4. 低温・乾燥によって誘導される植物遺伝子発現制御(セミナー「低温環境への植物の適応-基礎と応用」)

概要

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Plants respond to conditions of drought and cold stress with various physiological and developmental changes to tolerate these stresses. Many genes are induced by drought and cold stress, and they seem to function in the protection of cells from dehydration in plants. Abscisic acid (ABA) plays important roles in the tolerance of plants to drought and cold stress. Many genes that respond to drought and/or cold stress are also induced by exogenous application of ABA. It appears that dehydration triggers the production of ABA, which, in turn, induces various genes. Czs-acting and tram-acting factors involved in ABA-induced gene expression have been extensively analyzed. Several genes that are induced by drought and cold stress, are not responsive to exogenous ABA treatments. These findings suggest the existence of ABA-independent as well as ABA-dependent signal-transduction cascades between the initial stress signal and the expression of specific genes. Analyses of the promoters of drought- and cold-inducible genes have revealed a novel as-acting element (DRE) that function in the ABA-independent gene expression by dehydration or low temperature. Many genes for factors involved in the signal transduction cascades, such as protein kinases and transcription factors, are regulated by these stress signals. Molecular analyses of these genes should provide a better understanding of the signal transduction cascades under drought and cold stress.
1996-07-28