Micropropagation, phytochemical content and antioxidant activity of gamma-irradiated blackberry ( Rubus fruticosus L.) plantlets

In vitro methods were used to study the consequences of gamma irradiation on morphological and biochemical changes in blackberry plantlets. Gamma-irradiated (20, 40, and 60 Gy) plantlets were subcultured using Murashige and Skoog (MS) media. Each irradiation treatment dose consisted of ten jars containing three shoots per jar. Methanolic extracts were used for determination of total phenolic content, phenolic acids, flavonoid contents, antioxidant activity using DPPH, and ascorbic acid. The rise in γ-irradiation dose (40 Gy) significantly increased percent rooting. Raising the dose level of γ-irradiation to 40 Gy in the first, second and third subcultures of Rubus fruticosus plantlets resulted in significant enhancement of vegetative traits. In plantlets exposed to 40 Gy γ-irradiation, a significant increase was observed in chlorophyll a, b and carotenoid levels. Meanwhile, chlorophyll and carotenoid content decreased when the irradiation dose level was increased to 60 Gy. The maximum significant increase was obtained by gamma irradiation dose level 60 Gy with values of 165.08 ± 0.36 mg-100 g −1 F.W., 110.92 ± 0.99 mg-100 g −1 F.W. and 13.37 ± 0.74 mg-100 g −1 F.W. for total phenolic content, phenolic acid content and flavonoid content, respectively. The same pattern was found in ascorbic acid values. Total antioxidant capacity and antioxidant activity by DPPH of the plantlets steadily increased significantly when the irradiation dose was increased to 60 Gy. Results showed that gamma irradiation (40 Gy) improved the growth of in vitro shoot propagation, while the phytochemical content and antioxidant activity of blackberry plantlets were enhanced by dose level 60 Gy.