|Mclaughlin, John - Rutgers University|
|Bin-umer, Mohamed - Rutgers University|
|Widiez, Thomas - Rutgers University|
|Finn, Daniel - Rutgers University|
|Tumer, Nilgun - Rutgers University|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2015
Publication Date: 6/9/2015
Publication URL: http://handle.nal.usda.gov/10113/62207
Citation: McLaughlin, J.E., Bin-Umer, M.A., Widiez, T., Finn, D., McCormick, S., Tumer, N.E. 2015. A lipid transfer protein increases the glutathione content and enhances Arabidopsis resistance to a trichothecene mycotoxin. PLoS One. 10(6):e0130204.
Interpretive Summary: In this research, we looked at a collection of Arabidopsis mutants to identify those that are resistant to the ill-effects of trichothecene mycotoxins. Fusarium Head Blight (FHB), a disease of cereal crops, is caused by a fungus that produces these mycotoxins. The disease has serious economic and health impacts; these toxins are important factors in determining the severity of the disease. One strategy to combat FHB in wheat and barley is to modify genes that will make them less sensitive to trichothecenes. We found that an Arabidopsis mutant that overexpressed two genes for lipid transfer proteins were resistant to the toxins. In addition, yeast expressing these genes had decreased oxidative stress. These genes are promising candidates to manipulate in cereal crops to increase their resistance to trichothecenes and FHB and thereby improve food safety and crop production.
Technical Abstract: Fusarium head blight (FHB) or scab is one of the most important plant diseases worldwide, affecting wheat, barley and other small grains. Trichothecene mycotoxins such as deoxynivalenol (DON) accumulate in the grain, presenting a food safety risk and health hazard to humans and animals. Despite considerable breeding efforts, highly resistant wheat or barley cultivars are not available.We screened an activation tagged Arabidopsis thaliana population for resistance to trichothecin (Tcin), a type B trichothecene in the same class as DON. Here we show that one of the resistant lines identified, trichothecene resistant 1 (trr1) contains a T-DNA insertion upstreamof two nonspecific lipid transfer protein (nsLTP) genes, AtLTP4.4 and AtLTP4.5. Expression of both nsLTP genes was induced in trr1 over 10-fold relative to wild type. Overexpression of AtLTP4.4 provided greater resistance to Tcin than AtLTP4.5 in Arabidopsis thaliana and in Saccharomyces cerevisiae relative to wild type or vector transformed lines, suggesting a conserved protection mechanism. Tcin treatment increased reactive oxygen species (ROS) production in Arabidopsis and ROS stain was associated with the chloroplast, the cell wall and the apoplast. ROS levels were attenuated in Arabidopsis and in yeast overexpressing AtLTP4.4 relative to the controls. Exogenous addition of glutathione and other antioxidants enhanced resistance of Arabidopsis to Tcin while the addition of buthionine sulfoximine, an inhibitor of glutathione synthesis, increased sensitivity, suggesting that resistance was mediated by glutathione. Total glutathione content was significantly higher in Arabidopsis and in yeast overexpressing AtLTP4.4 relative to the controls, highlighting the importance of AtLTP4.4 in maintaining the redox state. These results demonstrate that trichothecenes cause ROS accumulation and overexpression of AtLTP4.4 protects against trichothecene-induced oxidative stress by increasing the glutathione-based antioxidant defense.