Site-specific binding of a nuclear factor to the carrot extensin gene is influenced by both ethylene and wounding.

Experiments conducted in vitro using the electrophoretic mobility shift assay have shown that a single region of the extensin gene of carrot (Daucus carota L.) interacts with a protein factor designated Extensin Gene Binding Factor-1 (EGBF-1) present in nuclear extracts obtained from carrot roots. This interaction is sequence-specific as judged by the failure of other plant gene sequences to compete with the extensin gene for EGBF-1 binding. The EGBF-1 activity is organspecific, not being expressed in nuclear extracts obtained from carrot leaves or stems. Both ethylene treatment and wounding of roots are shown to have a controlling influence on the expression of EGBF-1 activity in nuclear extracts. These results demonstrate that at least three distinct signals: ethylene treatment, wounding, and development, are important in determining the activity of EGBF-1 in nuclear extracts, and indicate a role for EGBF-1 in stress-related signal transduction and the regulation of extensin-gene expression.