Mediates degradation of arginine for nitrogen recycling. Plays a role in non-host disease resistance by regulating pyrroline-5-carboxylate metabolism-induced hypersensitive response. a 2-oxocarboxylate + L-ornithine = an L-alpha-amino acid + L-glutamate 5-semialdehyde The activity was enhanced in young plants under salt-stress conditions. Amino-acid biosynthesis; L-proline biosynthesis; L-glutamate 5-semialdehyde from L-ornithine: step 1/1. Homotetramer. By salt stress in young plants. Up-regulated during low water potential. Induced upon non-host pathogen infection. Unable to use arginine or ornithine as nitrogen source. Displays sensitivity against type II non-host pathogen infection. Belongs to the class-III pyridoxal-phosphate-dependent aminotransferase family.