Polyamine And Proline Metabolism And Correlation Between Them In Plants Under NaCl Treatment

Halophytes Suaeda salsa and Suaeda glauea Bge, and glycophytes barley (Hordewn Vulgare, Jian4 and KP7), maize (Zea mays, LY II) were used in the experiments to study the metabolism of proline and polyamines and the correlation between them under salt stress, and the effects of proline and polyamines on salt tolerance of plants. Morever, locations of conjugated and bound polyamines in cell membranes were also investigated, and a unknown polyamine PAx was purified and determined its molecular weight. The results showed that proline content increased 4 I folds which result from the changes of key enzyme activities in proline metabolism such as P5CS, Arginase, OAT, GDH and ProDH under different concentration NaCI treatments, and with the changes of key enzyme such as ADC, ODC, TGase and PAO activities in polyamine metabolism, Put level increased markedly. Free Spd, PAx and bound po]yamine contents increased with low concentration NaCl treatment, but decreased under super-high NaCI concentrations. iRGRhNaCl (the decreased value of relative growth rate of plant when NaCI concentrations increased at per unit) represented salt tolerance of five supplied experimental materials. Three parameters related to salt resistance of plants mostly were selected by the method of gradual regression analysis and the regression equation was Y2.399+3.197X1+0.l65X2-0.365X3, among the equation Y means lO0ORGRIANaCl, X1 means IOOM(Spd+PAx)/fPutAI/NaCI (the decreased value of tRSpd+PAx)/fPut ratio in roots of glycophyte and leaves of halophyte when NaCI concentrations increased at per unit), X2 means I000MPA/bPAM/NaCI (the decreased value of tfPA/bPA ratio in roots of glycophyte and leaves of halophyte when NaCI concentration increased at per unit), X3 means l0OiPro/(ArgGlu)MiaCl (the increased value of Pro/(Arg+Glu) ratio in leaves of glycophyte and halophyte when NaCI concentrations increased at per unit). The partial regression coefficient of x1 was very significant by T tests, while those of x2 and x3 were significant, which suggest x1 is the best parameter to represent salt tolerance of plants. With the increasing of NaCl concentrations, osmotic adjustment ability of five supplied experimental materials increased markedly, which suggest that plant has the ability of water homeostasis preservation through osmotic adjustment when opposed to salinity. One of the functions in proline accumulation in plant is to regulate osmotic potential under salt stress, but free polyamines are not. When the addition of different concentration Spd, Put and their mixture combining 100 mmol/L NaCl treatment the changes were determined in f(Spd+PAx)/fPut in symplast of barley seedlings. The results showed that, within NaCI concentrations used in the experiments, the ratio of f(Spd+PAx)/fPut in leaves and roots of barley which unaffected barley growth were approximately 1.3.3 and I.0.l respectively, while l.7.0 and 1.8.8 promoted barley growth. The enzyme activities which catalyzed polyamines and proline degradation in Suaeda increased markedly after relieving salt stress, the degradations of bound polyamines was quicker than that of free ones. These results suggest that polyamines (especially bound ones) and proline accumulated under salt treatment were degraded to supply resource of N, C for plant when stress was relieved. Using Suaeda as materials the effects of polyamine metabolic inhibitors and ABA on polyamine and proline metabolism were studied. The results showed that OOC was the key enzyme in Suaeda which catalyzed free Pu...