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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » Research » Publications at this Location » Publication #349533
Title: Kauralexins and zealexins accumulate in sub-tropical maize lines and play a role in seedling resistance to Fusarium verticillioides

Author
item VEENSTRA, AMY - University Of Cape Town
item MOOLA, NAADIRAH - University Of Cape Town
item WIGHARD, SARA - University Of Cape Town
item KORSMAN, JEANNE - University Of Cape Town
item Christensen, Shawn
item RAFUDEEN, M. SUHAIL - University Of Cape Town
item MURRAY, SHANE - Centre For Proteomic And Genomic Research

Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2018
Publication Date: 7/24/2018
Citation: Veenstra, A., Moola, N., Wighard, S., Korsman, J., Christensen, S.A., Rafudeen, M., Murray, S.L. 2018. Kauralexins and zealexins accumulate in sub-tropical maize lines and play a role in seedling resistance to Fusarium verticillioides. European Journal of Plant Pathology. 153:223-237. https://doi.org/10.1007/s10658-018-1557-x.
DOI: https://doi.org/10.1007/s10658-018-1557-x

Interpretive Summary: Fusarium ear and stalk rot are caused by microbial pathogens and account for hundreds of millions of dollars in annual corn production losses in Africa, and throughout the world. A significant portion of these losses are due to the contamination of ears with fungal-produced toxins (mycotoxins) called fumonisins, which have been linked to adverse health effects in both humans and animals. Some African maize lines have inherent resistance to Fusarium, but the mode of resistance is not known. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, in collaboration with researchers from South Africa, looked at the concentrations of natural antibiotics produced by maize in response to Fusarium infection. The researchers determined that the maize-produced antimicrobial compounds, zealexins and kauralexins, were found in higher concentrations in Fusarium-resistant plants compared to susceptible lines. Collectively, this study sheds light on chemical factors that enhance resistance to Fusarium and identifies desired traits that can be targeted by breeders to combat agro-economically devastating pathogens.

Technical Abstract: Maize is a socially and economically important crop in Africa (and worldwide) that is severely affected by many fungal pathogens. The pathogen Fusarium verticillioides causes Fusarium ear rot in maize, a disease that greatly reduces quantity and quality of annual maize yields. The pathogen produces mycotoxins called fumonisins, which have been linked to adverse health effects in both humans and animals. In response to infection, maize produces terpenoid phytoalexins, which are antimicrobial compounds that directly reduce the growth of many fungal pathogens including F. verticillioides. Two families of maize phytoalexins, termed kauralexins and zealexins, have been characterized. Genes putatively involved in the biosynthetic pathway of these phytoalexins have been identified in rice and subsequent studies on maize. This research evaluates the induction of phytoalexin accumulation in diverse southern African maize lines (CML444 and CML144) as well as in B73 in response to F. verticillioides inoculation. A knock down mutant in the ZmAn2 gene, a gene involved in the kauralexin biosynthetic pathway, was also analyzed. Maize inoculated with F. verticillioides was analyzed for fungal growth, phytoalexin biosynthetic gene expression and phytoalexin accumulation. The study found that phytoalexin accumulation is more highly induced by F. verticillioides in maize characterized as partially resistant as in a susceptible maize line.