CHANGES IN LEVELS AND ISOZYMES OF PEROXIDASE IN WOUNDED PEACH BARK

Bark on one-yr-old branches from six peach cultivars was mechanically wounded then examined over time for changes in peroxidase isozymes, to tal peroxidase activity, and total protein. Four peroxidase isozymes w ere identified and changes in total activity were associated mostly wi th one isozyme. Changes in peroxidase activity in response to wounding were observed with activity increasing to the highest levels at 4 and 7 days post-wounding. At 10 and 14 days post-wounding, peroxidase lev els had returned to levels similar to the control. An unidentified wou ld response protein was detected in these experiments. The timing of t he appearance of this protein was correlated with the known relative s usceptibility of the cultivars to the peach canker pathogens, Leucosto ma persoonii and L. cincta. Comparisons of the peroxidase isozyme prof iles and total peroxidase activity among cultivars provided no indicat ion that peroxidase profiles could be used as a marker for resistance to the peach canker pathogens.