ARABIDOPSIS LEAFY COTYLEDON1 IS SUFFICIENT TO INDUCE EMBRYO DEVELOPMENT IN VEGETATIVE CELLS

The Arabidopsis LEAN COTYLEDON1 (LEC1) gene is required for the specif ication of cotyledon identity and the completion of embryo maturation. We isolated the LEC1 gene and showed that it functions at an early de velopmental stage to maintain embryonic cell fate. The LEC1 gene encod es a transcription factor homolog, the CCAAT box-binding factor HAP3 s ubunit. LEC1 RNA accumulates only during seed development in embryo ce ll types and in endosperm tissue. Ectopic postembryonic expression of the LEC I gene in vegetative cells induces the expression of embryo-sp ecific genes and initiates formation of embryo-like structures. Our re sults suggest that LEC1 is an important regulator of embryo developmen t that activates the transcription of genes required for both embryo m orphogenesis and cellular differentiation.