EAGER: Environmental signals in a marine diatom

Diatoms are microscopic aquatic organisms that are collectively responsible for approximately 20% of the photosynthetic activity on Earth. However, little is known of the response of these important organisms to changes in their environment. The primary goal of this project is to understand how these organisms sense the environment and alter their physiology to optimize their growth and productivity. This project will develop important novel tools that are anticipated to be of broad value to the research field, and will elucidate the mechanisms by which changes in the environment influence cell physiology. It will provide research opportunities for undergraduates and advance public science education. This project will elucidate how simple environmental signals lead to rapid and reversible physiological responses in a model marine diatom Phaeodactylum tricornutum. The signal transduction pathways that facilitate these responses are virtually unknown. The hypothesis will be tested that retrograde signals emanating from the electron transport system in the plastid are the primary means by which diatoms translate environmental signals into nuclear gene expression, leading to reversible physiological responses. Based on a bioinformatics analysis, a reverse genetics approach will initially be used to target five genes hypothesized to represent major components of the retrograde signal transduction system in diatoms. The project will utilize a rapid and robust gene-editing approach based on CRISPR/Cas9 technology, combined with a technique based on self-processing ribozyme sequences that flank the guide RNA to target the genes encoding the putative signal transduction proteins.