Professor of Biology
The diterpenoid phytohormone gibberellin (GA) plays pivotal roles in regulating growth and development throughout the life cycle of higher plants. Mutations affecting GA biosynthesis or GA response were the key to control plant stature in wheat and rice that led to dramatically increased grain yield and contributed greatly to the success of the ‘Green Revolution’ in the 1960s. Although the GA biosynthetic pathway had been characterized biochemically, little was known about the sites of GA production and the mode of GA action. By multi-faceted approaches using the model system Arabidopsis, my lab has made major breakthroughs in revealing the sites and regulatory mechanisms of GA biosynthesis. We also elucidated the conserved molecular events of GA perception and the early GA signaling pathway. We identified the nuclear transcriptional regulators DELLA proteins, which function as master growth repressors by inhibiting all aspects of GA responses. Binding of GA to its nuclear receptor GID1 enhances the GID1-DELLA interaction, which in turn leads to the rapid proteolysis of DELLA through the ubiquitin-proteasome pathway, and allows transcriptional reprogramming of GA-responsive genes. We and other researchers further showed that GA-GID1-DELLA is a key regulatory module that controls plant growth by integrating internal developmental cues, and external biotic and abiotic signals (light, cold, salt and pathogen stresses). Surprisingly, we recently found that DELLA directly interacts with multiple classes of key regulatory proteins in other signaling pathways. Our work is revealing the complex regulatory network between the GA pathway and other pathways to control plant growth and development.