Dehydrogenase that can use N-acetyl-gamma-aminobutyraldehyde (NAGABald), gamma-guanidinobutyraldehyde (GGBald), betaine aldehyde (Bet-ald), gamma-aminobutyraldehyde (GAB-ald), acetaldehyde, 4-aminobutylaldehyde (AB-ald), 3-aminopropionaldehyde (AP-ald), 4-N-trimethylaminobutyraldehyde (TMAB-ald) and 3-N-trimethylaminopropionaldehyde (TMAP-ald) as substrates. Catalyzes the oxidation of GAB-ald more efficiently than Bet-ald. Mediates the conversion of GAB-ald into gamma-aminobutyric acid (GABA), and prevents the formation of 2-acetyl-1-pyrroline (2AP) which gives fragrant rice its aromatic properties. betaine aldehyde + H2O + NAD(+) = glycine betaine + 2 H(+) + NADH Optimum pH is 10. Amine and polyamine biosynthesis; betaine biosynthesis via choline pathway; betaine from betaine aldehyde: step 1/1. Homodimer. Expressed constitutively in roots, embryos, seedlings, stems, leaves and flowers, with higher levels in young leaves, and lower levels in roots. Strongly expressed in inflorescence meristem during cell division. Following submergence treatment, transient decreased levels that recovers after re-aeration. Reduced crop productivity, but increased accumulation of gamma-4-aminobutyraldehyde (GAB-ald) and higher 2-acetyl-1-pyrroline (2AP) biosynthesis, which influences aroma. Present in a truncated form, mostly allele badh2.1, also called 'fgr' in fragrant rice varieties (e.g. basmati and jasmine rice). The loss of activity leads to accumulation of 2-acetyl-1-pyrroline (2AP) that confers the flavor of fragrant rice. Haplotype analysis suggests a single origin of the badh2.1 allele within the Japonica varietal group and demonstrates the introgression of this allele from Japonica to Indica (PubMed:17129318, PubMed:18599581, PubMed:18491070, PubMed:19371779, PubMed:19706531). Belongs to the aldehyde dehydrogenase family.