Genotoxic stress and DNA repair in plants: emerging functions and tools for improving crop productivity

Abstract

Crop productivity is strictly related to genome stability, an essential requisite for optimal plant growth/development. Genotoxic agents (e.g., chemical agents, radiations) can cause both chemical and structural damage to DNA. In some cases, they severely affect the integrity of plant genome by inducing base oxidation, which interferes with the basal processes of replication and transcription, eventually leading to cell death. The cell response to oxidative stress includes several DNA repair pathways, which are activated to remove the damaged bases and other lesions. Information concerning DNA repair in plants is still limited, although results from gene profiling and mutant analysis suggest possible differences in repair mechanisms between plants and other eukaryotes. The present review focuses on the base- and nucleotide excision repair (BER, NER) pathways, which operate according to the most common DNA repair rule (excision of damaged bases and replacement by the correct nucleotide), highlighting the most recent findings in plants. An update on DNA repair in organelles, chloroplasts and mitochondria is also provided. Finally, it is generally acknowledged that DNA repair plays a critical role during seed imbibition, preserving seed vigor. Despite this, only a limited number of studies, described here, dedicated to seeds are currently available.

Gene Networks and Chromatin and Transcriptional Regulation of the Phaseolin Promoter in Arabidopsis

“…These data suggest that a robust DNA repair pathway is activated under these conditions. This observation supports the critical role of DNA repair proteins during seed imbibition (Balestrazzi et al, 2011) and suggests that the combined effect of ABI3/Pv-ALF and ABA activates this pathway during seed development.…”

An alternative telomerase RNA in Arabidopsis modulates enzyme activity in response to DNA damage

“…In addition, TER2 is functionally linked to DDR: DDR transcripts are constitutively expressed in ter2-1 mutants, and plants are more sensitive to DNA damage than wild type. DDR is activated in seeds as a normal part germination (Balestrazzi et al 2011), and it is possible that ter2-1 mutants are particularly sensitive to the DNA damage associated with development. The net response to zeocin treatment in ter2-1 mutants is the same as in wild-type plants.…”

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

“…These agents cause variety of DNA damages including DNA base oxidation and alkylation, formation of pyrimidine dimers and abasic sites, single and double strand breaks (SSBs and DSBs), DNA inter-strand cross links and therefore seriously threat the integrity of plant genome. Lesions in the DNA, contributed by various damaging agents, may result in changes in both the chemical and physical structures of DNA and thus generate both cytotoxic and genotoxic effects, adversely affecting plant growth and development (Balestrazzi et al, 2011). Therefore, to survive under frequent and extreme environmental stress conditions, plant cells have evolved with highly efficient and wide-ranging mechanisms for the detection and repair of DNA damage to eliminate the chances of permanent genetic alterations and to maintain genome stability for faithful transfer of genetic information over generations (West et al, 2004; Kozak et al, 2009; Roy et al, 2011).…”