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A conserved Phytophthora apoplastic trypsin-like serine protease targets the receptor-like kinase BAK1 to dampen plant immunity

Nature Plants volume 11, pages 1401–1415 (2025)Cite this article

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Abstract

Perception of microbial pathogens by plant cell-surface pattern recognition receptors (PRRs) activates pattern-triggered immunity (PTI) in plants. The receptor-like kinase BAK1 functions as co-receptor of many PRRs and is a central immune regulator in PTI signal transduction. However, the molecular mechanism by which microbial pathogens manipulate BAK1 in the apoplast to overcome this layer of immunity remains largely unknown. In this study, we performed a large-scale screening of Phytophthora apoplastic effectors suppressing cell death triggered by Phytophthora elicitin INF1 and identified an apoplastic trypsin-like serine protease PsTry1. PsTry1 associates with BAK1 in soybean and N. benthamiana, and widely suppresses immune response triggered by different MAMPs. Further study revealed that PsTry1 cleaves the extracellular domain of soybean GmBAK1 and the ability of PsTry1 to suppress plant immunity depends on its proteolysis activity. An extensive Ala substitution mutagenesis screen revealed that Leu163 of GmBAK1 is a key residue essential for PsTry1 cleavage. Furthermore, PsTry1 is highly conserved among Phytophthora pathogens and multiple homologues are capable of suppressing PTI through cleavage of BAK1. Collectively, this study reveals a novel strategy exploited by phytopathogens to suppress plant apoplastic immunity.

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Fig. 1: Identification of P. sojae-secreted effectors suppressing MAMP-triggered cell death in the apoplast.
Fig. 2: PsTry1 is a P. sojae virulence factor that suppresses plant apoplastic immunity.
Fig. 3: Suppression of soybean immunity by PsTry1 is dependent on its proteolysis activity.
Fig. 4: PsTry1 cleaves BAK1 in the apoplast.
Fig. 5: L163 is a key residue of GmBAK1 for PsTry1 cleaving.
Fig. 6: BAK1 cleavage by trypsin-like effectors to suppress plant immunity is a conserved virulence mechanism exploited by different microbial pathogens.
Fig. 7: PsTry1 suppresses plant immunity by cleaving BAK1 extracellular domain.

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Data availability

The data that support the findings of this study are available in the Supplementary Information. The proteome data of the target species are available from the NCBI database (https://www.ncbi.nlm.nih.gov/). The CDS sequence of PsTry1 (Ps_139658) is listed in Supplementary Table 9. The CDS sequence for the GmBAK1 gene is available in the Phytozome database (https://phytozome-next.jgi.doe.gov/). The CDS sequence for the NbBAK1 gene is available in the Sol Genomics Network database (http://solgenomics.net/). RNA-seq data were obtained from NCBI SRA accession no. SRP073278. All MS raw data and analysis results were uploaded in the public database ProteomeXchange (https://www.ebi.ac.uk/pride/). P. sojae apoplastic effectors in soybean apoplastic fluid at different infection time points are available as Project accession PXD058375. The peptides of BAK1 identified by PsTry1 IP–MS are available as Project accession PXD060674. Differences in the number of extracellular domain peptides of GmBAK1 by treating with PsTry1 or PsTry1M in the apoplast are available as Project accession PXD062755. The MS data generated in this experiment are available in Supplementary Tables 3–8. Source data are provided with this paper.

Change history

  • 22 September 2025

    In the version of the Supplementary information initially published, the “Ps_139658” and “Ps_109227” images in Supplementary Fig. 1a were switched and have now been corrected. Additionally, the left panel in Supplementary Fig. 2b was incorrect and has been replaced. The amended Supplementary information is now available online.

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Acknowledgements

This research was supported by grants from the National Natural Science Foundation of China (32322070 and 32172423) and the National Key Research and Development Program of China (2022YFF1001500 and 2021YFA1300701) and by the China Agriculture Research System (CARS-004-PS14).

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Authors and Affiliations

  1. Sanya Research Institute, College of Plant Protection, Nanjing Agricultural University, Nanjing, China

    Sicong Zhang, Liyuan Wang, Haibin Jiang, Guangzheng Sun, Yeqiang Xia, Jinbin Wu, Xue Chen, Lei Wang, Tengfei Liu, Haibing Ouyang, Xi Chen, Yuanchao Wang & Yan Wang

  2. Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, China

    Sicong Zhang, Liyuan Wang, Haibin Jiang, Guangzheng Sun, Yeqiang Xia, Jinbin Wu, Xue Chen, Lei Wang, Tengfei Liu, Haibing Ouyang, Xi Chen, Yuanchao Wang & Yan Wang

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Contributions

Yan Wang, Yuanchao Wang and S.Z. conceived the study and designed the research. S.Z. and Lei Wang performed bioinformatics analysis. S.Z., Liyuan Wang, H.J., G.S., Y.X., Xue Chen, T.L., H.O. and Xi Chen performed experiments. S.Z. analysed data. S.Z., Yan Wang, Yuanchao Wang and J.W. wrote the paper. All authors read and approved the paper.

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Correspondence to Yuanchao Wang or Yan Wang.

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Nature Plants thanks Daniela Sueldo and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

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Information for Supplementary Tables 1–9 and Figs. 1–31.

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Supplementary Tables 1–9 (download XLSX )

Supplementary Table 1: PsTry1 and other effectors identified by mass spectrometry at 1.5 h, 3 h and 6 h of P. sojae infection. Table 2: The primers used in this study. Table 3: GmBAK1 and GmBAK1-like proteins identified by mass spectrometry. Table 4: NbBAK1 peptides identified by PsTry1 treatment. Table 5: NbBAK1 peptides identified by PsTry1M treatment. Table 6: Other potential interacting proteins in G. max. Table 7: Other potential interacting proteins treated by PsTry1 in N. benthamiana. Table 8: Other potential interacting proteins treated by PsTry1M in N. benthamiana. Table 9: PsTry1 and its homologous protein sequences in different species used for phylogenetic tree construction.

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Unprocessed western blots and gels.

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Zhang, S., Wang, L., Jiang, H. et al. A conserved Phytophthora apoplastic trypsin-like serine protease targets the receptor-like kinase BAK1 to dampen plant immunity. Nat. Plants 11, 1401–1415 (2025). https://doi.org/10.1038/s41477-025-02039-0

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