Cellular Dna, Rna, And Their Precursor Nucleotides Are At High Risk Of Being Oxidized By Reactive Oxygen Species, Resulting In The Generation Of Oxidized Forms Such As 8-Oxo-7,8-Dihydro-2’- (Deoxy)Guanosine 5’-Triphosphate [8-Oxo-(D)Gtp]. This Oxidized Base Can Pair With Both Adenine And Cytosine, And Thus Would Cause Both Replicational And Translational Errors. To Prevent The Mutagenic Consequences Of 8-Oxo-G, Organisms Have Developed Cellular Defense Mechanisms By The Sanitization Of Nucleotide Pools And Base Excision Repair Pathway. Previously, We Have Reported That Atnudx1 Protein Hydrolyzes 8-Oxo-Dgtp And Completely Suppresses Increased Frequency Of Spontaneous Mutations In The E. Coli Mutt Strain (Ogawa Et Al. 2005). Here, We Report The Physiological Function Of Atnudx1. The Results Obtained Here Indicate That Atnudx1 Functions In Cellular Defense System Against Oxidative Dna And Rna Damages Through The Sanitization Of Their Precursor Pools In The Cytosol Of Arabidopsis Cells.