Jasmonate as a Biological Elicitor of Conifer Defense

METHYL JASMONATE AS A BIOLOGICAL ELICITOR OF CONIFER DEFENSE 

MeJA has also been used successfully in other gymnosperm systems to induce secondary metabolism and defense responses. In species of Taxus, enzymes involved in the synthesis of the diterpene taxol are induced by MeJA in suspension cultures. Studies in white spruce seedlings and cell cultures have shown that MeJA treatment induces the expression of a 14-3-3 protein and chalcone synthase. MeJA application assists ectomycorrhizal colonization of Norway spruce roots, and MeJA application to Norway spruce seedlings also enhances their survival rate when they were challenged by Pythium ultimun In recent work with Sitka spruce, we have established comprehensive gene expression profiles of 

BIOCHEMICAL FUNCTIONS OF NORWAY SPRUCE TPS GENES AND THEIR ROLES IN CONSTITUTIVE AND INDUCED TERPENOID DEFENSES 

Recent studies have described the complex, constitutive, and MeJA- and insect-induced terpenoid defenses in Norway spruce and Sitka spruce at anatomical, chemical, and biochemical levels. Miller et al. compared the effect of MeJA treatment and white pine weevil attack on induced terpenoid defenses in Sitka spruce. They found that MeJA and real insects induce very similar terpenoid responses at the biochemical and molecular levels. The cloning and functional characterization of a family of ten, functionally diverse Norway spruce TPS genes not only allowed an improved phylogeny of the conifer TPS-d gene family but also allowed a detailed molecular and biochemical characterization of induced changes in terpenoid metabolite profiles in spruce defense. Many of the products of the recently identified Norway spruce TPS genes correspond with components of terpenoid metabolite profiles after MeJA treatment or insect attack in species of spruce. Our work on Norway spruce terpenoid responses to MeJA treatment is discussed here with an emphasis on those compounds that are products of the newly characterized spruce TPS genes.  

This correlative analysis of terpenoid accumulation, TPS enzyme activities, and functional characterization of a family of cloned TPS genes in Norway spruce and Sitka spruce in response to MeJA treatment and insect attack will guide future studies regarding differential expression of TPS genes in conifer defense, including in situ localization of gene expression and TPS enzymes. 

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