Fungal inoculation and methyl jasmonate application induced highly variable terpene accumulation in Norway spruce
2012
Zhao, T., Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemistry. Ecological Chemistry Group | Krokene, P., Norwegian Forest and Landscape Inst., Aas (Norway) | Hu, J., Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemistry. Ecological Chemistry Group | Christiansen, E., Norwegian Forest and Landscape Inst., Aas (Norway) | Bjoerklund, N., Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Ecology | Laangstroem, B., Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Ecology | Solheim, H., Norwegian Forest and Landscape Inst., Aas (Norway) | Borg-Karlson, A.-K., Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemistry. Ecological Chemistry Group
Spruce bark beetle Ips typographus (L.), the most serious killer of mature Norway spruce Picea abies (L.) Karsten, is often associated with several phytopathogenic fungi including Ceratocystis polonica (Siem.) C. Moreau to overcome tree resistance. Conifers have constitutive and inducible resistance again invader. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization. To gain a deeper understanding of conifer defence mechanisms against bark beetle, 60 mature Norway spruce trees in a pure stand were randomly assigned to C. polonica inoculation (Cp), methyl jasmonate (MeJA) or control treatment in 2008. Bark sample for chemical analysis was taken from each tree and analyzed by a gas chromatography-mass spectrometry (GC-MS) and a two-dimensional GC. The attacks of bark beetles in all the trees were checked in the end of the season. Cp inoculation and MeJA application induced very strong terpene accumulation. The terpene levels in the phloem of Cp- and MeJA- treated trees were significantly higher than that of control trees 14 days and 35 days after treatment. Correspondingly, significantly less treated trees died from bark beetle damage compared to control trees. Interestingly, the terpene accumulations and beetle attacks were highly variable among the trees subjected to Cp inoculation. Trees with low induced terpene levels had 20 fold more beetle attacks and 38 fold more beetle tunneling than trees with high terpene levels. Cp inoculation induced terpene accumulation in Norway spruce inhibits bark beetle colonization in a dose-dependent manner, evidencing that terpene induction may be instrumental in tree resistance. In addition, the observed highly variable terpene induction suggests trees differ extensively on their resistance. Further works should be done to select trees with resistance to bark beetle for future forestry.
显示更多 [+] 显示较少 [-]