UBC Theses and Dissertations
Transcriptomics of post-anthesis colour change in Lotus Boehm, Mannfred M. A.
Post-anthesis colour change (PACC) is widely thought to be an adaptation to signal floral viability to pollinators, and may be a developmental pre-pattern for bird pollination in Lotus. Lotus filicaulis and Lotus sessilifolius are insect-pollinated herbaceous legumes with flowers that open yellow, shift to orange and finally, red. This thesis examines the ecological and molecular basis for floral colour change in these Lotus species. L. filicaulis was cultivated in a glasshouse from which pollinating insects (bees) were excluded, and the rate of colour change was recorded in both unpollinated and manually pollinated flowers. Unpollinated flowers from both the yellow stage and red stage were sampled for sequencing. The transcriptomes of L. filicaulis and L. sessilifolius of both colour stages were analyzed for differentially expressed genes and enriched ontologies. Pollination significantly accelerates PACC in L. filicaulis, consistent with the hypothesis that PACC increases pollination efficiency by directing pollinators to unpollinated flowers. RNA-seq results show the synchronized upregulation of the entire cyanidin biosynthesis pathway in the red stage of PACC of both Lotus species – possibly at the expense of adjacent pathways competing for the same substrate. This thesis is the foundation for understanding the molecular evolution of PACC in Lotus and will be useful in testing the hypothesis that PACC is a preadaptation to bird pollination in Lotus.
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