ABIOTIC ELICITOR TREATMENTS STIMULATE CHANGES IN POLYPHENOL OXIDASE (PPO) ACTIVITY IN CUT GERBERA FLOWERS
Polyphenol oxidase (PPO) oxidises tannins from phenol to quinone form. Increased PPO activity is often related to lower disease and attack from herbivores. In the present study, we tested the effects of a low dose of ultraviolet-C (UV-C) irradiation on PPO activity in cut gerbera tissue. PPO activity showed a clear pattern in converting phenols to quinones immediately and 48 h after UV-C irradiation. Immediately after UV-C irradiation and during the first 30 s of the initial reaction, UV-C treated flowers showed a significantly increased PPO compared to the non-irradiated controls. Significant increase in PPO activity was also recorded in gerbera tissue 48 h after UV-C irradiation. Within this period (i.e., 0-48 h after UV-C irradiation) PPO values were similar in the irradiated and the non-irradiated flowers. We suggest that although the first peak in PPO immediately after UV-C irradiation was elicited by UV-C treatment, the following one (i.e., 48 h after UV-C irradiation) was possibly a result of tissue senescence. Elicitation of PPO may help gerbera growers or importers overcome postharvest infections caused by pathogens that develop rapidly under favourable conditions during storage or transportation.
Darras, A.I. and Demopoulos, V. (2013). ABIOTIC ELICITOR TREATMENTS STIMULATE CHANGES IN POLYPHENOL OXIDASE (PPO) ACTIVITY IN CUT GERBERA FLOWERS . Acta Hortic. 1002, 103-107
enzyme activity, induced resistance, UV-C irradiation