A balancing act: Exploring the interplay between HSPs and osmoprotectants in temperature stress responses

Abstract

High temperature (HT) stress is a most important environmental stress that restricts plant metabolism, growth, and productivity worldwide. Plant growth and development include several enzymatic reactions that are sensitive to temperature. The degree and duration of HT and the plant type influence plant responses to HT. Crop production is currently a major concern due to HT, and methods for maintaining high yields of crop plants under HT stress are essential agricultural aims. To cope with HT conditions, plants have a variety of adaptation, avoidance, or acclimation mechanisms. Heat stress induces a sudden surge in the expression of stress-associated proteins, which help plants to tolerate it by boosting their defense response. HSPs (heat-shock proteins) and antioxidants are important in encountering heat stress in plants. The heat-shock response is characterized by repression of normal cellular protein synthesis and induction of HSP synthesis. These HSPs are ubiquitous and are produced in all organisms from prokaryotes to eukaryotes, under stress conditions and are highly conserved and constitutively function as molecular chaperons, which multipurpose function. Beside heat stress, HSPs are known to be expressed during other stressful conditions such as tissue damage, inflammation, hypoxia, UV light, cold stress, water stress, etc. HSPs have been classified in plants on the basis of approximate molecular weight and their intracellular localization. Under HT, oxidative stress is generated as a result of the overproduction of reactive oxygen species (ROS), which alters the synthesis of macromolecules and nucleic acids. Thus, HSPs play an important role in maintaining cell membrane integrity, ROS scavenging, and producing antioxidants and osmolytes production. Plant survival under HT stress depends on perceiving the HT stimulus, generating and transmitting the signal, and initiating appropriate physiological and biochemical changes. This review thoroughly explores how plants respond to heat stress at physiological and biochemical levels. It delves into the molecular strategies employed by plants to mitigate the effects of high temperatures. The protective mechanisms against heat stress are discussed, encompassing various pathways that contribute to enhancing tolerance under these conditions.