Laboratory of Plant Molecular Biology

Chua, Nam-Hai
Andrew W. Mellon Professor

Our laboratory investigates how higher plants respond at the molecular level to environmental signals (e.g. light intensity, water deficit) and endogenous developmental cues (e.g. hormones).

Over the past decade, studies involving the model plant system Arabidopsis have identified several intermediates that link the perception of signals with physiological outputs. However, with a few exceptions, there is little insight into the relationship between known intermediates that transduce the same signal. Even less is understood concerning the mechanisms by which plants integrate multiple signals to ensure appropriate developmental responses to their constantly changing environment. Rational approaches to begin to understand how distinct signaling pathways mutually regulate each other in molecular terms are essential to understand plant growth and development at the cellular level.

Post-translational modification of signaling intermediates appears to be particularly important both in signal integration as well as ensuring rapid and reversible changes in the ability of plants to respond to specific stimuli. We are focusing in particular on the role of covalent tagging of gene products with ubiquitin and ubiquitin-like proteins in modifying the abundance, localization, and activities of signaling proteins. The versatility of this mode of regulation suggests that it likely plays an important contribution in ensuring the developmental plasticity that is essential for plant survival.

Broadly, our research program aims to:

  1. use in vitro assays to establish the mechanisms by which signaling intermediates exert their effects, and in particular to identify the relationships between distinct intermediates that transduce the same signal;
  2. confirm the validity of these in vitro data by in vivo molecular analyses using mutant and transgenic plants affected in the signaling intermediate(s) under investigation - ideally, these effects should be manifested by clear phenotypic consequences at the whole plant level;
  3. elucidate how these intermediates and their reaction partners are regulated at the pre- and post-translational levels;
  4. investigate the role of regulated changes in the subcellular localization of signaling intermediates in affecting physiological outputs;
  5. continue to identify signaling intermediates through protein-protein interaction studies and classical genetic screens of knockout and activation-tagged populations.

Within the context of these overall goals, the laboratory's research goals are organized into two primary research areas:

  1. Light signal transduction
  2. ABA-dependent responses to environmental stress