Chapter 3 Ultraviolet-B Induced Changes in Gene Expression and Antioxidants in Plants

Abstract

The depletion of the stratospheric ozone layer leads to an increase in the level of ultraviolet-B radiations reaching the Earth's surface. UV-B radiations are known to have damaging effects on all forms of life. In plants, the UV-B exposure leads to the generation of reactive oxygen species (ROS), eventually resulting in oxidative stress. ROS induce lipid peroxidation of biological membranes, destroy the natural lipid-soluble antioxidants, and alter the expression of several genes through nonspecific signaling pathways. The integration of the thylakoid membrane appears to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts in the photosynthetic complexes and other chloroplast proteins are among the early events of UV-B damage. Other genes, encoding defense-related proteins are rapidly upregulated under UV-B irradiation. UV-B radiation induced production of ROS, increased the antioxidant capacity and thus, minimized the magnitude of negative impact of UV-B on plants. Specific signaling pathway includes the UVR8 component that regulates the expression of a set of genes essential for the protection of plant against UV-B. This chapter comprises information regarding the UV-B perception, signal transduction, regulation of gene expression, ROS formation, and its metabolism from various studies performed under growth chamber, green house, and field conditions.