Transcriptomic Reprogramming and Genetic Variations Contribute to Western Hemlock Defense and Resistance Against...

Area of Science:

• Forestry and Plant Pathology
• Molecular Biology and Genomics

Background:

• Western hemlock (Tsuga heterophylla) is vulnerable to Annosus root and butt rot disease caused by Heterobasidion occidentale.
• Understanding tree defense mechanisms and genetic resistance is crucial for forest management and breeding.

Purpose of the Study:

• To investigate host transcriptome reprogramming in western hemlock upon H. occidentale infection.
• To identify genes and genetic variations associated with disease resistance.

Main Methods:

• RNA-sequencing (RNA-seq) analysis of inoculated western hemlock seedlings.
• De novo transcriptome assembly and differential gene expression analysis.
• Identification and characterization of non-synonymous single nucleotide polymorphisms (ns-SNPs).

Main Results:

• Quantitative resistant (QR) seedlings exhibited enhanced biosynthesis of secondary metabolites for defense.
• Susceptible (Sus) seedlings showed altered defense responses, with some processes enhanced and others suppressed.
• High genetic variability in defense- and resistance-related genes was observed, with distinct phylogenetic groupings of QR and Sus seedlings.

Conclusions:

• This study provides insights into the molecular defense strategies and genetic basis of western hemlock resistance to H. occidentale.
• Identified genes and DNA variations can support genomics-based breeding for enhanced tree resistance.