TaADF4, an actin‐depolymerizing factor from wheat, is required for resistance to the stripe rust pathogen Puccinia striiformis f. sp. tritici

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 the severing and depolymerization of actin filaments. 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 (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 accumulation of TaADF4 mRNA. Interestingly, accumulation of TaADF4 mRNA 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 increased production of reactive oxygen species and 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.

Plant–microbe interactions: organelles and the cytoskeleton in action

“…A wheat ADF4 (TaADF4) is required for resistance to a virulent strain of P. striiformis f. sp. tritici (Zhang et al ., ), and TaADF7 contributes to resistance to an avirulent strain of P. striiformis f. sp. tritici in wheat (Fu et al ., ).…”

Genome-Wide Identification and Characterization of Actin-Depolymerizing Factor (ADF) Family Genes and Expression Analysis of Responses to Various Stresses in Zea Mays L.

“…Currently, there are only a few reports on the analysis of plant ADF genes. The ADF gene family is well known to make a special contribution to the processes of plant growth and stress responses, including pollen tube development [12][13][14][15][16], cotton fiber development [17,18], root hairs and trichomes (leaf hairs) morphogenesis [14], pathogen defense [19][20][21][22][23], drought tolerance [24], etc. For example, knockdown or overexpression of AtADF1 significantly elongates or shortens organ length, such as that of roots, hypocotyls, cotyledons, and stems.…”

“…Whereas OsADF3 is reduced by salt stress and induced by exogenous ABA and cold, and OsADF3-transgenic Arabidopsis shows increased drought stress tolerance [24]. TaADF4 is also upregulated by JA and ABA, but differs from TaADF3, which positively modulates wheat resistance to Pst [23]. Similar to TaADF4, TaADF7 also positively contributes to wheat resistance to Pst [21].…”

The tomato Arp2/3 complex is required for resistance to the powdery mildew fungus Oidium neolycopersici

“…neolycopersici . Although it remains to be investigated, we suggest that this process is likely associated with actin polymerization catalysed by the Arp2/3 complex, and moreover, functions as a pivotal component in the plant defence signalling cascade (Tian et al, ; Welch & Mullins, ; Zhang et al, ).…”