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Riboflavin-induced Priming for Pathogen Defense in Arabidopsis thaliana

Zhang, Shujian, Yang, Xue, Sun, Maowu, Sun, Feng, Deng, Sheng, Dong, Hansong
Journal of integrative plant biology 2009 v.51 no.2 pp. 167-174
Arabidopsis thaliana, Pseudomonas syringae pv. tomato, abscisic acid, callose, cell death, ethylene, genes, hydrogen peroxide, jasmonic acid, pathogens, riboflavin, salicylic acid, signal transduction, systemic acquired resistance, virulence
Riboflavin (vitamin B₂) participates in a variety of redox processes that affect plant defense responses. Previously we have shown that riboflavin induces pathogen resistance in the absence of hypersensitive cell death (HCD) in plants. Herein, we report that riboflavin induces priming of defense responses in Arabidopsis thaliana toward infection by virulent Pseudomonas syringae pv. tomato DC3000 (Pst). Induced resistance was mechanistically connected with the expression of defense response genes and cellular defense events, including H₂O₂ burst, HCD, and callose deposition in the plant. Riboflavin treatment and inoculation of plants with Pst were neither active but both synergized to induce defense responses. The priming process needed NPR1 (essential regulator of systemic acquired resistance) and maintenance of H₂O₂ burst but was independent of salicylic acid, jasmonic acid, ethylene, and abscisic acid. Our results suggest that the role of riboflavin in priming defenses is subject to a signaling process distinct from the known pathways of hormone signal transduction.