Evaluation of actin cytoskeleton in non-host resistance of pepper to Puccinia striiformis f. sp. tritici stress

• Actin polymerization is involved in non-host resistance of pepper against Puccinia striiformis f. sp. tritici (Pst).
• We analyzed the expression level of Rho, profilin and actin depolymerizing factor in pepper leaves inoculated with Pst.
• We examined the effects of Latrunculin B on H2O2 accumulation and HR in pepper-Pst interaction.

Non-host resistance endows plants with immunity to most microbial pathogens. To evaluate the role of actin cytoskeleton in nonhost resistance of pepper against the wheat stripe rust, the expression levels of actin-binding protein genes Rho, profilin and actin depolymerizing factor (ADF) were detected in pepper leaves inoculated with the nonpathogen Puccinia striiformis f. sp. tritici (Pst) by qRT-PCR. In addition, actin polymerization inhibitor Latrunculin B was used to reveal how actin is involved in defense responses of the nonhost pepper against Pst infection. The results showed that Rho, profilin and actin depolymerizing factor were induced with different expression levels after inoculation with Pst. Furthermore, a reduced incidence of H2O2 accumulation and hypersensitive response occurred in pepper leaves treated with Latrunculin B compared with the control. Both gene expression and pharmacological results suggest that the actin cytoskeleton is likely to contribute to the non-host resistance of pepper against Pst, and a dynamic actin cytoskeleton is necessary for the pepper against Pst infection.