IN VITRO PLANT REGENERATION FROM CHINESE CASSAVA CULTIVARS VIA ORGANGENESIS
HE Ya Wen HAN Mei Li HE Hong ZHANG Lan Yin LI Geng Guang (South China Institute of Botany, Academia Sinica, Guangzhou 510650)
Chinese cassava cultivars in vitro regeneration from 4 types of explants was studied. The results showed that thick shoots developed directly from the cut surfaces of "NZ 188" decapitated germination embryos on MS medium supplemented with 0. 05mg/L TIBA, 1.0mg/L BA with a regeneration frequency of 43%. When inoculated on MS medium with 0. 5mg/L NAA, 0. 5mg/L BA for 3 weeks, cotyledons from "SC 201" mature embryos produced shoots directly at a frequency of 42% , on MS medium with 0. 5mg/ L IBA, 1. 5mg/L BA, at a freuqency of 31%. Adding AgNO3 only or both AgNO3 and ABA to the media had an unfavorable effect on the shoot-induction. Calli could be induced when hypocotyl segments from "HZ 188" germination embryos were cultured on MS medium supplemented with 0. 5mg/L NAA, 0. 5mg/L BA in two weeks. After 4 weeks of culture on MS medium with 1mg/ L NAA, 2 mg/L BA green dots appeared on most calli, only 4. 4% calli produced shoots. Calli formed two weeks later when "NZ 188" stem segments were cultured on MS medium with 0. 05mg/L TIBA, 2mg/L BA. After 4 weeks of subculture only one callus produced shoots on the same medium.