Shaping the Dicot Fruit: Molecular and Genomic Approaches to Fruit Development

The fruit is one of the most complex and important structures produced by flowering plants, and understanding the development and maturation process of fruits in different angiosperm species with diverse fruit structures is of immense interest. In the work presented here, molecular genetics and genomic analysis are used to explore the processes that form the fruit in two species: The model organism Arabidopsis and the diploid strawberry Fragaria vesca. One important basic question concerns the molecular genetic basis of fruit patterning. A long-standing model of Arabidopsis fruit (the gynoecium) patterning holds that auxin produced at the apex diffuses downward, forming a gradient that provides apical-basal positional information to specify different tissue types along the gynoecium’s length. The proposed gradient, however, has never been observed and the model appears inconsistent with a number of observations. I present a new, alternative model, wherein auxin acts to establish the adaxial-abaxial domains of the carpel primordia, which then ensures proper development of the final gynoecium. A second project utilizes genomics to identify genes that regulate fruit color by analyzing the genome sequences of Fragaria vesca, a species of wild strawberry. Shared and distinct SNPs among three F. vesca accessions were identified, providing a foundation for locating candidate mutations underlying phenotypic variations among different F. vesca accessions. Through systematic analysis of relevant SNP variants, a candidate SNP in FveMYB10 was identified that may underlie the fruit color in the yellow-fruited accessions, which was subsequently confirmed by functional assays. Our lab has previously generated extensive RNA-sequencing data that depict genome-scale gene expression profiles in F. vesca fruit and flower tissues at different developmental stages. To enhance the accessibility of this dataset, the web-based eFP software was adapted for this dataset, allowing visualization of gene expression in any tissues by user-initiated queries. Together, this thesis work proposes a well-supported new model of fruit patterning in Arabidopsis and provides further resources for F. vesca, including genome-wide variant lists and the ability to visualize gene expression. This work will facilitate future work linking traits of economic importance to specific genes and gaining novel insights into fruit patterning and development.

LIONEL TERTIS AND THE FLOWERING OF EARLY TWENTIETH CENTURY ENGLISH VIOLA REPERTOIRE

This performance project focused on English viola literature written in the first half of the twentieth century. During this time, numerous English composers were influenced by Lionel Tertis' unprecedented approach to the viola as a virtuosic and solo instrument. In addition to being an inspiration to composers of whom he was not in direct contact, Tertis' innovative vision for the viola led to numerous collaborations with prominent English composers of his generation. Ralph Vaughan Williams, Arnold Bax, York Bowen, Frank Bridge, Benjamin Britten, and Rebecca Clarke -his own protégé - composed some of the most important works for viola thus directly shaping the impression of the instrument as we know it today. Tertis' artistry as a performing violist was unmatched at the beginning of the twentieth century. He had a unique approach to the instrument which focused on concept of sound, tone color, concentrated listening, continuous vibrato, discreet portamento, and expressive interpretation. His convincing musical and technical ideas led him to write a treatise about how to achieve a beautiful tone. His passion for teaching and concern for the viola's posterity greatly enhanced the development of the viola. Tertis transcribed, edited, and premiered many works during his career. The music that Lionel Tertis influenced can be seen as a microcosm for a musical resurgence in England during the first half of the twentieth-century. The catalyst for this was artistic influences in the form of nationalism, folk music, romanticism, modernism, and impressionism, among others. Before this, England was widely referred to as ''the land without music" but in a very real sense, .Lionel Tertis was one of the pioneers who, through his artistry of the viola, led the way to the renaissance of music in England in the twentieth century.