector. Later, tertiary androecial primordia are formed by the subdivision of secondary androecial primordia, which then differentiate into androecial units. Three types of double flowers were identified regarding androecial development. The first type of double flowers shows a more or less disorganised nature. However, 10 proliferation zones can be indentified in the proximal and distal tips of the androecial sectors. In the second and third types of double flowers, androecial development follows similar developmental pathways to that of single flowers. However, in second-type double flowers, the secondary androecial primordia differentiate into petals and the stamens then develop from the free space between the two rows of secondary androecial primordia. In third-type double flowers, after complete primordial partitioning, some primordia on the marginal parts of each androecial sector develop into petaloids or intermediate appendages. The gynoecium appears similarly in both floral types as numerous congenitally united carpel primordia. The double-flowered phenotypes of Alcea appear to fit the criteria for homoheterotopy with complete or partial replacement of stamens with petals, as well as for neoheterotopy, with the formation of stamens in a new position. Based on mutant phenotypes, it is suggested that different functions possibly contribute to the proliferation and differentiation of common primordia.

The increase in the capitula of zinnia plants (Zinnia violacea Cav.) was investigated by analyzing the production of shoots. The effects of removing the buds for capitula and application of BA on the production of shoots were also evaluated. It took ≈40 to 50 days from the emergence of axillary buds to the opening of the capitula at the apices of the shoots from these axillary buds. The application of BA shortened the number of days for the same process. The difference in the number of days from emergence of the axillary buds to that of the first descendant axillary buds was ≈25. The total number of capitula opened was greater in plants with the bud removal treatment than in intact plants. Chemical name used: (N-phenylmethyl)-1H-purine-6-amine (BA).

A naturally occurring mutant of Chamelaucium uncinatum Schauer (Geraldton wax) is described. It has double flowers with the staminodes transformed into petals. Pollen is exuded from the anthers but is not deposited on the pollen presenter in a lipid droplet, which is normal for the species. An anomalous secondary flower with petals, stamens, and gynoecium is present in the ovary.

The sterility of double-flowered freesia is caused by the abnormal structure of the flower. It proved possible, by cultivation at higher temperatures, to induce fertile single flowers in a double-flowered variety. In winter, under natural light conditions, the most favourable temperature range is 18–20°C.

Since the author (1929) found that the resistance of the toxic action of KClO3 correlated positively with the drought resitance in seedlings of rice varieties, the close relationships of the toxicant resistance to the other several kinds of characteristics of certain plants have feen observed by him as well as others, the results hitherto obtained being briefly summarized as follows. (1) Cold resistance: The cold resistant varieties are less resistant to the toxicant (Wheat, Barley, Rape, Genge, Radish, Brassica, Loquat and pine trees.) (2) Drought resistance: The drought resistant varieties are more resistant to the toxicant (Rice-Paddy and Upland rice-Upland rice only.) (3) Earliness in ripening: The earlier varieties are less resistant to the-toxicant than the later ones (Rice and Sugar-cane) (4) Sex: (a) The males are more resistant than the females (Hemp, Spinach Aucula Japonica and Remux Acetosa L.) (b) The males are less resistant than the females. (Papaya, Strawberry and Asparagus) (5) Double flowered and single flowered plants: Double flowered plants are more resistant than the single flowered ones. (Matthila incana and other many kinds of flower plants) (5) Virus diseased plants: Diseased plants are less resistant than healthy ones (Many kinds of vegetable crops and Tobacco plant.) (7) F1 plants: F1 plants are more resistant than either of their parents (Egg-plant) (8) Teratological forms: Teratological forms, especially in sexual organs, are more resistant than the normal ones (Rice) showing the materials used in the auther's experiments. Basing on the results of various kinds of tests with rice and wheat plants, the auther has ever put forward the hypothesis pertaining to the physiological cause of the toxicant resistace as is shown below: The chlorate itself is practically harmless to plants, but the salts are reduced by the reducing substances contained in plants, such as glucose, aldehydes, etc., resulting in the formation of hypochlorite which acts directly poisenous on plants and consequently the resistance to the toxicant is dependent on the amount of the substances concerned, i. e., the more the amount of the latter, the less the resistance to the toxicant. (Here, the amount of the reducing mattersiod in plants was compared by that of the ine consumed by the oxidation.) By the further study, the above-noted hypothesis is found also applicable in the case of the toxicant resistance with thesex es as well as double versus single flowering. The reducing substances, it may be believed, have much to do with the problem of the oxidation-reduction within plants. This idea is supported by estimating the activity of catalase (oxidizing agent) and the amount of the ascorbic acid (reducing agent) with rice, wheat and flower plants. From the results of the present research, it may be noticed of most importance to find out the reason why the characteristics conserned have the certain relationships with the oxidation-reduction reaction within plants for which some study along this line is now under way in the author's laboratory.

1. The single form is usually hermaphrodite, but as in the Carnation certain individuals become female through abortion or suppression of the stamens. 2. Double flowered individuals are on the other hand mostly female owing to complete petalody of the androecium. 3. When simple petalody occurs unaccompanied by splitting the double usually shows 15 petals in three alternating whorls of 5 each. In individual flowers oreven heads of flowers on such plants the petaloid modification may however be incomplete, and some stamens with normal pollen may be formed, the number of ‘petals’ in these flowers being then correspondingly fewer. Double-flowered plants showing some of these incompletely double flowers behave however as regards the transmission of the double character like the purely female doubles in which petalody is complete. 4. In other cases petalody is accompanied by a certain amount of splitting, thus giving rise to more than 15 ‘petals.’ In extreme cases the flower becomes monstrous with an abnormally large ovary. 5. All the doubles investigated when fertilised with pollen from incompletely double flowers yielded only double offspring.

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On Petalody of the Ovules and Other Changes in a Double-Flowered form of “Dianella Caerulea”