Abstract
In Arabidosis, LEAFY COTYLEDON1 (LEC1) is thought to play important roles in embryogenesis and shares significant sequence identity with HAP3 subunit of the CCAAT-box binding factor (CBF). We had already isolated C-LEC1, a carrot homolog of LEC1, and found that the expression of C-LEC1 was limited in embryonic tissues, especially in the early stage of somatic and zygotic embryos. Based on the published reports on CBF in other organisms, it is considered that C-LEC1 may form a complex with carrot-HAP2 and carrot-HAP5 and bind to the CCAAT sequence in the promoter of embryo-specific genes.
By the yeast two-hybrid screening and PCR using degenerate primers, we had cloned four factors that might interact with C-LEC1. C-HAP2A and C-HAP2B showed high similarity to HAP2. C-HAP5A and C-HAP5B showed high similarity to HAP5. C-HAP5A and C-HAP5B could interact with C-LEC1 in vitro. Moreover, C-HAP2B/C-LEC1/C-HAP5A or C-HAP5B could form complex showing CCAAT-box binding activity.
