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Title: Leaf-shape mutants and homeobox genes in Antirrhinum majus
Author: Roccaro, Mario
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1997
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Plants are composed of homologous repeating structures produced continuously by the apical meristem. Cells of the apical meristem show few morphological differences, but may have vastly different fates depending on their position. For instance, group of cells in the flanking parts of the apical meristem will form leaves, while those in the central zone of the meristem will remain in an undifferentiated state of growth. This suggests that patterns exist in the meristem. However, meristems are small and not suited to biochemical and surgical analysis. As a result, relatively little is known of the mechanisms which determine patterns and cell fate in the apical meristem, and in the leaves produced by them. To investigate the genetic control of leaf development two alternative approaches were used. The first approach was to identify transposon induced leaf-shape mutations in an attempt to isolate and characterise the affected genes by transposon tagging. The second approach was to isolate by homology genes which show patterns of expression within the meristem and have the potential to control developmental fate. Fourteen different leaf shape mutants were identified by screening populations of Antirrhinum plants carrying active transposons. The mutants were characterised genetically of transposon-induced mutations. Southern hybridisation was used to identify a transposon copy that appeared to be responsible for the mutation. Unfortunately, it was not possible to determine whether sequences flanking the transposon contain part of the graminifolia gene. Moreover three new homeobox genes, SNAP1, SNAP2 and SNAP3 were isolated by sequence homology. The gene product of SNAP1 shows a high degree of homology with the product of the homeobox gene KNOTTED1 of maize, whereas in SNAP2 and SNAP3 products, the homology is restricted to characteristic highly conserved regions of the KNOTTED1 protein. Using in situ hybridisation the mRNA expression patterns of these three hox-genes have been determinated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available