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The phenylpropanoid pathway plays an important role when plants are exposed to environmental stresses, such as wounding or pathogen attack. Its activity leads to the production of lignin, flavonoids, and phytoalexins. Cinnamate 4-hydroxylase (C4H) is a cytochrome P450-dependent monooxygenase that catalyses the hydroxylation of cinnamic acid to p-coumaric acid. We isolatedC4H cDNA fromCamptotheca acuminata and investigated the expression pattern of the C.acuminata C4H (CaC4H) gene following stress treatments. A search against the BLOCKS database of conserved protein motifs indicated that CaC4H shares common features with C4Hs from other species. C4H transcripts accumulated in the leaves in response to mechanical wounding or the application of molecules involved in the stress response, i.e., ethylene, methyl jasmonate, and hydrogen peroxide. Interestingly, the application of aminoethoxyvinylglycine, salicylic acid, or diphenylene iodonium, which are biosynthetic inhibitors of ethylene, methyl jasmonate, and hydrogen peroxide, respectively, did not inhibit this wound-induced expression. Based on these results, we suggest that C4H functions in response to various stresses in Gacuminata leaves.
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