Regeneration in Plants

Dring N. Crowell, PhD
Stephen K. Randall, PhD
John C. Watson, PhD

Dring N. Crowell, PhD

Positions

• Professor of Biology
• Adjunct Professor of Biochemistry and Molecular Biology

Address
Department of Biology
723 W. Michigan St.
Indiana University-Purdue University Indianapolis
Indianapolis, IN 46202-5132

Phone: (317) 274-4119
Fax: (317) 274-2846
Email: dcrowell@iupui.edu

Research Interests

Research in my laboratory is focused on the role of isoprenoid compounds in plant growth and development. All plant cells are totipotent and, as such, have the potential to develop into a mature, fertile plant. This regenerative capacity is dependent on the plant growth factors cytokinin and auxin. Auxin promotes root organogenesis and mediates tropic responses to gravity and light. Cytokinin, on the other hand, promotes shoot organogenesis, cotyledon and leaf expansion, release of lateral buds, and chloroplast development. Cytokinin is one of several isoprenoid plant growth factors. Other isoprenoid plant growth factors include abscisic acid, which promotes seed dormancy and stomatal closure, gibberellin, which promotes seed germination, stem elongation, and flowering, and brassinolide, a steroid plant growth factor that represses photomorphogenesis in the dark. Thus, it is clear that isoprenoid compounds have profound effects on plant growth and development. Another role for isoprenoids in plant growth and development is mediated by the covalent attachment of a fifteen- or twenty-carbon isoprenoid to a cysteine residue at the carboxyl terminus of certain proteins. This process of protein isoprenylation is followed by further modifications that result in the formation of a prenylcysteine methyl ester at the carboxyl terminus. My research is currently focused on the processes of protein isoprenylation and methylation and metabolism of prenylcysteine compounds in plants. We have demonstrated that methylation of isoprenylated proteins and metabolism of prenylcysteine compounds is necessary for negative regulation of abscisic acid signaling. This work suggests multiple strategies for metabolic engineering of plants (e.g., soybean, a drought-sensitive crop) for drought tolerance via targeted alterations in prenylcysteine metabolism.

Recent Publications

• Johnson, C. D., Chary, S. N., Chernoff, E. A., Zeng, Q., Running, M. P., and Crowell, D. N. (2005) Protein geranylgeranyltransferase I is involved in specific aspects of abscisic acid and auxin signaling in Arabidopsis thaliana. Plant Physiol. 139: 722-733.
• Deem, A. K., Bultema, R. L., and Crowell, D. N. (2006) Prenylcysteine methylesterase in Arabidopsis thaliana. Gene 380(2): 159-166.
• Downes, B. P., Saracco, S. A., Lee, S. S., Crowell, D. N., and Vierstra, R. D. (2006) MUBS: a family of ubiquitin-fold proteins that are plasma membrane-anchored by prenylation. J. Biol. Chem. 281 (37): 27145-27157 (cover article).
• Hemmerlin, A., Gerber, E., Hartmann, M.-A., Tritsch, D., Crowell, D. N., Rohmer, M., and Bach, T. J. (2006) The use of tobacco BY-2 cells to elucidate the biosynthesis and essential functions of isoprenoids, pp. 241-272. In: Nagata, T., Matsuoka, K., and Inzé, D., eds., Biotechnology in Agriculture and Forestry, Vol. 58, Tobacco BY-2 Cells: From Cellular Dynamics to Omics. Springer-Verlag, Berlin, Heidelberg.
• Crowell, D. N., Huizinga, D. H., Deem, A. K., Trobaugh, C., Denton, R., and Sen, S. E. (2007) Arabidopsis thaliana plants possess a specific farnesylcysteine lyase that is involved in detoxification and recycling of farnesylcysteine. Plant J., in press.

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Stephen K. Randall, PhD

Positions

• Associate Professor of Biology
• Adjunct Associate Professor, Department of Biochemistry & Molecular Biology, IU School of Medicine, IUPUI

Address
Department of Biology
723 W. Michigan St.
Indiana University-Purdue University Indianapolis
Indianapolis, IN 46204

Phone: (317) 274-0059
Fax: (317) 274-2846
Email: srandal@iupui.edu

Research Interests

My laboratories research emphasis is on how plants respond to environmental stress. Sudden exposure to environmental stress is a major problem for agriculture in temperate parts of the world, resulting in catastrophic economic and productivity losses. Some plants have the ability to develop a tolerance to chilling and dehydration injury, and some additionally can develop a significant tolerance to freezing injury. The presence and expression of dehydrin genes correlates with freezing tolerance. The activation of genes with promoters containing the cold and dehydration responsive element (C-repeat/DRE) is sufficient to confer freezing tolerance in Arabidopsis. The focus of our work is to characterize the biochemical properties of a subfamily of the cold- and dehydration-induced dehydrin proteins using as prototype, the Erd14 dehydrin. We further extended our studies to several additional classes of dehydrins. We are now characterizing the structure and function a specific subset of the dehydrin genes which possess phosphorylation-dependent, ion (calcium)-binding properties; using genetic, biochemical, and physiological approaches.

