부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.abb.2005.09.019 Byline: Dae-Kyun Ro, Jurgen Ehlting, Christopher I. Keeling, Roy Lin, Nathalie Mattheus, Jorg Bohlmann Keywords: Arabidopsis thaliana; Terpene synthase; Sesquiterpene; (Z)-[gamma]-bisabolene; Cytochrome P450; Rhizosphere Abstract: The Arabidopsis thaliana genome contains at least 32 terpenoid synthase (AtTPS) genes [Aubourg et al., Mol. Genet. Genom. 267 (2002) 730] a few of which have recently been characterized. Based on hierarchical cluster analysis of AtTPS gene expression, measured by microarray profiling and validated with published expression data, we identified two groups of predominantly root expressed AtTPS genes containing five members with previously unknown biochemical functions (At4g13280, At4g13300, At5g48110, At1g33750, and At3g29410). Among the root expressed AtTPS genes, a pair of tandem-organized genes, At4g13280 (AtTPS12) and At4g13300 (AtTPS13), shares 91% predicted amino acid identity indicating recent gene duplication. Bacterial expression of cDNAs and enzyme assays showed that both At4g13280 and At4g13300 encode sesquiterpene synthases catalyzing the conversion of farnesyl diphosphate to (Z)-[gamma]-bisabolene and the additional minor products E-nerolidol and [alpha]-bisabolol. Expression of [beta]-glucuronidase (GUS) reporter gene fused to upstream genomic regions of At4g13280 or At4g13300 showed constitutive promoter activities in the cortex and sub-epidermal layers of Arabidopsis roots. In addition, highly localized promoter activities were found in leaf hydathodes and flower stigmata. Mechanical wounding of Arabidopsis leaves induced local expression of At4g13280 and At4g13300. The functional characterization of At4g13280 gene product AtTPS12 and At4g13230 gene product AtTPS13 as (Z)-[gamma]-bisabolene synthases, together with the recent characterization of two flower-specific AtTPS [At5g23960 and At5g44630; Tholl et al., Plant J. 42 (2005) 757], concludes the biochemical functional annotation of all four predicted Arabidopsis sesquiterpene synthase genes. Our data suggest biological functions for At4g13280 and At4g13300 in the rhizosphere with additional roles in aerial plant tissues. Author Affiliation: Michael Smith Laboratories, Department of Botany and Forest Science, University of British Columbia, Vancouver, BC, Canada V6T1Z4 Article History: Received 3 September 2005; Revised 21 September 2005