Abstract
An EST encoding the GAMYB binding protein (GAMYBBP) of Phalaenopsis amabilis subsp. formosa was isolated from a cDNA library constructed using the PCR-select cDNA subtraction method. Gibberellin (GA) signaling plays important roles in plant growth and development. The full length cDNA was 2552 bp obtained with RT-PCR and 5’RACE and designated PaGAMYBBP. The predicted coding region of PaGAMYBBP contains 1899 nucleotides. The deduced peptide sequence of GAMYBBP has a conserved SKIP/SNW domain from residues 205 to 368. The SKIP (Ski interacting protein) is a nuclear protein exists in chromatin and functions as a transcriptional regulator in Drosophilia. The expression of PaGAMYBBP in leaf was similar to that in floral bud. The expression of PaGAMYBBP was inhibited by GA at concentration of 10-4 M. Abnormal temperature that caused heat stress increased the expression of PaGAMYBBP but cold stress did not affect the expression. We hypothesize that the PaGAMYBBP binds to GAMYB with the SKIP/SNW and thus regulate the expression of GA-responsive genes to prevent the precocious expression of downstream hydrolase gene under insufficient GA signal.