Symposium II: Adapting to a Dynamic Environment

Abs # 20003: Gene networks involved in abiotic stress responses

Presenter:	Shinozaki, Kazuo , sinozaki@rtc.riken.go.jp
Authors	Shinozaki, Kazuo  (A) (C)  Yamaguchi-Shinozaki, Kazuko  (B)   Seki, Motoaki  (A) (C)  Osakabe, Yuriko  (B)   Yoshida, Ri-ichiro  (C)   Maruyama, Kyonoshin  (B)   Imura, Yoshiyuki  (B)
Affiliations:	(A): Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute (B): Biological Resources Division, Japan International Research Center for Agricultural Sciences (JIRCAS) (C): Plant Functional Genomics Research Group, RIKEN Genomic Sciences Center

Plants respond and adapt to a variety of environmental stresses including drought, cold and high salinity to survive in severe stress conditions. These stresses induce a variety of genes at transcriptional level. Their gene products are thought to function in stress tolerance and response. Many stress-inducible genes have been used to improve stress tolerance of plants by gene transfer. In this conference, we present recent progress on global analysis of expression profiles of stress responsive gene expression using 7,000 full-length cDNA microarray, and functions of stress-inducible genes (Seki et al. Plant J. 31: 279-292, 2002). Dehydration triggers the production of abscisic acid (ABA), which, in turn, not only causes stomata closure but also induces various genes. We have analyzed expression profiles of the drought-inducible genes and identified at least four independent regulatory systems in drought-responsive gene expression, two are ABA-dependent and two are ABA-independent (Shinozaki et al. Curr Opin Plant Biol 3: 217-223, 2000). Cis- and trans-acting elements that function in ABA-independent and ABA-responsive gene expression by drought stress have been precisely analyzed. In one of the ABA-independent pathways, a cis-acting element (DRE/CRT) and its binding proteins, DREB1/CBF and DREB2, are important cis- and trans-acting elements in stress-responsive gene expression (Liu et al., Plant Cell 11: 1743-1754, 1998). Based on microarray analysis, many DREB1A/CBF-target genes that function in stress tolerance have been identified (Seki et al., Plant Cell 13: 61-72, 2000; Maruyama et al., unpublished data). An upstream factor that controls DREB1/CBF expression in response to cold stress will be discussed. We have analyzed signal transduction cascades in osmotic stress and ABA responses. Recently, we have analyzed two types of protein kinases that are involved in ABA signaling. They are a receptor like kinase (Osakabe et al. Unpublished data) and a SnRK2 protein kinase (Yoshida et al. Plant Cell Physiol 43: 1473-1483, 2002). Functions of these protein kinases are analyzed using T-DNA tagged mutants and transgenic overexpressors. The roles of these protein kinases will be discussed.