Abstract
To date, many genes that are transcriptionally activated upon wounding have been identified, but their biological functions are not necessarily clear yet. In order to understand the molecular basis of wound response, we have identified genes whose transcripts accumulated at very early stages of wounding in tobacco plants. In the present study, we focused on one of such particular genes, WI4.
WI4 consists of 221 amino acids, and has a bHLH (basic-helix-loop-helix). Using dual-luciferase assay, WI4 was demonstrated to repress luciferase transcription in BY2. WI4 was shown to localize in the plastid. In leaves, WI4 transcripts and proteins transiently and locally accumulated 1 h after wounding. In contrast, in non-photosynthetic tissues, its transcripts were constitutively accumulated. Transgenic tobacco, that over-expressed WI4, showed abnormal phenotype with pale-green leaves, no stems and roots. These results suggested that WI4 is a transcriptional repressor that functions in plastid, possibly regulating transcription of photosynthetic genes.
