Micropropagation of Mountain Mulberry (Morus bombycis Koidz.) ‘Kenmochi’ on Cytokinin-Free Medium

Abstract

The aim of the study was to compare two methods of micropropagation of mulberry: single-node culture (“SNC”), and axillary-branching (“AxB”). The experiments were carried out on in vitro cultures for 6 successive passages. The “AxB” cultures were propagated on modified MS medium (+ 25% Ca²⁺ and Mg²⁺), supplemented with WPM vitamins, sucrose (30 g L⁻¹), and BA (1.5 mg l^-1). The “SNC” cultures were grown on cytokinin-free 1/2 MS (macro- and micronutrients) medium supplemented with WPM vitamins, IBA (0.05 mg l^-1), and sucrose (15 g l^-1). Both media (pH 5.8) were solidified with agar (7.0 g l^-1). Initiation of in vitro cultures from explants taken from adult trees and young, potted plants was feasible on both media. Cultures were established from about 1 cm long nodal explants. Generally “SNC” cultures formed one well rooted, significantly longer axillary shoot with bigger leaves than “AxB” cultures, which developed significantly more shoots and big callus at the explant base. All shoots collected from “SNC” and “AxB” cultures rooted in vivo in peat mixture and developed into similar plantlets. The single-node method based on application of cytokinin-free medium is a good alternative for the axillary-branching method for micropropagation of mountain mulberry (Morus bombycis) ‘Kenmochi”’.