Tracking the molecular background of phenotypic change in fruit evolution and plant domestication

Understanding molecular changes of phenotypic adaptation are central goals in evolutionary biology. This thesis contributes to these goals by presenting two case studies comparing the molecular network of fruit dehiscence in three Brassicaceae species that differ in prominent fruit traits and by summarizing data on the molecular background of convergent crop domestication. Fruits of L. campestre and A. thaliana share a common mechanism of dehiscence but differ in overall morphology. Data presented here highlight that despite this morphological variability the molecular pathway of fruit dehiscence is conserved between both species. My results further contribute to a better understanding of Brassicaceae fruit development by identifying the transcription factors ALC and SPT to be repressors of IND gene expression.L. appelianum is a close relative of L. campestre and serves as a representative of those Brassicaceae species that have evolved indehiscent fruits. The molecular change causing this phenotypic adaptation is identified to be a loss of expression of dehiscence zone identity genes at the valve-replum border of L. appelianum fruits.Plant domestication is often accompanied by dramatic phenotypic changes, presenting an excellent model to study molecular principles of adaptation. A survey of genes known to carry causative mutations responsible for domestication-related changes reveals that convergent plant domestication is often based on mutations at orthologous loci. Furthermore, factors are identified that influence the probability of a certain gene to serve as a target for mutations driving phenotypic adaptation. This thesis combines studies targeting the molecular background of phenotypic conservation as well as phenotypic change and searches for general patterns that may allow explaining or even predicting the likely course of molecular evolution. The results are of relevance for basic evolutionary biology and future agronomic applications, alike.