Intellectual Merit: The TCPs constitute a large family of plant-specific transcription factors that are defined by a conserved basic helix-loop-helix domain. They fall into two classes with Class I TCPs promoting cell proliferation, and Class II members promoting leaf and floral differentiation. TCPs are sequence-specific DNA binding proteins that bind to shared or overlapping motifs as homo- or heterodimers. Given the complexity of the TCP family and its potential to function combinatorially, it is likely to be governed by an intricate array of regulatory mechanisms. The overall goal of the project is to examine the role of the GRIK-SnRK1 protein kinase cascade in TCP regulation. Although SnRK1 is best known for controlling and coordinating carbon metabolism and energy balance in plants, there is increasing evidence that it also plays an essential role in plant development and controls plant gene expression by phosphorylating transcription factors. GRIK, which activates SnRK1, only accumulates in young plant tissues, cultured cells and geminivirus-infected cells, all of which replicate plant chromosomal DNA. A subset of Arabidopsis TCPs are phosphorylated by the GRIK-SnRK1 kinase cascade, and Class I TCP binding motifs are enriched in SnRK1-down regulated genes. The project will characterize GRIK-SnRK1 target residues of selected TCPs and examine the consequence of altering their phosphorylation status on TCP function. This research represents an important first step in understanding how TCPs are regulated by phosphorylation and the role of post-translational mechanisms in modulating this unique transcription factor family in plants. A better understanding of TCP regulatory mechanisms and the role of the GRIK-SnRK1 cascade in TCP control could lead to the development of new strategies for modulating plant growth, especially under metabolic stress conditions.
Broader Impacts: The combined application of molecular, cellular and biochemical techniques to TCP phosphorylation provides a unique training opportunity for undergraduate, graduate and senior researchers. The PIs will work together to foster intellectual and collaborative interactions between their laboratories to ensure that participants are broadly trained and develop the skills necessary to apply integrated approaches to complex biological problems. Project participants will also work with local educators and the NC Museum of Life and Science to offer a two-day workshop based on a genetic "Science in a Suitcase" kit for middle school teachers. The kit is designed as a supplemental teaching aid for teachers embarking on genetics content in the middle school grades and is aligned to the NC Standard Course of Study to ensure maximum potential use. Workshop topics will include kit contents, the NC Standard Course of Study requirements, classroom implementation, overview of genetic science at the middle grades level, and assessment of learning strategies. The outreach project has the potential to reach 3,600 middle school students in NC Granville and Durham Counties, both of which have large numbers of minority and economically disadvantage students. The broader impacts include engaging 30 middle grades math and science teachers in the workshops, providing follow-up support through the Museum staff, and providing the kit at no-cost to participating teachers during the following academic year.
