A simple and rapid procedure to establish embryogenic cell suspensions as a source of protoplasts for efficient plant regeneration from two Chinese commercial rice cultivars

An efficient and rapid procedure has been developed to establish embryogeni c cell suspension cultures of two Japonica Chinese commercial rice cultivar s, Zhonghua 8 and Eryi 105. Embryogenic cell suspensions of both varieties were established from 0.5-1.0 g fresh weight of embryogenic callus in AA me dium within 2.5 months of the initiation of callus from sterilised seeds. T he previously reported subculture of callus on semi-solid medium for 4-8 we eks prior to transfer into liquid medium was unnecessary and caused delay i n the establishment of embryogenic cell suspensions. Protoplasts were isola ted reproducibly from cell suspensions up to 18 months after their initiati on, with protoplast plating efficiencies attaining 0.15-0.37%. Reproducible plant regeneration from 14-26% of the protoplast-derived tissues was achie ved without the requirement for nurse cells.