Bing Zhang, Yuan Hua, Juan Wang, Yan Huo, Masaki Shimono, Brad Day, Qing Ma.TaADF4, an Actin-depolymerizing factor from wheat, is required for resistance to the stripe rust pathogen Puccinia striiformis f. sp. Tritici

TaADF4, an Actin-Depolymerizing Factor from Wheat, is Required for Resistance to the Stripe Rust Pathogen Puccinia Striiformis f. sp. Tritici.

Bing Zhang, Yuan Hua, Juan Wang, Yan Huo, Masaki Shimono, Brad Day, Qing Ma.

 The Plant Journal

Abstract: Actin filament assembly in plants is a dynamic process, requiring the activity of more than 75 actin-binding proteins. Central to the regulation of filament assembly and stability is the activity of a conserved family of actin-depolymerizing factors (ADFs), whose primarily function is to regulate actin filament severing and depolymerization. In recent years, the activity of ADF proteins has been linked to a variety of cellular processes, including those associated with response to stress. Herein, a wheat ADF gene, TaADF4, was identified and characterized. TaADF4 encodes a 139-amino acid protein containing five F-actin binding sites and two G-actin binding sites, and interacts with wheat (Triticum aestivum) Actin1 (i.e., TaACT1), in planta. Following treatment of wheat, separately, with jasmonic acid, abscisic acid, or with the avirulent race, CYR23, of the stripe rust pathogen Puccinia striiformis f. sp. tritici, we observed a rapid induction in TaADF4 mRNA accumulation. Interestingly, TaADF4 mRNA accumulation was diminished in response to inoculation with a virulent race, CYR31. Silencing of TaADF4 resulted in enhanced susceptibility to CYR23, demonstrating a role for TaADF4 in defense signaling. Using a pharmacological-based approach, coupled with an analysis of host response to pathogen infection, we observed that treatment of plants with the actin modifying agent latrunculin B enhanced resistance to CYR23, including an increased production of reactive oxygen species and an enhancement of localized hypersensitive cell death. Taken together, these data support the hypothesis that TaADF4 positively modulates plant immunity in wheat via the modulation of actin cytoskeletal organization.