Screening spring wheat for midge resistance in relation to ferulic acid content.

The concentration of ferulic acid (FA), the major phenolic acid in the wheat kernel, was found to differ significantly in the mature grain of six wheat cultivars known to have a range of tolerance to the orange wheat blossom midge (Sitodiplosis mosellana). Differences in FA content were correlated with floret infestation level of the cultivars. The wheat cultivars ranked similarly in FA content at the four locations where they were tested, despite a significant effect of environment. Ferulic acid was synthesized mainly during the early stages of grain filling but at different rates among cultivars. Ferulic acid was concentrated primarily in the shorts and bran fractions in an insoluble-bound form. A high correlation was obtained between FA contents as determined by GLC, fluorometry, UV, and colorimetry. The colorimetric procedure was modified as a qualitative, simple, and rapid test for identifying midge-resistant wheat and evaluated in several field trials. The method should provide a rapid tool in the preliminary screening of experimental lines in the development of midge-resistant wheat cultivars.