Botrytis cinerea infection in three cultivars of chrysanthemum in ‘Alchimist’ and its mutants: Volatile induction of pathogen-infected plants

• Infection with Botrytis cinerea induced volatile emission in chrysanthemum plants.
• Induced plants released volatile organic compounds that varied qualitatively.
• The largest emission was recorded for (Z)-3-hexenal and (Z)-3-hexenyl acetate.
• Three cultivars tested showed different responses in terms of VOCs emission.

Three closely related chrysanthemum cultivars were examined in terms of the effect of Botrytis cinerea infection and leaves injury on the emission rates of fourteen volatile organic compounds (VOCs). Mechanical injury or pathogen infestation of vegetative tissues can induce VOCs production, which can provide defensive functions to plants. Infection with B. cinerea induces the plant defense system in chrysanthemum leaves and stimulates the emission of VOCs that may deter herbivores and attack natural enemies. The change in VOCs emission, as a result of injury or fungal infection in chrysanthemum, has not been studied yet.Our results indicate that a pathogen can induce several VOCs in chrysanthemum plants. In the greenhouse, we measured VOCs from chrysanthemum 3 or 7 days following foliar inoculation. We confirmed that several green leaf volatiles ((GLVs); (Z)-3-hexenal, (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-yl acetate), terpenes (β-pinene, β-myrcene, (Z)-ocimene, linalool, β-caryophyllene, (E)-β-farnesene), and shikimic acid pathway derivatives (benzyl acetate, methyl salicylate, indole) were positively induced from chrysanthemum plants infected with B. cinerea ( Pietrowska et al., 2015). The quantities of the VOCs induced were higher 7 than 3 post infection days. Control plants released only very little but detectable amounts of VOCs. We also set up additional control plants (pierced plants) to facilitate pathogen infection. It was an additional stress and we collected odors also from those plants. In this case the quantities of the VOCs induced were higher 3 than 7 post-injury days. Also our paper suggests a large qualitative and quantitative overlap of VOCs induction from chrysanthemum plants with a mechanical injury when compared to both mechanical injury and the injury from fungal pathogens.