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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #99268
Title: EVALUATION OF WHEAT (TRITICUM AESTIVUM L.) PHENOLIC ACIDS DURING GRAIN DEVELOPMENT AND THEIR CONTRIBUTION TO FUSARIUM RESISTANCE

Author
item MCKEEHEN, JOHN - UNIVERSITY OF MINNESOTA
item Busch, Robert - Bob
item FULCHER, R - UNIVERSITY OF MINNESOTA

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fusarium head blight, generally known as "scab", has emerged in recent years as an industry-threatening disease of wheat causing major losses in yield and test weight. The disease has been especially severe in the spring wheat area causing over a billion dollars in losses. Scab infected grain is usually contaminated with "vomitoxin", a toxic product of the fungus that causes the scab disease. This contaminated wheat is greatly devalued in th marketing system. Although this disease has been known for many years, adequate controls and resistant varieties have not been developed. Further, it is not known what may cause differences in resistance in wheat, especially the kernels. Certain compounds, phenolic acids, in a kernel of wheat have been shown to provide protection to some diseases. These compounds were studied to determine if they could be responsible for the different resistance levels of scab found in certain varieties of wheat. The effect of two phenolic acids, coumaric and ferulic acid, stopped the growth of the scab fungus when extracted from growing kernels of wheat. Further, varieties with most resistance produced ferulic acid more rapidly during the first 20 days of kernel filling than susceptible varieties. At kernel maturity, the varieties had similar amounts of ferulic acid implying that baking quality would probably not be affected if varieties were selected with high levels of ferulic acid production during early kernel filling. These results provide scab researchers with at least one compound in the grain that inhibits scab growth and gives direction for further research to enhance scab resistance.

Technical Abstract: The phenolic acid profiles of six cultivars of spring wheat with known tolerance to Fusarium head blight were evaluated throughout plant development. Analysis by HPLC at anthesis revealed that coumaric and ferulic acid were the two principal phenolic compounds present. The effect of these two phenolic acids on Fusarium species was evaluated in vitro. Both phenolic acids demonstrated significant reductions (p<0.05) of Fusarium species growth at all concentrations tested. Changes in the phenolic acid profiles were evaluated from anthesis through maturity. Ferulic acid is the primary phenolic acid in grain at all stages of development, and its concentration increased steadily during grain development prior to a 50% decrease during grain ripening. The rate of ferulic acid synthesis from anthesis until approximately 20 days after anthesis appears related to the cultivar's resistance to Fusarium. Concentrations of ferulic acid in the grain tended to become similar at maturity, implying that the end-use quality would not be influenced by breeding resistant cultivars if ferulic acid is a major factor in resistance.