Maintenance of genome stability in plants: repairing DNA double strand breaks and chromatin structure stability

Abstract

Plant cells are subject to high levels of DNA damage resulting from plant's obligatory dependence on sunlight and the associated exposure to environmental stresses like solar UV radiation, high soil salinity, drought, chilling injury, and other air and soil pollutants including heavy metals and metabolic by-products from endogenous processes. The irreversible DNA damages, generated by the environmental and genotoxic stresses affect plant growth and development, reproduction, and crop productivity. Thus, for maintaining genome stability, plants have developed an extensive array of mechanisms for the detection and repair of DNA damages. This review will focus recent advances in our understanding of mechanisms regulating plant genome stability in the context of repairing of double stand breaks and chromatin structure maintenance.

Keywords: DNA damage response; chromatin remodeling; double strand breaks; environmental and genotoxic stress; plant genome stability.

FIGURE 1

DNA damage response and chromatin remodeling activity in plants. Detection of DNA damage by the sensors- MRN complex, followed by the subsequent transduction of signals carried out by ataxia telangiectasia mutated (ATM) and ATR and Rad3-related (ATR) through phosphorylation of various target proteins including Histone H2AX, Chk1, Chk2, resulting in the activation of DNA repair, cell-cycle checkpoint function, programmed cell death via SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1), a plant-specific transcription factor plays key role in DNA damage signaling. DNA damage also results in the change in chromatin structure, activation of remodeling activities and alteration of heterochromatin mediated by the activity of CAF-1, FAS1 and -2, and SMC proteins. Thick arrows indicate a major role, while thin arrows indicate small effects.