Promising Application of Automated Liquid Culture System and Arbuscular Mycorrhizal Fungi for Large-Scale Micropropagation of Red Dragon Fruit

Red dragon fruit (Hylocereus polyrhizus) is an economic and promising fruit crop in arid and semi-arid regions with water shortage. An automated liquid culture system using bioreactors is a potential tool for micropropagation and large-scale production. In this study, axillary cladode multiplication of H. polyrhizus was assessed using cladode tips and cladode segments in gelled culture versus continuous immersion air-lift bioreactors (with or without a net). Axillary multiplication using cladode segments (6.4 cladodes per explant) was more effective than cladode tip explants (4.5 cladodes per explant) in gelled culture. Compared with gelled culture, continuous immersion bioreactors provided high axillary cladode multiplication (45.9 cladodes per explant) with a higher biomass and length of axillary cladodes. Inoculation of H. polyrhizus micropropagated plantlets with arbuscular mycorrhizal fungi (Gigaspora margarita and Gigaspora albida) significantly increased the vegetative growth during acclimatization. These findings will improve the large-scale propagation of dragon fruit.