Transgenic approaches to control aflatoxins in maize
R. SAYLER (1), B. Bluhm (1), J. Cary (2), K. Rajasekaran (3), J. Jaynes (4). (1) University of Arkansas, Fayetteville, AR, U.S.A.; (2) Food and Feed Safety Research Unit, USDA, New Orleans, LA, U.S.A.; (3) Food and Feed Safety Research Unit, USDA, New Orleans, AR, U.S.A.; (4) Tuskegee University, Tuskegee, AL, U.S.A.
Aflatoxins produced by the fungus <i>Aspergillus flavus</i> pose a chronic contamination risk in maize and other susceptible food crops worldwide. Two novel antifungal proteins offer the potential to provide resistance to infection and prevent aflatoxin synthesis in a way that can be incorporated into elite breeding lines without the yield drag of resistant breeding lines. 1) A novel seed lectin from <i>Lablab purpurea</i> (hyacinth bean) was previously shown be a potent inhibitor of the α-amylase of <i>A. flavus</i> and of spore germination. We have constitutively expressed this α-amylase inhibitor in maize and monitored expression levels of the transprotein throughout the development of homozygous inbred lines. <i>In vitro</i> spore growth inhibition using leaf extracts of these lines and their segregation controls has shown that this α-amylase inhibitor may reduce spore germ tube growth of <i>A. flavus</i>. 2) A designed antimicrobial peptide AGM182 was shown to be effective at inhibiting the germination of <i>A. flavus</i> spores at concentrations as low as 5 µM <i>in vitro</i>. Transgenic maize calli expressing AGM182 are currently being regenerated. Transgene expression levels will be monitored using an antibody specific to AGM182. The ability of the expression construct for AGM 182 to produce the peptide was first validated <i>in planta</i> by transiently expressing the construct in tobacco. The latest results from transgenic approaches using both the gene constructs will be presented.
View Presentation |
