Research
Evolution of Molecular Mechanisms Governing Pollen Tube Growth Regulation
Before successfully double fertilizing the female gametophyte’s egg and central cells, the male gametophyte must successfully deliver its sperm cells from the stigma to the ovule via its pollen tube, all while surpassing a number of reproductive checkpoints. These checkpoints are specifically controlled by interactions between the male gametophyte and the female reproductive tissues, and together they work to prevent incompatible pollen from fertilizing female gametophytes. We study a Tripartite Signaling system, composed of Catharanthus roseus Receptor-Like Kinase 1-Like (CrRLK1L), their Lorelei-Like GPI-AP (LLG) co-receptors, and their Rapid Alkalinization Factor (RALF) ligands, that governs cell wall integrity. As the pollen tube grows through the pistil, it releases its own RALFs that promote steady state pollen tube growth. Once the pollen tube reaches the female gametophyte, it is then exposed to another set of female-specific RALFs that cause the pollen tube to burst and release its sperm cells. Interestingly, this system in pollen tubes is homologous to other female-specific Tripartite Signaling systems that are employed at the stigma and by the female gametophyte. We use evolutionary, reproductive, and molecular biology approaches to understand Tripartite Signaling in pollen tubes. Currently, we are investigating the conservation of RALF-perception and signaling of pollen tube CrRLK1Ls across Rosids and Asterids using heterologous expression systems. Moreover, pollen tubes employ CrRLK1Ls from two distinct clades, ANXUR (ANX) and Buddha’s Paper Seal (BUPS). We are also working to discern the functional differences between ANX and BUPS and understand why both are necessary for homeostatic pollen tube growth.
Evolution of Soil Nitrogen Perception
This collaborative research project focuses on the CEPR1 (C-TERMINALLY ENCODED PEPTIDE RECEPTOR 1) signaling pathway, a key regulator of nitrogen perception and shoot-root communication in plants. Our work spans three connected areas: uncovering the molecular basis of CEPR1 signaling, examining its conservation across flowering plants, and exploring how downstream components can be modified to fine-tune nutrient responses. In Arabidopsis thaliana, we are working to identify the proteins and regulatory elements involved in CEPR1-mediated nitrogen signaling. This includes investigating gene expression patterns and response dynamics in the context of nitrogen availability. A second area of focus explores how CEPR1 and its peptide ligands function across diverse angiosperm species, including tomato, Medicago, cotton, and maize. By comparing orthologs across species, we aim to understand which aspects of the signaling pathway are conserved and how they contribute to nutrient signaling and growth regulation in different contexts. The third area targets the downstream outputs of CEPR1 signaling, with the goal of identifying key regulatory elements that control developmental and physiological responses. Insights from this work may inform new strategies to engineer plants with improved nitrogen use efficiency. Together, these efforts build a comprehensive view of the CEPR1 pathway and its role in plant nutrient signaling, with applications ranging from basic biology to the development of more sustainable crop systems.
