Achillea collina response to biotic and abiotic stresses: a comparative evaluation of volatile emissions pathways

Plants have evolved wide range of mechanisms to cope with biotic and abiotic stresses. It's suggested that hormone signaling pathways, in particular jasmonic acid, salicylic acid, abscisic acid and ethylene, can be involved in plant responses to stress [1]. Our attention was focused on volatile compounds emissions (VOCs) from Achillea collina Becker, a medicinal plant, exposed to biotic and abiotic stressing conditions.

Headspace Solid-Phase-Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC/MS) „in vivo“ method [2] was used to evaluate A. collina VOCs.

Biotic stress was obtained by the infestation of A. collina plants with Myzus persicae or Macrosiphoniella millefolii, the generalist and specialist aphid species respectively. Mechanical stresses were obtained by applying a pressure to the plants using a specially designed equipment or by pricking the leaves with a needle.

VOCs emissions are reported in figure1. As shown, some compounds were induced by both the biotic and abiotic stresses (eg. 1-Hexanol, Pinocarvone, α-Fenchene) while some other VOCs were specific to the type of stress applied. As an example Spathulenol was only induced by M. millefolii and β-Linalool was induced only by the mechanical damage. Aromadendrene, Terpineol-cis-β, Tetradecanal were only induced by the biotic stresses. A. collina shows a great plasticity in the VOCs biosynthesis, highly modulated by the external stimuli, a possible good model for future investigations at a molecular level.

Figure 1: VOCs induced by different stress conditionsVolatile emission pathways of induced VOCs of Achillea collina under biotic and abiotic stresses

Keywords: SPME, VOCs, Aphids, Achillea collina

References: 1] Fujita M et al. (2006) Current option i n Plant Biology 9: 436–442

[2] Giorgi A et al. (2010) Planta Med 76: 1337