Effects of Short Period High-Salinity Stress on Antioxidant Enzyme Activities and Photosynthesis Enzyme Activities of Gracilaria chouae

Abstract:

The effects of acute hypersalinity stress on the antioxidant and photosynthetic enzyme activities of Gracilaria chouae were studied. Plants were exposed to different levels of salinity ranging from 33 (control) to 60 under laboratory conditions. After incubation, plants were then transferred to seawater with a controlled level of salinity and recovered after 12 or 24 hours, respectively. The activity of antioxidant enzyme SOD increased (P<0.05), the activity of POD was fluctuated (P<0.05), the activity of CAT gradually decreased without significant difference (P>0.05) but the content of MDA was significantly increased (P<0.01). The activity of SOD、POD、CAT and MDA reached the maximum in 50~55 psu groups but decreased significantly at salinity 60; The activity of Rubisco, a key enzyme in photosynthesis of C3, gradually decreased with the increase of salinity (P<0.01). The content of CA slightly increased with the increase of salinity (P<0.05). With the increase of recovery time, SOD, POD and CAT activities gradually increased (P<0.05), and the activity of each antioxidant enzyme showed a maximum value in 50~55 psu groups, but MDA content decreased considerably (P<0.05). Rubisco activity was significantly higher than that in 0.5 h (P<0.05), and CA content fluctuated with salinity. Short period high-salinity stress significantly affected the activities of antioxidant enzymes and photosynthetic enzymes in G. chouae. Algae responded to hypersalinity stress by increasing the activities of antioxidant enzymes, and enhancing the absorption and utilization of inorganic carbon by CA. The alga gradually returned to the normal level after the stress was removed. The purpose of this study is to provide a theoretical basis for improving the efficiency of large-scale cultivation of G. chouae, and to provide basic data for the study of salt tolerance mechanism of macroalgae.