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Elucidating the basis of poorly understood floral traits associated with pollination biology
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- Author / Creator
- Zenchyzen, Brandi
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Flowering plants have evolved a stunning array of floral colours, scents, and structures, which act synchronously as cues for pollinators. Comprehensive investigations of the extraordinarily diverse floral features involved in plant-pollinator interactions requires expansion of the comparative landscape beyond the traditional model organisms. Cleomaceae (Brassicales) is an ideal focal clade for such studies as it exhibits substantial floral variation. I explore floral features related to pollination biology in an evolutionary developmental context by integrating developmental morphology, chemical characterizations, and comparative transcriptomics of Cleomaceae. First, I describe and compare floral nectaries, the structures responsible for nectar secretion, within and among Cleomaceae genera. I reveal the substantive diversity in form with dramatic variation in floral nectary size and shape across Cleomaceae, and introduce a modified fast green and safranin O staining protocol to yield vibrant histological sections without highly hazardous chemicals. Second, I present the first in vivo colour images of ultraviolet-fluorescent nectar. Ultraviolet radiation induces vibrant blue fluorescence of Cleomaceae nectar, a crucial reward for pollinators. Next, I shift attention to Gynandropsis gynandra (Cleomaceae), an underutilized crop native to Africa and Asia. I characterize and compare the floral fragrance of African and Asian accessions of G. gynandra (Cleomaceae) and examine the floral morphology and gene expression patterns associated with scent production and emission. I discover drastically different floral scent profiles between the African and Asian accessions and identify the stalk-like floral structures as those putatively involved in olfactory signalling. Lastly, I focus on G. gynandra’s androgynophore, a stalk-like structure that elevates the reproductive organs of the flower, to provide a detailed description throughout development, examine global gene expression patterns, and identify candidate elongation genes. I show that the radially symmetric androgynophore of G. gynandra rapidly lengthens primarily via cell elongation and is characterized by complex gene expression patterns including differential expression of floral organ identity genes and genes associated with organ development and growth in Arabidopsis thaliana. Overall, my research contributes to our understanding of floral features involved in plant-pollinator interactions by exploring the diversity of floral nectaries and exquisite nectar across Cleomaceae. It also provides a more holistic picture of G. gynandra’s flower from the unique floral structures (i.e., inconspicuous nectary and androgynophore) to the geographically variable floral scent.
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- Graduation date
- Fall 2023
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.