Activation of the plant immune receptor AvrPphB Response 1 by cleavage of PBS1-like proteins is conserved across monocots

Authors: Jaiswal, Namrata; Myers, Ariana; Scofield, Steven; Helm, Matthew

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: N/A

Technical Abstract: We previously showed that an immune receptor from barley, AvrPphB Response 1 (PBR1) mediates recognition of the Pseudomonas syringae effector protease, AvrPphB. However, our general knowledge regarding how PBR1 specifically recognizes AvrPphB protease activity remains limited. Here, we demonstrate that cleavage of several barley PBS1-like proteins, including the barley homologs of Arabidopsis PBS1-LIKE gene2 (HvPBL2), Arabidopsis PBS1-LIKE gene11 (HvPBL11), and Arabidopsis PBS1-LIKE gene29 (HvPBL29), but not the barley homologs of Arabidopsis PBS1 (HvPBS1-1 and HvPBS1-2), strongly activated barley PBR1-mediated immune signaling. Furthermore, we show the kinase domain from HvPBL11 is essential for PBR1-mediated activation of HR-like cell death and contains the key molecular determinants underlying PBR1 specificity. We also show cleavage of barley PBL11 homologs from wheat (TaPBL11), rice (OsPBL11), maize (ZmPBL11), and sorghum (SbPBL11) also activate PBR1-mediated immune signaling, demonstrating PBR1 detects the cleavage products of PBL11 proteins from other monocot crop plant species. Lastly, we identified PBR1 homologs from sorghum and rice and show the PBR1-PBL11 immune recognition module is functionally conserved in these crop plants. Collectively, our results provide new insights into how AvrPphB protease activity is recognized in monocot crop plants and suggests the decoy bioengineering strategy can be extended into sorghum and rice to introduce novel disease resistance specificities.