Effects of exogenous S-nitrosoglutathione on PSⅡ activity and photopro-tective capacity of tomato seedlings under NaCl stress

ZHU Xiaoling; XU Jing; LIU Huiying

doi:10.16861/j.cnki.zggc.2024.0359

Abstract：In order to explore the photoprotective effect of exogenous GSNO on alleviating photoinhibition of tomato seed-lings under salt stress,the tomato variety Zhongshu No.4 was used as material to study the effects of different treat-ments(tomato seedling leaves sprayed with distilled water(control),0.1 mmol·L-1 GSNO,0.05 mmol·L-1 cPTIO,0.1 mmol·L-1 GSNO+0.05 mmol·L-1cPTIO,respectively)on seedling growth,leaf pigment content,photochemical efficiency,light energy partitioning and reactive oxygen species(ROS)scavenging capacity under 100 mmol·L-1 NaCl stress.The results showed that 0.1 mmol·L-1 GSNO effectively alleviated the NaCl stress induced inhibition of tomato seedlings growth and net photosynthetic rate(Pn),while significantly increasing chlorophyll content,maximum and actual photochemical efficiency of PSⅡ(Fv/Fm and Y(Ⅱ))and PSⅡ photochemical reaction share(P)by 19.7％-31.4％,9.1％-10.3％,13.2％-51.8％,and 7.4％-44.6％,respectively.The PSⅡ photoenergy antenna heat dissipation share(D),the PSⅡ photoenergy reaction center dissipation share(Ex),and the excitation energy distribution unbalanced deviation coef-ficient between the two optical systems(β/α-1)were significantly reduced by 9.7％-14.1％,11.6％-34.8％,and 18.2％-53.9％,respectively.The application of exogenous GSNO also significantly increased the activity of antioxidant enzymes under salt stress,and significantly decreased the levels of malondialdehyde(MDA)and reactive oxygen species(ROS).In summary,0.1 mmol·L-1 GSNO increased the chlorophyll content of tomato seedlings leaves under salt stress,optimized the light energy distribution of PSⅡ,maintained the balanced distribution of excitation energy between photosystems,improved the photochemical activity and antioxidant stress damage ability of PSⅡ,thereby effectively reducing the degree of photoinhi-bition caused by salt stress and promoting tomato seedling growth.