IN VITRO PROPAGATION OF WILD BULGARIAN SMALL BERRY FRUITS (BILBERRY, LINGONBERRY, RASPBERRY AND STRAWBERRY)

Abstract

Recently, an increased interest in the identification of valuable possibilities for preserving the antioxidant properties of wild berry fruits rich in bioactive compounds can be noticed.
The interest in small berry cultivation is growing because of the high value of the fruit in global food markets. Tissue culture provides an efficient propagation method for the selected berry genotypes both for the breeding and cultivation purposes.
Four wild Bulgarian species - strawberry (Fragaria vesca L., Rosaceae), raspberry (Rubus idaeus L., Rosaceae), bilberry (Vaccinium myrtillus L., Ericaceae) and lingonberry (Vaccinium vitis-idaea L.) were evaluated in terms of their regeneration capacity when propagated in vitro by auxiliary organogenesis.
The highest average number of shoots (12.6) was accounted in wild strawberry, followed by wild raspberry (6.8) on MS medium supplemented with IBA, BAP and GA. The multiplication indices for bilberry and lingonberry were respectively 7 and 4.6 shoots per explant, cultivated on WPM + vitamin C with addition of growth regulators 6-[4-hydroxy-3-methylbut-2-enylamino] purine (zeatin) and N6-[2-isopenteny1] adenine (2iP). The rooting of wild strawberry was successful on MS medium supplemented with IBA, BAP and GA, while for raspberry the addition of only IBA. The rooting potential of bilberry and lingonberry varied between 1.4% to 33.3% (medium R10 and R12).
Folin-Cio+calteu, DPPH and FRAP spectrophotometric assays were used for the assessment of the total phenolic content and the antioxidative properties of methanolic fruit extracts obtained from ex vitro and in vivo species. The antioxidant capacity determined by FRAP method was presented the values between 18.73-35.22 mM TE/g DW and in the case of DPPH assay the obtained values were situated in the range 63.75-95.65 mM TE/g DW. TPC from analyzed samples was situated in the range 28.95-53.16 mg GAE/g DW.