Postdoctoral Scholar The Pennsylvania State University State College, Pennsylvania
Body of Abstract: Sorghum (Sorghum bicolor (L.) Moench) produces a class of flavonoids called 3-deoxyanthocyanidins (3-DAs) that are induced by biotic and abiotic stress. We have developed a method to extract 3-DAs from sorghum biomass. In our current study, we aimed to determine the efficacy of 3-DAs against fall armyworm (FAW) (Spodoptera frugiperda J.E. Smith), a globally invasive pest that causes significant yield losses in sorghum and maize (Zea mays L.). Larvae reared on a 3-DAs supplemented artificial diet showed significant mortality and decreased body weight. When sprayed on leaves of susceptible maize lines, 3-DAs extract effectively reduced the growth and increased the mortality of FAW larvae. The 3-DAs accumulation is regulated by an MYB transcription factor yellow seed1 (y1) in sorghum, and its orthologue pericarp color1 (p1) in maize. We developed transgenic maize lines expressing sorghum y1 as well as a near isogenic maize line that over-accumulates flavonoids. As FAW is a major pest of maize, we further investigated the larval mortality when reared on these maize lines compared to their near-isogenic wildtype lines. The detached leaf assays showed significantly high mortality of larvae that were fed on flavonoid producer lines compared to the wildtype. The peritrophic membrane that protects the midgut was severely damaged in larvae fed on leaves of flavonoid producer lines compared to the wildtype. The effectiveness of the flavonoids as feeding deterrents by endogenous expression and exogenous application demonstrates the eco-friendly potential for the management of FAW larvae.