A study of the petal epidermis may be useful to systematics as well as to the knowledge of ecological and coevolutionary adaptations between the parasites and their pollinators. Another aspect of the evolutionary conversion of epidermis into a persistent tissue almost certainly altered epidermis development. Mechanism of floral scent production in osmanthus fragrans. The epidermis from the greek, meaning overskin is a single layer of cells that covers the leaves, flowers, roots and stems of plants. Cincinnata controls both cell differentiation and growth in petal lobes and leaves of antirrhinum1 brian c. The plant surface is by default flat, and development away from this default is thought to have some function of evolutionary advantage. Sem studies of epidermal patterns of petals in the angiosperms.
This change in cell morphology had a consequence for petal colour, in that the mutant flowers appeared slightly paler and less velvety. Novel functions of the arabidopsis transcription factor. This fountainlike pattern is the most characteristic feature of the petal epidermis, manifested in both the wildtype dorsal petal and the dorsalized petal of the backpetals mutant. The nature of the selective pressures which have resulted in the conicalpapillate shape of the cells of the adaxial epidermis of many petals has been a matter for considerable speculation. To observe petal epidermal cells, detached petal samples were directly observed with a tm3000 table. This effect is discussed in more detail below, but was shown by noda et al. Papillae were found to occur in the epidermis on both sides of all the petals spurred, lateral and. Thick skin, found on the palms of the hands and soles of the feet, consists of five layers while thin skin consists. We observed a wide range of wettability of the petal surface among seven herbaceous species native to alpine habitats. Singlestep surface replication of flower petals for sem. The present work is a comparative study of the microsculpture of nectar guides and landing. The altered morphology of abcg flower organs was evident when observing with scanning electron microscopy sem. Study of the leaf epidermis in some egyptian taxa of fagonia l. Petal micromorphology observed by sem the petal abaxial and adaxial epidermis differs in cell shape and size, and has the same structure in all analyzed abc d ef i g h jk fig.
Oberkochen, germany or a hitachi s4700 sem for critical. Figures 1b and 1c display sem images of the ue and le, respectively, of a rose petal note that the morphologies of ue and le on di. Physical interaction of floral organs controls petal. D, the same flower with c after 3 d, with the straight growth of petals. The study has demon strated that only adaxial epidermal cells form conical papillae covered by massive cuticular striae. Petal conical cells across various species have been shown to function in pollinator attraction, light capture and reflectance, and maintaining temperature and wettability 35,36,37,38. Epidermal focusing of light and modelling of reflectance. Approximately 80% of angiosperm species have specialized conical cells in the petal epidermis 35,36,37,38. F, scanning electron microscopy image of petal epidermis in fop11, where a sepal has been removed and petals grow straight. Coen john innes centre, norwich nr4 7uh, united kingdom to understand how differentiation and growth may be coordinated during development, we have studied the action of the. Cincinnata controls both cell differentiation and growth. Merkel cells occur deep in the epidermis at the epidermal. Characters of both the adaxial and abaxial surfaces of the petal epidermis, including cell type papillose conical cells, papillose knobby.
For sem, the material was dehydrated in a graded ethanol series, then criticalpoint dried with liquid carbon dioxide, further dissected and coated with carbon. Petal wettability and microstructures of the petal epidermis. In shape, modified cells of the inner petal epidermis resembled skittles rather than cones. Petal characterization at flower development stages 9 a and 14 b in bpe. Sem visualization of the adaxial petal epidermis revealed that in the bpe. Surface of epidermal cells, especially those at the marginal region, are flattened. Nanoridges that characterize the surface morphology of. The sem study revealed differences in cellular morphology and patterning on the epidermal layers of differently coloured flower petals. Ultrastructure and optics of the prismlike petal epidermal cells of.
Petals grow from petal primordia that emerge from stage 5 flower buds smyth et al. A theoretical approach to the relationship between. In comparison, cyp77a62 exhibited a much more severe ridge formation defect on both the petal blade and stock, with very few ridges formed figure 1h and 1k. When we think of protecting our bodies from the elements, we may think of putting on a jacket, or shoes and socks. The arabidopsis abcg transporter is required for flower cuticle secretion and patterning of the petal epidermis. Important goals in understanding leaf development are to identify genes involved in pattern specification, and also genes that translate this information into cell types and tissue structure. Growth and cellular patterns in the petal epidermis of. The pathways of biosynthesis of the essential oils and other. The increase in petal size associated with loss of function of opr3 or bpep occurs after stage 9 during flower development. Previous studies have shown that ducts, cavities, secreting trichomes, conicalpapillate cells, and other essential oils secretory tissues usually possess specialized cellular structures 510. Crawford, utpal nath2, rosemary carpenter, and enrico s.
It forms a boundary between the plant and the external environment. Pdf diversity in the structure of the petal epidermis. An ortholog of mixtalike2 controls epidermal cell shape. A model of floral reflectance of petals with conicallyshaped epidermal cells is presented for nerium oleander and oxalis pescaprae. Esem and cryo sem revealed an absence of secretory structures on the surface of the sweet osmanthus petals. Cp sem images of petal epidermis adaxial and abaxial, respectively derided from knock out plants of at5g23970. E, scanning electron microscopy image of petal epidermis in fop11. Evolution of petal epidermal micromorphology in leguminosae and. Structurebased color of natural petals discriminated by polymer replication. Observations and photographic documentation employed a scanning. Spatiotemporal orientation of microtubules controls. Original scanning electron microscope image of nicotiana alata leafs epidermis, showing trichomes hairlike appendages and stomata eyeshaped slits, visible at full. In this study, we found substantial variation in both petal wettability and the morphology of the petal epidermis.
