The basal medium used in the transformation wasa modified SH medium (MSH) [35–37], which was composedof SH macro-elements, MS micro-elements and iron, 1× vita-min B (9.9 mg l−1thiamine, 4.5 mg l−1nicotinic acid, 9.5 mg l−1pyridoxine), 30 g l−1sucrose, 2 g l−1casein hydrolysate, 7.5 g l−1agar, pH value was adjusted to 5.8 [36].