Identification of high-affinity nicotinic acid transporter genes from Verticillium dahliae and functional analysis based on HIGS technology

Abstract Background Verticillium dahliae , a soil-borne fungi, can cause Verticillium wilt, and seriously diminish the yield and quality of cotton. However, the pathogenic mechanism of V. dahliae is complex and not clearly understood at the moment. This study aimed to identify the high-affinity nicotinic acid transporter genes in V. dahliae . The gene expression profiles in V. dahliae following sensing of root exudates from susceptible and resistant cotton varieties were analyzed. The function of VdNAT1 in the pathogenic process of V. dahliae was studied using the tobacco rattle virus (TRV)-based host-induced gene silencing (HIGS) technique. Results Eight high-affinity nicotinic acid transporter genes were identified from V. dahliae through the bioinformatics method. Each protein contains a conserved major facilitator superfamily (MFS) domain, which belongs to the MFS superfamily. Evolutionary relationship analysis revealed that all 8 genes belong to the anion: cation symporter (ACS) subfamily. All proteins have transmembrane domains, ranging from 7 to 12. The expression levels of most VdNAT genes were significantly increased after induction by root exudates from susceptible cotton varieties. Silencing VdNAT1 gene by HIGS significantly inhibited the accumulation of fungal biomass in cotton plants, and alleviated the disease symptoms of cotton. Conclusions Eight VdNAT genes were identified from V. dahliae , and most VdNAT genes was up-regulated after induced by root exudates from susceptible cotton variety. In addition, VdNAT1 is required for the pathogenicity of V. dahliae. Overall, these findings will facilitate the pathogenic molecular mechanism of V. dahliae and provide candidate genes.