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Tai-ping Sun

Professor of Biology
Biology
(919) 613-8166
Research Interest: 
Genetics
Plants
Signal transduction
Research Summary: 
Molecular genetics of growth hormone-mediated plant development.
Research Description: 

Bioactive gibberellins (GAs) are plant growth hormones, controlling diverse processes such as seed germination, stem elongation, leaf expansion, and flower and fruit development. GA-mediated growth events can be modulated by changing the level of bioactive GAs and/or altering the tissue responsiveness to GAs. To understand the developmental and environmental regulation of GA biosynthesis, we and others have cloned several Arabidopsis genes encoding enzymes that catalyze early and late steps in GA biosynthetic pathway. Mutant and developmental expression analyses indicate that the first gene GA1 may serve as a gate keeper to control the flow of metabolites into the GA pathway, whereas the late genes (GA3ox) are important for fine-tuning the amount of active GAs in specific tissues. We also found that local GA transport is required to support proper development during reproductive growth. To dissect the GA signaling pathway, our previous genetic studies identified DELLA proteins, which are major repressors of GA signaling. GA, upon binding to its receptor GID1, de-represses its signaling pathway by targeting rapid degradation of DELLA, via the SCFSLY1 E3 ubiquitin-26S proteasome pathway. Our biochemical studies and structural analysis of the GA-GID1-DELLA complex reveal the exciting molecular mechanism how GA-GID1 recognizes DELLA. The DELLA proteins are likely nuclear transcriptional regulators, which may control target gene expression via interaction with other transcription factors. 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.

Publications: 
The molecular mechanism and evolution of the GA-GID1-DELLA signaling module in plants.
Sun TP.
Curr Biol. 2011. 21:R338-45.

Gibberellin-induced DELLA recognition by the gibberellin receptor GID1.
Murase K, Hirano Y, Sun TP, Hakoshima T.
Nature. 2008. 456:459-63.

Scarecrow-like 3 promotes gibberellin signaling by antagonizing master growth repressor DELLA in Arabidopsis.
Zhang ZL, Ogawa M, Fleet CM, Zentella R, Hu J, Heo JO, Lim J, Kamiya Y, Yamaguchi S, Sun TP.
Proc Natl Acad Sci U S A. 2011. 108:2160-5.

Global analysis of della direct targets in early gibberellin signaling in Arabidopsis.
Zentella R, Zhang ZL, Park M, Thomas SG, Endo A, Murase K, Fleet CM, Jikumaru Y, Nambara E, Kamiya Y, Sun TP.
Plant Cell. 2007. 19:3037-57.

Potential sites of bioactive gibberellin production during reproductive growth in Arabidopsis.
Hu J, Mitchum MG, Barnaby N, Ayele BT, Ogawa M, Nam E, Lai WC, Hanada A, Alonso JM, Ecker JR, Swain SM, Yamaguchi S, Kamiya Y, Sun TP.
Plant Cell. 2008. 20:320-36.