Interaction between Spruce and Ips typographus: the role of Spruce physiology.

Vivek Vikram Singh

Disertační práce

Abstract:

Norway spruce [Picea abies (L.) Karst.] is among the most ecologically and economically significant coniferous species in Europe. Naturally adapted to cool, moist environments, its distribution range spans from central and eastern Norway across Fennoscandia, the Baltic states, Belarus, Russia, and into Central and Southeastern Europe. As a dominant component of boreal forests and a primary host of the Eurasian spruce bark beetle (Ips typographus), the species is highly vulnerable to climatic changes. Drought and rising temperature are critical stressors that predispose Norway spruce to bark beetle attack; however, the physiological and molecular mechanisms underlying this vulnerability are not fully understood. The presented thesis contributes to a better understanding of spruce responses to abiotic stress by combining field-based observations with molecular analyses. Firstly, the ecology and infestation dynamics of I. typographus are reviewed to identify key factors that impair spruce defenses and promote the development of outbreaks. Current management approaches are critically assessed, and molecular-based strategies for future bark beetle control are proposed. Secondly, the influence of stand density on spruce physiology is examined through sap flow measurements, providing insights into tree transpiration, forest stand structure, and their relationship with susceptibility to infestation. At the functional genomics level, methodological limitations are addressed by identifying reliable internal control genes across tissues, developmental stages, and environmental conditions, thereby improving the accuracy of gene expression studies in spruce. Finally, genome-wide transcriptome analysis was performed to identify genes associated with drought stress, followed by functional enrichment analyses, Transcription factor identification, pathway mapping, and RT-qPCR validation of key genes, providing a robust drought transcriptome atlas. Collectively, this research aims to advance the understanding of spruce responses to drought and temperature stress at both ecological and molecular scales. The generated housekeeping genes and the comprehensive transcriptome catalogue together provide a robust foundation for future research, including breeding and conservation initiatives aimed at climate-smart forest management. These resources will support efforts to enhance the resilience of P. abies to increasingly severe environmental stressors.

Keywords

climate change, drought, Picea abies, sap flow and transpiration, RT-qPCR, gene expression

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 23. 12. 2025

Obhajoba závěrečné práce

• Vedoucí: Ing. Rastislav Jakuš, PhD.

Česká zemědělská univerzita v Praze

Fakulta lesnická a dřevařská

Doktorský studijní program:
Global Change Forestry