Volatile organic compounds released by maize following herbivory or insect extract application and communication between plants

Abstract

AbstractTo protect themselves from herbivory, plants have evolved an arsenal of physical and chemical defences and release a variety of volatile organic compounds (VOCs). By releasing theseVOCs, a signalling plant can both reduce herbivory, sometimes by more than 90%, and also warn neighbouring plants about an attack. The aim of this study was to assess the influence of herbivory and insect extract application onVOCrelease by damaged/treated and nearby undamaged/untreated maize plants. We confirmed that European corn borer (Ostrinia nubilalis) larvae attack or larvae extract application induced maizeVOCrelease. Greater amounts of (Z)‐3‐hexenal, (E)‐2‐hexenal, (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol,β‐myrcene, (Z)‐3‐hexen‐1‐yl acetate, 1‐hexyl acetate, (Z)‐ocimene, linalool, benzyl acetate, methyl salicylate, indole, methyl anthranilate, geranyl acetate,β‐caryophyllene, (E)‐β‐farnesene and (Z)‐3‐hexenal, (Z)‐3‐hexen‐1‐ol, (Z)‐3‐hexen‐1‐yl acetate, (Z)‐ocimene, linalool, indole, methyl anthranilate, geranyl acetate,β‐caryophyllene and (E)‐β‐farnesene were released as a result of biotic stress after insect attack or insect extract application. The amounts of eachVOCreleased were qualitatively and quantitatively distinct and dependent on time after biotic stress exposure. However, for all biotic stresses, significantly lowerVOCinduction was measured when leaves were damaged/treated for three days, as compared to seven days. Our work also demonstrated that undamaged/untreated neighbouring plants also release significant amounts ofVOCs. This suggests thatVOCemission by a damaged/treated plant stimulatesVOCinduction in nearby undamaged/untreated plants. However, the concentrations of allVOCs released by neighbouring undamaged/untreated maize plants were lower than those from damaged/treated plants and were negatively correlated with distance from a damaged/treated plant. Still, significantVOCinduction occurred in undamaged/untreated plants even at 3 m distance from a damaged/infected plant. Our work suggests that maize plant protective defence responses (VOCemission) can be induced via application of European corn borer extracts.