Abstract
NF-Y is a trimeric complex that binds to the CCAAT box, a ubiquitous eukaryotic promoter element. Each of the three NF-Y subunits, NF-YA, NF-YB and NF-YC, is represented by a single copy gene in yeast and mammal. However in model plant species (Arabidopsis and rice), each subunit is encoded by a multi gene family. A large number of NF-YA/NF-YB/NF-YC trimer combinations is considered to play multiple roles in plants, however, relatively little is known about the function of each subunit. Using yeast two hybrid system, we have isolated a NF-YC gene (PpNF-YC1) from the basal land plant Physcomitrella patens that interacts with the Physcomitrella ortholog of ABI3, an essential transcription factor of ABA signaling in seeds. Co-expression of PpABI3A and PpNF-YC1 synergistically activated ABA-responsive gene expression in a Physcomitrella transient assay, suggesting that PpABI3A interacts with PpNF-YC1 even in vivo.
