Response of Photosynthetic Organelles to Abiotic Stress: Modulation by Sulfur Metabolism.

Sulfur metabolism mediated modulation of plant response to various abiotic stress factors is the focus of this review. Since chloroplast is extremely sensitive to abiotic stress factors and at the same time a major location of sulfur assimilation, the organelle plays a major role in the modulation of stress response. The photosynthetic organelle coordinates carbon, nitrogen, and sulfur metabolic pathways and provides the essential precursors for synthesis of sulfur compounds. The abiotic stress factors like high light, low light, temperature extremes, drought, and UV radiations which the organelle experiences lead to creation of an oxidative environment and production of reactive oxygen species (ROS). Sulfur metabolites containing thiol residues with reversible oxidation-reduction potential effectively scavenge ROS in a series of biochemical reactions. Abiotic stress factors cause up- and downregulations of several stress-related genes. The stress signals, their transmission, and downstream signaling network regulating gene expression are complex. The stress-induced redox signals generated in chloroplast play a major role in different signal transduction systems and expression of stress-responsive genes in green plants. [ABSTRACT FROM AUTHOR]