XVI International Botanical Congess

The techniques for isolating egg cell (EC), central cell (CC), and zygote (Z) have been well developed in rice and tobacco. In vitro fusion between single tobacco sexual cells enabled us to monitor the dynamics of this process in detail. Microculture of Zs has led to the formation of proembryo-like structures in both species. Unfertilized ECs have undergone first division in rice, unfertilized or fertilized Ccs have been induced to either multicellular or coenocytic structures in tobacco and rice. Besides, by using immunocytochemical and in situ hybridization techniques, special temporal bands of calmodulin protein and mRNA were found between the egg apparatus and CC in tobacco during fertilization. Dramatic increase of calcium within the ECs after fertilization were observed in rice.