Ectopic expression of a truncated NLR from wild Arachis enhances resistance against Fusarium oxysporum

Fusarium oxysporum is the causative agent of vascular wilt diseases in dozens of crop species, leading to severe yield losses. The F. o. f.sp. conglutinans Arabidopsis thaliana model system enables the identification of meaningful genotype-phenotype correlations and was applied in this study to evaluate the effects of overexpressing a NLR gene (AsTIR19) from Arachis stenosperma against the pathogen infection. AsTIR19-OE plants exhibited enhanced resistance against F. oxysporum without showing any phenotype penalties. To better comprehend the mechanisms underlying this tolerance, we compared the whole transcriptome sequences of AsTIR19-OE line and wild-type (WT) plants before and after challenge with the pathogen using Illumina HiSeq4000. Through comparison of AsTIR19-OE and WT plants, we identified 778 DEGs resulting from transgene expression, while fungal infection led to 534 DEGs in the OE line. DEGs between the OE line and WT plants were annotated into GO categories, with the most enriched annotations in stress response, oxidoreductase, and cell membrane categories. Meanwhile, plant defense, secreted, and oxidoreductase were the most prevalent categories between infected AsTIR-OE plants and controls. KEGG annotations revealed genes involved in secondary metabolites and phenylpropanoid biosynthesis to be upregulated in OE plants compared to WT, with the MAPK signaling pathway specifically enriched in OE plants after fungal infection. This comprehensive transcriptomic analysis revealed that AsTIR19 overexpression reprogrammed transcriptional networks in transgenic plants, thereby altering the expression of stress-responsive genes across different metabolic pathways. These findings provide valuable insights into the molecular mechanisms underlying the role of this NLR gene under stress conditions.