DEFENSE GENE-TRANSCRIPTION IN CARROT CELLS TREATED WITH OLIGOGALACTURONIDES

In vitro nuclear run-off transcription has been used to monitor transc riptional activation of defense-related genes in carrot cell suspensio ns challenged with oligogalacturonide elicitors. The response of the c ells depended on the size and the conformation of the elicitors. Only oligogalacturonides with a degree of polymerization (DP) greater than 9 in a calcium-induced conformation triggered a massive accumulation o f RNA transcripts. Polygalacturonic acid had only a small effect on ge ne activation. Oligomers with a DP<9 did not induce RNA polymerase act ivity associated with defense gene sequences.