Establishment of an Efficient Somatic Embryogenesis Protocol for Giant Reed (Arundo donax L.) and Multiplication of Obtained Shoots via Semi-Solid or Liquid Culture

This study developed an efficient protocol for the in vitro propagation of giant reed (Arundo donax L.) biomass, defining a complete cycle of the induction of somatic embryogenesis from immature inflorescences, followed by the maturation of somatic embryos and the subsequent multiplication of the derived shoots in liquid culture in a temporary immersion system (TIS). The best explants were found to be 30 cm long immature inflorescences, preferably collected in spring. Such an explant type was easy to decontaminate, and the spikelets isolated from it provided over 100 embryogenic callus lines. Among the callus induction media tested, gelled MS medium supplemented with 1.1 mg/L 2,4-D provided the highest percentage of responsive spikelets and the highest density of embryogenic callus. Maturation of the embryogenic callus was easily triggered on gelled MS medium devoid of plant growth regulators. The obtained shoots could be further multiplied on previously optimized gelled DKW medium supplemented with 30 g/L sucrose, 5 mg/L BA, 0.1 mg/L IBA, and 6.8 g/L plant agar. Subsequent high multiplication of the developed shoots was achieved in liquid culture in TIS using a Plantform™ bioreactor, with an immersion cycle of 12 min every 8 h.