Lossoffunction mutations at the jagged jag locus result in arabidopsis plants with abnormally shaped lateral organs including serrated leaves, narrow floral organs, and. In an ephemeral epidermis, for example that of a leaf or flower petal, the cuticle and waxes produced while the organ is young are sufficient to control water movement for the rest of the life of the organ. Diversity in the structure of the petal epidermis emitting odorous compounds in viola. American journal of botany botanical society of america. Sophisticated patterning of pigments, cuticular elaborations, and multicellular papillate trichomes make the g. Fragment of the rosa rugosa plant and petal tissue sem. The present work is a comparative study of the microsculpture of nectar guides.
The surface morphology of a flower petal can be a significant marker for the characterization of its variety. They form merkel discs, which, in association with nerve endings, serve a sensory function. Published online 14 december 2011 directional scattering. Petals and sepals with flat cells and a tightly packed mesophyll had a glossy. Scanning electron microscopy sem and freeze fracture floral tissue was dissected, fixed overnight in formaldehydeacetic acidalcohol faa, dehydrated for 30 min through an alcohol series 50, 60, 70, 80, 95 and 100%, then criticalpoint dried, mounted and sputter coated. We used scanning electron microscopy to describe petal epidermal cell patterns and evaluate their systematic implications for 22 representative taxa belonging to all 9 genera of the rosaceae tribe spiraeeae, including the monotypic korean genus pentactina. In general, the surface of a plants petal features upper epidermis ue and lower epidermis le tissues. The activity of the mixta gene in petal epidermal cells of the snapdragon. Nanoridges that characterize the surface morphology of flowers require the synthesis of cutin polyester yonghua libeissona,1, mike pollarda, vincent sauveplaneb, franck pinotb, john ohlroggea, and fred beissona,c,1,2 adepartment of plant biology, michigan state university, east lansing, mi 48824. The aim of the study was to identify the characteristics of the epidermis of both sides of the petal and to observe whether adaxial and abaxial epidermal cells can secrete essential oil. Although the functions of many plant epidermal cells have been described, the function of conical epidermal cells, a defining feature of petals in the majority of insectpollinated flowers, has not 1, 2. In particular, conical shaped petal epidermal cells have been shown to have an. Spatiotemporal orientation of microtubules controls conical cell shape in arabidopsis thaliana petals. The petal epidermis of rubus species were studied by using scanning electron microscope.
Petal epidermal micromorphology in holoparasitic orobanchaceae and its signi. Khafagi botany and microbiology department, faculty of science girls branch, al azhar university, cairo, egypt abstract leaf epidermis structure of fagonia taxa has been studied by light microscope lm and. Ab sem images of the wt petal adaxial and abaxial side, respectively. Study of the leaf epidermis in some egyptian taxa of. Observations were made in a jeol jsm840a scanning electron. The investigations were conducted using light and scanning electron microscopy. The micromorphology of the adaxial and aba xial epidermis of petals and their cross sections were analyzed with the use of scanning electron microscopy.
Petal micromorphology and its systematic implications in. Characters of both the adaxial and abaxial surfaces of the petal epidermis, including cell type papillose. Scanning electron microscopy sem was performed using a. Structurebased color of natural petals discriminated by. Instead, the petal cells protruded slightly outward, and the cell surfaces of both. In contrast, the mature cus21 petal stalk also had greatly reduced ridges on the epidermis, similar to the cus21 sepal phenotype figure 1i and 1j. Shine transcription factors act redundantly to pattern the. Bigpetalp, a bhlh transcription factor is involved in the. Scanning electron microscope sem, petal pattern, taxonomy, iran. Defective nanoridge phenotypes observed on the surfaces of floral organs other than petals in 35s. Why do so many petals have conical epidermal cells. Figure 3 shows sem images of the surface structures of an airdried. A total of 175 species were studied representing 26 tribes and 89.
The epidermis of the mutant petals was composed of flat hexagonalbased cells. Using light and scanning electron microscopy and histology, we identified three distinct specialized cell types of the petal epidermis that compose the petal spot. The arabidopsis abcg transporter is required for flower. Interspecific variations in the surface wettability and. The model was achieved by combined microscopicscale structures and optical properties of petals. Scanning electron microscopy revealed that petal cells of transgenic tobacco plants expressing any one of the three genes grew to a greater length than in wild type. Epidermis botany, perhaps could be added to trichome or stoma. Dendrobium, pigment distribution, epidermal cell shape, flower color, petal. Initially, the petal primordia remain small, but the cells start to divide faster from stage 7 and 8 of flower development onwards and cell division rate reaches a plateau around stages 911, after which it rapidly declines. Flowers of holoparasitic plants have evolved several adaptations for pollination as part of their parasitic strategies. Control of cell and petal morphogenesis by r2r3 myb transcription. Intraspecific variation in the petal epidermal cell morphology of vicia.
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