Effects of flavonoid altered maize lines on plant volatiles, arthropod ecology, and genetic regulation in the field

To defend themselves from insect herbivores, plants have evolved a diverse chemical toolkit of various defenses both direct and indirect. Despite this, agricultural plants are still vulnerable to insect attack which leads to significant plant damage. To reduce harmful pesticide use, we search for alternative avenues for improving natural plant protection, such as selectively breeding for advantageous mutations within plant lines. This allows for the creation of crop lines that hyper-express desirable defenses. In maize, flavonoids are a polyphenolic specialized metabolite that has detrimental effects on herbivores, and preliminary data shows key differences in the volatile profile of these lines. This could have cascading effects on insect recognition and performance, particularly in a field setting where multiple elements effect plant performance. In order to determine how altered flavonoid expression influences plant indirect defense and insect recognition in the field, we analyzed the volatile profiles of hyper expressive flavonoid line UE, a silenced flavonoid line US, and a background wildtype line B73 after 6 hours of collection both constitutively and with known maize pest Spodoptera frugiperda damage. Additionally, we conducted an arthropod survey to determine the diversity of insects that visited the different maize plots throughout June, July and August. Finally, we analyzed the differences in genetic expression of key volatiles found in the preliminary data that are important for insect recognition. Understanding the impacts of defense tradeoffs and their effects on the arthropod community in hyper-expressive maize lines is essential for advancing integrated pest management strategies without pesticide use.