Cross-Kingdom RNAi of Pathogen Effectors Leads to Quantitative Adult Plant Resistance in Wheat

Cross-kingdom RNA interference (RNAi) is a biological process allowing plants to transfer small regulatory RNAs to invading pathogens to trigger the silencing of target virulence genes. Transient assays in cereal powdery mildews suggest that silencing of one or two effectors could lead to near loss of virulence, but evidence from stable RNAi lines is lacking. We established transient host-induced gene silencing (HIGS) in wheat, and demonstrate that targeting an essential housekeeping gene in the wheat powdery mildew pathogen (Blumeria graminis f. sp. tritici) results in significant reduction of virulence at an early stage of infection. We generated stable transgenic RNAi wheat lines encoding a HIGS construct simultaneously silencing three B.g. tritici effectors including SvrPm3(a1/f1), a virulence factor involved in the suppression of the Pm3 powdery mildew resistance gene. We show that all targeted effectors are effectively downregulated by HIGS, resulting in reduced fungal virulence on adult wheat plants. Our findings demonstrate that stable HIGS of effector genes can lead to quantitative gain of resistance without major pleiotropic effects in wheat

Cross-kingdom RNAi of pathogen effectors leads to quantitative adult plant resistance in wheat

Cross-kingdom RNA interference (RNAi) is a biological process allowing plants to transfer small regulatory RNAs to invading pathogens to trigger the silencing of target virulence genes. Transient assays in cereal powdery mildews suggest that silencing of one or two effectors could lead to near loss of virulence, but evidence from stable RNAi lines is lacking. We established transient host-induced gene silencing (HIGS) in wheat, and demonstrate that targeting an essential housekeeping gene in the wheat powdery mildew pathogen (Blumeria graminis f. sp. tritici) results in significant reduction of virulence at an early stage of infection. We generated stable transgenic RNAi wheat lines encoding a HIGS construct simultaneously silencing three B.g. tritici effectors including SvrPm3a1/f1, a virulence factor involved in the suppression of the Pm3 powdery mildew resistance gene. We show that all targeted effectors are effectively downregulated by HIGS, resulting in reduced fungal virulence on adult wheat plants. Our findings demonstrate that stable HIGS of effector genes can lead to quantitative gain of resistance without major pleiotropic effects in wheat

Vitamin A and retinoid signaling: genomic and nongenomic effects

Vitamin A or retinol is arguably the most multifunctional vitamin in the human body, as it is essential from embryogenesis to adulthood. The pleiotropic effects of vitamin A are exerted mainly by one active metabolite, all-trans retinoic acid (atRA), which regulates the expression of a battery of target genes through several families of nuclear receptors (RARs, RXRs, and PPARβ/δ), polymorphic retinoic acid (RA) response elements, and multiple coregulators. It also involves extranuclear and nontranscriptional effects, such as the activation of kinase cascades, which are integrated in the nucleus via the phosphorylation of several actors of RA signaling. However, vitamin A itself proved recently to be active and RARs to be present in the cytosol to regulate translation and cell plasticity. These new concepts expand the scope of the biologic functions of vitamin A and RA