Herbivory by the insect Diaphorina citri induces greater change in citrus plant volatile profle than does infection by the bacterium, Candidatus Liberibacter asiaticus

Abstract

The volatile organic compound (VOc) profle in plant leaves often changes after biotic and abiotic stresses. Monitoring changes in VOcs in plant leaves could provide valuable information about multitrophic interactions. In the current study, we investigated the efect of asian citrus psyllid (acP) infestation, citrus greening pathogen (Candidatus Liberi-bacter asiaticus [CLas]) infection, and simultaneous attack by acP and CLas on the VOc content of citrus leaves. Leaf volatiles were extracted using hexane and analyzed with gas chromatography-mass spectrometry (Gc-Ms). although acP is a phloem-sucking insect that causes minimal damage to plant tissues, the relative amount of 21 out of the 27 VOcs increased 2- to 10-fold in acP-infested plants. The relative amount of d-limonene, β-phelandrene, citronellal, and unde-canal were increased 4- to 20- fold in CLas-infected plants. a principle component analysis (Pca) and cluster analysis (ca) showed that VOc patterns of acP-infested and CLas-infected plants were diferent from each other and were also diferent from the controls, while the VOc pattern of double-attacked plants was more like that of the controls than that of acP-infested or CLas-infected plants. VOc amounts from leaves were compromised when plants were attacked by acP and CLas. The results of this study showed that a simple direct extraction of citrus leaf volatiles could be successfully used to discriminate between healthy and CLas-infected plants. Information about the efects of insect and pathogen attack on the VOc content profle of plants might contribute to a better understanding of biotic stress. © 2013 Landes Bioscience.