Embryological Studies on Apospory in Rice HDAR

An embryological investigation on the development of female gametophyte formation and embryogenesis in rice HDAR was made. The results revealed that the aposporous embryo sacs originated from certain somatic cells in the vicinity of megasporocyte. As aposporous initials developed simultaneously with megaspore mother cell and competed with each other,either multiple embryo sacs or sometimes only single embryo sac could be observed at later stage in one ovule. Their multiple embryo sacs differed extensively to each other in shape, structure, and polarity. Also, egg-cell in certain embryo sacs, which were difficult to determine their origins, possessed the capacity for parthenogenesis. The coexistence between apomictic ovary and sexual suggested that apospory in observed materials might be a typical facultative apomixis.