Stopping a Harmful Fungus with RNA Interference Targeting Specific Genes

Greg Howard
15th May, 2024

Stopping a Harmful Fungus with RNA Interference Targeting Specific Genes

Image Source: Natural Science News, 2024

Key Findings

  • The study from the University of Delhi explores RNAi-based strategies to combat the fungal pathogen Sclerotinia sclerotiorum
  • Applying dsRNA to plants (SIGS) delayed fungal infection and reduced its growth, showing potential as a biofungicide
  • Genetically modified plants (HIGS) expressing dsRNA exhibited enhanced resistance to the fungus, suggesting a long-term crop protection strategy
Sclerotinia sclerotiorum is a formidable fungal pathogen responsible for white rot disease, affecting a wide array of crops and causing significant economic losses globally. Traditional control measures have proven inadequate, necessitating innovative biotechnological approaches. A recent study from the University of Delhi[1] explores the potential of RNA interference (RNAi)-based strategies, specifically Spray-Induced Gene Silencing (SIGS) and Host-Induced Gene Silencing (HIGS), to combat this pathogen. RNA interference (RNAi) is a biological process where RNA molecules inhibit gene expression by neutralizing targeted mRNA molecules. In the context of plant pathology, this technology can be harnessed to silence critical genes in pathogens, thereby hindering their ability to infect and cause disease. The study investigates the efficacy of SIGS and HIGS against S. sclerotiorum. SIGS involves the topical application of double-stranded RNA (dsRNA) to plants, while HIGS entails the genetic modification of plants to produce dsRNA internally. Both methods target specific genes in the fungus, such as SsPac1, a pH-responsive transcription factor, and SsSmk1, a MAP kinase involved in fungal development and pathogenesis. The researchers applied dsRNA targeting SsPac1 and SsSmk1 to Nicotiana benthamiana and Brassica juncea. They observed delayed infection initiation and progression, altered hyphal morphology, and reduced radial growth of the fungus. This demonstrates the potential of SIGS as a biofungicide, offering a sustainable and environmentally friendly alternative to chemical fungicides. In parallel, the study explored HIGS by engineering Arabidopsis thaliana to express dsRNA targeting S. sclerotiorum genes. The transgenic plants exhibited enhanced resistance to the fungus, underscoring the viability of HIGS as a long-term strategy for crop protection. These findings build on previous research highlighting the complex interactions between S. sclerotiorum and its host plants. For instance, earlier studies have shown that S. sclerotiorum's genome exhibits subtle signatures of enhanced mutation of secreted proteins due to transposition and repeat-induced point mutation (RIP) activity[2]. Understanding these genomic characteristics helps in identifying potential targets for RNAi-based interventions. Furthermore, research has demonstrated that resistant Brassica oleracea varieties can suppress the expression of key virulence genes in S. sclerotiorum during early infection stages[3]. This aligns with the current study's focus on targeting essential fungal genes to curb disease progression. Another relevant study identified the importance of the Sscnd1 gene in S. sclerotiorum's virulence and appressorium formation, revealing that silencing this gene reduces the pathogen's ability to infect host plants[4]. This supports the current study's approach of targeting critical fungal genes to enhance plant resistance. In conclusion, the University of Delhi's research presents compelling evidence for the use of RNAi-based strategies, such as SIGS and HIGS, in managing S. sclerotiorum infections. By targeting vital fungal genes, these methods offer a promising avenue for sustainable crop protection, reducing reliance on chemical fungicides and mitigating the economic impact of this pervasive pathogen.

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References

Main Study

1) Control of Sclerotinia sclerotiorum via an RNA interference (RNAi)-mediated targeting of SsPac1 and SsSmk1.

Published 14th May, 2024

https://doi.org/10.1007/s00425-024-04430-1

Related Studies

2) The complete genome sequence of the phytopathogenic fungus Sclerotinia sclerotiorum reveals insights into the genome architecture of broad host range pathogens.

https://doi.org/10.1093/gbe/evx030

3) Simultaneous Transcriptome Analysis of Host and Pathogen Highlights the Interaction Between Brassica oleracea and Sclerotinia sclerotiorum.

https://doi.org/10.1094/PHYTO-06-18-0204-R

4) Host-Induced Gene Silencing of a Multifunction Gene Sscnd1 Enhances Plant Resistance Against Sclerotinia sclerotiorum.

https://doi.org/10.3389/fmicb.2021.693334


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