Host-Induced Silencing of Pathogenicity Genes Enhances Resistance to Fusarium oxysporum Wilt in Tomato

Abstract

This study presents a novel approach of controlling vascular wilt in tomato by RNAi expression directed to pathogenicity genes of Fusarium oxysporum f. sp. lycopersici. Vascular wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici leads to qualitative and quantitative loss of the crop. Limitation in the existing control measures necessitates the development of alternative strategies to increase resistance in the plants against pathogens. Recent findings paved way to RNAi, as a promising method for silencing of pathogenicity genes in fungus and provided effective resistance against fungal pathogens. Here, two important pathogenicity genes FOW2, a Zn(II)2Cys6 family putative transcription regulator, and chsV, a putative myosin motor and a chitin synthase domain, were used for host-induced gene silencing through hairpinRNA cassettes of these genes against Fusarium oxysporum f. sp. lycopersici. HairpinRNAs were assembled in appropriate binary vectors and transformed into tomato plant targeting FOW2 and chsV genes, for two highly pathogenic strains of Fusarium oxysporum viz. TOFOL-IHBT and TOFOL-IVRI. Transgenic tomatoes were analyzed for possible attainment of resistance in transgenic lines against fungal infection. Eight transgenic lines expressing hairpinRNA cassettes showed trivial disease symptoms after 6-8 weeks of infection. Hence, the host-induced posttranscriptional gene silencing of pathogenicity genes in transgenic tomato plants has enhanced their resistance to vascular wilt disease caused by Fusarium oxysporum.

Fusarium oxysporum f. sp. lycopersici causal agent of vascular wilt disease of tomato: Biology to diversity– A review

“…The mutant strain displayed comprehensive loss of virulence, and characterization of the insertion site revealed inactivation of the chsV gene. These findings suggest that the chsV gene is necessary to resist the defense compounds, a prerequisite for pathogenicity (Bharti et al, 2017).…”

RNA-Spray-Mediated Silencing of Fusarium graminearum AGO and DCL Genes Improve Barley Disease Resistance

“…In addition to the generation of RNA-silencing signals in planta, plants can be protected from pathogens and pests by spray-applied RNA biopesticides designated as spray-induced gene silencing (SIGS) (Koch et al, 2016;Wang et al, 2016;Konakalla et al, 2016;Mitter et al, 2017a;Kaldis et al, 2018;Koch et al, 2019). Regardless of how target-specific inhibitory RNAs are applied (i.e., endogenously or exogenously), the use of HIGS and SIGS technologies to control Fusarium species have been shown to be a potential alternative to conventional pesticides (Koch et al, 2013;Ghag et al, 2014;Cheng et al, 2015;Hu et al, 2015;Chen et al, 2016;Pareek and Rajam, 2017;Bharti et al, 2017;Baldwin et al, 2018;Koch et al, 2018Koch et al, , 2019 supporting the notion that RNAi strategies may improve food safety by controlling the growth of phytopathogenic, mycotoxin-producing fungi (reviewed by Majumdar et al, 2017;Machado et al, 2018).…”

Host-induced silencing of theColletotrichum gloeosporioides conidial morphology 1gene (CgCOM1) confers resistance against Anthracnose disease in chilli and tomato

“…Cheng et al (2015) successfully improved resistance of wheat against Fusarium graminearum pathogen that causes Fusarium head blight and Fusarium seedling blight by silencing of the fungal virulence gene chitin synthase 3b ( Chs3b ) through HIGS. Similarly, Bharti et al (2017) demonstrated host induced silencing of FOW2 and chsV genes in Fusarium oxysporum in transgenic tomato plants conferring enhanced resistance to vascular wilt disease. Recently, Song and Thomma (2018) through host-induced silencing of Ave1, Sge1 and NLP1 genes of Verticillium dahliae created tomato and Arabidopsis plants resistant to Verticillium wilt disease.…”

“…Since last ten years, HIGS strategy is widely employed to control plant diseases via suppression of pathogen infection by targeting and silencing a variety of pathogen genes to disable pathogen development/differentiation and pathogenicity (Bharti et al , 2017; Chen et al , 2016; Ghag et al , 2014; Jahan et al , 2015; Koch et al , 2013; Nowara et al , 2010; Song and Thomma, 2018; Thakare et al , 2017). These studies showed that selection of appropriate target gene(s) is the most important requirement for developing an effective HIGS to incapacitate fungal pathogens.…”