Jackson, David. NSF 0642707. Hormonal and Genetic Networks in Phyllotaxy.
Plant development proceeds through the continuous initiation of organs from groups of stem cells called meristems, and shoot organs such as leaves and flowers, are initiated in regular patterns known as phyllotaxies. The aim of this project is to understand how these patterns are generated, a question that has been of long-term interest to mathematicians, physicists and biologists. In this project, genes that regulate leaf initation and phyllotaxy will be studied. Mutations in these genes cause plants to make extra leaves, and develop with opposite phyllotaxy rather than the alternating pattern that is normal for maize. One of the genes, ABPHYL1, has been isolated, and encodes a cytokinin response regulator homolog. Cytokinin is a plant hormone, and the regulation of ABPHYL1 and its interaction with another important plant hormone, auxin, will be studied. Genes that are regulated by ABPHYL1 have also been identified, and their functions will be elucidated. A second locus, ABPHYL2, also regulates phyllotaxy, and this gene will be isolated. The impact of this work will be to provide a greater understanding of the cross talk between plant developmental and hormone signaling. The studies could also lead to crop improvement, since the initiation of leaves in regular patterns optimizes light capture for efficient photosynthesis, and in some plants provides architectural support. These broader impacts of these studies will be through contributions to several areas, including developmental regulation, morphogenesis, and hormonal signaling. The studies will also be of interest to researchers in other disciplines, such as mathematics and computer science. In addition, a postdoctoral fellow, graduate student and undergraduate or high school students will be trained in plant developmental genetics and bioinformatics. Materials generated from the study will be used in teaching at CSHL and at the Dolan DNA Learning Center.