Smoke tree (Cotinus coggygria Scop.) propagation and biotechnology: A mini-review

Cotinus coggygria Scop. (Anacardiaceae), commonly referred to as 'smoke tree' or 'smoke bush', is an attractive ornamental tree or large bush that has medicinal properties and multiple bioactivities. Seed germination can be high after treating seeds with H2SO4, but to avoid growing male trees that will not form attractive inflorescences, the rooting of cuttings from female trees is a preferred method of vegetative propagation. One method to intensify the rooting of stem cuttings is by shading mother plants and simultaneously applying an exogenous auxin or biostimulator. This method can increase the quality of rooted cuttings. In addition, shading causes anatomical changes in the stem structure and leads to the formation of adventitious root primordia. New EU regulations have forced member states to change or withdraw existing authorization for products used in plant protection that contain active substances like auxin (indole-3-butyric acid, IBA). Consequently, there is an active search for alternative measures to support the process of rooting woody plants. Examples of such preparations are biostimulators, including AlgaminoPlant, HumiPlant and Route®, which can increase the rooting of cuttings, affect processes associated with oxidative stress, and increase the intensity of gas exchange and the content of organic compounds. The most effective in vitro micropropagation protocol for C. coggygria involves the use of Murashige and Skoog basal solid or liquid media enriched with one of two cytokinins, 6N-benzyladenine or meta-metoxytopolins. The use of IBA has shown most success, both ex vitro and in vitro. All other aspects of Cotinus species biotechnology still need to be developed.