Developing a long-term and powerful in vitro culture and Agrobacterium-mediated transformation system for Miscanthus sinensis (Poaceae)

•Seed explants of Miscanthus sinensis produce a high percentage of embryogenic calli.•Timely subculture of calli lasts the embryogenic activity for a long period of time.•Reducing moisture in cocultivation significantly increases transformation frequency.•Gradually reducing the selective agent concentration improves selection efficiency.•GUS gene is not a reliable reporter for genetic transformation of M. sinensis.