Abstract
ABI3, a transcription factor known as a major regulator of seed development, is evolutionarily conserved in the moss Physcomitrella patens, and is essential for abscisic acid (ABA)-mediated dessication tolerance in the moss. To further investigate the molecular basis how ABI3 regulates gene expression in Physcomitrella, we searched for the interacting factors of PpABI3 using yeast two hybrid system and isolated a gene encoding NF-YC, a subunit of CCAAT binding protein (NF-Y) complex. We showed that activation of the ABA-responsive Physcomitrella PpLEA1 gene promoter by PpABI3 was not affected by co-expression of PpNF-YC, however, Arabidopsis LEC1, which encodes NF-YB and known to genetically interact with ABI3, greatly enhanced PpABI3-mediated activation of the PpLEA1 gene promoter in combination with PpNF-YC in Physcomitrella. Activation of PpLEA1 gene promoter in Physcomitrella was also observed when Arabidopsis ABI3, LEC1 and Arabidopsis NF-YC were used as effectors. These results suggest that NF-Y complex is involved in ABI3-mediated gene expression in Physcomitrella.
