Plant Metallothioneins as Regulators of Environmental Stress Responses

Abstract

Scientific research has focused to delineate the core aspects of stress tolerance mechanisms and to apply the crucial components for enhancing the tolerance of plants and their growth under stressed environments. Metallothioneins (MTs) are known to play pivotal roles in stress regulation. They are known in bacteria, fungi, and all other eukaryotic organisms. MTs are low molecular weight, cysteinerich proteins. They are important metal chelators and also possess antioxidant properties. MTs work upon reactive oxygen species (ROS), whose production is induced by different stresses and is known to damage various cellular biomolecules. MT proteins are classified into two classes, plant MTs belong to class II type, while animal MTs belong to class I type. MTs have been investigated in the vast number of plant species and their crucial roles in stress modulation has been uncovered. Hence, MTs are a promising tool for stress management, acting as essential stress biomarkers and ensuring food security in the coming future to achieve sustainable development goals worldwide. This review discusses the roles of MTs in plants under different abiotic stresses, including drought, salinity, low temperature, light, in oxidative stress regulation and heavy metals homeostasis and detoxification including toxic nanoparticle management in plants.