Collaborative Research: How do plants control sperm nuclear migration for successful fertilization?

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

Life commences with the union of gametes in both animals and plants. After the fusion, the gametic nuclei from both parents migrate towards each other and blend the genetic materials to initiate the next generation. While most organisms rely on microtubules for gamete nuclear migration, flowering plants have evolved a distinctive system that instead utilizes actin filaments (F-actin). This collaborative research project between the University of Kentucky and the University of Tennessee, Knoxville, seeks to unravel the complexities surrounding the orchestration of F-actin dynamics and sperm nuclear migration in Arabidopsis thaliana. The Broader Impacts of the project span scientific and educational outcomes. Agriculturally, understanding the mechanisms governing early fertilization events may help address the predicted future loss of crop plant fertility due to an increasingly unstable climate. To nurture STEM education, undergraduate students will participate in collaborative research experiences spanning experimental and computational biology. An annual plant biology workshop, featuring both molecular and computational approaches, will engage university and community college students in hands-on learning. The team will promote appreciation for plant science by participating in county science fairs and elementary school science nights, and an interactive visualization tool will be developed to enable participants to explore cell features and comprehend their consequences. Most animals and early diverging land plants, such as ferns, control gamete nuclear migration by microtubules. However, flowering plants have evolved a novel system where sperm nuclear migration is instead controlled by F-actin. Prior to fertilization, female gametes generate constant movement of an F-actin meshwork from the plasma membrane towards the center of the cell, where the nucleus is located. Upon sperm nucleus release into the female gamete, the sperm nucleus migrates along with the F-actin meshwork for karyogamy. However, the mechanisms controlling F-actin dynamics and sperm nuclear migration in flowering plants remain largely unknown. This project combines real-time live-cell imaging and computational modeling to elucidate the molecular and cellular mechanisms controlling the movement of F-actin meshwork in the female gamete for sperm nuclear migration in the flowering plant, Arabidopsis thaliana. The project will address critical scientific questions, including understanding the role of the ARP2/3-independent WAVE/SCAR pathway and unraveling the functions of class XI myosin through real-time live-cell imaging, which has been established by the team. Additionally, it aims to explore the biophysical mechanisms underlying F-actin motion via computer simulations, identify factors governing sperm nuclear migration in the egg cell, and uncover new contributors to F-actin movement using reverse genetics approaches. The interdisciplinary approach, encompassing plant biology, real-time live-cell imaging, and computational modeling, will reveal detailed molecular insights into plant fertilization. The outcomes will not only advance understanding of fundamental biological processes but also contribute insights into the evolution of sperm nuclear migration mechanisms in land plants. This project is jointly funded by the Cellular Dynamics and Function program in the Division of Molecular and Cellular Biosociences along with the Established Program to Stimulate Competitive Research (EPSCoR). This 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.