Enhanced insect and fungal resistance of maize callus transgenically expressing a maize E2F regulatory gene

Authors: Dowd, Patrick; Johnson, Eric

Submitted to: AGRI GENE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2019
Publication Date: 3/21/2019
Citation: Dowd, P.F., Johnson, E.T. 2019. Enhanced insect and fungal resistance of maize callus transgenically expressing a maize E2F regulatory gene. AGRI GENE. 12:100086. https://doi.org/10.1016/j.aggene.2019.100086.
DOI: https://doi.org/10.1016/j.aggene.2019.100086

Interpretive Summary: Insects and disease greatly reduce corn yields. Corn ear molds can produce toxins harmful to people and animals, causing hundreds of millions of dollars in losses in the U.S. alone. Plant resistance is an economical means to reduce corn ear damage caused by insects and corn ear molds, but there continues to be a need to determine what genes are involved in producing resistance. A gene isolated from a chromosome region that was previously associated with ear rot resistance was evaluated for its resistance role. The gene had a postulated role as a repressing regulatory protein. When introduced into corn cells, cell clumps that had the gene reduced growth of maize pest caterpillars and representative ear rot fungi compared to cell clumps that did not contain the gene. Analysis of the cell clumps that were active against insects and fungi indicated differences in protein presence supported a regulatory repressing role of the gene. This knowledge can be used to guide breeding for insect and ear rot resistance in crop plants, thereby enhancing yield, quality and safety.

Technical Abstract: A maize gene coding for an E2F regulatory protein located in a quantitative trait locus (QTL) for Fusarium ear rot resistance was cloned and transgenically introduced into maize callus. Several of the transformants were more resistant to feeding by corn earworms and fall armyworms, and retarded growth of Fusarium proliferatum compared to GUS control transformants. More effective transformants contained higher levels of E2F product than GUS controls as indicated by antibody detection. Increased and decreased levels of regulated proteins were noted in E2F overexpressing compared to GUS expressing control transformants. These differentially produced proteins were previously reported to be interactors with the E2F protein, suggesting E2F is affecting the production of these proteins. Other proteins coded for by genes reported to interact with the relevant E2F protein and associated phenotypic effects that could be promoting resistance include those that would increase cell resistance to water stress, increase the presence of reactive oxygen species, and increase the density of indigestible components. Although the full complex of responsible proteins regulated by the E2F examined that promote resistance to insects and fungi remains to be determined, overproduction of the E2F in transgenic callus enhances resistance to some maize insect and fungal pests.