Changes in soluble‐phenol content of Norway‐spruce (Picea abies) phloem in response to wounding and inoculation with Ophiostoma polonicum

Abstract

The aim of this stuciy was to uivestigate the temporal changes in Norway-spruce {Picea abies) phloem phenolics during wound-mduced response. Two Norway spruces were inoculated with Opbiostoma polonicum and sterile agar; unwounded phloem was simultaneously tested as control. Both unwounded and inoculated phloem were then sampled 6, 11, 21, 30, and 60 days later. Monophenols were analysed by HPLC, and the tanning capacity of the phloem extracts was estimated from their ability to precipitate proteins. The response to inoculation was eharaeterized by radical changes in the phloem phenolic composition. Initially, an increase in (+)-catechin concentration was obsei^ved, concomitant with a slow decrease m both glycoside concentrations and tanning capacity. After day 6, this decrease was accelerated in the event of fungus inoculation. The appearance of aglyeones did not take place during the decrease in glycosides, but was delayed. The phenolic response of Noi"way-spiuce phloem to inoculation is modulated by the presence of the fungus and is focused on the formation of insoluble compounds.

Exogenous application of methyl jasmonate elicits defenses in Norway spruce (Picea abies) and reduces host colonization by the bark beetle Ips typographus

“…These chemicals occur in phenolic parenchyma cells, resin ducts, resin blisters, and resin cells in the phloem and xylem (Bannan 1936;) and provide immediate resistance to invasion. An invasion also activates inducible defenses, which may include secondary resin production (Raffa and Berryman 1983;Christiansen 1985;Croteau et al 1987;Alfaro 1995;Klepzig et al 1995;Luchi et al 2005) and production of additional phenolics, leading to qualitative and quantitative changes in chemical composition (Brignolas et al 1995;Klepzig et al 1995;Bonello and Blodgett 2003;Lieutier et al 2003;Blodgett et al 2005). Collectively, these constitutive and inducible compounds may deter beetle invasion, impede fungal growth, and seal entrance wounds (Berryman 1972;Klepzig et al 1995;Phillips and Croteau 1999;Franceschi et al 2005).…”

Differential anatomical response of Norway spruce stem tissues to sterile and fungus infected inoculations

“…However, as the attacking organisms may overcome these constituents that provide an immediate resistance to invasion of the bark, conifers have also evolved inducible defense mechanisms. Challenges can induce changes in cell metabolism, such as synthesis of secondary resin (Raffa and Berryman 1982;Croteau et al 1987;Klepzig et al 1995) and production of new phenolics, leading to changes in chemical composition (Brignolas et al 1995a(Brignolas et al , 1995bKlepzig et al 1995) or the appearance of phenolic bodies in tissues where they normally are absent (Nagy et al 2000). Challenges can also induce changes in the activity or patterns of cell division, and in cell differentiation, resulting in the formation of new structures such as wound periderm (Fahn 1990;Oven and Torelli 1994;Franceschi et al 2000) and traumatic resin ducts (TDs) (Reid et al 1967;Berryman 1969;Werner and Illman 1994;Alfaro 1995;Tomlin et al 1998;Christiansen et al 1999a;Nagy et al 2000, Krokene et al 2003.…”

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

“…It develops around each point of attack in both the phloem and the superficial sapwood and is visible as a longitudinal elliptical resin impregnated zone associated with more or less extended cell necrosis (Berryman, 1972;Reid et al, 1967). Such a zone is considerably enriched with terpenes and neosynthesized phenolic compounds (Bois and Lieutier, 1997;Brignolas et al, 1995;Delorme and Lieutier, 1990;Långström et al, 1992;Lieutier et al, 1991a;Paine et al, 1987;Raffa and Berryman, 1982a;Russell and Berryman, 1976) contributing to stop the aggressors. Resin flow released by a section of resin ducts can constitute another important resistance mechanism, at least for beetles of which the females bore transversal egg galleries (Berryman, 1972;Lieutier, 2002).…”

“…In addition to mass inoculations, low density inoculations (usually less than 20 inoculations per tree) far below the critical threshold of inoculation density, are also very useful to evaluate fungus ability to stimulate tree defenses, especially because the tree stays alive and can better exhibit the intensity of its response to aggression. Such inoculations allow understanding basic mechanisms of tree defenses and the processes leading to their stimulation, prior the alterations due to high inoculation densities (see for example Brignolas et al, 1995;Franceschi et al, 2005;Kim et al, 2008;Lieutier et al, 1995Lieutier et al, , 1996. Moreover, different fungal species and strains can be compared on the same trees, thus limiting variations due to trees .…”