Comparison and characterization of chitinase in Cornus species

This research has demonstrated that there is a significant difference between a Dogwood Anthracnose resistant Cornus species than a susceptible species in chitinase activity following inoculation with Discula. Cornus mas (resistant) and Cornus florida (susceptible) were inoculated with Discula destructiva, (cause of Dogwood Anthracnose disease) and leaves were collected over a 12 day period. Protein from the inoculated leaves was extracted and assayed colorimetrically and enzymatically for chitinase in this investigation. Chitinase characterization was accomplished through the use of the Phastsystem to determine the iso-electric points and SDSpolyacrylamide gel electrophoresis for the molecular weight determinations.

Colorimetric assay indicates chitinase activity in Cornus mas is expressed earlier than Cornus florida following infection. The enzymatic assay indicates the presence of activity over all days post-inoculation in both Cornus mas and Cornus florida. Two iso-electric points were determined for Cornus florida and three determined for Cornus mas. By using SDS-polyacrylamide gel electrophoresis, the molecular weights were identified as 65 +/- 5 kDa and 21 kDa in for both Cornus species. The iso-electric points were determined to be 5.6, 6.8, and 8.9 for Cornus mas and 5.6 and 6.8 for Cornus florida.