Maize Resistance to Stem Borers can be modulated by Systemic Maize Responses to Long-term Stem Tunneling

Abstract

Scarce 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. The maize responses to short and long-term attacks by the Mediterranean corn borer (MCB, Sesamia nionagrioides) have been previously studied but 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 Sesamia nonagrioides (Mediterranean Corn Borer; MCB) larvae for two days (short-term feeding) and nine days (long-term feeding), (ii) to characterize the metabolome of the stem short and long-term responses to borer attack and (iii) to look for metabolic pathways that could modulate plant resistance to MCB. Adjustment of plant performance under subsequent conspecific attack due to previous insect damage was genotype-dependent; defenses were progressively induced in the resistant inbred and constitutive defenses were broken down in the susceptible inbred. Results suggest that the different resistance of the two inbreds to stem tunneling by MCB could depend on their ability to stablish a systemic response.