ARS | Publication request: Transgenic phenolic production in corn silks moderately enhances insect resistance

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 29, 2007
Publication Date: March 25, 2007
Citation: Johnson, E.T., Berhow, M.A., Dowd, P.F. 2006. Transgenic phenolic production in corn silks moderately enhances insect resistance [abstract]. American Chemical Society Abstracts. Paper No. AGFD 155.

Technical Abstract: Some phenolic compounds produced in corn silks, such as maysin, can promote resistance to caterpillar pests. We evaluated transgenic maize engineered to express a maize cDNA controlled by a putative silk specific promoter for secondary metabolite production and corn earworm resistance. Transgene expression did not enhance silk color, but 56% of newly emerged silks and 57% of mature silks displayed browning when cut, which indicated the presence of P1-produced secondary metabolites that are substrates of silk peroxidases. Maysin levels were highest in newly emerged browning silks and declined as the tissue matured. Insect resistance of transgenic silks, regardless of a visible browning reaction, was highest at emergence and declined with maturity. In addition, mean survivor weights of corn earworm larvae fed mature browning silks were significantly lower than weights of those fed mature non-browning silks. Some transgenic kernels browned upon drying, suggesting the promoter may not be silk specific.