Arabidopsis has 5 paralogs of the S-adenosylmethionine decarboxylase (SAMDC) gene. Neither their specific role in development nor the role of positive/purifying selection in genetic divergence of this gene family is known. While some data are available on the organ-specific expression of AtSAMDC1, AtSAMDC2, AtSAMDC3 and AtSAMDC4 at transcript level, not much is known about their promoters including AtSAMDC5 (another paralog), which is believed to be non-functional.