Adventitious regeneration of blackberry and raspberry shoots and the assessment of the LED-lighting impact

Blackberry (Rubus fruticosus L.) and raspberry (Rubus idaeus L.) are well known throughout the world due to their nutritional and medicinal importance. Obtaining regenerants is an important stage for the application of cell technologies in plant growing, plant breeding, and genetic engineering. The objective of this study was to determine the best regeneration pathways for understudied blackberry and raspberry cultivars. Adventitious shoot regeneration of thornless blackberry cultivars ‘Smoothstem’, ‘Triple Crown’ and ‘Karaka Black’, and raspberry cultivars ‘Glen Ample’, ‘Gusar’ and ‘Maria’ has been studied depending on the cultivar, type explant, hormonal composition of nutritional medium, and LED lighting. To induce adventitious shoot bud formation, three types of explants: leaves, internodes, and roots obtained from in vitro plants, were cultured in a growth chamber on MS medium supplemented with different concentrations of plant growth regulators. In most cases, regeneration became visible after three weeks of cultivation. Blackberry cultivar ‘Smoothstem’ showed the best results and regenerated at a maximum rate of 73.3% on leaf blades and stem segments on MS supplemented with 2.0 mg L-1 TDZ. The best shoot proliferation rates of raspberries (65.5%) were observed in the ‘Glen Ample’ on root segments at MS medium supplemented with 0.5 mg L-1 ZEA. The blackberry and raspberry explants were exposed under LED lighting with a ratio of quanta red (R) to blue (B) light at 1:1, 1:2, 2:1, 1:4 and 4:1, monochrome red (650–670 nm) and monochrome blue (440–460 nm), and recorded regeneration. Efficient regeneration percentage (>80%) was obtained by the incubation of raspberry and blackberry explants under illumination with a ratio of red to blue spectrum: R2:B1 and R1:B1. Monochrome blue and red light inhibited shoot growth. The obtained results indicate that certain combinations of spectra LED lighting enhances plant morphogenesis. The regeneration system described here will be useful for developing a gene transfer system and can be efficient for selected raspberries and blackberries cultivars.