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Over centuries, in many European countries, the white mulberry trees (<em>Morus alba</em> L.) became an integral part of the cultural landscape, bearing witness to past sericulture activities. The distribution records of white mulberry trees in the cultural landscape are incomplete and in general poorly documented. The aim of the presented research was to collect data regarding geographical locations of mulberry trees and to define their morphological and biochemical variability in Goriška region, one of the historical sericulture regions in Slovenia. Principal component analysis of all morphometrical leaf traits allowed us to characterize two separate groups of morphotypes. Recordings of the tree pruning management revealed that annual base cutting is traditionally used in Goriška region. Significant correlations between pruning management and leaf morphology traits showed that frequently pruned trees form larger leaves. Biochemically, mulberry leaves are shown to be rich in proteins containing threonine, arginine, asparagine, serine, and glutamine as the most prominent free amino acids. The main phenolic compounds were identified as caffeoylquinic acid derivatives, quercetin malonyl-hexoside, rutin, kaempferol acetyl-hexoside, quercetin-3-glucoside, and <em>p</em>-coumaric acid derivatives. The difference in concentrations of the investigated metabolites is correlated either with the pruning management or the morphotype. Pruning significantly affected the levels of asparagine, alanine, and serine, which were higher in the annually pruned trees regardless of the morphotype. Furthermore, we were able to confirm a significant effect of pruning on total phenolics as well as on the levels of rutin, quercetin malonyl-hexoside, and quercetin-3-glucoside contents. Multivariate analysis allowed us to determine seven chemotypes with distinctive biochemical traits. Our results are the basis for defining superior high-yielding genotypes with optimum metabolic composition for both silkworm feeding as well as for innovative usage in food processing and pharmaceutical industries.

Bark beetles and their fungal associates are integral parts of forest ecosystems, the European spruce bark beetle (Ips typographus Linnaeus, 1758) and the associated pathogenic blue stain fungus Ceratocystis polonica (SIEM.) C. MOREAU, are the most devastating pests regarding Norway spruce [Picea abies (L.) H. KARST.]. Bark beetles commonly inhabit weakened and felled trees as well as vital trees. They cause physiological disorders in trees by destroying a phloem and cambium or interrupt the transpiration -ow in the xylem. Conifers have a wide range of effective defence mechanisms that are based on the inner bark anatomy and physiological state of the tree. The basic function of bark defences is to protect the nutrient-and energy-rich phloem, the vital meristematic region of the vascular cambium, and the transpiration -ow in the sapwood. The main area of defence mechanisms is secondary phloem, which is physically and chemically protected by polyphenolic parenchyma (PP) cells, sclerenchyma, calcium oxalate crystals and resin ducts. Conifer trunk pest resistance includes constitutive, inducible defences and acquired resistance. Both constitutive and inducible defences may deter beetle invasion, impede fungal growth and close entrance wounds. During a successful attack, systemic acquired resistance (SAR) becomes effective and represents a third defence strategy. It gradually develops throughout the plant and provides a systemic change within the whole tree’s metabolism, which is maintained over a longer period of time. The broad range of defence mechanisms that contribute to the activation and utilisation of SAR, includes antioxidants and antioxidant enzymes, which are generally linked to the actions of reactive oxygen species (ROS). The presented review discusses the current knowledge on the antioxidant defence strategies of spruce inner bark against the bark beetle (Ips typographus) and associated blue stain fungus (Ceratocystis polonica).