Establishment of a simple and efficient system for somatic embryo induction via ovule culture in Arabidopsis thaliana.

We established a simple and effective system to induce somatic embryos in Arabidopsis via ovule culture. Agar-solidified B5 basic medium supplemented with 10 micro M 2,4-dichlorophenoxyacetic acid was used for callus induction. Ovules at all developmental stages were tested, and among these, ovules older than 48 h after anthesis could be successfully induced to form embryogenic calli at high frequencies (42-82%). Structural and molecular probe analyses confirmed that the embryogenic calli were derived from embryos in the ovules. These calli were then easily induced to generate somatic embryos at frequencies of 63-95%. Subculture of the somatic embryos onto 1/2 strength MS medium resulted in their direct conversion into plants. The regenerants appeared morphologically normal and were fertile. This method provides a useful alternative tool to create sufficient numbers of somatic embryos for the study of biochemical and molecular mechanisms of embryogenesis, especially to recover early defective embryos in some mutations for cell-biological analyses.