Open AccessSignatures of selection and host‐adapted gene expression of the Phytophthora infestans RNA silencing suppressor PSR2
Author(s) -
de Vries Sophie,
von Dahlen Janina K.,
Uhlmann Constanze,
Schnake Anika,
Kloesges Thorsten,
Rose Laura E.
Publication year - 2017
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/mpp.12465
Subject(s) - phytophthora infestans , biology , effector , virulence , gene silencing , gene , genetics , pathogen , rna silencing , phytophthora , rna interference , gene expression , host (biology) , rna , botany , microbiology and biotechnology
Summary 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.