TEMPERATURE-SENSITIVE MUTATION, EMBRYOLESS-1, AFFECTS BOTH EMBRYO ANDENDOSPERM DEVELOPMENT IN RICE

How the embryo and endosperm interact during seed development is an im portant subject for elucidating mechanisms of both embryo genesis and endosperm development. We have identified a single temperature-sensiti ve mutation, embryoless 1 (eml1), affecting both embryo and endosperm development. At a high temperature, eml1 causes embryoless seeds conta ining large endosperm. Rarely, small embryos with or without organs ar e formed. At a low temperature, however, the frequency of embryoless s eeds drops and seeds are often detected which contain a large embryo a nd a defective or no endosperm. Thus, in this mutant, embryo size is n egatively correlated with endosperm size. Temperature-shift experiment s suggest that this mutant becomes insensitive to the temperature chan ge after 4 days post pollination. Accordingly, the seed phenotype of t his mutant would be temperature-dependently determined before 4 days a fter pollination. The negative correlation in size between embryo and endosperm suggests that they developmentally interact from the early s tage of seed formation.