Abstract
Plants live in environments where they are exposed to a variety of biotic and abiotic stresses. Abiotic stresses include salinity, drought, heavy metal toxicity, extremes of temperature and nutrient deficiency, which can lead to morphological, physiological, biochemical and molecular changes that can ultimately affect plant growth and development. Plants tolerate abiotic stresses by developing adaptation and defence mechanisms, such as the regulation of stomatal guard cells and changes in the expression of multiple genes associated with various metabolic pathways and/or defensive systems. A common consequence of abiotic stresses in plants is the excess generation of methylglyoxal (MG) and reactive oxygen species (ROS), both of which are potentially toxic, but also have important signalling functions. As a highly reactive compound, MG is able to induce the aggregation of cellular proteins and can react directly, or through enzyme‐catalysed reactions, with critical target molecules resulting in the activation of specific signalling pathways. MG and environmental stresses are inextricably intertwined and an increase in MG levels in plants is considered as a general stress response. Plants possess enzymatic defence systems to protect themselves against the cytotoxic effects of MG. The glyoxalase pathway is the main detoxification pathway for MG in plants and is composed of two enzymes (glyoxalase I and glyoxalase II). The overexpression of the glyoxalase pathway enzymes confers tolerance to multiple abiotic stresses in plants. In this chapter, we will discuss the signalling roles of MG and the ameliorating functions of the glyoxalase system on plant growth and development under normal and abiotic stress conditions.