Tai-ping Sun, Professor  

Tai-ping Sun

Education:
PhD, Duke University, 1987

Office Location: 3104 French Science Building
Office Phone: 919-613-8166, 919-613-8167
Email Address: tps@duke.edu

Specialties:
Cell and Molecular Biology
Developmental Biology
Genetics

Research Categories: Molecular mechanisms of plant hormone controlled growth and 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. Their expression patterns suggest 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 are important for fine-tuning the amount of active GAs in specific tissues. To monitor the sites of bioactive GA synthesis, we analyzed the developmental expression profiles of the GA3ox genes that encode enzymes for the final step of bioactive GA synthesis. These studies indicate that local GA transport is required to support proper development during reproductive growth. Our previous genetic studies identified DELLA proteins, which are major repressors of GA signaling. GA, upon binding to its receptor, de-represses its signaling pathway by targeting rapid degradation of DELLA, via the SCFSLY1 E3 ubiquitin-26S proteasome pathway. DELLA proteins are nuclear localized, but do not contain known DNA binding domains. The current hypothesis is that DELLA proteins are transcriptional regulators, which control target gene expression via interaction with other transcription factors. To identify DELLA target genes, microarray analysis was performed, and chromatin immunoprecipitation followed by quantitative PCR (ChIP-qPCR) analysis is in progress to verify these putative targets.

Recent Publications   (More Publications)   (search)

  1. Zentella, R., Zhang, Z.-L., Park, M., Stephen G. Thomas, S.G., Akira Endo, A., Murase, K, Fleet, CM, Jikumaru, Y., Nambara, E., Kamiya, Y and Sun, T-p., Global Analysis of DELLA Direct Targets in Early Gibberellin Signaling in Arabidopsis, Plant Cell, vol. 19 (2007), pp. 3037-3057 .
  2. Oh, E., Yamaguchi, S., Hu, J., Yusuke, J., Jung, B., Paik, I., Lee, H.-S., Sun, T.-p., Kamiya, Y. and Choi, G., PIL5, a phytochrome-interacting bHLH protein, regulates gibberellin responsiveness by binding directly to the GAI and RGA promoters in Arabidopsis seeds, Plant Cell, vol. 19 (2007), pp. 1192-1208 .
  3. Silverstone, A.L., Tseng, T.-S., Swain, S., Dill, A., Olszewski, N.E., and Sun, T.-p., Functional Analysis of SPINDLY in Gibberellin Signaling in Arabidopsis, Plant Physiology, vol. 143 (2007), pp. 987-1000 .
  4. Seo, M., Hanada, A., Kuwahara, A., Endo, A., Okamoto, M., Yamauchi, Y., North, H., Marion-Poll, A., Sun, T.-p., Koshiba, T., Kamiya, Y., Yamaguchi, S. and Nambara, E., Regulation of hormone metabolism in Arabidopsis seeds: Phytochrome regulation of abscisic acid metabolism and abscisic acid regulation of gibberellin metabolism, Plant J., vol. 48 (2006), pp. 354-366 .
  5. Mitchum, M.G., Yamaguchi, S., Hanada, A., Kuwahara, A., Yoshioka, Y., Kato, T., Tabata, S., Kamiya, Y., and Sun, T.-p., Distinct and overlapping roles of two gibberellin 3-oxidases in Arabidopsis development, Plant J., vol. 45 (2006), pp. 804-818 .

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