Differences in the Rates of Ethylene Production and Growth between the Calluses Derived from Rice (Oryza sativa L.) and Soybean (Glycine max (L.) Merr.)

The differences in the rates of ethylene production and growth between the calluses derived from the seeds of rice (16 cultivars of Oryza sativa L., Japonica and Indica types) and soybean (10 cultivars of Glycine max (L.) Merr.) were investigated. On the medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) and benzylaminopurine (BAP), soybean calluses produced a larger amount of ethylene (208-1541 nLg–1 FW 24 h–1) than rice calluses (8-37 nLg–1 FW 24 h–1) and the rate of ethylene production from the calluses of both species greatly varied with the cultivar. The combined application of 2,4-D and BAP greatly increased the ethylene production rate and the growth of calluses in soybean, but not in rice. Moreover, the addition of BAP to the medium strikingly promoted ethylene production in soybean calluses cultured on the medium containing 2,4-D, but not in those cultured on the medium containing indolebutyric acid (IBA). The rate of ethylene production in both soybean and rice negatively correlated with the growth of calluses. The ethylene production and growth of calluses cultured under various conditions greatly differed between soybean and rice, and also varied with the cultivar of each species. The different aspects of the growth and ethylene production between soybean and rice calluses may represent the difference between dicots and monocots