Alice Cheung

Research Summary

Our overall research interest is in understanding signaling strategies in plants that support growth and reproduction. A focus area of our work is in understanding the cell-cell communicative processes between male (pollen)-female (pistil) that lead to fertilization. Another focus area is in deciphering signal transduction mechanisms that have general impacts on plant growth and development. While our research spans the early seedling and the mature flowering stages of the life cycle of a plant, we focus on common regulatory nodes, mediated by RAC/ROPs (plant RHO GTPases), polarized pollen tube and root hair growth as our main experimental systems.

Our research utilizes cell biological, biochemical, molecular, and more recently biophysical approaches. Over the years, our efforts have elucidated cellular mechanisms that regulate polarized cell growth and molecular mechanisms with broad biological significances. Our recent work focuses on a family of receptor kinases, here referred to as the FERONIA-BUPS family, names of the key female and seedling-expressed member (FERONIA) and a cell surface receptor for RAC/ROPs, and its pollen-expressed counterparts (BUPS).

In reproduction, pollen tubes grow in the pistil to transport the sperm to the egg chamber (female gametophyte) inside the ovules. Pollen tube growth is driven by the pollen cytoplasm but is regulated by signals that originate from the female tissues to nourish and guide them to enter the female gametophyte. Then the pollen tube bursts to release sperm and enables fertilization, while mechanisms are activated to prevent further pollen tube entrance to prevent polyspermy, which ensure progeny health and maximize reproductive yield (seed production). Our efforts are centered on identifying female signal molecules, their receptors on the pollen surface, the pollen components that relate these signals, drive and regulate the polarized cell growth machinery, and also mechanisms that control sperm delivery and the prevention of polyspermy. Our current work largely surrounds processes regulated by FERONIA-BUPS and additional homologs expressed in pollen and pistillate cells. Our goal is to gain a comprehensive understanding of pollen-pistil interactions starting from pollen germination on the pistil receptive surface, the long distance and local regulation of pollen tube guidance till sperm delivery for fertilization.

Our work in plant growth development mainly takes advantage of the relatively facile seedling growth process (compared with reproduction) to decipher signal transduction mechanisms. Our current work has evolved from an earlier interest in RAC/ROP-mediated auxin signaling to the current focus on understanding how diverse growth-regulatory signaling pathways are coordinated. Our efforts led to the discovery of a key co-receptor complex comprised of FERONIA and a glycosylphosphatidylinositol-anchored protein (LLG1) that has almost global impact on plant growth and survival. Building from this, we now focus on elucidating how FERONIA-LLG1 achieves its global signaling role.  

We welcome inquiry from prospective graduate students and postdocs to join us; we also welcome undergraduate participants in our research.