The role of hydrogen peroxide in tomato axillary shoot growth

Abstract The plasticity of shoot branching determines the aerial structure of plants. The establishment of shoot branching depends on the capability of axillary meristem to grow, which is regulated in part by the balance of plant hormones auxin and cytokinin. Emerging evidence indicates that reactive oxygen species also play a regulatory role in axillary shoot branching. This study explored the concentration dependence of hydrogen peroxide (H₂O₂) on axillary bud outgrowth of tomatoes under two growth conditions, a glasshouse and a controlled environment room (CER). Here we showed the effect of oxidative treatments was inconsistent between the two growth conditions. H₂O₂ repressed axillary bud outgrowth in glasshouse-grown plants, while in CER-grown plants, H₂O₂ positively regulates axillary bud outgrowth in concentrations up to 5 mM, indicating that growth conditions influence the effect of H₂O₂ treatment. Furthermore, results suggest that the effect of H₂O₂ in modulating axillary bud outgrowth appeared to be concentration-dependent. This study has identified the significance of reactive oxygen species in regulating axillary shoot branching in tomatoes, highlighting the importance of H₂O₂ dosage and the influence of environmental conditions which potentially affect the oxidative treatments.