ABSTRACT
Plants are exposed to various environmental stresses due to their sessile nature. Stress at the molecular level results in reactive oxygen species (ROS) or active oxygen species (AOS) production, which are known to alter the physiological and biological processes in the plants. This chapter outlines the regulation of the important metabolic processes, that is, glycolysis and Krebs cycle that contributes to plant development and acclimation to environmental stresses. The changes made in the metabolic processes are an important survival strategy for the plants to overcome stress conditions. This can affect the activity of enzymes and might bring intricate changes in metabolite pools during carbon metabolism. Abiotic stress factors leading to oxidative stress conditions can inhibit or activate the enzymes that are involved in glycolysis and Krebs cycle. It results in the accumulation of specific compounds like raffinose, sucrose, proline, and γ-aminobutyric acid that are capable of defending cell membranes, which is a requirement for survival under stress conditions. An important enzyme of glycolysis, hexokinase, has been known to play a dual role by regulating the entry of glucose molecules into glycolysis and also the regulation of expression of sugar-responsive genes. During biotic stress, the oxidative bursts limit the spread of the pathogen. Following infection, there are localized accumulations of carbohydrate and source-sink imbalance leading to the altered levels of metabolic enzymes in the plant. The secondary messenger cAMP furthermore plays an imperative role in eliciting plant responses to various stresses that can affect the abundance levels of enzymes involved in the glycolysis and Krebs cycle. The chapter finally highlights some of the important happenings during the interaction between the abiotic and biotic stresses that have both positive and negative effects on the plants.
