Abstract
Spiraea thunbergii (Rosaceae) allelochemicals, cis-cinnamonyl acid (cis-CA), had high growth-inhibitory activity against several plants. To elucidate the mechanism of growth-inhibitory activity of cis-CA, gene expression of Arabidopsis thaliana was analyzed by using DNA microarrays. After 6-h exposure, the expression of 75 genes was significantly up-regulated, and that of 116 genes was significantly down-regulated. The up-regulated genes mainly consisted of pathogenesis-related genes, and the down-regulated genes consisted of jasmonic acid/ethylene-responsive genes, superoxide dismutase genes encoding defensive enzymes against reactive oxygen species, the genes expressed specific to cell walls essential for cell-enlargement process, and a transcription factor up-regulated in response to environmental stresses. Based on these results, cis-CA acted mainly in two mechanisms: an influence on plant defense systems against environmental stresses and deregulation of cell wall-associated genes involved in cell elongations.
