Down-regulation of Fusarium oxysporum endogenous genes by Host-Delivered RNA interference enhances disease resistance

Abstract

Fusarium oxysporum is a devastating pathogen causing extensive yield losses in a variety of crops and development of sustainable, environmentally friendly methods to improve crop resistance is crucial. We have used Host-Delivered RNA interference (HD-RNAi) technology to partially silence three different genes (FOW2, FRP1, and OPR) in the hemi-biotrophic fungus F. oxysporum f. sp. conglutinans. Expression of double stranded RNA (dsRNA) molecules targeting fungal pathogen genes was achieved in a number of transgenic Arabidopsis lines. F. oxysporum infecting the transgenic lines displayed substantially reduced mRNA levels on all three targeted genes, with an average of 75, 83, and 72% reduction for FOW2, FRP1, and OPR, respectively. The silencing of pathogen genes had a clear positive effect on the ability of the transgenic lines to fight infection. All transgenic lines displayed enhanced resistance to F. oxysporum with delayed disease symptom development, especially FRP1 and OPR lines. Survival rates after fungal infection were higher in the transgenic lines compared to control wild type plants which consistently showed survival rates of 10%, with FOW2 lines showing 25% survival; FRP1 lines 30–50% survival and OPR between 45 and 70% survival. The down-regulation effect was specific for the targeted genes without unintended effects in related genes. In addition to producing resistant crops, HD-RNAi can provide a useful tool to rapidly screen candidate fungal pathogenicity genes without the need to produce fungal knockout mutants.

Targeting cancer-specific glycans by cyclic peptide lectinomimics

“…Significant efforts have been undertaken to produce glycan-specific antibodies (Dalziel et al 2014; Fuster and Esko 2005) However, these have been difficult, as glycans are poor immunogens often resulting in weak affinity IgM antibodies with limited clinical value and low specificity of existing antibodies (Pinho and Reis 2015; Sterner et al 2016) One of the most promising and the most widely explored tumor-associated glycan structures in many diagnostic and (immuno)therapeutic approaches are truncated mucin-type O -glycans such as Tn (αGalNAc-Thr/Ser), sTn (αNeu5Ac-(2,6)-αGalNAc-Thr/Ser), and T (Galβ1-3GalNAcα1- O -Ser/Thr) (Cazet et al 2010) The major protein carrier of these tumor-associated glycans is the MUC1 glycoprotein, highly expressed in a variety of epithelial cancers, but absent from normal tissues (Nath and Mukherjee 2014) Despite the great potential, the generation of clinically relevant human antibodies with good affinity and specificity for tumor-associated glycans of MUC1 proves to be a challenging task (Loureiro et al 2015; Feng et al 2016) Identification of MUC1 glycan/peptide epitopes within a MUC1 tandem repeat, which are able to overcome immunological self-tolerance and yet induce stronger and long-lasting immune response is the current focus of immunotherapy approaches (McDonald et al 2015; Hossain and Wall 2016) An excellent example of such approaches is the PankoMab-GEX, a humanized monoclonal antibody that binds to a novel carbohydrate-induced conformational epitope on MUC1 (glycopeptide epitope) with a high affinity, which is currently undergoing clinical trials for ovarian cancer (Fiedler et al 2016)…”

RNAi as an emerging approach to control Fusarium head blight disease and mycotoxin contamination in cereals

“…Some of these are discussed in greater detail. Based on recent studies, HIGS of pathogen‐specific deemed 'essential for life' genes could be an efficient strategy to control FHB, as well as other fungal diseases and pests 37, 45, 46. Broad spectrum control of multiple pathogens using a single approach is highly desirable.…”

Perspectives of RNAi studies in plant pathogenic fungi

“…HIGS cũng được ứng dụng thành công trong việc ngăn chặn sự lây nhiễm của nấm Puccinia striiformis f.sp. tritici và Fusarium oxysporum trên cây trồng (Hu et al, 2015;Yin et al, 2015). Các kết quả này đã chỉ ra rằng các phân tử RNA nhỏ có thể dịch chuyển từ tế bào thực vật sang tế bào nấm trong suốt quá trình xâm nhiễm và làm câm lặng một cách hiệu quả các gen liên quan đến khả năng gây bệnh của nấm.…”