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Dehydrodimers of Ferulic Acid in Maize Grain Pericarp and Aleurone: Resistance Factors to Fusarium graminearum

First, fourth, fifth, sixth, tenth, and eleventh authors: Ottawa-Carleton Institute of Biology, University of Ottawa, 30 Marie Curie, P.O. Box 450, Stn A, Ottawa, Ontario, K1N 6N5, Canada; second author: Eastern Cereal and Oilseed Research Center, Agriculture and Agri-Food Canada, Ottawa, Ontario K1A 0C6, Canada; third and ninth authors: Department of Plant Agriculture, University of Guelph, Guelph, Ontario, N1G 2W1, Canada; seventh author: INRA, Laboratoire de microbiologie et technologie céréalières, LMTC, rue Géraudière F-44072 Nantes cedex 3, France; and eighth author: Laboratoire d'écologie Moléculaire, Institut de Biologie de l'Environnement Aquitaine-Sud, Université de Pau et des Pays de l'Adour, F-64000, Pau, France

The relationship between the primary cell wall phenolic acids, dehydrodimers of ferulic acid, and maize grain resistance to Fusarium graminearum, the causal agent of gibberella ear rot, was investigated. Concentrations of dehydrodimers of ferulic acid were determined in the pericarp and aleurone tissues of five inbreds and two hybrids of varying susceptibility and in a segregating population from a cross between a resistant and susceptible inbred. Significant negative correlations were found between disease severity and diferulic acid content. Even stronger correlations were observed between diferulic acid and the fungal steroid ergosterol, which is an indicator of fungal biomass in infected plant tissue. These results were consistent over two consecutive field seasons, which differed significantly for temperature and rainfall during pollination, the most susceptible stage of ear development. No correlation was found between the levels of these phenolics and deoxynivalenol levels. This is the first report of in vivo evidence that the dehydrodimers of ferulic acid content in pericarp and aleurone tissues may play a role in genotypic resistance of maize to gibberella ear rot.

Additional keywords: cell wall cross-linking, diferulate, HPLC, kernel, phenolics, segregating population.