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Effects of Botrytis cinerea and Pseudomonas syringae infection on the antioxidant profile of Mesembryanthemum crystallinum C₃/CAM intermediate plant

Libik-Konieczny, Marta, Surówka, Ewa, Kuźniak, Elżbieta, Nosek, Michał, Miszalski, Zbigniew
Journal of plant physiology 2011 v.168 no.10 pp. 1052-1059
Botrytis cinerea, C3 plants, Crassulacean acid metabolism, Mesembryanthemum crystallinum, Pseudomonas syringae, antioxidants, bacteria, enzyme activity, fungi, hyphae, leaves, lifestyle, pathogens, peroxidase, plant response, superoxide dismutase
Mesembryathemum crystallinum plants performing C₃ or CAM (crassulacean acid metabolism) appear to be highly resistant to Botrytis cinerea as well as to Pseudomonas syringae. Fungal hyphae growth was restricted to 48h post-inoculation (hpi) in both metabolic types and morphology of hyphae differed between those growing in C₃ and CAM plants. Growth of bacteria was inhibited significantly 24hpi in both C₃ and CAM plants. B. cinerea and P. syringae infection led to an increase in the concentration of H₂O₂ in C₃ plants 3hpi, while a decrease in H₂O₂ content was observed in CAM performing plants. The concentration of H₂O₂ returned to the control level 24 and 48hpi. Changes in H₂O₂ content corresponded with the activity of guaiacol peroxidase (POD), mostly 3hpi. We noted that its activity decreased significantly in C₃ plants and increased in CAM plants in response to inoculation with both pathogens. On the contrary, changes in the activity of CAT did not correlate with H₂O₂ level. It increased significantly after interaction of C₃ plants with B. cinerea or P. syringae, but in CAM performing plants, the activity of this enzyme was unchanged. Inoculation with B. cinerea or P. syringae led to an increase in the total SOD activity in C₃ plants while CAM plants did not exhibit changes in the total SOD activity after interaction with both pathogens. In conclusion, the pathogen-induced changes in H₂O₂ content and in SOD, POD and CAT activities in M. crystallinum leaves, were related to the photosynthetic metabolism type of the stressed plants rather than to the lifestyle of the invading pathogen.