Abstract
Effects of radiation processing on the endogenous phytochemical production in blackberry (Rubus fructicosus L.) were investigated through a metabolites analysis, using high-performance liquid chromatography with a diode array detector and a triple quadrupole mass spectrometer (HPLC-DAD-ESI-MS/MS). Four mutant cultivar lines (B, C, D, and E) were developed through the treatment of various doses of gamma irradiation (80, 60, 40, and 20 Gy) on the control blackberry cultivar (V3). These mutant cultivar lines were selected according to their different morphological variations in leaf shape and branch color. In the present study, we performed quantitative analyses of the four standard compounds in blackberry mutant cultivars: cyanidin-3-O-glucoside, cyanidin-3-O-xyloside, cyanidin-3-O-malonylglucoside, and cyanidin-3-O-dioxalylglucoside. The HPLC fingerprints displayed different profiles for six blackberry cultivar lines, demonstrating that the accumulation of total anthocyanins was affected by the gamma irradiation. The contents of cyanidin-3-O-glucoside and cyanidin-3-O-xyloside were high in the gamma-irradiated mutant cultivars of blackberries, compared to those of the control cultivar (V3) and the cross breeding cultivar (R. fructicosus × R. parvifolius; CB). Cyanidin-3-O-malonylglucoside and cyanidin-3-O-dioxalylglucoside were also analyzed for their quantification in six cultivar lines, as metabolites contributing to the discrimination of six cultivar lines. Among gamma irradiated mutant blackberry cultivars, the highest dose level of gamma irradiation (80 Gy) resulted in the highest cyanidin-3-O-glucoside content enhancement. Therefore, these results can be useful to determine the optimized gamma irradiated value at which anthocyanins reaches an abundant level in Rubus species.