Development and Evolution of Complex Reproductive Traits in the Brassicaceae and Cleomaceae

• Author / Creator

  Carey, Shane F

• Flowering plants exhibit a bewildering diversity of forms, which raises fundamental questions on how that diversity arises. A cornerstone of evolutionary developmental biology is the expansion of comparative landscapes and establishment of focal clades that enable investigation of complex and ecologically important traits. The overarching goal of this thesis is to elucidate the developmental and genetic bases of ecologically important traits in sister families Brassicaceae and Cleomaceae. I analyze developmental and anatomical data, which are key to interpreting gene expression and functional studies. RNA-seq is a powerful tool to examine differential gene expression between and within developmental stages, floral organs, and species. While gene expression data are crucial for exploring the genetics underlying morphologies across taxa, they are only correlational. As such, I established the use of virus-induced gene silencing in Cleomaceae, which provides a causal link between gene function and phenotype. Combined, these approaches are essential for assessing the genetic pathways underlying diversity of form.
  Using these approaches, I address a range of questions that answer how changes in gene regulation have led to morphological diversity in Cleomaceae and Brassicaceae. First, I examine how a novel fruit morphology of segmented fruits in two species of Brassicaceae is likely due to modification of an existing fruit-patterning pathway. Second, I demonstrate that there is a high degree of conservation in the genetic basis of nectary formation and nectar secretion between Cleome violacea and model species Arabidopsis thaliana. Next, I show that a key regulator, which has been recruited across the angiosperms for the formation of monosymmetry is also necessary to impart monosymmetry in C. violacea. Finally, I show that differences in floral color between two species of Cleomaceae is due to broad downregulation of the anthocyanin biosynthesis pathway, and modulation of the carotenoid biosynthesis pathway. Thus, my work examines floral and fruit traits in two families. Altogether, my thesis discusses the evolution of symmetry, pigmentation, and nectar gland development in Cleomaceae, and fruit dehiscence/disarticulation in Brassicaceae. In each case, parallel evolution explains much of the observed diversity of form, i.e., across the core eudicots similar gene pathways are responsible for the same traits, such as fruit dehiscence, nectary initiation, monosymmetry, and pigmentation. However, there is also novel gene expression underlying each explored trait, denoting the complex and beautiful nature of fruit and floral evolution.

• Subjects / Keywords

  • Evolution
  • Development
  • Brassicaceae
  • Cleomaceae
  • RNA-seq
  • VIGS
  • Monosymmetry
  • Nectary
  • Pigmentation

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-wv83-b804

• 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.