Maize Resistance to Stem Borers Can Be Modulated by Systemic Maize Responses to Long-Term Stem Tunneling

Abstract

Limited attention has been paid to maize (Zea mays L.) resistance induced by corn borer damage, although evidence shows that induced defenses have lower resource allocation costs than constitutive defenses. Maize responses to short- and long-term feeding by the Mediterranean corn borer (MCB, Sesamia nionagrioides) have been previously studied, but the suggested differences between responses could be due to experimental differences. Therefore, in the current study, a direct comparison between short- and long-term responses has been made. The objectives were (i) to determine changes in the level of antibiosis of the stems induced by feeding of S. nonagrioides larvae for 2days (short-term feeding) and 9days (long-term feeding), (ii) to characterize the metabolome of the stems’ short- and long-term responses to borer feeding, and (iii) to look for metabolic pathways that could modulate plant resistance to MCB. Defenses were progressively induced in the resistant inbred, and constitutive defenses were broken down in the susceptible inbred. Results suggest that the different resistance levels of the two inbreds to stem tunneling by MCB could depend on their ability to establish a systemic response. Based on these results, a high throughput look for specific metabolites implicated in systemic induced resistance to maize stem borers is recommended; the current focus on constitutive defense metabolites has not been successful in finding molecules that would be valuable tools for pest control.

Recent trends in management strategies for two major maize borers: Ostrinia nubilalis and Sesamia nonagrioides

“…Those indirect selection approaches were successful for developing maize varieties with increased resistance, probing that hydroxamic content of the leaf-whorl and pith cell-wall strength are important components of resistance to the first and second generations of stem borers, respectively (Russell et al 1975;Barros-Rios et al 2015). Rodriguez et al (2021) recently reported that levels of resistance in the field should depend on induced defense responses of maize plants infested by S. nonagrioides rather than on constitutive resistance levels, evaluating the concentrations of candidate metabolites that may be involved. Therefore, specific methodologies for evaluation of induced plant resistance on stem borer biological performance are needed, as well as the quantification of those potential secondary compounds underlying induced resistance, which could be added as a complementary control method in IPM systems, especially where transgenic Bt hybrids are not allowed or in organic agriculture.…”

Large genetic variability of maize leaf palatability to european corn borer : metabolic insights

“…In the course of the evolutionary arms race between plants and pests, plants developed many different defense strategies, including physical defenses to minimize the entry of pathogens like cell wall or spines, and biochemical defenses that can be repulsive or toxic (67). They can be constitutive or induced with different resource allocation costs (53). The setting-up of chemical plant defenses is a paradigm of biological complexity.…”