[The relations between polyamine types and forms and polyamine oxidase activities in barley seedlings under salt...

The three polyamines (Put, Spd and Spm) and their different forms (free, perchioric acid soluble and insoluble conjugated) together with polyamine oxidase (PAO) activities were measured in barley (Hordeum vulgare L. KP7) seedlings under salt stress. The results showed that the free polyamines were dominant forms among three polyamines, account about 2/3 total polyamines. All three polyamines decreased in roots and leaves after 8 d under NaCl 200 mmol/L stress. The free polyamine content decreased dramatically as well as soluble conjugated polyamine content, while the insoluble ones changed little. Different concentration salt stress increased markedly the ratios of (Spd+Spm)/Put and decreased significantly the total polyamine content in roots and leaves. PAO activities in roots was increased at first and then decreased under NaCl stress, while in leaves the activities changed in opposite direction. It has been noted that the sum of free Spd and Spm (Spd+Spm) content is reversely correlated with PAO activity changes, which suggests that PAO might regulate the free polyamine content, therefore, the contents of the soluble and insoluble conjugated polyamines were affected.