ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
Proximity labelling suggests association of the nonhost receptor PSS1 protein with enzymes of multiple defense pathways in Arabidopsis
Provisionally accepted
- Iowa State University of Science and Technology, Ames, United States
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Word count: 302 PSS1 encoding a glycine-rich integral plasma membrane protein plays a pivotal role in nonhost resistance of Arabidopsis against the soybean pathogens, Phytophthora sojae and Fusarium virguliforme. The P. sojae fails to penetrate the wildtype Col-0 ecotype. To elucidate the molecular basis of PSS1-mediated nonhost immunity, we employed miniTurbo-based proximity labeling approach. The miniTurbo fused to either wild-type PSS1 or its mutant variant, PSS1G119D, were expressed in the pss1 knockout mutant background. Seedlings were challenged with or without P. sojae zoospores and biotinylated proteins were isolated for mass spectrometry. Li PSS1 associated with thioglucoside glucohydrolase 1 (TGG1) involved in glucosinolate (GLS) metabolism presumably for expression of nonhost immunity. PSS1 also interacts with a coproporphyrinogen III oxidase (LIN2), which is involved in tetrapyrrole biosynthesis and reactive oxygen species (ROS) production linked to defense-related cell death. The PSS1-interactome of the P. sojae-infected plants includes three distinct proteins involved in cellulose biosynthesis and cell wall modification suggesting that PSS1 may regulate cell wall-associated immunity responses through interaction with these proteins. It was also observed that several candidate PSS1-interacting proteins are predominantly localized to the plastid and cytosol suggesting a possible relocation of the integral plasma membrane PSS1 protein to multiple cellular organelles following infection. It was observed that the association of PSS1 with the plasma membrane H+-ATPase 6 transporter disappeared following infection supporting the notion of relocalization of PSS1 following P. sojae infection. We hypothesize that PSS1 relocalizes to multiple cellular organelles to accomplish its possible positive feedback regulatory role on multiple defense mechanisms to confer broad-spectrum and durable nonhost immunity in Arabidopsis. Based on consistent enrichment and functional relevance, we consider TGG1, LIN2, H+-ATPase 6 and three proteins involved in cellulose biosynthesis and cell wall modification as the priority candidates for functional validation in the context of their possible role in the PSS1-mediated nonhost immunity.
Keywords: Arabidopsis, Mass Spectrometry, miniTurbo, nonhost resistance, Phytophthorasojae, Protein interactome, Proximity labeling, PSS1
Received: 08 Sep 2025; Accepted: 29 Dec 2025.
Copyright: © 2025 Akintayo, Montes Serey, Walley and Bhattacharyya. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Madan K. Bhattacharyya
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