The pine wood nematode (PWN) Bursaphelenchus xylophilus is a highly destructive forest quarantine pest and causal agent of pine wilt disease. The molecular response mechanism of Larix kaempferi (Japanese larch) to B. xylophilus infection remains unclear. This study aims to reveal the dynamic patterns of its defense response and screen key genes through time series transcriptomics. We found larch trees can proactively adjust their defense strategies to deal with the invasion of B. xylophilus. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, plant hormone signal transduction, MAPK signal pathway, and genes related to phenylpropane biosynthesis were more important. Through weighted gene coexpression network analysis (WGCNA), we identified two core modules that were rich in terpenoids, genes related to phenylpropane metabolism and cell wall strengthening, hormone signaling and defense regulation, and cytoskeleton and transport. Ultimately, we identified 20 core genes that were associated with several resistance-related processes, including the biosynthesis of resistance metabolites, post-translational regulation of protein homeostasis and defense signals, and transcriptional and translational reprogramming of gene expression. This study systematically depicted for the first time the continuous transcriptional regulatory network of L. kaempferi in response to pine wood nematodes. The key genes discovered provide important targets for subsequent functional verification and resistance breeding.

The pinewood nematode (Bursaphelenchus xylophilus, PWN) induces pine wilt disease in Pinaceae plants, causing severe destruction to pine forests. Previous studies report that by 2023, 663 cities across 18 provinces in China had been infested by the PWN, necessitating immediate control measures. To identify the genetic variations associated with the PWN’s adaptation to new environments, we conducted whole-genome sequencing (WGS) on 13 indigenous PWN samples from two distinct geographic zones within China, specifically Anhui, Liaoning, and Jiangxi provinces. We identified genetic variants and analyzed the genetic structure of these populations, followed by functional gene enrichment analyses. Our findings reveal genetic variants associated with secretion, immune system function, membrane processes, metabolism, catabolism, and cell wall regulation, supporting the hypothesis that the PWN genome has been shaped by local ecosystems.

To elucidate the effect of cold stress on Dendroctonus valens larvae, a study was conducted under controlled laboratory conditions to examine the physiological and biochemical mechanisms associated with cold stress, coupled with transcriptome sequencing. Physiological and biochemical assessments indicated stable water content in larvae during cold stress initiation, with triglycerides and fats serving as primary energy reserves that decreased over cold stress progression. Glycogen and trehalose were identified as energy sources for larval energy metabolism, with their levels increasing as cold stress duration extended. Superoxide dismutase (SOD) activity exhibited an initial decline followed by an increase, while peroxidase (POD) activity initially rose before decreasing over induction time, and catalase (CAT) activity decreased during cold stress induction. Transcriptome sequencing at various time points revealed 4630 upregulated and 1554 downregulated genes, predominantly involved in metabolic pathways such as carbohydrate, amino acid, and lipid metabolism. Quantitative polymerase chain reaction (qPCR) results validated the transcriptome data accuracy. This investigation delineated the physiological, biochemical, and transcriptome alterations during cold stress, offering a theoretical framework for the rational prediction of Dendroctonus valens outbreaks.

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, poses a severe threat to coniferous forests worldwide, yet conventional control measures remain limited. Therefore, identifying resistance genes from resilient species such as Larix kaempferi has become crucial for developing genetic strategies to protect forests. The overexpression of LKF3H2 (LKF3H2-OE) from L. kaempferi in A. thaliana significantly enhanced both plant growth and resistance to B. xylophilu. Compared to wild-type (WT) plants, LKF3H2-OE transgenic lines exhibited a 61.4% increase in plant height, a 61.5% increase in silique number per plant, and accelerated bolting and flowering by 6 days and 5 days, respectively. Following nematode inoculation, the disease incidence in transgenic plants was 40%, significantly lower than that in WT plants (76%). This enhanced resistance was associated with the density- and time-dependent induction of LKF3H2 expression, which reached 2.04-fold under high inoculum pressure and 5.48-fold at 7 days post-inoculation. Furthermore, transgenic plants accumulated higher levels of defense-related metabolites, including flavonoids (up to 3.12 mg/g) and proline (up to 34.35 mg/g). These results demonstrate that LKF3H2 significantly improves nematode resistance by synergistically enhancing growth traits and activating disease-resistant metabolic pathways, highlighting its potential as a key genetic resource for breeding disease-resistant wood plants.