Influence of Zinc Oxide Nanoparticles in In Vitro Culture and Bacteria <i>Bacillus thuringiensis</i> in Ex Vitro Conditions on the Growth and Development of Blackberry (<i>Rubus fruticosus</i> L.)

Abstract

The blackberry, valued for its delicious fruit, has gained attention for its medicinal bioactive compounds. In vitro cultivation methods, including nanoparticle enhancement, are increasingly chosen due to their advantages over traditional propagation techniques. We tested the effect of commercial zinc oxide nanoparticles (ZnONPs) on the growth and development of blackberry (Rubus fruticosus L.) of the Navaho variety in an in vitro culture on MS medium supplemented with 0.6 mg dm−3 BA, 0.1 mg dm−3 IBA, 0.01 mg dm−3 GA3, and various concentrations of zinc oxide nanoparticles: 0 (control), 10, 20, 30, and 40 mg dm−3. The morphological features of the plantlets were assessed two and three months after the start of the culture. Selected biological characteristics of the plantlets were determined. The values of the morphological and biological parameters assessed in the plantlets from in vitro culture depended on the concentration of ZnONPs in the medium. Increasing the concentration of ZnONPs negatively affected the number and length of shoots and roots and the fresh weight of the plantlets. The total phenolic content in the plantlets from the treatments with ZnONPs was lower than in the control plants, but the total antioxidant capacity as measured by the ABTS method was higher. The content of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids in the blackberry plantlets decreased at higher concentrations of ZnONPs in the medium. The addition of zinc oxide nanoparticles increased the zinc content and reduced the iron content in the blackberry plantlets. Concentrations of 10–30 mg dm−3 ZnONPs increased the concentrations of potassium, calcium, magnesium, zinc, manganese, and copper, while at the highest concentration of 40 mg dm−3 ZnONPs, the concentrations of these minerals were similar to the control, except for a lower content of calcium and manganese. The plantlets from the in vitro culture growing in the presence of ZnONPs were acclimatized to ex vitro conditions in control soil and soil inoculated with Bacillus thuringiensis. Bacteria added to the ex vitro substrate favourably influenced the growth and development of the shoots and roots of the blackberry plants and their fresh weight.

Keywords

• ZnONPs
• blackberry
• PGPB
• phenols
• antioxidants
• photosynthetic pigments