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Fwd: Comparative labellum micromorphology of the sexuallydeceptive temperate orchid genus Ophrys: diverseepidermal cell types and multiple origins of

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  • Peter Bernhardt
    Dear Colleagues: Have you seen this? Ryan and Kingsley, have you put those Caladenia labella under that wonderful SEM in your lab? Peter ... From: Neal Smith
    Message 1 of 1 , Mar 31, 2010
    Dear Colleagues:

    Have you seen this?  Ryan and Kingsley, have you put those Caladenia labella under that wonderful SEM in your lab?
      
    Peter

    ---------- Forwarded message ----------
    From: Neal Smith <smithn@...>
    Date: Tue, Mar 30, 2010 at 7:06 PM
    Subject: Comparative labellum micromorphology of the sexuallydeceptive temperate orchid genus Ophrys: diverseepidermal cell types and multiple origins of
    To: Neal Smith <smithn@...>


    NOTA BENE:I thought long before deciding to send this one out. Plant morphology can be pretty thick. But if you are interested in orchids especially the terrestrial Ophrys orchids of the OLD World upon which so much brilliant work has been done in recent years, this is a TOUR DE FORCE!!!!!!!!

    The details of the scanning microscopy are extraordinary and the text detailing the possible functions will knock your eye out.    If it were just this, it would be wonderful but the last sentence in the abstract slaps you in the face:

     

    "The relative contributions of olfactory, visual and tactile cues to the sophisticated pseudocopulatory pollination mechanism that characterizes Ophrys

    remain unclear, but the degree of reproductive isolation achieved, and thus the speciation rate, have certainly been greatly exaggerated by most observers."

     

    This is why it got into the Biological Journal of the Linnaean Society!!!!!!

     

    I compressed the PDF from 6.98 MB!!!

     

    Comparative labellum micromorphology of the sexually deceptive temperate orchid genus

    Ophrys: diverse epidermal cell types and multiple origins ofstructural colourboj_1033 504..540

     

    ELIZABETH BRADSHAW

    1,2, PAULA J. RUDALL1, DION S. DEVEY1,

    M. MURPHY THOMAS

    1,3, BEVERLEY J. GLOVER3 and RICHARD M. BATEMAN1*

    1

    Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK

    2

    John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7RH, UK

    3

    Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK

    Received 30 September 2009; accepted for publication 19 January 2010

    Labellum micromorphology was imaged via scanning electron and light microscopy in 32 microspecies and one artificial hybrid of the European terrestrial orchid genus

    Ophrys, together representing all ten macrospecies circumscribed in the genus via molecular phylogenetics. Imaging of homologous regions of the adaxial surface,

    paying particular attention to the diagnostic feature of the comparatively reflective speculum, revealed the presence of between three and seven epidermal cell types on each labellum, the less complex labella being plesiomorphic. Epidermal protuberances range from short, domed papillae to long, twisted unicellular filaments.Multiple origins are inferred for pale labellar margins, large yellow appendices (both putative smophores exuding pseudopheromones), broad flat labella and long lateral horns. Homoplasy in the speculum is manifested in unusually complex or simple outlines and the presence or absence of a pale margin or iridescence. The reflectivity of the speculum is caused by a combination of chemical and physical colour, whereas iridescence can be caused only

    by physical properties. The specula of most microspecies studied bear striated trichomes, albeit maturing comparatively late in ontogeny and being sufficiently narrow to allow light to reach the flat polygonal trichome bases. Reflectivity appears to be negatively correlated with the convexity and degree of cuticular corrugation shown

    by these epidermal cells. Two clades (the

    Speculum + Tenthredinifera + Bombyliflora group and Bertolonii subgroup of the Sphegodes group) have lost specular trichomes and include the most iridescent species; their flat, polygonal, nonstriated cells resemble those observed on the paired pseudoeyes that bracket the stigmas of all Ophrys except

    the

    Fusca group. The smooth thick-layered cuticle and dense layers of organelles and starch bodies revealed by preliminary transmission electron microscopy study provide alternative candidates for the primary reflective surface of the speculum; in contrast, the trichomes and conical cells that dominate Ophrys labella, and occur on the specula of all but the most reflective species, absorb and/or diffuse light. Multiple MYB family genes are hypothesized to control epidermal micromorphology. The relative contributions of olfactory, visual and tactile cues to the sophisticated pseudocopulatory pollination mechanism that characterizes Ophrys remain unclear, but the degree of reproductive isolation achieved, and thus the speciation rate, have certainly been greatly exaggerated by most observers. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162,

    504–540.

    ADDITIONAL KEYWORDS

    : iridescence – ontogeny – phylogeny – plant–pollinator co-evolution

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