DNA mismatch repair in plants

SPAMPINATO, C.

Rosario

Simposio; Plant Biotechnology and Economic Regional Development; 2005

Deutscher Akademischer Austausch Dienst (DAAD)

DNA MISMATCH REPAIR IN PLANTS The mismatch repair (MMR) system is critical for maintaining the overall integrity of the genetic material, and the basic features of this system have been highly conserved during evolution. The MMR system is best known for its role in the post-replicative repair of DNA polymerization errors, in recognizing and processing DNA mismatches in heteroduplex recombination intermediates and in responses to DNA damage arising from modification by a variety of genotoxic agents including alkylating agents or bulky adducts. Cells deficient in MMR exhibit a mutator phenotype in which spontaneous mutation rates are greatly elevated; most of these cells exhibit microsatellite repeat instability. In other words, in MMR absence, mutations accumulate at elevated rates. In addition, these cells are hyper-recombinogenic because MMR normally imposes a barrier to recombination between divergent sequences. Thus, MMR plays a critical role as a guardian of the genome. The mismatch repair (MMR) system is critical for maintaining the overall integrity of the genetic material, and the basic features of this system have been highly conserved during evolution. The MMR system is best known for its role in the post-replicative repair of DNA polymerization errors, in recognizing and processing DNA mismatches in heteroduplex recombination intermediates and in responses to DNA damage arising from modification by a variety of genotoxic agents including alkylating agents or bulky adducts. Cells deficient in MMR exhibit a mutator phenotype in which spontaneous mutation rates are greatly elevated; most of these cells exhibit microsatellite repeat instability. In other words, in MMR absence, mutations accumulate at elevated rates. In addition, these cells are hyper-recombinogenic because MMR normally imposes a barrier to recombination between divergent sequences. Thus, MMR plays a critical role as a guardian of the genome. The mismatch repair (MMR) system is critical for maintaining the overall integrity of the genetic material, and the basic features of this system have been highly conserved during evolution. The MMR system is best known for its role in the post-replicative repair of DNA polymerization errors, in recognizing and processing DNA mismatches in heteroduplex recombination intermediates and in responses to DNA damage arising from modification by a variety of genotoxic agents including alkylating agents or bulky adducts. Cells deficient in MMR exhibit a mutator phenotype in which spontaneous mutation rates are greatly elevated; most of these cells exhibit microsatellite repeat instability. In other words, in MMR absence, mutations accumulate at elevated rates. In addition, these cells are hyper-recombinogenic because MMR normally imposes a barrier to recombination between divergent sequences. Thus, MMR plays a critical role as a guardian of the genome. The mismatch repair (MMR) system is critical for maintaining the overall integrity of the genetic material, and the basic features of this system have been highly conserved during evolution. The MMR system is best known for its role in the post-replicative repair of DNA polymerization errors, in recognizing and processing DNA mismatches in heteroduplex recombination intermediates and in responses to DNA damage arising from modification by a variety of genotoxic agents including alkylating agents or bulky adducts. Cells deficient in MMR exhibit a mutator phenotype in which spontaneous mutation rates are greatly elevated; most of these cells exhibit microsatellite repeat instability. In other words, in MMR absence, mutations accumulate at elevated rates. In addition, these cells are hyper-recombinogenic because MMR normally imposes a barrier to recombination between divergent sequences. Thus, MMR plays a critical role as a guardian of the genome. Plants face unique obstacles to long term genetic integrity. They lack reserved germ lines: gametes arise from meristem cells that have already divided many times. During meristem growth and subsequent floral development, DNA integrity is jeopardized by multiple opportunities for replication errors, environmental mutagens from which plants cannot escape, such as solar UV-B light and genotoxic chemicals, endogenous DNA-damaging oxyradicals arising from photosynthesis by chloroplasts and oxygen metabolism in mitochondria. For this reason, plants, like all living things, have mechanisms that enable them to tolerate or repair the DNA damage they inevitably experience. Since even long-lived trees do not show extraordinary mutation rates, plant somatic genome-maintenance activities must be as efficient as mammalian counterparts, perhaps more so.