Teh-hui Kao
Professor of Biochemistry and Molecular Biology
333 South FrearUniversity Park, PA 16802
Research Interests
Biochemical and molecular bases of self/non-self recognition during plant reproduction
Research Summary
Mechanism of self/non-self recognition between pollen and pistil in self-incompatible plants
Self-incompatibility (SI) is a self/non-self recognition mechanism that allows the pistil of flowering plants to distinguish between self (genetically related) and non-self (genetically unrelated) pollen to prevent inbreeding and promote out-crossing. We use Petunia inflata (a relative of garden petunia) as a model to study the SI mechanism possessed by three families of flowering plants. Here, SI is controlled by the highly polymorphic S-locus. If the S-haplotype of haploid pollen matches either S-haplotype of the diploid pistil, the pollen is recognized as self-pollen and the growth of self-pollen tubes in the style is inhibited. If the S-haplotype of pollen is different from both S-haplotypes of the pistil, the pollen is recognized as non-self pollen and their tubes are allowed to grow down through the style to the ovary to effect fertilization. We are interested in two fundamental questions: (i) How does a pistil distinguish between self and non-self pollen? (ii) How does the self and non-self recognition lead to growth arrest of self-pollen tubes in the style? Over the past more than two decades of research, we have identified the S-RNase gene as the gene that controls pistil specificity (Lee et al., Nature 367: 560-563, 1994) and the PiSLF (P. inflata S-locus F-box) gene as the gene that is involved in controlling pollen specificity (Sijacic et al., Nature 429: 302-305, 2004). We have proposed a protein-degradation model, which invokes specific degradation of non-self S-RNases mediated by an allelic variant of PiSLF in the cytoplasm of a pollen tube, to explain the biochemical basis of S-haplotype-specific inhibition of pollen tube growth. A current focus is to use in vivo approaches to test this model. The information gained will be valuable to understanding not only this SI system, but also many cellular and developmental processes in a variety of organisms in which regulation of protein degradation has been implicated.
Structure and function of cellulose synthase complex of a cellulose-synthesizing bacterium, Gluconacetobacter hansenii, and a model plant, Arabidopsis
We have recently initiated a new direction of research as part of the Center of Lignocellulose Structure and Formation (http://www.lignocellulose.org/), an Energy Frontier Research Center funded by the Department of Energy. We focus on one of the three basic questions the Center is seeking to address: how does the cellulose synthase complex produce the cellulose microfibril? We are working closely with the lab of Dr. Ming Tien to use molecular and biochemical approaches to elucidate the structure and function of the proteins that compose cellulose synthase complex in both Gluconacetobacter hansenii and Arabidopsis. For example, in G. hansenii, we are interested in the identification of interacting partners of AcsAB, AcsC and AcsD involved in cellulose synthsis, and the expression of soluble portions of AcsAB for structural and biochemical studies. It is hoped that the knowledge acquired from our study will allow for modifications to the complex and subsequent alterations of cellulose structure and crystallinity, facilitating the use of cellulosic biomass for fuel production.
Representative Publications
- Fields, A.M., Wang, N., Hua, Z., Meng, X. and Kao, T.-h. (2010). Functional characterization of two chimeric proteins between a Petunia inflata S-locus F-box protein, PiSLF2, and a PiSLF-like protein, PiSLFLb-S2. Plant Mol. Biol., in press
- Iyer, P.R., Geib, S.M., Catchmark, J., Kao, T.-h. and Tien M (2010). Genome sequence of a cellulose producing bacterium, Gluconacetobacter hansenii ATCC 23769. J. Bacteriol. 192, 4256-4257.
- Meng, X., Hua, Z., Wang, N., Fields, A.M., Dowd, P.E. and Kao, T.-h. (2009). Ectopic expression of S-RNase of Petunia inflata in pollen results in its sequestration and non-cytotoxic function. Sex. Plant Reprod. 22, 263-275.
- Hua, Z., Fields, A. and Kao, T.-h. (2008). Biochemical models for S-RNase-based self-incompatibility. Mol. Plant. 1, 575-585.
- Hua, Z. and Kao, T.-h. (2008). Identification of major lysine residues of S3-RNase of Petunia inflata involved in ubiquitin-26S proteasome-mediated degradation in vitro. Plant J. 54, 1094-1104.
- Hua, Z., Meng, X., Kao, T.-h. (2007). Comparison of Petunia inflata S-locus F-box protein (Pi SLF) and Pi SLF-like proteins reveals its unique function in S-RNase-based self-incompatibility. Plant Cell 19, 3593-3609.
- Kokubun, H., Nakano, M., Tsukamoto, T., Watanabe, H., Hashimoto, G., Marchesi, E., Bullrich, L., Basualdo, I. L., Kao, T.-h. and Ando, T. (2006). Distribution of self-compatible and self-incompatible populations of Petunia axillaris (Solanaceae) outside Uruguay. J. Plant Res. 119, 419-430.
- Skirpan, A.L., Dowd, P. E., Sijacic, P., Jaworski, C. J., Gilroy, S. and Kao, T.-h. (2006). Isolation and characterization of PiORP1, a Petunia oxysterol-binding-protein related protein involved in receptor-kinase mediated signaling in pollen, and analysis of the ORP gene family in Arabidopsis. Plant Mol. Biol. 61, 553-565.
- Dowd, P. E., Coursol, S., Skirpan A. L., Kao, T.-h. and Gilroy, S. (2006). Petunia phospholipase C1 is involved in pollen tube growth. Plant Cell 18, 1438-1453.
- Hua, Z. and Kao, T.-h. (2006). Identification and characterization of components of a putative PiSLF-containing E3 ligase complex involved in S-RNase-based self-incompatibility. Plant Cell 18, 2531-2553.
