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ARS Home » Pacific West Area » Wenatchee, Washington » Physiology and Pathology of Tree Fruits Research » Research » Publications at this Location » Publication #148215

Title: BIOCHEMICAL CHANGES IN 'FUJI' APPLE FRUIT PEEL INDUCED BY UV-B IRRADIATION

Author
item GONG, YIPING
item Mattheis, James

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2003
Publication Date: 8/3/2003
Citation: Gong, Y., Mattheis, J.P. Biochemical changes in 'Fuji'apple fruit peel induced by UV-B irradiation. HortScience 38: 856. 2003.

Interpretive Summary:

Technical Abstract: Exposure to ultraviolet-B (UV-B) irradiation in the field or after harvest can induce peel disorders in `Fuji¿ apples. Harvested `Fuji¿ apples were used to determine if development of peel disorders is accompanied by changes in activity of enzymes involved in oxidative and secondary metabolism. Apples were exposed to UV-B irradiation or held in the dark (control) at 20 C for five days then stored at 0 C for 90 days to allow development of disorders. Analysis of enzyme activity was conducted at the end of the five day irradiation period. Exposure to UV-B induced development of both stain and sunburn, and irradiated fruit had increased NADH oxidase and NADPH oxidase activities compared to controls. Fruit exposed to UV-B had higher phenylalanine ammonia-lyase (PAL) activity compared to controls, but UV-B exposure did not alter the activity of 4-coumarate: coenzyme A ligase (CL) relative to activity at harvest. Activities of PAL and CL from control fruit were lower and higher, respectively compared to values at harvest. Superoxide dismutase (SOD) activity was not impacted by UV-B irradiation and SOD activity for controls and UV-B irradiated fruit was lower than activity at harvest. Catalase activity in controls and UV-B irradiated fruit increased relative to activity at harvest, but was slightly lower in UV-B irradiated fruit. Treatment of fruit at harvest with the SOD inhibitor N, N,-diethyldithiocarbamate (DE) plus UV-B irradiation resulted in a higher occurrence of sunburn in fruit, but UV-B irradiation alone did not. The occurrence of stain was not affected by DE treatment. The results indicate SOD activity may be important for avoiding UV-B-induced sunburn, while stain is accompanied by enhanced activity of NADH oxidase and PAL and reduced CL activity.