Аңдатпа
Abstract Niedzwetzky’s apple ( Malus niedzwetzkyana Dieck ex Koehne) is an endangered Central Asian species whose declining and fragmented populations highlight the need for effective ex situ conservation of its genetic resources. Here, an in vitro slow-growth storage protocol for the medium-term conservation of M. niedzwetzkyana was optimized. Plant material was collected from a natural population in Zhongar-Alatau State National Natural Park (Kazakhstan), where only five trees were identified. Microshoots were established in vitro from apices sterilized with 12% H₂O₂ and multiplied on Quoirin–Lepoivre (QL) medium. Storage conditions were optimized by testing sucrose (3–6%), mannitol (2 and 4%), and abscisic acid (1.0–3.0 mg L⁻ 1 ) concentrations on QL and ½QL media under standard (25 °C, 16/8 h photoperiod) and cold (+ 4 °C in darkness) conditions for 6 months. Performance was assessed using morphometric parameters and the percentage of explant viability recovery after storage. Basal medium and growth-retarding treatment significantly affected nearly all morphometric parameters, with the Medium × Treatment interaction being most pronounced under cold storage. The most effective growth suppression while maintaining viability was achieved on ½QL medium supplemented with 2% mannitol and no growth regulators, under storage at + 4 °C in darkness; under these conditions, shoot elongation was almost completely suppressed, and explant viability recovery after 6 months reached 100%. The optimized protocol enables medium-term conservation of M. niedzwetzkyana with a substantially reduced subculturing frequency and provides a practical basis for establishing an in vitro collection of this endangered species.