Reactive oxygen species (ROS) burst is one of the earliest plant defense responses during plant and pathogen interactions. However, the complex roles of ROS during FHB development remain unclear. Fungal cell walls consist of two main components, chitin, and β-glucans, which play important roles in elicitor triggered-immunity. Using luminol-based chemiluminescent assays, we investigated ROS burst in different wheat and barley tissues triggered by chitin and laminarin (a β-1,3-glucan polymer with degree of polymerization).  We discovered: 1) chitin triggers tissue-specific ROS burst in wheat tissues, primarily rachis and rachis nodes, whereas chitin triggers high ROS in barley leaves but low ROS in lemmas and paleae; 2) laminarin induces high and broad ROS in wheat and barley head tissues; 3) ROS induction is enhanced in both wheat and barley head tissues treated with the combination of chitin and laminarin. In addition, we found that the expression of plant defense genes was upregulated in wheat heads treated with chitin, laminarin or both. Furthermore, we showed that chitin treatments reduce Fusarium head blight spread in wheat and mycotoxin contamination. 

This material is based upon work supported by the U.S. Department of Agriculture. This is a cooperative project with the U.S. Wheat & Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.