DISSERTATION RESEARCH: Evolution and Development of Petals in Aizoaceae (Caryophyllales)

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The origin of the petal in flowering plants has long been a subject of speculation and controversy among botanists. Traditional theories suggest multiple independent evolutionary origins of bracteopetals (derived from leaf-like organs) and andropetals (derived from sterilized male organs). More recently, the discovery of deeply conserved genetic programs controlling petal formation suggests that all petal-like organs may be under similar genetic control. This hypothesis will be tested by examining the genetic pathways controlling the formation of petals in Aizoaceae: a group of succulent plants that possess two very different types of petal-like structures derived from either leaf-like organs or sterilized male parts. Petals are an extremely important evolutionary innovation that has undoubtedly contributed to the success of flowering plants in colonizing the terrestrial ecosystem. Petals are also of major significance for agriculture as many crops rely on petals to attract pollinators to ensure fertilization, fruit set and good crop yields. This study, in conjunction with ongoing studies in other groups of flowering plants, will help to understand how, why and when the petal evolved. In elucidating the genetic mechanisms underlying petal formation it will be possible to better appreciate the impact of this evolutionary innovation. Furthermore, this knowledge could be used to genetically improve agricultural cultivars.