A second project (collaborative with Dr. Pam Crowell) encompasses the characterization of human isoprenylated protein phosphatases (PRL’s) that are involved in signal transduction and cell division; processes which are not properly regulated in cancer cells. We are presently evaluating the expression patterns of the PRL 1,2 genes in human tissues and the oncogenic properties of these proteins.

Recent Publications

• Werner, SR, Lee, PA, Schirtzinger, LM, DeCamp, MW, Crowell, DN, Randall, SK, and Crowell, PL 2003 Enhanced cell cycle progression and down regulation of p21cip1/Waf1 by PRL tyrosine phosphatases. Cancer Letters 202(2): 201-211.
• Alsheikh, MK, Heyen, BJ, and Randall, SK 2003 Ion Binding properties of the dehydrin ERD14 are dependent upon phosphorylation. J. Biol Chem 278 (42) 40882-40889 (first published as JBC Papers in Press, August 13, 2003)
• Alsheikh, MK, Svensson, JT, and Randall, SK 2005 Phosphorylation regulated ion-binding is a property shared by the acidic subclass dehydrins. Plant, Cell and Environment 28, 1114-112
• Dumaual, CM, Sandusky, GE, Crowell, PL, and Randall, SK 2006 Cellular localization of PRL-1 and PRL-2 gene expression in normal adult human tissues. J. Histochemistry and Cytochemistry, (J Histochem Cytochem. 2006 Sep 6; [Epub ahead of print]) published: J. Histochem. Cytochem. 2006; 54: 1401

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John C. Watson, PhD

Position

• Associate Professor

Address
Department of Biology
School of Science
Indiana University-Purdue University Indianapolis
723 W. Michigan St.
Indianapolis, IN 46202

Phone: (317) 278-1366
Fax: (317) 274-2846
Email: jcwatso@iupui.edu

Research Interests

We study a set protein kinases and their genes from the garden pea and Arabidopsis in order to understand their role in seedling development. To identify protein kinases that might transduce light signals, we identified kinase genes whose expression is regulated by light. These pea genes, called PsPK1 through PsPK5, are differentially expressed in apical buds during de-etiolation in continuous white light. We now have reasonable insight into the function of 4 of the 5 members of the original PsPK series:

(1) Based on their sequences, PsPK4 and PsPK5 are members of the phototropin 1 family. The phototropins are blue light photoreceptors for phototropism and a few other responses in plants. Indeed, we showed that PsPK4 encodes a functional blue light photoreceptor for phototropism by transgenic expression in an Arabidopsis phot1 null mutant.

(2) PsPK2 encodes the pea homolog of PINOID, which is involved in polar auxin transport. PsPK3 is a close relative of an auxin- and gibberlin-inducible kinase from cucumber called CsPK3.

(3) PsPK3 autophosphoryates primarily on serines and polypeptide levels are regulated by light in a pattern distinct from the changes in mRNA levels. We also study WAG1 and WAG2, the two Arabidopsis homologs of PsPK3, which like PsPK3 are light regulated at the mRNA level. The distinctive phenotype in knockout mutants of these two Arabidopsis kinases is constitutive root waving. Our data suggest that wag phenotype may result from a defect auxin transport. We are also genetically dissecting the WAG signaling pathway to understand the role of graviperception, auxin transport, and circumnuation in root waving.

Recent Publications

• Santner A.A., Watson J.C.: The WAG1 and WAG2 protein kinases negatively regulate root waving in Arabidopsis. Plant J. 45: 752-764 (2006).
• Khanna R., Santner A.A., Watson J.C.: Activity and photoregulated expression of PsPK3. Plant Sci. 170: 347-355 (2006).
• Bai F., Watson J.C., Walling J., Weeden N., Santner A.A., DeMason D.: Molecular characterization and expression of PsPK2, a PINOID-like gene from pea (Pisum sativum). Plant Sci. 168: 1281-1291 (2005).
• Elliott R.C., Platten D., Watson J.C., Reid J.B.: Phytochrome regulation of peaphototropin. J. Plant Physiol. 161: 265-270 (2004).
• Briggs, W.R., Beck, C.F., Cashmore, A.R., Christie, J.M., Hughes, J., Jarillo, J.A., Kagawa, T., Kanegae, H., Liscum, E., Nagatani, A., Okada, K., Salomon, M., Rudiger, W., Sakai, T., Takano, M., Wada, M. and Watson, J.C. (2001) The phototropin family of photoreceptors. Plant Cell 13: 993-7.

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