Four-month-old calli without organogenesis; organogenic calli
grown on medium supplemented with 4 mg/l BAP, cells cultured
in suspension, three-month-old plantlets, and five-year-old wild
plants were lyophilized overnight (Labconco Instrument, USA),
before being ground to a powder with a pestle in a mortar, using
liquid nitrogen to facilitate sample homogenization, and stored at
−20 ◦C.