A maize gene coding for a chimeric superlectin reduces growth of maize fungal pathogens and insect pests when expressed transgenically in maize callus

Authors: Dowd, Patrick; Naumann, Todd; Johnson, Eric

Submitted to: Plant Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2022
Publication Date: 4/6/2022
Citation: Dowd, P.F., Naumann, T.A., Johnson, E.T. 2022. A maize gene coding for a chimeric superlectin reduces growth of maize fungal pathogens and insect pests when expressed transgenically in maize callus. Plant Gene. 30. Article 100359. https://doi.org/10.1016/j.plgene.2022.100359.
DOI: https://doi.org/10.1016/j.plgene.2022.100359

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 in producing a protein that binds to pest tissues. 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 higher protein levels caused lesser growth of maize pests. 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: Plant breeding for pest resistance is a long process, and the rate of development of resistant varieties would be accelerated if resistance genes to multiple pests could be identified. A gene located in a resistance locus was cloned from a maize inbred with resistance to Fusarium spp. pathogens. This gene codes for an unusual lectin with regions of high histidine and proline frequency and two apparent sugar binding moieties. Binding studies with yeast-produced versions indicated N-acetyl glucosamine residues are a likely target. When the gene was expressed transgenically in maize callus, reduced growth of pathogenic Fusarium species (up to 71%) and caterpillar pests (up to 65%) was noted compared to control transformants, and the degree of growth inhibition was associated with levels of the protein detected. Available sequence of the gene from other maize inbreds indicated it was often disrupted and likely to code for proteins with reduced function. Incorporation of functional versions of the gene into crops will likely assist with sustainable crop production by promoting enhanced pest resistance.