Patricia Leon Mejia, Ph.D.

Research

My research group is interested in two main aspects: One is understanding the pathways that participate in the communication between plastids (chloroplasts) and the nucleus, and the other involves discerning the mechanism(s) of sugar sensing and signaling. These two processes have a major impact on plant development and productivity. To address these questions, we use different plant model systems, including Arabidopsis thaliana, tomato, and Marchantia polymopha, as well as other multidisciplinary approaches. Plastids are responsible for essential cellular activities. They are the main energy providers, and they also synthesize diverse essential compounds, many of which are of medical and biotechnological value to humans. These organelles communicate their differentiation and functional status to the nucleus through the production of signals capable of reprogramming nuclear gene expression. Identifying the elements that participate in this communication will advance our understanding of this fundamental biological process and will introduce avenues for future manipulation of this organelle. Our work has demonstrated that some of these signals are derived from carotenoids, and our present goal is to identify their nature, dissect their signaling pathways, and understand their role in plant development. One of the most important processes carried out in plastids is the synthesis of sugars, which is required for both plant and human development. Glucose acts as a hormone-like molecule that modulates central metabolic, developmental, and environmental responses in plants through multiple signaling pathways. Our group aims to identify important components of sugar signaling pathways and understand their participation in the regulation of major transitions in plants, such as the autotrophic establishment after seed germination.

As an Innovation Fund investigator, Patricia Leon Mejia, Ph.D., is teaming up with Luis Brieba de Castro, Ph.D., to explore how the plastid, a key organelle in plants responsible for metabolism and producing nutrients, communicates with the nucleus to respond to external stressors. To maintain plastid homeostasis, communication signals from the nucleus to plastids are well documented; however, signals going from the plastid to the nucleus are not well understood. But recent evidence indicates that proteins called apocarotenoids play a role. The Leon Mejia lab will use expertise in apocarotenoid proteins coupled with Brieba de Castro’s research in protein folding and biochemistry to identify receptors that aid in the transport of these signaling molecules. Uncovering the details of this critical signaling pathway will shed light on how plants react to stress and introduce avenues to improve crop production and yield.