title: Signatures of selection and host-adapted gene expression of the Phytophthora infestans RNA silencing suppressor PSR2.
abstract: Phytophthora infestans is a devastating pathogen in agricultural systems. Recently, an RNA silencing suppressor (PSR2, 'Phytophthora suppressor of RNA silencing 2') has been described in P. infestans. PSR2 has been shown to increase the virulence of Phytophthora pathogens on their hosts. This gene is one of the few effectors present in many economically important Phytophthora species. In this study, we investigated: (i) the evolutionary history of PSR2 within and between species of Phytophthora; and (ii) the interaction between sequence variation, gene expression and virulence. In P. infestans, the highest PiPSR2 expression was correlated with decreased symptom expression. The highest gene expression was observed in the biotrophic phase of the pathogen, suggesting that PSR2 is important during early infection. Protein sequence conservation was negatively correlated with host range, suggesting host range as a driver of PSR2 evolution. Within species, we detected elevated amino acid variation, as observed for other effectors; however, the frequency spectrum of the mutations was inconsistent with strong balancing selection. This evolutionary pattern may be related to the conservation of the host target(s) of PSR2 and the absence of known corresponding R genes. In summary, our study indicates that PSR2 is a conserved effector that acts as a master switch to modify plant gene regulation early during infection for the pathogen's benefit. The conservation of PSR2 and its important role in virulence make it a promising target for pathogen management.
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.|iGRAD-Plant Graduate School, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Sophie
authors: 0000-0002-5267-8935
authors: S
authors: de Vries
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Janina K
authors: JK
authors: von Dahlen
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Constanze
authors: C
authors: Uhlmann
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Anika
authors: A
authors: Schnake
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Thorsten
authors: T
authors: Kloesges
authors: Institute of Population Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.|iGRAD-Plant Graduate School, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.|Ceplas, Cluster of Excellence in Plant Sciences, Heinrich-Heine University Duesseldorf, Duesseldorf, 40225, Germany.
authors: Laura E
authors: LE
authors: Rose
mesh_terms: D000596:Amino Acids / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D016153:Genes, Suppressor; D058507:Host Specificity; D054884:Host-Pathogen Interactions / Q000235:genetics*; D055750:Phytophthora infestans / Q000235:genetics*; D010935:Plant Diseases / Q000382:microbiology; D011110:Polymorphism, Genetic; D017433:Protein Structure, Secondary; D034622:RNA Interference; D032322:Solanum / Q000382:microbiology; D013045:Species Specificity
chemical_list: D000596:Amino Acids
keywords: effectors; evolution; oomycetes; small RNA silencing; tomato