Expression of PR-5d and ERF genes in cultured tobacco cells and their NaCl stress-response

The expression of pathogenesis-related protein-Sd CPR-Sd) and ethylene-responsive transcriptional factors (ERF1-4 for basic PR-proteins was measured in cultured tobacco cells, The PR-Sd transcript markedly increased with culture, but only constant levels of transcripts of ERF1 (trans-activator) and ERF3 (repressor) were detected in cells, These different responses of PR-5d and ERF genes were also observed under NaCl stress; PR-Sd transcript decreased and ERF levels were constant under NaCl stress. The effect of post-transcriptional regulation of ERF activity, especially ERF3, on the expression of basic PR genes including PR-Sd is discussed.