Rust effector PNPi interacting with wheat TaPR1a attenuates plant defense response

Weishuai Bi,Xiumei Yu,Daqun Liu,Zhensheng Kang,Xiaojie Wang,Shuqing Zhao,Jiaojie Zhao,Jun Su,Xiaodong Wang

doi:10.1186/s42483-020-00075-6

Abstract

NPR1 is a key regulator of systemic acquired resistance (SAR) in plant species. In our previous study, we identified a conserved fungal effector PNPi from Puccinia striiformis f. sp. tritici (Pst) that can suppress acquired resistance in local leaf by directly targeting the wheat NPR1 protein. In this investigation, we identified and validated a novel protein interaction between PNPi and wheat pathogenesis-related TaPR1a in the apoplastic space. TaPR1a-overexpressing wheat lines exhibited enhanced resistance to both Pst and Puccinia triticina (Pt). We further determined that exogenous expression of PNPi RNA in transgenic wheat lines reduced the degree of acquired resistance to Magnaporthe oryzae isolate P131 in the region adjacent to Pseudomonas syringae pv. tomato DC3000 infection area. Additionally, when PNPi was overexpressed, the expression levels of two plant defense responsive genes were suppressed upon P. syringae DC3000 infection in the local infiltration region. These findings established the mechanism of a single rust effector that can suppress multiple defense responses in wheat plants by targeting different components.

Highlights

Plants are constantly subjected to biotic and abiotic stresses, triggering various plant resistance mechanisms that are mediated by different hormones, such as salicylic acid (SA), jasmonate (JA), and abscisic acid (ABA) (Smith et al 2017)
The wheat pathogenesis-related protein TaPR1a was targeted by the rust effector PNPi A yeast two-hybrid (Y2H) library screening approach was used to identify proteins that interact with the rust effector PNPi (GenBank accession KT764125)
The gene expression patterns of these PNPi interactors during barley systemic acquired resistance (SAR)-like response triggered by P. syringae DC3000 were examined using data from one of our previously established transcriptome databases (Additional file 2: Figure S1) (Gao et al 2018)

Summary

Introduction

Plants are constantly subjected to biotic and abiotic stresses, triggering various plant resistance mechanisms that are mediated by different hormones, such as salicylic acid (SA), jasmonate (JA), and abscisic acid (ABA) (Smith et al 2017). SA is a crucial component of plant disease resistance, mediating plant immune response to pathogen infection and generating systemic acquired resistance (SAR) beyond the infection area (Ryals et al 1995). The genes downstream of the plant defense response and SAR belong to 18 gene families, and are considered pathogenesis-related (PR) genes that respond to various pathogens (van Loon et al 2006; Ferreira et al 2007; Sels et al 2008; Wang et al 2018). Among the PR genes characterized in wheat and barley, PR1 is a hallmark of (2020) 2:34 the activation of plant defense pathways (Molina et al 1999) and is downstream of NPR1 in the acquired resistance triggered by Pseudomonas syringae pv. Arabidopsis AtPR1 can be targeted by a cerato-platanin protein, SsCP1 from Sclerotinia sclerotiorum, which suppresses the plant defense response (Yang et al 2017)

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Results

Discussion

Conclusion