The physiological mechanism by which exogenous salicylic acid enhances salt tolerance in Vicia faba seedlings
[Objective]To investigate the mitigating effects of exogenous salicylic acid(SA)on the salt stress response of Vicia faba seedlings.[Method]The influence of varying SA concentrations(0(T1),0.5(T2),1.0(T3),1.5(T4),and 2.0 mmol/L(T5))on the physiological and biochemical attributes of V.faba seedlings under 150 mmol/L NaCl stress was assessed via foliar application.The physiological mechanisms were elucidated through correlation and principal component analysis(PCA).[Result]Under salt stress,SA concentrations of 0.5 to 1.5 mmol/L significantly reduced malondialdehyde(MDA)levels and enhanced the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and root activity(Ra).SA also facilitated the accumulation of proline(Pro),soluble sugar(SS),and soluble protein(SP),increased the content of chlorophyll a(Chl a),chlorophyll b(Chl b),and total chlorophyll,and decreased the Na+ content in roots and leaves.Additionally,it enhanced the uptake of K+,Ca2+,and Mg2+ ions(P<0.05).The mitigat-ing effect of 2.0 mmol/L SA on salt stress was less pronounced.Correlation analysis indicated that MDA was positively correlated with Na+ levels in leaves and roots(P<0.01)and negatively correlated with Ra,Chl a,Chl b,K+,Ca2+,and Mg2+ in both tissues(P<0.01).PCA identified two principal components with eigenvalues>1,accounting for 71.878%and 25.628%of the variance,respectively,with a cumulative vari-ance contribution rate of 97.507%.Based on the principal component scores,the efficacy of SA in alleviat-ing salt stress in V.faba seedlings was ranked as follows:T3>T4>T2>T5>T1.[Conclusion]SA can miti-gate the effects of salt stress and improve the salt tolerance of V.faba seedlings by enhancing osmotic regu-lation and antioxidant capacity,improving root activity and chlorophyll content,maintaining ion absorption balance,and stabilizing the membrane.The optimal treatment concentration was determined to be 1.0 mmol/L.
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