Apple fruit exposed to full solar radiation increase antioxidant response

COLAVITA G.M; VENTURINO A; FRASSETTO F; ORIOLI G

Bs As

Congreso; 12th Biennial Meeting of the Society for Free Radical Research International (SFRR); 2004

SFRR

Fruit under solar stress present sunburn disorder related with reactive oxygen species generation. During growing of sun-exposed vs. shaded apple fruits of ?Braeburn? (susceptible) and ?Red-Delicious? (resistant), we examined the effect of full solar radiation (FSR) on: a) thiobarbituric acid-reactive-substances (TBARS) and electrolytes leakage; b) ascorbate (AsA), glutathion (GSH), superoxide-dismutase (SOD) and catalase (CAT). At harvest, FSR induced higher membrane peroxidation compared to controls (7.4 vs. 4.5 mmoles TBARS g-1FW in Braeburn). Lipid peroxidation was positively correlated to electrolytes leakage (R2 = 0.81, p<0.001). During fruit development, SOD increased in exposed and shaded fruits. FSR induced more SOD activity in Braeburn  than in Red-Delicious (5448.2 and 791.3 IU·g-1FW respectably, at harvest). CAT increased in Red-Delicious (6 to 36 IU·g-1FW), decreased in Braeburn (26 to 15 IU·g-1FW), and was enlarged by FSR in both cultivars. AsA content increased early in sun-exposed fruits, at harvest was higher in Braeburn (97 nmol·g-1FW) than in Red-Delicious (48 nmol·g-1FW). GSH content was similar in shaded fruits of both cultivars but the increment due to FSR was higher in Red-Delicious (160 nmol·g-1FW, 2X vs Braeburn). Early exposure of apple fruits to FSR would cause adaptive response by induction of antioxidant compounds and enzymes in both cultivars.