Photosynthesis under stressful environments: An overview

TLDR

Stressful environments such as salinity, drought, and high temperature alter physiological, biochemical, and molecular processes in plants, severely impairing photosynthesis at all stages and reducing overall photosynthetic capacity. This review aims to detail stress‑induced damage and adverse effects on pigments, photosystems, electron transport components, enzyme activities, and gas exchange characteristics in agricultural plants. It examines how these stresses disrupt each component of the photosynthetic machinery, from pigments and photosystems to CO₂ reduction pathways and associated enzymes. The review highlights progress over the last two decades in engineering transgenic C3 crops with enhanced photosynthetic performance through overexpression of C3 enzymes, transcription factors, or introduction of C4 genes, and critically evaluates global efforts to identify signaling components such as MAPKs involved in stress adaptation.

Abstract

Stressful environments such as salinity, drought, and high temperature (heat) cause alterations in a wide range of physiological, biochemical, and molecular processes in plants. Photosynthesis, the most fundamental and intricate physiological process in all green plants, is also severely affected in all its phases by such stresses. Since the mechanism of photosynthesis involves various components, including photosynthetic pigments and photosystems, the electron transport system, and CO2 reduction pathways, any damage at any level caused by a stress may reduce the overall photosynthetic capacity of a green plant. Details of the stress-induced damage and adverse effects on different types of pigments, photosystems, components of electron transport system, alterations in the activities of enzymes involved in the mechanism of photosynthesis, and changes in various gas exchange characteristics, particularly of agricultural plants, are considered in this review. In addition, we discussed also progress made during the last two decades in producing transgenic lines of different C3 crops with enhanced photosynthetic performance, which was reached by either the overexpression of C3 enzymes or transcription factors or the incorporation of genes encoding C4 enzymes into C3 plants. We also discussed critically a current, worldwide effort to identify signaling components, such as transcription factors and protein kinases, particularly mitogen-activated protein kinases (MAPKs) involved in stress adaptation in agricultural plants.