AUTHOR=Yuan Hongbo , Jin Cong , Pei Hongcui , Zhao Lifang , Li Xue , Li Jiali , Huang Wanting , Fan Renchun , Liu Wende , Shen Qian-Hua 

TITLE=The Powdery Mildew Effector CSEP0027 Interacts With Barley Catalase to Regulate Host Immunity

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.733237

DOI=10.3389/fpls.2021.733237

ISSN=1664-462X

ABSTRACT=<p>Powdery mildew is one of the most important fungal pathogen diseases. The genome of barley mildew fungus, <italic>Blumeria graminis</italic> f. sp. <italic>hordei</italic> (<italic>Bgh</italic>), encodes a large number of candidate secreted effector proteins (CSEPs). So far, the function and mechanism of most CSEPs remain largely unknown. Here, we identify a <italic>Bgh</italic> effector CSEP0027, a member of family 41, triggering cell death in <italic>Nicotiana benthamiana</italic>. CSEP0027 contains a functional signal peptide (SP), verified by yeast secretion assay. We show that CSEP0027 promotes <italic>Bgh</italic> virulence in barley infection using transient gene expression and host-induced gene silencing (HIGS). Barley catalase <italic>Hv</italic>CAT1 is identified as a CSEP0027 interactor by yeast two-hybrid (Y2H) screening, and the interaction is verified in yeast, in <italic>vitro</italic> and <italic>in vivo</italic>. The coexpression of CSEP0027 and <italic>Hv</italic>CAT1 in barley cells results in altered localization of <italic>Hv</italic>CAT1 from the peroxisome to the nucleus. Barley stripe mosaic virus (BSMV)-silencing and transiently-induced gene silencing (TIGS) assays reveal that <italic>Hv</italic>CAT1 is required for barley immunity against <italic>Bgh</italic>. We propose that CSEP0027 interacts with barley <italic>Hv</italic>CAT1 to regulate the host immunity and likely reactive oxygen species (ROS) homeostasis to promote fungal virulence during barley infection.</p>