Fertilization in plants is fundamental to producing fruits and seeds, which are the harvested product for many crop species and critical for agriculture. For successful fertilization the male sperm cell, contained within the pollen tube, must reach the female egg cell. However, the progress of land plant evolution is marked by increasing protection of the egg cell, with the majority of plant species burying these cells deep within many layers of female tissues. The project focuses on the problem of how the female tissues help the pollen tube grow to the relatively inaccessible egg cell. The specific focus is on the reproductive tract, which is the part of the female plant tissue that interacts with pollen tubes. Development of the female reproductive tract in plants has received relatively little research attention despite its complexity and fundamental importance. This project will identify the major regulatory genes that control how the plant makes the reproductive tract using a combination of genetics and molecular biology in the model plant Arabidopsis thaliana. Several genes have already been identified that control different parts of the reproductive tract and are providing unique insights into the process of fertilization. It is likely that these Arabidopsis genes will have counterparts (orthologs) in diverse plant species, including many agriculturally important crops. Therefore, this project will form the foundation for a wide range of future studies aimed at understanding the genes that control fertilization in diverse plant species and lead to significant increases in overall yield of important crops. The broader impact of this project will derive from the identification of key regulatory genes that pattern the Arabidopsis reproductive tract in the carpel and fruit. It will provide excellent training opportunities for students and postdoctoral fellows, and the resources created by this research will be incorporated into laboratory courses and outreach efforts.
The female organ of angiosperm plants contains ovules that, upon fertilization, become the seeds. Upon fertilization, this female organ becomes the fruit, which nourishes and ultimately disperses the seeds. Our studies aimed to identify genes that play a central role in promoting the fertilization process. The yield of agriculturally important crop plants relies on efficient fertilization of ovules by pollen. The transmitting tract region of the female reproductive organ, called the carpel or pistil, is essential for pollen tube movement and fertilization. Our studies identified the major genes that are required for the formation of the transmitting tract region of carpels. Through the analysis of mutants, together with the study of expression patterns of relevant genes, our studies provide a framework for understanding the complex network of gene interactions that underlies transmitting tract formation. These studies may ultimately provide insights that could increase the yield of crop plants as well as tools to understand the evolution of the transmitting tract region of higher plants. In addition, our studies identified three genes that play an essential role in root initiation during embryo development within the developing seeds. These studies could have a broad impact on stem cell biology and the role of plant hormones during embryo patterning.
