title: Sequence analysis of diamine oxidase gene from fava bean and its expression related to γ-aminobutyric acid accumulation in seeds germinating under hypoxia-NaCl stress.
abstract: BACKGROUND
  γ-Aminobutyric acid (GABA) is synthesized via the polyamine degradation pathway in plants, with diamine oxidase (DAO) being the key enzyme. In this study the cDNA of DAO in fava bean was cloned and its expression in seeds germinating under hypoxia-NaCl stress was investigated.
  
  
  RESULTS
  Fava bean DAO cDNA is 2199 bp long and contains 2025 bp of open reading frame that encodes 675 amino acid peptides with a calculated molecular weight of 76.31 kDa and a pI of 5.41. Hypoxia and hypoxia-NaCl stress enhanced DAO activity and resulted in GABA accumulation in germinating fava bean. However, DAO gene expression was down-regulated under hypoxia compared with non-stress condition, while its expression in the cotyledon and shoot was up-regulated under hypoxia-NaCl. In addition, DAO expression could be promoted to enhance GABA accumulation after increasing the stress intensity using NaCl. DAO gene expression was significantly inhibited by aminoguanidine treatment under hypoxia but increased under hypoxia-NaCl.
  
  
  CONCLUSIONS
  Under hypoxia, GABA accumulation due to NaCl was mainly concentrated in the cotyledon. The GABA content increase under hypoxia did not result from DAO gene expression, but DAO existing in seeds was activated under hypoxia. DAO gene expression was up-regulated to enhance GABA accumulation after increasing the stress intensity.
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
authors.forename: Runqiang
authors.initials: R
authors.lastname: Yang
authors.forename: Yongqi
authors.initials: Y
authors.lastname: Yin
authors.forename: Liping
authors.initials: L
authors.lastname: Guo
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Han
authors.forename: Zhenxin
authors.initials: Z
authors.lastname: Gu
mesh_terms: D006631:Amine Oxidase (Copper-Containing) / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination; D006146:Guanidines / Q000494:pharmacology; D010100:Oxygen / Q000008:administration & dosage; D012639:Seeds / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000008:administration & dosage; D031307:Vicia faba / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis*
chemical_list: D018744:DNA, Plant; D006146:Guanidines; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; D006631:Amine Oxidase (Copper-Containing); D010100:Oxygen; C004479:pimagedine
keywords: GABA accumulation; diamine oxidase; fava bean; gene expression; germination; hypoxia-NaCl stress