|El Ghaouth, Ahmed|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2002
Publication Date: 3/1/2003
Citation: El Ghaouth, A., Wilson, C.L., Callahan, A.M. 2003. Induction of chitinase b-1,3-glucanase and phenylalanine ammonia lyase in peach fruit by uv-c treatment. Phytopathology, Vol. 93:349-355. Interpretive Summary: We have relied heavily on synthetic fungicides for the control of postharvest decay of fruits and vegetables that can destroy over 25% of the harvested fruit. Because of human health and environmental concerns, world trends are moving towards reduced pesticide use. In response, several physical and biological means are being evaluated as safer alternatives to synthetic fungicides for the control of postharvest diseases of harvested commodities. Scientists at the USDA Appalachian Fruit Research Station, Kearneysville, WV have discovered that low-dose UV-C light will elicit resistance in fruit to postharvest decay and extend their shelf-life. In their studies of peach they discovered that low-dose UV-C "turns on" defensive enzymes in the peach such as chitinase, beta-1,3-glucanase, and phenylalanine ammonia lyase. The production of these enzymes may partially explain the mechanism where by low-dose UV-C light elicits resistance in harvested commodities. Studies continue to see how this technology may be adapted as an alternative to synthetic fungicides for the control of postharvest diseases of fruits and vegetables.
Technical Abstract: Treatment of peach fruit with UV-C light caused a rapid induction of chitinase, P-1,3-glucanase, and phenylalanine ammonia lyase (PAL) activities starting 6 h after treatment and reaching maximum levels at 96 h after treatment. By 96 h after UV-C treatment, chitinase, P-1,3-glucanase, and PAL activities in UV-C-treated fruit were over twofold above that observed in control levels. In non-treated control fruit, no apparent increase in chitinase, P-1,3-glucanase or PAL activities was detected. The transient increase in chitinase, P-1,3-glucanase and PAL activities in UV-C-treated fruit was preceded by a gradual activation of the corresponding genes. UV-C treated fruit showed an increase in accumulation of 9-1,3-glucanase and chitinase mRNAs at 3 h after treatment, which peaked approximately 96 h post-treatment. A similar induction kinetic pattern was observed for PAL MRNA in response to UV-C treatment, except the induction started 6 h after UV-C treatment. These results show that the response of peach fruit to elicitor treatment is similar to that seen in other plant-elicitors interactions and suggests the involvement of peach biochemical defense-responses in UV-C mediated disease resistance.