Increasing Fusarium verticillioides resistance in maize by genomics-assisted breeding: Methods, progress, and prospects

Maize (Zea mays L.) is an indispensable crop worldwide for food, feed, and bioenergy production. Fusarium verticillioides (F. verticillioides) is a widely distributed phytopathogen and incites multiple destructive diseases in maize: seedling blight, stalk rot, ear rot, and seed rot. As a soil-, seed-, and airborne pathogen, F. verticillioides can survive in soil or plant residue and systemically infect maize via roots, contaminated seed, silks, or external wounds, posing a severe threat to maize production and quality. Infection triggers complex immune responses: induction of defense-response genes, changes in reactive oxygen species, plant hormone levels and oxylipins, and alterations in secondary metabolites such as flavonoids, phenylpropanoids, phenolic compounds, and benzoxazinoid defense compounds. Breeding resistant maize cultivars is the preferred approach to reducing F. verticillioides infection and mycotoxin contamination. Reliable phenotyping systems are prerequisites for elucidating the genetic structure and molecular mechanism of maize resistance to F. verticillioides. Although many F. verticillioides resistance genes have been identified by genome-wide association study, linkage analysis, bulked-segregant analysis, and various omics technologies, few have been functionally validated and applied in molecular breeding. This review summarizes research progress on the infection cycle of F. verticillioides in maize, phenotyping evaluation systems for F. verticillioides resistance, quantitative trait loci and genes associated with F. verticillioides resistance, and molecular mechanisms underlying maize defense against F. verticillioides, and discusses potential avenues for molecular design breeding to improve maize resistance to F. verticillioides.