A Novel Deoxynivalenol-Activated Wheat Arl6ip4 Gene Encodes an Antifungal Peptide with Deoxynivalenol Affinity and Protects Plants against Fusarium Pathogens and Mycotoxins.

Deoxynivalenol (DON) is one of the most widespread trichothecene mycotoxins in contaminated cereal products. DON plays a vital role in the pathogenesis of Fusarium graminearum, but the molecular mechanisms of DON underlying Fusarium-wheat interactions are not yet well understood. In this study, a novel wheat ADP-ribosylation factor-like protein 6-interacting protein 4 gene, TaArl6ip4, was identified from DON-treated wheat suspension cells by suppression subtractive hybridization (SSH). The qRT-PCR result suggested that TaArl6ip4 expression is specifically activated by DON in both the Fusarium intermediate susceptible wheat cultivar Zhengmai9023 and the Fusarium resistant cultivar Sumai3. The transient expression results of the TaARL6IP4::GFP fusion protein indicate that TaArl6ip4 encodes a plasma membrane and nucleus-localized protein. Multiple sequence alignment using microscale thermophoresis showed that TaARL6IP4 comprises a conserved DON binding motif, 67HXXXG71, and exhibits DON affinity with a dissociation constant (KD) of 91 ± 2.6 µM. Moreover, TaARL6IP4 exhibited antifungal activity with IC50 values of 22 ± 1.5 µM and 25 ± 2.6 µM against Fusarium graminearum and Alternaria alternata, respectively. Furthermore, TaArl6ip4 interacted with the plasma membrane of Fusarium graminearum spores, resulting in membrane disruption and the leakage of cytoplasmic materials. The heterologous over-expression of TaArl6ip4 conferred greater DON tolerance and Fusarium resistance in Arabidopsis. Finally, we describe a novel DON-induced wheat gene, TaArl6ip4, exhibiting antifungal function and DON affinity that may play a key role in Fusarium-wheat interactions.