Investigation of the interaction of cysteine and HSP90 proteins mediated by glyoxalase in high temperature stress tolerance in Arabidopsis thaliana

High temperature (HT), which has increased in recent years, is an important abiotic stress factor that adversely affects plant growth and yield. However, the mechanisms of plant tolerance to HT are not fully understood. In this thesis, the effects of cysteine (CYS) treatment on the relationship between heat shock proteins (HSPs) and glyoxalase system and its role in enhancing stress tolerance under high temperature stress in Arabidopsis thaliana were investigated. Results revealed that cysteine treatment significantly increased key physiological parameters such as relative water content (RWC) and chlorophyll levels, while decreasing oxidative damage markers such as thiobarbituric acid-reactive substances (TBARS) and hydrogen peroxide (H₂O₂) in A. thaliana exposed to high temperature stress. Results from Col-0, hsp90.1 and hsp90.4 mutants and A. thaliana plants exposed to glyoxalase I inhibitor (S-p-bromobenzylglutathione cyclopentyl diester (BBGD)) reveal that cysteine acts as a positive regulator of the GSH-dependent glyoxalase (GLX) system by increasing the activities of GLX enzymes along with HSP90.1 and HSP90.4 proteins. This study demonstrates that CYS treatment enhances the stress tolerance of Arabidopsis thalianaunder HT stress through the GLX system in conjunction with HSP90 and plays a critical role in developing resistance to HT stress