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A non-classical PUF family protein in oomycetes functions as a pre-rRNA processing regulator and a target for RNAi-based disease control

Summary

Scientists discovered a critical protein called Puf4 in harmful water mold pathogens (oomycetes) that damage crops. When they removed this protein from the pathogens, the organisms grew poorly and couldn’t infect plants effectively. They also developed a new method to deliver therapeutic RNA directly through zoospores (swimming spores) that successfully reduced disease in infected plants, offering an eco-friendly alternative to traditional pesticides.

Background

Ribosome biogenesis is essential for cell proliferation and growth, but its regulatory mechanisms in oomycetes remain unclear. PUF proteins are conserved RNA-binding proteins involved in various cellular processes. This study investigates the role of a non-classical PUF protein (Puf4) in oomycete pre-rRNA processing and pathogenicity.

Objective

To identify and characterize Puf4, a non-classical PUF family protein in oomycetes, and determine its role in pre-rRNA processing and pathogenicity. To develop an RNAi-based disease control strategy targeting Puf4 through zoospore-specific dsRNA delivery.

Results

PuPuf4 is an L-shaped PUF protein with 11 Pumilio repeats that localizes to the nucleus. Knockout of PuPuf4 or PsPuf4 resulted in defective vegetative growth, impaired development, and reduced pathogenicity. PuPuf4 binds to H68 component of 25S rRNA and its deletion causes overaccumulation of rRNA processing intermediates (5′ETS, ITS1, ITS2). A novel AG-rich binding motif was identified for L-shaped PUF proteins. Exogenous dsRNA targeting Puf4 effectively attenuated virulence in both Pythium aphanidermatum and Ph. sojae through zoospore uptake.

Conclusion

Puf4 is a conserved regulator of pre-rRNA processing crucial for oomycete growth and pathogenicity. The novel zoospore-specific dsRNA delivery system overcomes previous limitations of oomycete dsRNA uptake without requiring nanomaterials. This study presents both fundamental insights into ribosome biogenesis in oomycetes and a promising RNAi-based strategy for sustainable disease control of destructive plant pathogens.
  • Published in:PLoS Pathogens,
  • Study Type:Experimental Research,
  • Source: PMID: 40743283, DOI: 10.1371/journal.ppat.1013379
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