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Title: Examination of CYCLOIDEA-like genes in the Leguminosae
Author: Citerne, Helene Lucie
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2004
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The genetic control of floral symmetry in the Leguminosae and the genetic basis for the apparent reversal to radial symmetry in Cadia were investigated using a candidate gene approach. In the model organism Antirrhinum majus (snapdragon, Lamiales), two paralogous genes CYCLOIDEA (CYC) and DICHOTOMA (DICH) determine dorsal (adaxial) floral identity and play a crucial role in the establishment of zygomorphy. The orthologue of CYCIDICH in Arabidopsis thaliana TCP1 also has adaxial expression in the early stages of floral development. CYC-like genes may therefore be good candidates for the control of dorso-ventral floral symmetry in lineages outside of Antirrhinum. Using a phylogenetic approach, homologous of CYCITCP1 were identified in legume taxa from the major clades of the Papilionoideae, as well as from subfamilies Caesalpinioideae and Mimosoideae. LEGCYC genes have duplicated prior to the evolution of the Papilionoideae and form three main groups (LEGCYC1A, LEGCYC1B and LEGCYC2). Within these major gene groups, the precise relationships of paralogues between species from the main clades of the Papilionoideae was difficult to determine because of the rapid rate of sequence evolution outside of the conserved TCP and R domains characterise of CYC-like genes. Nevertheless, the phylogenetic framework enabled the identified of orthologous gene pairs in the radially symmetrical papilionoid taxa Cadia purpurea and in a closely related species, Lupinus nanus, with typical zygomorphic flowers. LEGCYC1A and LEGCYC1B expression in L. nanus was restricted to the adaxial part of the floral meristem and was maintained throughout flower development. This pattern is very similar to Antirrhinum CYC and suggests these genes are important for the development of bilateral symmetry in legumes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available