Poster: Plant-pathogen interactions

Abs # 505: Diferuloylputrescine and p-coumaroylferuloylputrescine inhibit aflatoxin biosynthesis in Aspergillus flavus

Presenter:	Mellon, Jay E., jmellon@srrc.ars.usda.gov
Authors	Mellon, Jay E. (A)   Moreau, Robert A. (B)
Affiliations:	(A): USDA-ARS, Southern Regional Research Center (B): USDA-ARS, Eastern Regional Research Center

Aspergillus flavus is an opportunistic fungal pathogen that reduces corn value by producing the highly carcinogenic aflatoxin during seed infection. A class of diconjugated polyamines has been isolated and characterized from maize kernels. Since monoconjugated polyamines are known to possess a variety of biological activities, an investigation was initiated to ascertain possible activities in this class of polyamines. A purified mixture (85:15, w/w) of diferuloylputrescine (DFP) and p-coumaroylferuloylputrescine (CFP) was prepared by acclerated solvent/solid phase extraction of corn bran. This DFP/CFP mixture was tested in a concentration range of 0 to 100 μg/mL for its effect on growth and aflatoxin biosynthesis by A. flavus. The DFP/CFP mixture demonstrated inhibitory activity against aflatoxin B₁ biosynthesis in A. flavus isolate AF13. Inhibition was concentration dependent, with an ED₅₀ of 30 μg/mL. Aflatoxin inhibiton levels of up to 93% were achieved using the DFP/CFP mixture. This material did not display inhibitory effects on A. flavus growth at any of the concentrations tested. Analysis of hand-dissected kernel tissues (endosperm, germ, pericarp, wax) revealed that DFP/CFP was mainly localized in the pericarp tissue. In addition, a series of maize kernel accessions was analyzed for DFP/CFP concentrations to look for correlations with known resistance factors. The localization of DFP/CFP components in pericarp tissue surrounding internal tissues of the corn kernel where food reserves are situated suggests a defensive role for these compounds.