Abstract:

【Objective】 To study the triggering defense responses in tobacco suspension cells after treated with riboflavin, reactive oxygen species (ROS) and defense-related responses were investigated together with their related effects involving in calcium signals and protein kinases. 【Method】 Tobacco suspension cells were treated with 1 mmol•L-1 riboflavin or pretreated with inhibitors including calcium surrogate La3+, calcium chelator EGTA and staurosporine which is an inhibitor of serine/threonine protein kinase. A series of dynamic defense responses were then studied with several methods, including semiquantitative RT-PCR (reverse transcriptase-polymerase chain reaction) and HPLC (high performance liquid chromatography) techniques. 【Result】 It was identified that a series of defense-related responses were induced in tobacco suspension cells after treated with riboflavin, such as an oxidative burst, resulting in alkalization of the extracellular medium, activated the expression of four defense-related genes, and the scopoletin accumulation. And all the tested three inhibitors were shown in suppressing the riboflavin triggered defense responses at difference levels. 【Conclusion】 These results suggest that riboflavin triggers plant basal defense signal pathway which are also concerned with calcium signal pathway and protein phosphorylation in tobacco cell suspensions as an elicitor.

Key words: riboflavin, tobacco, reactive oxygen species, defense response