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Beth KrizekAssociate Professor of Biological Sciences |
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Beth KrizekAssociate Professor of Biological Sciences |
Although growth is a fundamental aspect of development, the molecular basis of organ size/body size regulation is not well understood. Why do organs grow to a certain size and then stop? The size of an organ is dependent upon both the number and size of its constituent cells. Cell division is usually coordinated with cell growth but the relationship between these two processes has not been clearly defined. One protein that plays a critical role in controlling organ size in the model plant Arabidopsis thaliana is AINTEGUMENTA (ANT). Mutations in ANT result in the production of smaller organ primordia and ectopic expression of ANT is sufficient to increase organ size. ANT is a member of the AP2/ERF family of transcription factors, and we have shown that ANT is capable of DNA binding and transcriptional activation. Thus ANT's role in organ growth presumably results from regulation of genes involved in cellular growth and/or division. Since ANT is one of only a few genes shown to be sufficient for organ growth, further characterization of its role in this process will significantly enhance our understanding of organ size regulation in plants and may allow the design of plants with increased biomass.
Another aspect of floral variation is the presence and/or degree of floral organ fusion. Compound floral structures result from the fusion of individual organ primordia. While organs of primitive flowers were most likely separate entities, fusion of floral organs is now quite common. While only carpels are fused in wild-type Arabidopsis flowers, mutants that exhibit fusion between other floral organs have been identified. We are studying the role of the RABBIT EARS (RBE) gene in the formation of distinct sepals in the outermost whorl and the development of normal petals in the second whorl of Arabidopsis flowers.
Selected Publications:
Ciftci-Yilmaz, S., Morsy, M.R., Song, L., Coutu, A., Krizek, B.A., Lewis, M.W., Warren, D., Cushman, J., Connolly, E.L., and Mittler, R. (2007) The EAR-motif of the C2H2 finger protein ZAT7 plays a key role in the defense response of Arabidopsis to salinity stress. J. Biol. Chem. 282, 9260-9268.Krizek, B.A. and Sulli, C. (2006) Mapping sequences required for nuclear localization and the transcriptional activation function of the Arabidopsis protein AINTEGUMENTA. Planta 224, 612-621.
Nole-Wilson, S. and Krizek, B.A. (2006) AINTEGUMENTA contributes to organ polarity and regulates growth of lateral organs in combination with YABBY genes. Plant Phys. 141, 977-987.
Krizek, B.A., Lewis, M.W., and Fletcher, J.C. (2006) RABBIT EARS (RBE) is a second whorl repressor of AGAMOUS that maintains spatial boundaries in Arabidopsis flowers. Plant J. 45, 369-383.
Krizek, B.A. (2006) Molecular biology of floral organogenesis. In The molecular biology and biotechnology of flowering. , pp. 100-123, B.R. Jordan (ed), CABI Publishing, Oxfordshire.
Li, J., Yang, H., Peer, W.A., Richter, G., Blakeslee, J., Bandyopadhyay, A., Titapiwantakun, B., Undurraga, S., Khodakovskaya, M., Krizek, B., Murphy, A., Gilroy, S., and Gaxiola, R. (2005) Arabidopsis H+-PPase AVP1 regulates auxin-mediated organ development. Science, 310, 121-125.
Krizek, B.A. and Fletcher, J.C. (2005) Molecular mechanism of flower development: An armchair guide. Nat. Rev. Genet. 6, 688-698.
Nole-Wilson, S., Tranby, T., and Krizek, B.A. (2005) AINTEGUMENTA-like (AIL) genes are expressed in young tissues and may specify meristematic or division-competent states. Plant Mol. Biol. 57, 613-628.
Krizek, B.A. (2003) AINTEGUMENTA utilizes a mode of DNA recognition distinct from that used by proteins containing a single AP2 domain. Nucleic Acids Res. 31, 1859-1868. down load paper
Krizek, B.A., Prost, V., Joshi, R.M., Stoming, T. and Glenn, T.C. (2003) Developing transgenic Arabidopsis plants to be metal-specific bioindicators. Environ. Toxicol. Chem. 22, 175-181.
Nole-Wilson, S. and Krizek, B.A. (2000) DNA binding properties of the Arabidopsis floral development protein AINTEGUMENTA. Nucleic Acids Res. 28, 4076-4082.
Sakai, H., Krizek, B.A., Jacobsen, S.E., and Meyerowitz, E.M. (2000) Regulation of SUP expression identifies multiple regulators involved in Arabidopsis floral meristem development. Plant Cell 12, 1607-1618.
Krizek, B.A., Prost, V., and Macias, A. (2000) AINTEGUMENTA promotes petal identity and acts as a negative regulator of AGAMOUS. Plant Cell 12, 1357-1366.
Krizek, B.A. (1999) Ectopic expression of AINTEGUMENTA in Arabidopsis plants results in increased growth of floral organs. Developmental Genetics 25: 224-236.
B.A. Krizek, J.L. Riechmann, and E.M. Meyerowitz. (1999) Use of the APETALA1 promoter to assay the in vivo function of chimeric MADS box genes. Sexual Plant Reproduction, 12, 14-26.
Krizek, B.A., and Meyerowitz, E.M. (1996) The Arabidopsis homeotic genes APETALA3 and PISTILLATA are sufficient to provide the B class organ identity function. Development 122: 11-22.Krizek, B.A., and Meyerowitz, E.M. (1996) Mapping the protein regions responsible for the functional specificities of the Arabidopsis MADS domain organ identity proteins. Proc. Natl. Acad. Sci. USA 93: 4063-4070.
Riechmann, J.L., Krizek, B.A., and Meyerowitz, E.M. (1996) Dimerization specificity of Arabidopsis MADS domain homeotic proteins APETALA1, APETALA3, PISTILLATA, and AGAMOUS. Proc. Natl. Acad. Sci. USA 93, 4793-4798.