Molecular and Genetic Analysis of Flower Development in Arabidopsis thaliana and the Diploid Strawberry, Fragaria vesca

Abstract

In a world with a warming climate and a rapidly growing population, plant biology is becoming a field of increasing importance. Deciphering the molecular and genetic mechanisms behind the development of the flower, the fruit and seed progenitor, will enhance the agricultural productivity needed to ensure a sustainable food supply. My PhD research ties in with this need by furthering the basic knowledge of the mechanisms underlying flower development in two ways.

First, using <italic>Arabidopsis thaliana</italic>, the classic model plant, I investigated the regulation of a gene, SPATULA (SPT), necessary for the proper development of the gynoecium, the female flower organ that, upon fertilization, directly gives rise to fruit. For flower and fruit to properly develop, the expression of SPT, must be tightly regulated both spatially and temporally. My research examined the mechanism of transcriptional repression of SPT in the sepals and petals by several interacting transcription factors (LEUNIG, SEUSS, APETALA2) and the molecular and genetic interaction between ETTIN and SPT in patterning gynoecium.

The second focus of my research was to develop <italic>Fragaria vesca</italic> (the diploid strawberry), as a model Rosaceae for the study of flower and fruit development. <italic>Arabidopsis</italic> has much value as a small, fast growing, flowering plant with a multitude of genetic and genomic resources, however the flower of this mustard family weed is not representative of all crop flowers. The Rosaceae family, including many agriculturally important fruit trees such as apple, peach, blackberry, and strawberry, warrants its own model plant to investigate the distinct mechanisms behind their unique reproductive biology. Toward developing <italic>F. vesca</italic> as the model plant for studying Rosaceae flowers, I characterized and described developmental progression of F. vesca flowers morphologically through scanning electron microscopy and histological analysis as well as molecularly through transcriptomes and in situ hybridization. In addition, I pioneered a small-scale mutagenesis screen of <italic>F. vesca</italic> that will lead to future genetic resources. My thesis work places the groundwork for future discoveries in <italic>F. vesca</italic> and Rosaceae and benefits research, education, and agricultural applications for the Rosaceae and the plant biology communities.