Effects Of Waterlogging On Enzyme Activities And Isoenzyme Of Syringa Oblata And Syringa Reticulate (Blume)

Syringa with various advantages including strong growth ability, graceful, easy cultivation and management, is commonly used as garden greening tree species in the north of China. Despite it has a strong adaptability to varieties of environmental stress, Syringa is vulnerable to the waterlogging. In this study, Syringa oblata and Syringa reticulata were selected as test material for waterlogging assay, the impact of waterlogging on enzyme activities and isoenzyme of the two Syringa was discussed and relevant reasons for the change of varieties of enzymes in different resistance of two Syringa were analysised. Also, the mechanism to flooding harm in Syringa was explored in order to provide the basic theoretical basis for further study of plant waterlogging and high-tolerance Syringa plant selection.Main studies results in this studies are displayed as follows:(1) Effects of waterlogging on antioxidant enzymes of annual Syringa oblata and Syringa reticulata seedling leaves:based on the experiment result, we found that peroxidase (POD)n superoxide dismutase (SOD)、catalase (CAT) activity of the two Syringa showed an upward trend after waterlogging, each enzyme activity of Syringa leaves functioned at different times, which lead to different sensitivity towards waterlogging, SOD is most sensitive to waterlogging, its activity increased significantly in2-day treatment under waterlogged. SOD, POD activity variation in Syringa reticulata was much higher than Syringa oblata, proves the former a strong submersion.POD、SOD、CAT isozymogram in Syringa oblata under waterlogging showed a remarkble rise as time went by, which is consistent with the measurement results of the three enzyme activity. POD and SOD isozymogram in both two Syringa species varied a lot in band number and protein concentration, while CAT isoenzyme of Syringa oblata only showed single band. Syringa reticulata had two isozymes bands in total after stress, CAT isoenzyme bands revealed weak diversity. In comparison, CAT is not sensitive to waterlogging.(2) Effects of waterlogging on anaerobic respiration enzymes of annual Syringa oblata and Syringa reticulata seedling leaves:Under waterlogging, Syringa seedlings were incubated in a low oxygen environment. Related anaerobic respiration alcohol dehydrogenase (ADH)^lactate dehydrogenase (LDH)、pyruvate decarboxylase (PDC) under duress all first increased then showed a decreased trend. In the early stress stage, ADH、LDH and PDC maintain a relatively high activity in two Syringa. The rise range of PDC、ADH activity in Syringa oblata is far lower than Syringa reticulata during waterlogging.(3) Effects of waterlogging on Amylase (AMY) and esterase (EST) of annual Syringa oblata and Syringa reticulata seedling leaves:AMY activity of two Syringa seedling leaves showed a gradual upward trend during continuing waterlogging. The activity climbed in a relatively moderate way in the early stage, then drastically rised during late stage. When AMY activity continued accumulating, more starch was transformed into soluble sugar to meet the substrates demand during anaerobic respiration and enhance the adaptability of waterlogging. AMY isozyme spectrum of two Syringa species both had only one stripe, the enzyme activity of band are consitent with activity determination results. EST zymogram and the active expression of Syringa oblata indicated a attenuated trend after enhancement. There was only one stripe before stress treatment. However, another new enzyme band was displayed in gel after the stress. Unlike Syringa reticulata, EST zymogram of Syringa oblata showed only one band, also the strength kept increasing when the stress time lasted. AMY and EST isozyme band polymorphism is less changeable and AMY is not sensitive to waterlogging.In summary, POD、SOD、CAT、AMY activity of Syringa oblata and Syringa reticulata increased to resist the damage of stress on plant organisms when subjected to flooding stress. At the same time, ADH、LDH、PDC activity significantly enhanced aimed at improving the ability of anaerobic respiration under low oxygen environment in the early stage of stress. EST activity of Syringa reticulata showed a upward trend then decreased while in Syringa oblata the enzyme kept rising. It’s activity towards ester compounds catalyzing became stronger in order to maintain physiological metabolism in normal cell. SOD activity of Syringa oblata was higher than Syringa reticulate. Due to SOD is antioxidant system’s first line of defense, Syringa oblata response more quickly on waterlogging than Syringa reticulate. On the other hand Syringa oblata’s PDC and ADH activity is lower than Syringa reticulata, more harmful substance would accumulate during anaerobic respiration process, resulted weak resistance towards waterlogging in Syringa oblata. Isozyme spectrum of two Syringa varied a lot to adapt to waterlogging. Weak anaerobic respiration of Syringa oblata might be the main reason of low waterlogging tolerance. The reason why ester compounds hydrolysis ability of Syringa oblata reduced needs further research.