ADH2/GSNOR1 is a key player in limiting genotoxic damage mediated by formaldehyde and UV‐B in Arabidopsis

Abstract Maintenance of genome stability is an essential requirement for all living organisms. Formaldehyde and UV‐B irradiation cause DNA damage and affect genome stability, growth and development, but the interplay between these two genotoxic factors is poorly understood in plants. We show that Arabidopsis adh2/gsnor1 mutant, which lacks alcohol dehydrogenase 2/ S ‐nitrosoglutathione reductase 1 (ADH2/GSNOR1), are hypersensitive to low fluence UV‐B irradiation or UV‐B irradiation‐mimetic chemicals. Although the ADH2/GSNOR1 enzyme can act on different substrates, notably on S ‐hydroxymethylglutathione (HMG) and S ‐nitrosoglutathione (GSNO), our study provides several lines of evidence that the sensitivity of gsnor1 to UV‐B is caused mainly by UV‐B‐induced formaldehyde accumulation rather than other factors such as alteration of the GSNO concentration. Our results demonstrate an interplay between formaldehyde and UV‐B that exacerbates genome instability, leading to severe DNA damage and impaired growth and development in Arabidopsis , and show that ADH2/GSNOR1 is a key player in combating these effects.