Mechanism of trehalose control of shoot development

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How plants coordinate their growth and development according to the availability of resources, including sugars produced through photosynthesis, is largely unknown. The project will study a gene called RAMOSA3 that produces an enzyme that can degrade a type of sugar called trehalose-6-phosphate (T6P). T6P is thought to be an important hormone in plants, similar to insulin in animals. The researchers have found unexpected properties of the RAMOSA3 enzyme, including being present in the nucleus of cells, and interacting with a class of proteins that bind to ribonucleic acids. These findings suggest that RAMOSA3 is doing something different to its expected function as an enzyme, and the researchers will explore the ways in which RAMOSA3 is able to control how plants grow. Broader Impacts: Plants adapt their growth according to available resources, but how crosstalk between metabolism and development is achieved is not well understood, and the project outcomes will give a clearer understanding of relevance to agricultural productivity. The researchers will also contribute to outreach and education by training graduate and high school students as well as a post-doctoral researcher. The investigator directs a program, which allows local high school students, including minorities, to experience life in a research lab. The investigator's lab will also develop an educational and research exchange with a Middle School in Brooklyn, New York, with hands on experiments used to confer the excitement of scientific research to students, and discussions of how science benefits society. The disaccharide trehalose and its intermediate trehalose-6-phosphate (T6P) have emerged as important regulators of sugar metabolism in plants, and trehalose pathway mutants or mis-expression lines have specific phenotypes affecting branching, flowering time and drought sensitivity. However, the molecular mechanism by which T6P controls these processes is unknown. This research project is to understand the mechanism by which RAMOSA3 (RA3), which encodes a trehalose phosphate phosphatase (TPP) enzyme, controls maize shoot branching. Preliminary results suggest that RA3 acts in the nucleus, where it is found in sub-nuclear domains, and interacts genetically and physically with RNA binding proteins. These findings suggest that RA3 may act in a gene regulatory network with RNA binding proteins, to control expression of downstream genes in response to metabolic signals. The discovery of RNA binding proteins that interact with RA3 provides an opportunity to understand how a metabolic enzyme can control gene expression necessary to direct plant development or other aspects of plant growth. The research will build on these findings by elucidating downstream factors and interacting proteins and RNAs that will lead to new emergent models of how RA3 functions as an integrator across scales in metabolic and developmental control. The project will also train students at multiple levels and will contribute to public education of plant biology research at middle and high school levelsThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.