Induction of defense-related enzymes in patchouli inoculated with virulent Ralstonia solanacearum

Background: Defense-related anti-oxidative response is a vital defense mechanism of plants against pathogen invasion. Ralstonia solanacearum is an important phytopathogen. Bacterial wilt caused by R. solanacearum is the most destructive disease and causes severe losses in patchouli, an important aromatic and medicinal plant in Southeast Asia. The present study evaluated the defense response of patchouli inoculated with virulent R. solanacearum.
Results: Results showed that the basic enzymatic activities differed not only between the leaves and stems but also between the upper and lower parts of the same organ of patchouli. POD, SOD, PPO, and PAL enzymatic activities were significantly elevated in leaves and stems from patchouli inoculated with R. solanacearum compared to those in control. The variation magnitude and rate of POD, PPO, and PAL activities were more obvious than those of SOD in patchouli inoculated with R. solanacearum. PAGE isoenzymatic analysis showed that there were one new POD band and two new SOD bands elicited, and at least two isoformic POD bands and two SOD bands were observably intensified compared to the corresponding control.
Conclusion: Our results suggest that not only defense-related enzymatic activitieswere elevated but also the new isoenzymatic isoforms were induced in patchouli inoculated with R. solanacearum.

Keywords
Pogostemon cablin; Ralstonia solanacearum; Peroxidase; Phenylalanine ammonia-lyase; Polyphenol oxidase; Superoxide dismutase