Loss-of-function mutations of the rice GAMYB gene impair the α-amylase expression in aleurone and flower development.

Abstract

GAMYB was first isolated as a positive transcription regulator of gibberellin (GA)-dependent α-amylase expression in aleurone. However, the role of GAMYB outside of aleurone is not well understood. To investigate the function of GAMYB outside of aleurone, we isolated loss-of-function mutants from a panel of rice mutants by the Tos17 insertion. Through PCR screening, we isolated three independent mutant alleles. No α-amylase expression in the endosperm was induced in these mutants, indicating that the Tos17 insertion had knocked-out OsGAMYB function. We found no significant defects in the growth and development of the mutants before and at the flowering time. After the pahse transition to reproductive stage, however, defects in floral organ development, especially a defect in pollen development, were observed. These results demonstrate that, in addition to its role in the induction of α-amylase in aleurone, OsGAMYB is also important for the floral organ development and essential for pollen development.