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UBC Theses and Dissertations

Identification, cloning, and functional characterization of Lavandula floral development genes Wells, Rebecca


The molecular aspects of flower initiation and development have not been adequately investigated in lavender (Lavandula). In order to identify genes that control these processes, I employed RNA-Seq to obtain sequence information for transcripts originating from the vegetative shoot apical meristem (SAM) and developing inflorescence tissues of Lavandula angustifolia and Lavandula × intermedia plants, and assembled a comprehensive transcriptome of 105,294 contigs. Homology-based annotation provided gene ontology terms for the majority of transcripts, including over 100 genes homologous to those that control flower initiation and organ identity in Arabidopsis thaliana. Expression analysis revealed that most of these genes are differentially expressed during flower development. For example, LaSVP, a homolog of the floral repressor SHORT VEGETATIVE PHASE (SVP), was strongly expressed in vegetative SAM compared to developing flowers, implicating its potential involvement in flowering repression in lavender. In total, fourteen full-length lavender transcription factor homologs were identified. To investigate these genes further, I constitutively expressed each gene in transformed A. thaliana plants, evaluating the effects on flower initiation and morphology. Expression of the Lavandula genes in A. thaliana was gene- dependent. Phenotypic effects were observed for LaCC, LaFT, and LaSVP transformants. For example, constitutive expression of the LaSVP gene in A. thaliana delayed flowering and affected flower organ identity in a dosage- dependent manner. Four of the highest expressing lines produced sepals instead of petals and were sterile as they failed to develop proper seed pods. This study provides the foundation for future investigations aimed at elucidating flower initiation and development in lavender.

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