Submitted to: Plant, Cell & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2025
Publication Date: 3/31/2025
Citation: Gorman, Z.J., Liu, H., Sorg, A.M., Grissett, K.S., Yactayo-Chang, J.P., Li, Q., Rivers, A.R., Basset, G.J., Rering, C.C., Beck, J.J., Hunter Iii, C.T., Block, A.K. 2025. Flood-induced insect resistance in maize involves flavonoid-dependent salicylic acid induction.. Plant, Cell & Environment. https://doi.org/10.1111/pce.15496.
DOI: https://doi.org/10.1111/pce.15496

Interpretive Summary: Environmental factors such as extreme weather events and herbivory by insect pests can cause significant damage to crops, reducing the yield and quality of food production. To develop crops that are resilient to these environmental challenges ARS scientists in Gainesville FL examined the response of corn to simultaneous flooding and herbivory by fall armyworm. The combined exposure to flooding and herbivory resulted in the plant increasing its production of certain natural defense chemicals,which led to reduced fall armyworm growth. Understanding how these chemicals are controlled in corn would enable them to be produced even in the absence of flooding, and lead to the development of corn with enhanced resilience to insect pests. Plants that can better defend themselves against insects would require less pesticides.

Technical Abstract: Plants have evolved the ability to respond to a diverse range of biotic and abiotic stresses. Often, combining these stresses multiplies the challenge for the plants, but occasionally the combined stress can induce unexpected synergistic defenses. In maize, combined flooding and herbivory induces a salicylic acid (SA)-dependent defense against Spodoptera frugiperda (fall armyworm). In this study we used RNAseq and metabolic profiling to show that flavonoids are involved in maize response to combined flooding and herbivory. To assess the role of flavonoids in flood-induced S. frugiperda resistance, we analyzed the maize idf mutant that has compromised expression of chalcone synthase, the first enzyme in flavonoid biosynthesis. This flavonoid-deficient mutant was compromised both in flood-induced S. frugiperda resistance and in SA accumulation. These data revealed an unexpected requirement for flavonoids in SA induction. In contrast to idf, the flavonoid 3’ hydroxylase mutant, pr1, showed enhanced SA accumulation after combinatorial treatment, which closely correlated with elevated levels of select flavonoids. In contrast, the dihydroflavonol reductase, anthocyaninless1 (a1) mutant, was unaffected in its SA-induction. These data indicate that flavonoids likely derived from dihydrokaempferol, apigenin, or luteolin play a role in flood-induced SA accumulation and S. frugiperda resistance.