In vitro propagation, genetic evaluation and slow-growth storage of the endemic and endangered species Amygdalus ledebouriana

Abstract

Biotechnology-based conservation of the endemic and endangered Amygdalus ledebouriana, listed in the Red Book of Kazakhstan and IUCN Red List, can support biodiversity conservation and sustainable ecosystem management. This poorly studied species grows in eastern Kazakhstan in the foothills of the southwestern Altai, Tarbagatai and Dzungarian Alatau mountains, which are negatively affected by overgrazing, spring and autumn burning, flower harvesting and moisture deficits. As a rootstock, it is used for plum and peach tree cultivation (conferring drought resistance), for almond breeding; further, the species is used for soil protection. An effective micropropagation protocol was developed using the plant growth regulators meta-topolin (1.0 mg L− 1), gibberellic acid (GA3) (1.0 mg L− 1) and indole-3-butyric acid (IBA) (0.01 mg L− 1), generating 4.96 microshoots per explant. Effective in vitro rooting was achieved via shoot cultivation for 10 days in the dark on half-strength Quoirin and Lepoivre (QL) medium supplemented with 1.0 mg L− 1 IBA, followed by transfer to hormone-free half-strength QL medium, generating 4.2 roots per explant (68% rooting rate). Slow-growth storage of shoots was achieved at a low temperature (4 °C) in the dark on QL medium with either 2.0 g L− 1 ABA or 1.5% sucrose; this suppressed microshoot growth while maintaining up to 100% plant viability for four months without sub-cultivation. Molecular genetic analysis using eight SSR markers confirmed the complete identity of the regenerants and the maternal plant, demonstrating their genetic stability. The micropropagation and slow-growth storage protocol developed in this study may serve as a useful tool for the ex situ conservation of this endemic and endangered species. In vitro micropropagation of Amygdalus ledebouriana, via optimised micropropagation and slow-growth storage, was achieved. This protocol will support the medium-term conservation of this endemic, drought-tolerant species.