Cleavage of a pathogen apoplastic protein by plant subtilases activates host immunity

Shuaishuai Wang, Rongkang Xing, Yan Wang, Haidong Shu, Shenggui Fu, Jie Huang, Judith K. Paulus, Mariana Schuster, Diane G.O. Saunders, Joe Win, Vivianne Vleeshouwers, Yuanchao Wang, Xiaobo Zheng, Renier A.L. van der Hoorn, Suomeng Dong*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The plant apoplast is a harsh environment in which hydrolytic enzymes, especially proteases, accumulate during pathogen infection. However, the defense functions of most apoplastic proteases remain largely elusive. We show here that a newly identified small cysteine-rich secreted protein PC2 from the potato late blight pathogen Phytophthora infestans induces immunity in Solanum plants only after cleavage by plant apoplastic subtilisin-like proteases, such as tomato P69B. A minimal 61 amino acid core peptide carrying two key cysteines, conserved widely in most oomycete species, is sufficient for PC2-induced cell death. Furthermore, we showed that Kazal-like protease inhibitors, such as EPI1, produced by P. infestans prevent PC2 cleavage and dampen PC2 elicited host immunity. This study reveals that cleavage of pathogen proteins to release immunogenic peptides is an important function of plant apoplastic proteases.

Original languageEnglish
JournalNew Phytologist
DOIs
Publication statusE-pub ahead of print - 30 Nov 2020

Keywords

  • apoplast
  • cleavage
  • immunity
  • P69B
  • PC2
  • Phytophthora
  • serine protease
  • small cysteine-rich effector

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