Title : In vitro multiplication efficiency of Aronia melanocarpa ‘Alexandrina’ with meta-topolin
Abstract:
Aronia melanocarpa (Michx.), commonly known as black chokeberry, is a woody shrub belonging to the Rosaceae family, and originating from North America. It is cultivated in temperate areas for its small, dark berries, which are rich in antioxidants, including flavonoids and phenolic acids. The fruits are mainly intended for processing and less commonly consumed fresh, due to their pronounced astringent taste and bitter-almond smell. However, the interest in this fruit species has increased, as numerous studies have shown that they have potential health benefits. In vitro tissue culture techniques play and important role in the propagation this woody species, as they enable the production of disease-free and genetically uniform planting material. The present study aimed to evaluate the in vitro response of ‘Alexandrina’, a Moldavian cultivar, to different types of plant growth regulators. The initial plant material was obtained as in vitro cultures, from the National Botanical Garden (Institut) “Alexandru Ciubotaru” of the State University of Moldova and was subsequently multiplied in vitro at the University of Agronomic Sciences and Veterinary Medicine of Bucharest, Romania. In vitro multiplication of Aronia melanocarpa ‘Alexandrina’ was performed out on Murashige and Skoog (MS) medium, supplemented with five different cytokinins, each at a concentration of 4 μM: meta – topolin (mT), Zeatin (Z), kinetin (kin), 6-(γ, γ-Dimethylallylamino) purine (2iP) and thidiazuron (TDZ). All media variants also contained 2.9 μM indole-3-acetic acid (IAA) and 0.58 μM gibberellic acid (GA3).
The results showed that meta-topolin significantly enhanced the multiplication rate of A. melanocarpa explants, resulting in the highest average number of shoots (21.5 shoots/explant) and biomass accumulation (1.9455 g fresh weight/ explant). By comparision, the other media variants produced fewer shoots/explant: 1 shoot on medium with KIN, 1.8 shoots on 2iP and 4.5 shoots on Z. Explants grown on medium with KIN, even although showing limited proliferation, exhibited the greatest shoot elongation (44.94 mm), leaf development and rooting (100%), with an average of 3.1 roots/explant and 79.47 mm average length. A similar response was observed on medium with 2iP, with an average shoot length of 39.29 mm and 3.3 roots/shoot with a mean length of 49.98 mm. The inclusion of TDZ resulted in the formation of compact, globular masses of shoots (2.3258 g fresh weight/explant) that were small, highly friable, and hyperhydrated rendering them unsuitable for further multiplication. For rooting, shoots obtained on media with meta-topolin were cultivated on half-strength MS medium with 1 g/L activated charcoal, supplied either with Indole-3-Acetic Acid (IAA) or Indole-3-Butyric Acid (IBA). Copper sulphate (CuSO4·5H2O) concentration was increased to 0.125 mg/L to enhance root growth and plantlet development. All media variants promoted rhizogenesis and shoot growth, and the plantlets were succesfully acclimatized. In conclusion, the results demonstrate that meta-topolin is a highly effective cytokinin for the in vitro multiplication of Aronia melanocarpa ‘Alexandrina’, while kinetin and 6-(γ,γ-Dimethylallylamino) purine are more suitable for shoot elongation and rooting. The optimized protocol provides an efficient approach for the rapid multiplication of this species and may support large-scale production for horticultural and pharmaceutical applications.
