Revealing differentially expressed genes and identifying effector proteins of Puccinia striiformis f. sp. tritici in response to high-temperature seedling-plant resistance of wheat based on RNA-seq

Authors: TAO, FEI - Northwest A&f University; HU, YANGSHAN - Northwest A&f University; SU, CHANG - Northwest A&f University; LI, JUAN - Northwest A&f University; GUO, LILI - Northwest A&f University; XU, XIANGMING - East Malling Research; Chen, Xianming; SHANG, HONGSHENG - Northwest A&f University; HU, XIAOPING - Northwest A&f University

Submitted to: mSphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2020
Publication Date: 6/24/2020
Citation: Tao, F., Hu, Y., Su, C., Li, J., Guo, L., Xu, X., Chen, X., Shang, H., Hu, X. 2020. Revealing differentially expressed genes and identifying effector proteins of Puccinia striiformis f. sp. tritici in response to high-temperature seedling-plant resistance of wheat based on RNA-seq. mSphere. 5(3). https://doi.org/10.1128/mSphere.00096-20.
DOI: https://doi.org/10.1128/mSphere.00096-20

Interpretive Summary: Stripe rust is one of the most important diseases of wheat globally. Breeding cultivars with durable high-temperature seedling-plant (HTSP) resistance is an important strategy for control of stripe rust. Understanding the mechanism for wheat HTSP resistance against stripe rust is important for more efficient breeding to improve host resistance. In this study, transcriptomic analysis identified 25 differentially expressed genes from the stripe rust pathogen that were involved in the HTSP resistance in wheat variety XY6. Functional annotation indicated that these genes are related to membrane proteins, mRNA binding proteins, cell membrane transportors, and synthesis of cell nitrogen compounds. Among these genes, a candidate effector was identified and cloned. Host-induced gene silencing of the candidate effector gene reduced the pathogen virulence. Signal peptide verification and functional testing in tobacco indicated that the gene encodes a secreted protein and has the function of suppressing programmed cell death. The type three secretion system-mediated overexpression of the gene support it as an effector responding to wheat HTSP resistance via affecting the pathogenassociated molecular pattern triggered immunity and effector-triggered immunity. This study provides a key resource for understanding the biology and molecular basis of the stripe rust pathogen responses to wheat HTSP resistance.

Technical Abstract: Background Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat (Triticum aestivum L.) globally. Recently, more aggressive Pst races have evolved to acquire new virulence profiles and adapted better to high temperature than most of the previous races. Breeding cultivars with durable high-temperature seedling-plant (HTSP) resistance is an important strategy for control of stripe rust. Understanding the mechanism for wheat HTSP resistance against Pst is important for more efficient breeding to improve host resistance. Results Transcriptomic analysis identified 25 Pst differentially expressed genes (DEGs) that were involved in the HTSP resistance in wheat cultivar XY6. Functional annotation indicated that these DEGs are related to membrane proteins, mRNA binding proteins, cell membrane transportors, and synthesis of cell nitrogen compounds. Among these DEGs, a candidate effector Pst_13342 was identified and cloned, and its function verified. BSMV-mediated hostinduced gene silencing (HIGS) of Pst_13342 reduced Pst virulence. Signal peptide verification and functional testing in Nicotiana benthamiana indicated that Pst_13342 is a secreted protein and has the function of suppressing programmed cell death (PCD). Pst_13342 as a candidate effector was further supported by type three secretion system (TTSS)-mediated overexpression of Pst_13342 responding to wheat HTSP resistance via affecting the pathogen-associated molecular pattern (PAMPs) triggered immunity (PTI) and effectortriggered immunity (ETI). Conclusion This study provides a key resource for understanding the biology and molecular basis of Pst responses to wheat HTSP resistance, and Pst_13342 may be used in future studies to understand PTI and ETI processes in the Pst-wheat system.