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Currently, there is an increasing interest in the use of Aloe Vera in the food industry, with it being used as a source of functional foods in drinks, beverages, and ice creams. In addition, there are several reports about the antifungal activity of Aloe Vera on human mycological diseases. However, little evidence exists on the effect of Aloe extracts on fruit postharvest diseases caused by fungi, either ex-vivo or in vitro. In recent years, there have been some reports on the effect of Aloe extracts applied at postharvest in controlling fruit spoilage by fungi. However, no in-depth information has been reported on the role of Aloe extracts in decay development in fruits previously inoculated with fungi responsible for postharvest diseases or defense-related enzyme activities and modulation of antioxidant system activities. Thus, the objective of the present work was to evaluate the protective effects of Aloe extracts on Red Fuji apple fruit decay caused by Botrytis cinerea, as well as the effect of Aloe extracts on the disease resistance ability in Red Fuji apple fruit. In order to search for an alternative to synthetic fungicides for the control of the postharvest decay of Red Fuji apple fruits, the potential of using Aloe extract flavonoid for the control of postharvest gray mold incidence of Red Fuji apple fruits was investigated. Red Fuji apple fruits were disinfected with 75%(v/v) ethanol for 2 min., rinsed with tap water, air-dried, and then divided randomly into four treatment groups, with 140 fruit in each group. Three groups were dipped into 0.020, 0.035 and 0.050 g/mL Aloe extract flavonoid solutions for 5 min. at room temperature (23±1)°C. Another group (the control) was treated with distilled water. A uniform wound (4mm deepx3 mm wide) was made at the equator of each fruit using a sterile dissecting needle, followed by the inoculation of a20 μL conidial suspension of B.cinerea (1×108spores/mL) into each wound site. Inoculated fruit were placed in covered plastic boxes with small holes, and stored at (23±1)°C and RH 85%-90%. The diameters of lesions caused by B.cinerea in the apple fruit were recorded each day after inoculation, and each treatment had three replicates. The remaining fruit with inoculations were used for determination of physio-biochemical parameters. The results showed that Aloe extract flavonoid significantly decreased the incidence of gray mold rot in Red Fuji apple fruits, and effectively suppressed the expansion of lesions in vivo. After four-day storage, the gray mold rot incidence of Red Fuji apple fruits that were treated with the concentration of Aloe extract flavonoid (0.035 g/L, 0.050 mg/L) was 73% and 53% respectively, which was significantly lower than that of the control (93%). Concurrently, Aloe extract flavonoid increased the activity of peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia enzyme (PAL), chitinase (CHT), and β-1,3-glucanase (GLU). Phenolics content also increased significantly. These results indicated that increased disease resistance of Red Fuji apple fruit after Aloe extract flavonoid treatment during storage might be attributed to an elicitation of defense response involving the enhancement of defense-related enzyme activities and the modulation of antioxidant system activities. [ABSTRACT FROM AUTHOR]