Inducement and cultivation of novel red Cyclocarya paliurus callus and its unique morphological and metabolic characteristics

•A valuable red callus and a common yellow-green callus were induced and cultivated.•Morphological and metabolic differences between two calluses were described.•Cyanidin-3-O-galactoside and glucoside were first identified in C. paliurus callus.•Interpret the mechanisms causing the differences between two calluses by RNA-seq.