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Genetic and molucular analyses of the role of the Unusual Floral Organs gene in regulation of shoot and organ identity in Arabidopsis Thaliana

University of British Columbia

Shortly after initiation, shoot and floral organ primordia become determined to particular fates based on their spatial/temporal position in the plant. Many genes are known which affect the proper regulation of this process, and these genes are expressed in spatial/temporal patterns consistent with the developmental decisions they regulate. Little is known about the mechanisms by which these regulatory genes achieve their final patterns in the developing plant. I have identified a novel gene involved in regulation of flower initiation and development in Arabidopsis. This gene is designated UNUSUAL FLORAL ORGANS (UFO). Ufo plants generate more coflorescences than do the wild type and, unlike wild type, coflorescences often appear apical to the first floral shoot, indicating that UFO has a role in regulating coflorescence versus floral fate determination by lateral shoots. In addition, Ufo floral organs exhibit variable homeotic transformations to any of the four organ types in the second, and third whorls, suggesting that ufo mutations result in variable expression levels and/or patterns of the organ identity genes. These hypotheses are supported by phenotypic analysis of double mutants between ufo and other floral initiation and floral organ identity gene mutations. Surprisingly, in situ hybridization analysis revealed no obvious differences in mRNA levels or pattern for any organ identity gene examined. These results suggest that UFO may act post-transcriptionally to regulate the expression of floral organ identity genes. UFO was cloned by homology to the Antirrhinum gene FIMBR1ATA. Sequence analysis revealed no homology to any other gene in the sequence databases. UFO transcription is detected in spatial/temporal patterns consistent with its proposed roles in shoot and organ identity gene regulation, and does not appear to rely directly on any of the floral initiation genes. Collectively, the data indicate that UFO is required as part of the floral initiation process to establish the proper domains of shoot and organ identity gene function, and that this regulation occurs post-transcriptionally.

Thesis/Dissertation

application/pdf

2009-03-17

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http://hdl.handle.net/2429/6180

Botany

University of British Columbia

UBCV

DSpace