Molecular characterization of two genes encoding betaine aldehyde dehydrogenase from amaranth. Expression in leaves under short-term exposure to osmotic stress or abscisic acid

A genomic clone (ahybadh4) and a cDNA (ahybadh17) both encoding betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) were isolated from the plant Amaranthus hypochondiacus L. The gene extends 9 kilobases (kb) containing 15 exons with an open reading frame (ORF) of 501 amino acids (aa), a 1.3 kb 5' untranslated region (UTR) and a 3' UTR of 0.3 kb. The ahybadh17 cDNA encodes a BADH isoform of 500 aa which contains 10 aa substitutions with respect to AHYBADH4. Both encoded proteins share 98% identity at the amino acid level. Comparison of amaranth BADHs with other reported sequences showed high similarity. Analysis of ahybadh17 expression in amaranth leaves showed that mRNA and BADH protein are present in non-treated amaranth leaves and both transiently increased under short-term exposure to abscisic acid (ABA) and osmotic stress treatments.