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dc.contributor.advisorGlover, Beverley J.
dc.contributor.advisorRudall, Paula J..
dc.contributor.advisorBateman, Richard M.
dc.contributor.authorBox, Mathew S.
dc.date.accessioned2010-08-25T11:42:36Z
dc.date.available2010-08-25T11:42:36Z
dc.date.issued2010-06-08
dc.identifier.citation1) Box, M., Bateman, R., Glover, B. & Rudall, P. (2008). Floral ontogenetic evidence of repeated speciation via paedomorphosis in subtribe Orchidinae (Orchidaceae). Botanical Journal of the Linnean Society, 157, 429–454. 2) Bell, A., Roberts, D., Hawkins, J., Rudall, P., Box, M. & Bateman, R. (2009). Comparative micromorphology of nectariferous and nectarless labellar spurs in selected clades of subtribe Orchidinae (Orchidaceae). Botanical Journal of the Linnean Society, 160, 369–387. 3) Box, M.S. & Glover, B.J. (2010). A plant developmentalist's guide to paedomorphosis: reintroducing a classic concept to a new generation. Trends in Plant Science, In Press.en_GB
dc.identifier.otherPhD.33247
dc.identifier.urihttp://www.dspace.cam.ac.uk/handle/1810/226324
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/226324
dc.description.abstractA key question in biology is how changes in gene function or regulation produce new morphologies during evolution. The nectar spur is an evolutionarily labile structure known to influence speciation in a broad range of angiosperm taxa. Here, the genetic basis of nectar spur development, and the evolution of differences in nectar spur morphology, is investigated in Linaria vulgaris and two closely related species of orchid, the primitively longer-spurred Dactylorhiza fuchsii, and more derived short-spurred D. viridis (Orchidinae, Orchidaceae). Despite considerable morphological and phylogenetic differences, nectar spur ontogeny is fundamentally similar in each of the study species, proceeding from an abaxial bulge formed on the ventral petal relatively late in petal morphogenesis. However, spur development is progenetically curtailed in the short-spurred orchid D. viridis. In each case spur development involves class 1 KNOTTED1-like homeobox (KNOX) proteins. KNOX gene expression is not restricted to the spur-bearing petal, indicating that additional components are required to define nectar spur position, e.g. canonical ABC genes, determinants of floral zygomorphy, and additional (currently unknown) factors. However, constitutive expression of class 1 KNOX proteins in transgenic tobacco produces flowers with ectopic outgrowths on the petals, indicating that KNOX proteins alone are, to some degree, capable of inducing structures similar to nectar spurs in a heterologous host. Interestingly, KNOX gene expression is high in the ovary of all study taxa, suggesting that KNOX proteins may also have been involved in the evolution of this key angiosperm feature. Although principally involved in maintaining indeterminacy in the shoot apical meristem (SAM), members of the KNOX gene family have been co-opted in the evolution and development of compound leaves where they suppress differentiation and extend the morphogenetic potential of the leaf. A similar model is presented here to explain the role of KNOX proteins in nectar spur development. Co-option of KNOX gene expression to the maturing perianth delays cellular differentiation, facilitating the development of the nectar spur but requiring additional, unknown factors, to determine nectar spur fate. As facilitators of nectar spur development, changes in the spatio-temporal patterns of KNOX gene expression may alter the potential for nectar spur development and explain the critical length differences observed between the orchids D. fuchsii and D. viridis (and among other angiosperm taxa). Taken together, the available data indicate that KNOX genes confer a meristematic state upon plant tissues in a variety of morphogenetic contexts, making the gene family a potentially versatile tool to mediate a wide variety of evolutionary transformations.en_GB
dc.description.sponsorshipThanks for the generous financial support of the Dept. Plant Sciences, University of Cambridge and Corpus Christi College, Cambridge.en_GB
dc.language.isoenen_GB
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectSpuren_GB
dc.subjectEvolutionen_GB
dc.subjectDevelopmenten_GB
dc.subjectEvo-Devoen_GB
dc.subjectDactylorhizaen_GB
dc.subjectLinariaen_GB
dc.subjectPaedomorphosisen_GB
dc.subjectHeterochronyen_GB
dc.subjectProgenesisen_GB
dc.subjectNeotenyen_GB
dc.subjectKNOXen_GB
dc.subjectlabellumen_GB
dc.subjectOrchiden_GB
dc.subjectToadflaxen_GB
dc.subjectAntirrhinumen_GB
dc.subjectSnapdragonen_GB
dc.titleRole of KNOX genes in the evolution and development of floral nectar spursen_GB
dc.typeThesisen_GB
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridgeen_GB
dc.publisher.departmentDepartment of Plant Sciencesen_GB
dc.publisher.departmentCorpus Christi Collegeen_GB
dc.publisher.departmentRoyal Botanic Gardens, Kewen_GB
dc.identifier.doi10.17863/CAM.16449
datacite.issupplementto.doi10.1111/j.1095-8339.2008.00794.x


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