Investigation of Mechanisms that Control the Transition to Flowering in Higher Plants

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Plant biologists have been slowly deciphering how plants control flowering time for over a century. Until recently the nature of the signals that cause plants to flower remained a complete mystery. Early researchers discovered that a flower-inducing substance is synthesized in leaves and then transported a long distance to the central shoot of the plant to a region of stem cells from which the actual flowers originate. My research uses the tools of molecular biology, genetics, biochemistry and genomics to better understand the nature of the flowering process. Our research revolves around the study of the maize INDETERMINATE1 gene, or ID1, which is critically important for flowering. Maize plants with a functional version of this gene flower at the proper time, whereas maize plants with a defective ID1 gene flower very late and produce aberrant flowers. We used molecular techniques to isolate and characterize the ID1 gene and found that it encodes a zinc finger transcription factor protein that acts in leaves as a master regulator of other genes. This suggests that ID1 causes flowering in maize by turning 'on' or 'off' the genes that control the long distance leaf signal. There are three main goals of this proposal: 1) identify genes that are controlled by the ID1 gene, 2) characterize the molecular, biochemical and physiological components in plants that make up the leaf signals that specify time to flower; and 3) work out the basic molecular mechanism used by ID1 to make genes active or inactive. Recently we found evidence that one way that ID1 may control genes is by epigenetic mechanisms. Epigenetics represents an exciting new paradigm in our understanding of how genes are controlled. Ultimately we aim to decipher the epigenetic mechanisms that underpin ID1 function leading to the biochemical components and metabolic changes that affect the flowering process. Discovering how flowering time works is vitally important to agriculture. Global climate change, coupled with an expanding population, will have a severe impact on the world food supply. A better understanding of flowering in maize and agriculturally important relatives such as wheat, rice, sorghum and sugarcane could help stabilize food production. The ability to control time to flowering is of fundamental importance to agriculture because plants coordinate flowering for optimal seed and fruit production. Therefore understanding flowering will help to improve the productivity of vital crop plants.