Artificial polyploidy induction for improvement of ornamental and medicinal plants

Green plants provide food, fuel, materials, and medicine for humans. Amongst these, medicinal plants contain unique molecules with therapeutic applications. However, our understanding of these organisms is in its infancy. Landscaping plants also have a great impact on the human soul and emotional perception. These two groups of plants are part of natural wealth and have great economic value. One of the remarkable breeding strategies to improve the valuable properties of plants is artificial polyploidy induction. Medicinal and ornamental plants with duplicated whole sets of chromosomes, although not always, have more distinctive characteristics such as modified phytochemical profile, higher content of desired pharma molecules, plant form, flower color, size and style, fragrance, vase life, and prolonged flowering period. Therefore, artificial chromosome doubling (ACD) of ornamental and medicinal plants could have significant economic consequences. In medicinal plants with an ornamental flower/inflorescence, and/or in ornamental plants bearing essential oils, ACD is a dual beneficial breeding strategy. Working with both in vitro and in vivo chromosome doubling pathways, researchers are able to produce custom-designed plants with higher marketability. Some critical factors must be considered to establish a successful ACD protocol. The plant genotype and explant type are important parameters in this procedure. Type, dosage and duration of application (exposure time) of antimitotic agent (AMA) should also be considered as the main factors. Antimitotic agents can be classified according to their efficacy and toxicity. Although colchicine is the most applied and well-known AMA, there are other alternative mitotic spindle inhibitors with higher specificity for tubulin binding sites in plant materials and possessing less toxicity for animal tubulin. Testing the interaction effects of plant and AMA parameters is necessary for establishing an ACD breeding program and promoting the economic values of medicinal and ornamental plants. This paper reviews significant developments in polyploidization using different antimitotic agents over the last decade in the field of ornamental and medicinal plants. Key message Artificial polyploidy induction is one of the applicable breeding methods in ornamental and medicinal plants. Increasing the efficiency of chromosome doubling and fast-reliable screening of desired phenotypes are prerequisites for production of custom-designed medicinal and ornamental plants through artificial polyploidy induction.