RNAi Technology: A New Path for the Research and Management of Obligate Biotrophic Phytopathogenic Fungi

Abstract

Powdery mildew and rust fungi are major agricultural problems affecting many economically important crops and causing significant yield losses. These fungi are obligate biotrophic parasites that are completely dependent on their hosts for growth and reproduction. Biotrophy in these fungi is determined by the presence of haustoria, specialized fungal cells that are responsible for nutrient uptake and molecular dialogue with the host, a fact that undoubtedly complicates their study under laboratory conditions, especially in terms of genetic manipulation. RNA interference (RNAi) is the biological process of suppressing the expression of a target gene through double-stranded RNA that induces mRNA degradation. RNAi technology has revolutionized the study of these obligate biotrophic fungi by enabling the analysis of gene function in these fungal. More importantly, RNAi technology has opened new perspectives for the management of powdery mildew and rust diseases, first through the stable expression of RNAi constructs in transgenic plants and, more recently, through the non-transgenic approach called spray-induced gene silencing (SIGS). In this review, the impact of RNAi technology on the research and management of powdery mildew and rust fungi will be addressed.

Spray-induced gene silencing (SIGS) as a tool for the management of Pine Pitch Canker forest disease

“…Also, certain genes may possess counterparts or duplicates that can carry out comparable tasks or assume the function of the suppressed gene. Therefore, silencing such genes may not hinder the fungus from overcoming the RNAi (Padilla-Roji et al, 2023; Ray et al, 2022). Consequently, we designed dsRNA molecules that targeted more than one gene within the same pathway.…”

Simultaneous Application of Several Exogenous dsRNAs for the Regulation of Anthocyanin Biosynthesis in Arabidopsis thaliana

“…This approach includes treating plant surfaces with dsRNA solutions and induces RNAi-mediated silencing of a target gene in the plant genome or in the genome of the infecting pathogen, which is important for the regulated process or for the viability of the pathogen. There have been numerous studies where the utilization of exogenous dsRNA for virulence gene silencing in plant fungal pathogens has been documented [ 4 , 11 , 13 ], as well as studies on dsRNA antiviral effects [ 4 , 14 , 38 ]. However, there are only a few studies that have explored the effective silencing of plant genes through plant surface treatments with dsRNAs.…”

“…At present, multiple studies have been conducted reporting on plant pathogen protection using the SIGS approach with the application of exogenous dsRNAs designed to inhibit the expression of virulence-associated genes in the attacking pathogens [ 4 , 11 , 13 , 14 ]. It has been established that fungal pathogens can efficiently internalize exogenous dsRNAs applied to the plant surface.…”

“…It has been established that fungal pathogens can efficiently internalize exogenous dsRNAs applied to the plant surface. Once internalized, these dsRNAs undergo processing and subsequently trigger the silencing of the targeted pathogen genes [ 13 , 15 , 16 ]. Furthermore, several intriguing studies have demonstrated that external dsRNAs, which are designed to target plant genes, may lead to the down-regulation of the gene targets in the plant genome with the consequent biochemical or phenotypic changes, such as altered flower morphology, reductions in glucose and fructose content, drought stress tolerance, changed anthocyanin production, or fungal stress resistance [ 17 , 18 , 19 , 20 , 21 , 22 ].…”

Modern Breeding Strategies and Tools for Durable Late Blight Resistance in Potato

“…In this mechanism, the plant produces double-stranded RNA (dsRNA), targeting a specific gene in the pathogen, leading to the suppression of that gene’s expression [ 138 ]. HIGS can limit pathogen growth by targeting genes implicated in the development and/or growth of the pathogen, pathogenesis, or by silencing effector genes that are affecting plant immunity responses [ 139 ] (signal transduction, pathogenesis-related proteins, hypersensitive reaction). HIGS can be used by obtaining transgenic plants expressing RNAi constructs, by micro-bombardment, or by spraying.…”