Molecular and developmental responses of plants to environmental stresses
Plants are unable to escape from harsh environments and perhaps as a consequence have evolved the ability to
undergo adaptive changes in physiology and development. The mechanisms by which plants sense environmental stresses,
transduce signals into cells and regulate cellular and organismal alterations are largely unknown. We have taken a molecular
approach to investigating these aspects of plant biology. The TCH genes of Arabidopsis are rapidly and strongly
upregulated in expression in response to various environmental stimuli, including the seemingly innocuous stimulus of touch.
These genes are powerful molecular tools for investigating how plants perceive environmental conditions and how they mount
responses. We are investigating the cellular and genetic elements that control TCH expression and the biochemical and
physiological functions of the TCH products. The TCH genes encode calmodulin, calmodulin-related proteins and a
xyloglucan endotransglucosylase/hydrolase (XTH) predicted to act in modifying the plant cell wall. Current data support a hypothesis
that the TCH proteins collaborate in the fundamental process of plant cell expansion.
Selected Publications
Braam J (1999) If walls could talk. Current Opinion in Plant Biology 2:521-524.
Steele NM, Sulova Z, Campbell P, Braam J, Farkas V, Fry SC (2001) Ten isoenzymes of xyloglucan
endotransglycosylase from plant cell walls select and cleave the donor substrate stochastically. Biochemical Journal
355:671-679.
Rose JKC, Braam J, Fry SC, Nishitani K (2002) The XTH family of enzymes involved in xyloglucan
endotransglucosylation and endohydrolasis: current prospectives and a new unifying nomenclature. Plant & Cell
Physiology 43:1421-1435.
Iliev E, Xu W, Polisensky DH, Oh M-H, Torisky RS, Clouse SD, Braam J (2002) Transcriptional and
post-transcriptional regulation of Arabidopsis TCH4 expression by diverse stimuli: roles of cis regions
and brassinosteroids. Plant Physiology 130:770-783.
McCormack E, Braam J (2003) Calmodulins and related potential calcium sensors of Arabidopsis.
New Phytologist 159:585-598.
Braam J (2005) In touch: plant responses to mechanical stimuli. New Phytologist 165:373-389.
Lee D, Polisensky DH, Braam J (2005) Genome-wide identification of touch- and darkness-regulated Arabidopsis
genes: a focus on calmodulin-like and XTH genes. New Phytologist 165:429-444.
McCormack E, Tsai YC, Braam J (2005) Handling calcium signaling: Arabidopsis CaMs and CMLs. Trends
in Plant Science 10:383-389.
Delk NA, Johnson KA, Chowdhury NI, Braam J (2005) CML24, regulated in expression by diverse stimuli, encodes a
potential Ca2+ sensor that functions in responses to abscisic acid, daylength, and ion stress. Plant
Physiology 139:240-253.
Becnel J, Natarajan M, Kipp A, Braam J (2006) Developmental expression patterns of Arabidopsis XTH genes
reported by transgenes and Genevestigator. Plant Molecular Biology 61:451-467.
Contact Information
- Janet Braam, Ph.D.
- Department of Biochemistry and Cell Biology
- Rice University
- W-200P George R. Brown Hall
- 6100 S. Main
- Houston, Texas 77005-1892, U.S.A.
- Lab Website
- Tel: (713) 348-5287 and 348-4015
- Fax: (713) 348-5154
- E-mail: braam@bioc.rice.edu
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