Like animals, plants produce a number of substances that regulate growth and coordinate developmental transitions and responses to environmental signals. Ethylene gas is one such regulator of the plant life cycle, playing important roles in fruit ripening, pathogen defenses and the regulation of cell expansion. Because overall plant form is determined largely by the degree and directionality of cell expansion, ethylene is a crucial regulator of morphology, and ethylene production must be maintained at low levels during phases of rapid cell expansion, such as early seedling growth. Recent work has identified molecular mechanisms that program the degradation of specific enzymes required for ethylene synthesis; this degradation plays a key role in controlling ethylene production. The PI's group previously identified a highly conserved protein phosphatase complex that regulates degradation of ethylene-producing enzymes through dephosphorylation (the process of removing phosphoryl modifications from specific target proteins, or substrates). This project will use genetic and biochemical approaches to identify the components of the PP2A complex that are required, as well as the determinants required for recognition of substrate proteins. The project outcomes will lead to better understanding of the mechanisms that maintain optimal levels of hormone production in plants, allowing adaptive growth responses under conditions of environmental stress or pathogen attack as well as during normal development. The project will also provide training for undergraduate students from underrepresented groups and a graduate student. The Arabidopsis genetic stocks produced in this work will be contributed to the Arabidopsis Biological Resource Center (http://abrc.osu.edu/).
