Effects Of Salinity On Photosynthetic Traits, Ion Homeostasis And Nitrogen Metabolism In Wild And Cultivated Soybean

The understanding of physiological and biochemical responses of crops to salinity stress could help them to stabilize their growth performance and yield.In this study,we determined the growth,photosynthetic parameters,ion concentrations,and the activities of enzymes involved in nitrogen assimilation at the seedlings stage of wild and cultivated soybeans subjected to different saline and alkaline stresses.Both stresses had negatively influenced the growth and metabolism of both wild and cultivated soybean.The growth,photosynthesis,and gas exchange parameters showed a significant decrease in response to increasing salt concentrations.Additionally,a significant increase observed,in root sodium(Na~+)and chlorine(Cl~–)concentration.However,photosynthetic performance and ion regulation were higher in the wild than in cultivated soybean under saline and alkaline stresses.Nitrate reductase(NR)and the glutamine synthetase/glutamine oxoglutarate aminotransferase(GS/GOGAT)cycle showed a significant decrease in leaves of both genotypes.A significant increase in the activities of aminating glutamate dehydrogenase(NADH-GDH),deaminating glutamate dehydrogenase(NAD~+-GDH),alanine aminotransferase(AlaAT)and aspartate aminotransferase(AspAT)enzymes had been observed.In conclusion,the cultivated soybean was much more stress sensitive than the wild soybean.The decrease in growth,photosynthesis,ions regulation,and nitrogen assimilation enzymes was greater in cultivated soybean than in wild soybean.The impact of alkaline stress was higher than that of saline stress.Wild soybean regulated the physiological mechanisms of photosynthesis and nitrate assimilation more effectively than did cultivated soybean.The present findings provide a theoretical basis with which to screen and utilize wild and cultivated soybean germplasm for breeding new stress-tolerant soybean.