Mechanism Of Glutathione (GSH) Alleviating Cadmium Stress In Wheat Seedlings

Wheat is one of the most widely cultivated crops in the world,and it is of great significance to human survival.At present,the heavy metal Cd has become one of the main pollutants in the global soil environment,which has the characteristics of strong migration and high toxicity.When plants absorb a certain amount of Cd,they will cause irreversible damage,resulting in reduced grain production,and at the same time endangering human health through the food chain.Glutathione(GSH)is a low-molecular-weight tripeptide rich in non-protein sulfhydryl groups,which can effectively remove active oxygen in plants and chelate Cd2+,reducing Cd toxicity.We used wheat Xinong 20 as the material and used hydroponics to study the mechanism of exogenous application of GSH to alleviate the Cd toxicity of wheat seedlings.GSH-related physiological indicators in wheat seedlings were determined,the gene expression patterns of key GSH anabolism enzymes were analyzed,and the characteristics of Cd accumulation and distribution were studied.The results show that applying GSH through exogenous sources can improve Cd tolerance in wheat seedlings,the mechanism of GSH alleviating Cd toxicity in wheat seedling stage was further analyzed,and provided a certain theoretical basis and reference for ensuring food security.The main findings are as follows:1.The normal growth of wheat seedlings was inhibited,and seedling length and biomass were reduced exposed to Cd.Exogenous GSH significantly inhibited the decrease of seedling length and biomass.The application of BSO significantly reduced the growth of wheat seedlings exposed to Cd.In addition,exogenous GSSG,Cys and AsA can alleviate the toxicity of Cd to some extent.2.The content of ROS and MDA in wheat increased due to the presence of Cd,Promoted the key enzyme activity of GSH synthesis and metabolism.Exogenous GSH reduces the content of ROS and MDA in wheat,At the same time,SOD and POD activity and GSH content were increased,which helps maintain the integrity of cell membranes.The GSH content in wheat seedlings was reduced due to the application of BSO from outside sources.3.The expression of GSH anabolism genes in the roots of wheat seedlings fluctuates,as the time of Cd stress increases,After 14 days of Cd stress,the expression of GSH metabolism genes in wheat roots increased,which responded positively to Cd stress.Exogenous GSH formed a negative feedback regulation on the expression of γ-ECS,GS,GR and GPX genes,and their expression was reduced.4.Under hydroponic conditions,exogenous GSH will reduce the accumulation of Cd in the roots and leaves of wheat seedlings,and it reduced the Cd content in the organelles under the subcellular distribution,At the same time,the proportion of ethanol and deionized water in the roots and leaves of wheat seedlings is reduced,Reduced the migration activity of Cd2+ in the roots and leaves of wheat seedlings,Thereby reducing the transport of Cd to the upper part of the ground and alleviating the poisoning of Cd.The application of BSO increased the proportion of Cd content in the organelles of wheat roots and leaves,improved the migration activity of Cd,and further aggravated the Cd toxicity.