Fighting on two fronts: Elevated insect resistance in flooded maize

Authors: Block, Anna; Hunter, Charles; Sattler, Scott; Rering, Caitlin; MCDONALD, SAMANTHA - University Of Florida; BASSET, GILLES - University Of Florida; Christensen, Shawn

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2019
Publication Date: 8/14/2019
Citation: Block, A.K., Hunter III, C.T., Sattler, S.E., Rering, C.C., Mcdonald, S., Basset, G.J., Christensen, S.A. 2019. Fighting on two fronts: Elevated insect resistance in flooded maize. Plant Cell and Environment. https://doi.org/10.1111/pce.13642.
DOI: https://doi.org/10.1111/pce.13642

Interpretive Summary: To achieve optimum yields in crops it is important for farmers to be able to manage the various pests and weather related problems that their crops will be exposed to. It is usual for crops to be exposed to multiple such problems at the same time and detailed knowledge of the combined effects of these threats can enable farmers to effectively prioritize their management plans. To expand this knowledge base ARS scientists from Gainesville FL examined the effect of flooding on pest resistance in corn. They discovered that flooding increased the resistance of corn to the insect pest fall armyworm and caused changes in defense related compounds in the plants. These findings mean that farmers now can know that treatment for insect pests may be less of a priority in corn fields subjected to flooding.

Technical Abstract: To grow and thrive plants must be able to adapt to both adverse environmental conditions and attack by a variety of pests. Elucidating the sophisticated regulatory and metabolic mechanisms plants have developed to achieve this has been the focus of many studies. What is less well understood is how plants respond when faced with multiple stressors simultaneously. In this study we assess the response of Zea mays (maize) to the combinatorial stress of flooding and infestation with the insect pest Spodoptera frugiperda (fall armyworm). This combined stress leads to elevated production of the defense hormone salicylic acid, which does not occur in the individual stresses and the resultant salicylic acid dependent increase in S. frugiperda resistance. Remodeling of phenylpropanoid pathways also occurs in response to this combinatorial stress leading to increased production of the anti-insect C-glycosyl flavones (maysins) and the herbivore induced volatile phenolics, benzyl acetate and phenethyl acetate. Furthermore, changes in cellular redox status are also likely, as reductions in peroxidase and polyphenol oxidase activity were observed. These data suggest that metabolite changes important for flooding tolerance and anti-insect defense may act synergistically to provide extra protection to the plant.