# Transcriptomics of Three Larix Species in Response to Geographically Distinct Bursaphelenchus xylophilus Strains in China

## TL;DR

This study explores how three larch species respond at the gene level to different strains of a deadly pine wood nematode in China.

## Contribution

The study reveals species-specific and strain-specific transcriptional responses to geographically distinct PWN isolates in larch trees.

## Key findings

- Genes related to oxidative stress and secondary metabolite production were differentially expressed in larch species infected with PWN.
- The northern Fushun strain elicited a stronger and more distinct defense response compared to the southern Changde strain.
- Transcriptomic analysis identified potential genetic targets for improving resistance in larch trees.

## Abstract

Pine wood nematode (PWN, Bursaphelenchus xylophilus) is fatal to the pine trees around the world. Its northward and westward expansion in China endangers Larix spp., yet its molecular response remains understudied. We conducted transcriptomic analysis (RNA-seq) on three economically important larch species (Larix principis-rupprechtii, L. olgensis, and L. kaempferi) infected by geographically distinct PWN isolates (northern Fushun and southern Changde strains) at 1 and 3 days post-inoculation. Comparative RNA-seq analysis of 36 samples revealed that genes such as oxidative stress, and secondary metabolite production were differentially expressed in Larix spp. upon infection by the PWNs. Furthermore, compared to the Changde strain, infection with the Fushun PWN strain can elicit a consistently stronger and more distinct transcriptional defense response across all tested larch species. These results provide insights into the molecular mechanisms of plant defense against PWNs, offering genetic target for resistance breeding and informing the development of targeted control measures against this pathogen.