Long-lived trees are exposed to many risks of accumulating mutations due to DNA damage or replication errors and maintain to live long time. In this study, we focused on DNA repair as a mechanism to suppress mutations. To elucidate what DNA repair genes were increased in tree species, we performed systematic comparative analyses of the copy number variations of 120 DNA repair gene families in 59 plant species with different lifespans using a genetic database.
Among the 120 DNA repair gene families studied, the poly(ADP-ribose) polymerase (PARP) gene family was identified the gene revealing significant expansion in long-lived trees relative to annual and perennial herbs. Plant PARP genes are divided into three groups; PARP1, PARP2 and PARP3. Trees had significantly higher copy number of PARP1 and PARP2 than both annual and perennial herbs, but there was not significant difference in copy number of PARP3 among lifeforms.
PARPs catalyze poly(ADP-ribosyl)ation, a post-translational protein modification, and play pivotal roles in DNA repair and antipathogen defense in not only animals but also plants. Especially, PARP1 and PARP2 have a predominant role in PARP activity for DNA repair. Our study suggests the conserved role of PARPs in longevity between animals and plants.