The evolution of development of flowering plant reproductive cycles

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The great lability of their reproductive systems is central to the adaptability and rapid diversification of the flowering plants. With the origin of the group, ovules (future seeds) became enclosed within female tissues, necessitating a new site of pollen reception (the stigma) far removed from the site of fertilization (the egg). A critical innovation enabling this stigma-egg dissociation was the origin of a new pollen tube growth pattern in which sperm could be carried to the egg rapidly and through novel maternal tissues. The primary goal of this project is to understand the relationship between the evolution of pollen tube growth rates and reproductive cycles. The outcomes will bear on our understanding of ancient pollen-pistil interactions and floral biology, the focus of a great number of studies on more recently-evolved model and crop systems.The project will involve detailed and comprehensive quantitative characterizations of early and late pollen tube development in four angiosperm taxa that span the deepest divergences among extant angiosperms using in vivo and in vitro field and lab experiments. The goal is to identify underlying developmental causes of variation in pollen tube growth rates. These fine-scale mechanistic studies will be accompanied by broad-scale comparative analyses probing the relationship between pollen development and important ecological traits, such as the speed of reproduction, floral sizes and longevity, and vegetative metabolic rates.The PI has developed a synergistic teaching program in plant development and evolution that will provide graduate students with a focused intellectual environment. Training for a postdoctoral researcher and multiple undergraduate students is included. The project also features international collaborations, outreach, and teaching. The project bridges conceptual disciplines: the PI serves as a liaison between two NSF Research Coordination Networks, and is a founding board member of the Tennessee Plant Research Center. Outreach activities include public lectures and news media interviews.