Functional characterization of NBS-LRR genes reveals an NBS-LRR gene that mediates resistance against Fusarium wilt

Background Most disease resistance (R) genes in plants encode proteins that contain leucine-rich-repeat (LRR) and nucleotide-binding site (NBS) domains, which belong to the NBS-LRR family. The sequenced genomes of Fusarium wilt-susceptible Vernicia fordii and its resistant counterpart, Vernicia montana , offer significant resources for the functional characterization and discovery of novel NBS-LRR genes in tung tree. Results Here, we identified 239 NBS-LRR genes across two tung tree genomes: 90 in V. fordii and 149 in V. montana . Five VmNBS-LRR paralogous were predicted in V. montana , and 43 orthologous were detected between V. fordii and V. montana . The orthologous gene pair Vf11G0978-Vm019719 exhibited distinct expression patterns in V. fordii and V. montana : Vf11G0978 showed downregulated expression in V. fordii , while its orthologous gene Vm019719 demonstrated upregulated expression in V. montana , indicating that this pair may be responsible for the resistance to Fusarium wilt in V. montana . Vm019719 from V. montana , activated by VmWRKY64 , was shown to confer resistance to Fusarium wilt in V. montana by a virus-induced gene silencing (VIGS) experiment. However, in the susceptible V. fordii , its allelic counterpart, Vf11G0978 , exhibited an ineffective defense response, attributed to a deletion in the promoter’s W-box element. Conclusions This study provides the first systematic analysis of NBS-LRR genes in the tung tree and identifies a candidate gene that can be utilized for marker-assisted breeding to control Fusarium wilt in V. fordii .