|Liu, Yiqing - Chongqing University|
|Kennedy, John - Chembiotech Laboratories|
|Jiang, Yusong - Chongqing University|
|Tang, Jianmin - Chongqing University|
|Liu, Jia - Hefei University Of Technology|
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2016
Publication Date: 6/24/2016
Citation: Liu, Y., Wisniewski, M.E., Kennedy, J.F., Jiang, Y., Tang, J., Liu, J. 2016. Chitosan and oligochitosan enhance ginger (Zingiber officinale Roscoe) resistance to rhizome rot caused by Fusarium oxysporum in storage. Carbohydrate Polymers. 151:474-479.
Interpretive Summary: Finding alternative methods of controlling postharvest rots of harvested fruits and vegetables that do not rely on the use of synthetic fungicides is a critical need. Chitosan, a complex carbohydrate derived from shell fish, has been shown to inhibit pathogen growth and induce disease resistance in host tissues when it is applied to fruits and vegetables. Since it forms a biocoating, chitosan-derived products have also been demonstrated to preserve the quality (fresh weight, firmness, color, etc.) of harvested commodities. In the current study, the ability of chitosan and oligochitosan to enhance the resistance of harvested ginger rhizomes to rhizome rot, caused by the pathogen Fusarium oxysporum, and preserve the quality of the ginger rhizomes was investigated. Results indicated that of the two compounds, chitosan applied at 5g/L significantly inhibited rhizome rot in harvested ginger rhizomes. Both compounds also reduced losses in fresh weight in ginger rhizomes during storage. Soluble solids and titratable acidity were unaffected. The two compounds also induced the expression of two defense-related enzymes (glucanase and PAL) in rhizome tissues. These results further demonstrate the potential of using chitosan-derived products for managing postharvest diseases in harvested commodities and preserving quality parameters of harvested produce while it is in storage.
Technical Abstract: The ability of chitosan and oligochitosan to enhance the resistance of ginger (Zingiber officinale) to rhizome rot, caused by Fusarium oxysporum, in storage was investigated. Both chitosan and oligochitosan at 1 and 5 g/L significantly inhibited rhizome rot, relative to the untreated control, with the best control at 5 g/L. Chitosan and oligochitosan applied at 5 g/L also reduced weight loss, measured as a decrease in fresh weight, but did not affect soluble solids content or titratable acidity of the stored rhizomes. The two compounds applied at 5 g/L induced ß-1,3-glucanase and phenylalanine ammonia-lyase enzyme activity and the transcript levels of their coding genes, as well as the content of total phenolic compounds in rhizome tissues. Therefore, the ability of chitosan and oligochitosan to reduce rot in stored rhizomes appears to be associated with their ability to induce defense responses in ginger. These results have practical implications for the application of chitosan and oligochitosan to harvested ginger rhizomes to reduce postharvest losses.