Overexpression of S-adenosylmethionine decarboxylase gene in rice increases polyamine level and enhances sodium chloride-stress tolerance

S-adenosylmethionine decarboxylase (SAMDC) is a key enzyme involved in the biosynthesis of the polyamines, viz. spermidine and spermine. SAMDC cDNA from Tritordeum was introduced into the rice (Oryza sativa L.) genome using an Agrobacterium-mediated transformation method. Transgenic rice plants showed normal growth and development. DNA blot analysis confirmed stable integration of the transgene. ABA-induced SAMDC gene expression was observed in RI transgenic plants under NaCl stress, and the transgenic plants showed increased seedling growth compared to non-transgenic controls. There was a three- to fourfold increase in spermidine and spermine levels in transformed plants under the NaCl stress.