In response to cues from their environment, plants strategically redirect their energy and resources from growth, development, and reproduction towards processes that enable adaptation, defense, and survival. Plants need to regulate these processes to minimize wasteful expenditures of resources. This project will investigate how plants respond quickly and precisely to attack by using the production of a class of defense-related compounds (called alkaloids) from the Catharanthus roseus plant (commonly known as the Madagascar periwinkle) as an example. Under normal conditions, growth is promoted while the production of alkaloids is low. But in the presence of pathogens or attackers the plant responds by producing chemical signals (such as the plant hormone jasmonic acid) which rapidly activates the communication system that leads to the production of these defense-related alkaloids. This project seeks to determine how the plant coordinately regulates growth, development, and defense through a class of regulatory switches, known as the zinc finger transcription factors. This research will involve the interdisciplinary mentoring and advising of graduate students and undergraduates, and the outreach to K-12 and under-represented groups through a Research Experience for Teachers and Young Scholars Program.
In Catharanthus roseus, the mechanism for controlling the rapid defense response is partially mediated through activation of the zinc finger Catharanthus transcription (ZCT) factors leading to the production of terpenoid indole alkaloids. In addition to terpenoid indole alkaloid biosynthesis, zinc finger transcription factors appear to be involved in other defense and stress-related responses. In plants, Cys2-His2-type (C2H2) zinc fingers are an important class of transcription factors involved in controlling growth, development, and stress-responsive genes (cold, drought, salt, and oxidative stress) that contain a unique motif involved in gene repression. However, only a limited number of plant C2H2 zinc finger proteins have been studied in detail. Of these, ZCT is unique in that it is the only one involved in regulating growth and development and defense-related alkaloid biosynthesis. The goal of this project is to better understand how plants coordinately regulate growth, development, and defense to improve fitness and adaptation. This project seeks to elucidate the regulatory network by which hormone inputs coordinate the outputs of growth, development, and alkaloid biosynthesis through ZCT. This fundamental knowledge and insight regarding plant control mechanisms is anticipated to lead to improved resistance of crops towards stress and pathogens, to improved production of defense-related compounds that have medicinal value, and to artificial genetic circuits for enabling rapid regulation of a desired output. The aims for this project are to 1) elucidate the regulatory circuit by which ZCT's role in defense is activated through the hormone jasmonic acid; 2) elucidate the regulatory circuit by which ZCT's role in growth and development is activated through the hormone gibberellic acid; and 3) characterize how ZCT mediates growth, development, and defense-related alkaloid biosynthesis.
This project is supported jointly by programs in Systems and Synthetic Biology (Division of Molecular and Cellular Biosciences) and Biotechnology and Biochemical Engineering (Division of Chemical, Bioengineering, Environmental, and Transport Systems).
