Fighting on two fronts: Elevated insect resistance in flooded maize

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 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 defence hormone salicylic acid, which does not occur in the individual stresses, and the resultant salicylic acid‐dependent increase in S. frugiperda resistance. Remodelling 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 also occur, as indicated by reductions in peroxidase and polyphenol oxidase activity. These data suggest that metabolite changes important for flooding tolerance and anti‐insect defence may act both additively and synergistically to provide extra protection to the plant.

Maize metabolome and proteome responses to controlled cold stress partly mimic early‐sowing effects in the field and differ from those of Arabidopsis

“…Four flavonoids, including maysin and nine hydroxycinnamic acids (a caffeoylhydroxycitrate, four caffeoylquinates, a coumaroylhydroxycitrate, a coumaroylquinate, a feruloylhydroxycitrate and a feruloylquinate) were increased at 16°C. Maysin has recently been shown to respond to a combination of abiotic and biotic stresses in maize leaf (Block et al, 2020). The increase in hydroxycinnamates, besides their potential antioxidant role, may be related to vegetative growth reduction under cold, as a coumaroylquinate and a caffeoylquinate in maize leaf were previously shown to be negatively correlated with yield‐related traits (Cañas et al, 2017).…”

“…In the present experiment, cold also induced modifications of nitrogen assimilation (nitrate reductase), amino acid metabolism and protein synthesis. Maysin has recently been shown to respond to a combination of abiotic and biotic stresses in maize leaf (Block et al, 2020). The increase in hydroxycinnamates, besides their potential antioxidant role, may be related to vegetative growth reduction under cold, as a coumaroylquinate and a caffeoylquinate in maize leaf were previously shown to be negatively correlated with yield-related traits (Cañas et al, 2017).…”

The utility of metabolomics as a tool to inform maize biology

“…Additive and synergistic effects of flooding and anti-insect defense responses were also observed against Spodoptera frugiperda (fall armyworm) infestation in maize. In this case, the combined stress led to elevated production of salicylic acid, which did not occur in the individual stresses, resulting in extra salicylic acid-dependent protection against S. frugiperda ( Block et al., 2020 ). Moreover, the combination of flooding and herbivory led to a remodeling of the phenylpropanoid pathway, which in turn increased maysin accumulation by 2-fold compared with the control non-infested plants ( Block et al., 2020 ).…”

Plant Allelochemicals as Sources of Insecticides

“…Anti-herbivory compounds are secondary metabolites of plants suppressing herbivore insects [21]. They can be divided into several subgroups: nitrogen compounds including alkaloids, cyanogenic glycosides and glucosinolates [22], terpenoids and phenolics [23,24].…”