Florian Hartig

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Efficiency of RNAi-based gene silencing in fungi: a meta-analysis

Patrick Barth, Jakob Drumm, Alexandra Erika Schmidt, Florian Hartig & Aline Koch

New Phytologist (2026)
Cite this
@article{barth2026efficiency,
  author = {Patrick Barth and Jakob Drumm and Alexandra Erika Schmidt and Florian Hartig and Aline Koch},
  title = {Efficiency of RNAi-based gene silencing in fungi: a meta-analysis},
  journal = {New Phytologist},
  year = {2026},
  doi = {10.1111/nph.71552},
}

DOI: 10.1111/nph.71552
Citation statistics: 1 (Google Scholar) · 0 (OpenAlex), as of 29 October 2026

Google Scholar citations per year, as of 17 October 2026 (yearly counts are fetched separately from the total)

Funding

This study was supported through funding by Landesgraduiertenförderung Baden-Württemberg (LGFG), scholarship via University of Hohenheim, funded by the Ministry of Science, Research and the Arts of Baden-Württemberg; Deutsche Forschungsgemeinschaft (DFG), Research Training Group (RTG) 2355 'Mechanisms and Functions of RNA-based Regulation' (325443116). Open access funding: Projekt DEAL.

View article (DOI) Preprint

Abstract

RNA interference (RNAi) shows great potential to protect crops against fungal diseases, yet reported protection efficiencies vary greatly, and our understanding of the factors responsible for this variance remains limited. In this meta‐analysis, we evaluated 89 studies that compare the efficiency of host‐induced gene silencing (HIGS) and spray‐induced gene silencing (SIGS) in controlling fungal diseases, focusing on biotrophic, hemibiotrophic, and necrotrophic fungi, the use of formulations, and the dsRNA design as explanatory factors for differences between reported efficiency values. Our results indicate that SIGS is slightly more effective, particularly against biotrophs. Surprisingly, SIGS studies using formulations did not outperform those applying naked dsRNA. We also assessed parameters of RNA design. Differences in dsRNA length and the number of constructs and number of targets showed no consistent significant effect on resistance in either HIGS or SIGS. However, HIGS studies reported significantly higher efficiency when targeting genes closer to the 3′ end and SIGS when targeting genes closer to the 5′ end. We discuss potential reasons for the reported patterns, such as variability in dsRNA uptake mechanisms, intercellular trafficking, and Dicer processing, and conclude that more research is needed to understand the biological mechanisms determining RNAi efficiency for fungal control.

What the paper shows and why it matters

(AI-generated)

RNA interference (RNAi) can protect crops against fungal diseases. Plants can produce double-stranded RNA that silences genes of the fungus (host-induced gene silencing, HIGS), or the RNA can be sprayed onto the plant (spray-induced gene silencing, SIGS). Spraying is quicker and cheaper to deploy than transgenic crops. The paper notes that it has been suggested, however, that it gives weaker and less durable protection: sprayed RNA degrades and must cross several uptake barriers, whereas a transgenic plant supplies RNA continuously. Reported protection varies widely between studies, and this had not been tested formally. The paper questions the assumption behind it: that continuous supply inside the plant yields higher measured protection.

A meta-analysis of RNA-based protection of crops against fungi finds that sprayed RNA reaches at least as high reported resistance as transgenic expression, and that for SIGS the way the fungus infects its host (its lifestyle) was the strongest single predictor. It pools 343 resistance values from 89 studies in a meta-regression, which adjusts for differences between studies. Unadjusted, HIGS and SIGS did not differ overall; after adjustment, SIGS gave significantly higher resistance overall, particularly against biotrophic fungi, which feed on living tissue. HIGS did better against necrotrophic fungi (which kill host tissue) and hemibiotrophic fungi than against biotrophs. Formulations meant to protect sprayed RNA did not beat naked RNA, and RNA length and the number of RNA constructs or targeted genes had no significant effect. Position mattered: HIGS did better near the 3′ end of the gene, SIGS near the 5′ end. Direct comparisons of both routes on soybean rust (Hu et al. 2020) and on Fusarium graminearum in barley (Koch et al. 2019) agree.

Fig. 1. Difference in resistance between RNAi methods overall and grouped by fungal lifestyle, unadjusted for other explanatory variables. From Barth et al. (2026), New Phytologist, licensed under CC BY 4.0. Click the image to enlarge.

The results suggest that RNA uptake and the fungus’s infection biology are important determinants of efficiency, alongside target position, so delivery should be matched to fungal lifestyle. The paper presents SIGS as a non-transgenic option, effective against biotrophs and compatible with current regulatory frameworks. Its explanations for the performance of SIGS against biotrophs, such as close host–fungus contact or early exposure of spores to sprayed RNA, remain hypotheses. The model’s fixed effects explain only about 12% of the variance, and data on hemibiotrophs are sparse. Durability, where the authors consider HIGS possibly advantaged, was not assessed, so the patterns need confirmation.

References

  • Hu et al. (2020). Reduction of Phakopsora pachyrhizi infection on soybean through host‐ and spray‐induced gene silencing. Molecular Plant Pathology 21, 794–807. doi:10.1111/mpp.12931
  • Koch et al. (2019). SIGS vs HIGS: a study on the efficacy of two dsRNA delivery strategies to silence Fusarium FgCYP51 genes in infected host and non‐host plants. Molecular Plant Pathology 20, 1636–1644. doi:10.1111/mpp.12866