BS, Agricultural Chemistry, Korea University
PhD, Plant Biology, University of Georgia
Functional Genomics of Plant Transcription Factors
Jong Chan Hong’s lab has constructed Arabidosis transcription factor (TF) open reading frame genome (TF-ORFeome) in a highly efficient recombinational cloning system and is interested in the analysis of protein interaction networks involved in various plant developmental and stress responses. The protein-interaction network, named interactome, analysis will provide valuable information on the understanding of complex biological phenomena such as flowering time control and defense responses. The TF networks that are under investigation are 1) flowering time regulatory network that involve CONSTANS, a B-box zinc finger factor and flowering time (FT), 2) photomorphogenic control networks involving HY5 and COP1, 3) plant defense network that involves transcription factors specific to chitin, fungal cell wall elicitor. The identification of more than 30 CO-interacting proteins and reverse genetic analysis of these genes will be conducted to understand the interplay of pathways leading to photoperiodic flowering.
Currently 1,500 Arabidopsis TF ORFeomes are available in the Gateway Entry vector, a high throughput cloning vector based on recombinational cloning. 1,400 TF ORFs are cloned into Gal4-AD vectors. High throughput protein-protein interaction assay using co-transformation into yeast auxotroph are developed to screen whole TF ORFeome.
Characterization of regulatory network involved in photoperiodic flowering control
The CONSTANS (CO) gene promotes flowering of Arabbidopsis in response to long day conditions. The CO and the rice homolog Hd1 have been known to be a key regulator of flowering in response to appropriate day length, called photoperiod. The CO activates FT, which leads to expression of flower meristem identity genes such as LFY and CAL. While many genes involved in the determination of flowering time are identified by genetic screening, the molecular information related to the function of these isolated genes are mostly unknown. The Hong lab investigates CO function through the TFs interacting to CO using genetic, molecular and in vivo protein-protein interaction study. Recent identification of ASSYMETRIC LEAVES 1 (AS1) as CO interacting protein provides a clue how photoperiodic flowering and GA-mediated flowering pathways crosstalk at molecular level.
Chitin responsive transcription factor network
Chitin, found in the cell walls of true fungi is a well established elicitor of plant defense responses. The sophisticated mechanisms that plants use to respond to chitin elicitation are not well understood. Hong and his colleagues are interested in the construction of gene regulatory network models, which include chitin responsive transcription factors (TF), MAP kinases and E3-ligases. Gary Stacey and Dong Xu are collaborators in constructing and validating network model and functional analysis of a few functionally important genes. In order to build the regulatory network they will construct bait and prey vectors for 118 chitin responsive TFs and perform protein-protein interaction test using yeast two hybrid screen. MAP kinase-TF interaction and RingH2-E3 ligase-TF interaction will also be analyzed to construct chitin signaling networks from kinases to the target proteins. The gene identified as key hub gene in the network will be further analyzed for its functional role in plant defense response.