Expression network of transcription factors in resistant and susceptible tung trees responding to Fusarium wilt disease

Vernicia fordii (tung oil tree) is famous worldwide for its industrial oil. Unfortunately, devastating disasters were caused by the soil-borne fungus Fusarium oxysporum f. sp. fordiis (Fof-1). Conversely, this tree’s sister species (Vernicia montana) is highly resistant to this pathogen. Due to the complexity of the Vernicia-Fusarium interaction, the molecular mechanisms underlying this difference have not been thoroughly elucidated to date. Transcription factors (TFs) play vital roles in pathogen resistance. To better understand the interconnected networks of signalling pathways and key TFs, we conducted an essential comparative transcriptome analysis of TFs at different stages of Fof-1 infected Vernicia roots. Overall, a total of 1094 and 1096 putative TFs were identified in V. fordii and V. montana, respectively. K-means clustering demonstrated that a large fraction of the 959 pairs of one-to-one orthologous TFs shared similar expression patterns in response to Fof-1. Next, we respectively detected 434 and192 differentially expressed TFs (DETs) with significant expression patterns of repression during Fof-1 infection in both V. fordii and V. montana. Subsequent functional annotation enrichment analysis revealed that DETs have evolved divergent functions through different pathways and biological processes in resistance to wilt disease in Vernicia species. Co-expression network analysis further revealed that the B3 domain-containing transcription factor (VmB3-01), a novel and hub TF, might play significant roles in Fof-1 pathogen defence. These data represent a crucial step towards understanding complex internal networks initiated in response to pathogen infection and controlling Fusarium wilt disease in V. fordii through genetic engineering.