Submitted to: Plant Pathology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2015
Publication Date: 6/9/2015
Publication URL: http://handle.nal.usda.gov/10113/62337
Citation: Johnson, E.T., Evans, K.O., Dowd, P.F. 2015. Antifungal activity of a synthetic cationic peptide against the plant pathogens Colletotrichum graminicola and three Fusarium species. Plant Pathology Journal. 31(3):316-321.
Interpretive Summary: Plants defend themselves from fungal attack using a variety of natural compounds. But these compounds are usually not sufficient and crops must be further protected by application of antifungal chemical pesticides. We found that a small protein originally developed to control fungi infecting humans is also able to diminish growth of fungi that attack crop plants such as corn and sorghum. The small protein likely kills the fungi by disrupting the cell membrane covering each fungus cell and does not harm human red blood cells at concentrations that inhibit fungal spore growth. Expression of this small protein in crop plants such as corn or sorghum could reduce the need for treating these crops with chemical pesticides, which ultimately lowers farming costs. Reduced use of chemical pesticides will also be better for the environment.
Technical Abstract: A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricultural crops. JH8944 inhibited conidium growth in most of the tested plant pathogens with a dose of 50 µg ml 1, although one isolate of Fusarium oxysporum was inhibited at 5 µg ml 1. Most conidia of Fusarium graminearum were killed within 6 hours of treatment with 50 µg ml 1 of JH8944. Germinating F. graminearum conidia required 238 µg ml 1 JH8944 for 90% growth inhibition. The peptide did not cause any damage to tissues surrounding maize leaf punctures when tested at a higher concentration of 250 µg ml 1 even after 3 days. Liposomes consisting of phosphatidylglycerol were susceptible to leakage after treatment with 25 and 50 µg ml 1 of JH8944. These experiments suggest this peptide destroys fungal membrane integrity and could be utilized for control of crop fungal pathogens.