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Unformatted text preview: JARQ 39 (4), 221 – 229 (2005) http://www.jircas.affrc.go.jp 221 Introduction As plants are sessile organisms, they are directly exposed to environmental stresses such as drought, high salinity and low temperature. Plants respond to environ- mental stress, and the transduced signals cause expres- sion of numerous genes associated with stress tolerance. A number of genes have been described that respond to environmental stresses such as drought, high salinity and low temperature in plants 4,15,33,47,48,60 . We isolated more than 60 independent cDNAs for dehydration inducible genes using molecular techniques such as differential screening in a model plant Arabidop- sis thaliana 33,47,48 . Recently, 299 drought-inducible genes, 54 cold-inducible genes, and 213 high-salinity- stress-inducible genes were identified using a cDNA microarray containing around 7,000 independent Arabi- dopsis full-length cDNA groups 46,48 . Functions of their gene products have been predicted from sequence homol- ogy with known proteins. Genes induced during dehy- dration stress conditions are thought to function not only in protecting cells from dehydration by the production of important metabolic proteins (functional proteins) but also in the regulation of genes for signal transduction in the dehydration stress response (regulatory proteins). The functional proteins contain water channel proteins, chaperons, proteases, LEA (L ate E mbryogenesis A bun- dant) proteins, and enzymes for the synthesis of osmo- protectants (compatible solutes; sugars, proline, etc.). The regulatory proteins contain transcription factors, pro- tein kinases, and enzymes for phosphoinositide (PI) turn- REVIEW Molecular Studies on Stress-Responsive Gene Expression in Arabidopsis and Improvement of Stress Tolerance in Crop Plants by Regulon Biotechnology Kazuo NAKASHIMA 1 and Kazuko YAMAGUCHI-SHINOZAKI 1,2 * 1 Biological Resources Division, Japan International Research Center for Agricultural Sciences (JIRCAS) (Tsukuba, Ibaraki 305–8686, Japan) 2 Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo (Bunkyo, Tokyo 113–8657, Japan) Abstract Molecular studies have shown that several genes with various functions are induced by environmental stresses such as drought, high-salinity and low temperature in plants. Most of the dehydration respon- sive genes are induced by the plant hormone abscisic acid (ABA), but others are not. Expression anal- yses of dehydration-responsive genes have provided at least four independent regulatory systems (regulons) for gene expression in a model plant Arabidopsis thaliana . The cis-acting elements in the promoters of some genes that have a typical stress-inducible expression profile and the transcription factors that affect the expression of these genes have been analyzed. Transcription factors that bind to a DRE/CRT (d ehydration-r esponsive e lement / C-r epeat ) cis-acting element were isolated and termed...
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This note was uploaded on 08/01/2009 for the course HORT hor-11-12 taught by Professor Park during the Spring '09 term at A.T. Still University.
- Spring '09