Abstract:

Calmodulin (CaM), as the most important Ca²⁺ sensor, controls diverse cellular and physiological processes in higher plant. Many studies suggest that CaM plays vital roles during plant sexual reproductive process. The effects of CaM on development of early embryos in vitro are poorly understood despite those effects of CaM on zygotic embryo development reported from some researches. In this study the line of indica rice Xiaogan-01 was used to investigate the effects of CaM and trifluoperazine (TFP) on development of rice early embryos of 3－5 DAP (days after pollination) in vitro by adding 10^-8, 10^-7, 10^-6 or 10^-5 mol/L exogenous CaM to medium, and 10^-7, 10^-6, 10^-5 or 10^-4 mol/L TFP to the medium with 10^-7 mol/L CaM. CaM and TFP were found to exert different effects on the development of 3 to 5-day-old embryos in rice. The influence of CaM on the development of 3 to 5-day-old embryos in vitro was related to the concentration of CaM and the age of embryos. With the high concentration of CaM (10^-6－10^-5 mol/L), the growth and the development of 3 to 5-day-old embryos were inhibited in a certain degree, the higher the concentration of CaM used, the more evident the inhibition was (Fig.1). With 10-7 mol/L CaM, all embryos grew rapidly and the highest frequency of normal embryogenesis was reached. At the same concentration of CaM, the older the embryos were, the more quickly they grew and the higher their frequency in normal embryogenesis and in total induction (Table 1). The development of 3 to 5-day-old embryos in vitro was inhibited by TFP which was related to the concentration of TFP and the age of embryos. The younger the embryos were, the more obvious the inhibition appeared (Fig.2). The growth speed of all embryos in vitro, the frequency of normal embryogenesis and the total induction frequency were decreased with increasing TFP concentration (Table.2). The results indicate that CaM and TFP have very important and complex effects on the development of rice early embryos in vitro.

Key words: Oryza sativa L., CaM, TFP, Embryo in vitro, Development