The role of tomato S-nitrosoglutathione reductase (GSNOR) in plant development and disease resistance

Nitric oxide (NO) is a key small molecule that orchestrates plant growth, development and immune function. The chief mechanism for the transfer of NO bioactivity is thought to be S-nitrosylation, the addition of an NO moiety to a protein cysteine thiol to form an S-nitrosothiol (SNO). The enzyme S-nitrosoglutathione reductase (GSNOR) indirectly controls the total levels of cellular S-nitrosylation, by turning over S-nitrosoglutathione (GSNO), the major cellular NO donor. In tomato (Solanum lycopersicum. L) a decrease in GSNOR expression, which is expected to increase the extent of cellular SNO formation, resulted in morphological phenotypes and disabled disease resistance. In contrast, increased GSNOR activity enhanced protection against an ordinarily virulent bacterial pathogen. Collectively, these results are similar to previous findings using the reference plant, Arabidopsis thaliana. Thus, the role of GSNOR may be highly conserved across the plant kingdom and manipulating the function of this protein may control important agricultural traits in crop plants.