AUTHOR=Liu Jing , Peng Huan , Su Wen , Liu Maoyan , Huang Wenkun , Dai Liangying , Peng Deliang 

TITLE=HaCRT1 of Heterodera avenae Is Required for the Pathogenicity of the Cereal Cyst Nematode

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.583584

DOI=10.3389/fpls.2020.583584

ISSN=1664-462X

ABSTRACT=<p>Cereal cyst nematodes are sedentary biotrophic endoparasites that secrete effector proteins into plant tissues to transit normal cells into specialized feeding sites and suppress plant defenses. To understand the function of nematode effectors in <italic>Heterodera avenae</italic>, here, we identified a calreticulin protein HaCRT1, which could suppress the cell death induced by Bax when expressed in <italic>Nicotiana benthamiana</italic>. HaCRT1 is synthetized in the subventral gland cells of pre-parasitic second-stage nematodes. Real-time PCR assays indicated that the expression of <italic>HaCRT1</italic> was highest in parasitic second-stage juveniles. The expression of an HaCRT1-RFP fusion in <italic>N. benthamiana</italic> revealed that it was localized in the endoplasmic reticulum of the plant cell. The ability of <italic>H. avenae</italic> infecting plants was significantly reduced when <italic>HaCRT1</italic> was knocked down by RNA interference <italic>in vitro</italic>. <italic>Arabidopsis thaliana</italic> plants expressing <italic>HaCRT1</italic> were more susceptible than wild-type plants to <italic>Pseudomonas syringae</italic>. The induction of defense-related genes, <italic>PAD4</italic>, <italic>WRKY33</italic>, <italic>FRK1</italic>, and <italic>WRKY29</italic>, after treatment with flg22 was suppressed in <italic>HaCRT1</italic>-transgenic plants. Also, the ROS accumulation induced by flg22 was reduced in the <italic>HaCRT1</italic>-transgenic plants compared to wild-type plants. HaCRT1 overexpression increased the cytosolic Ca<sup>2+</sup> concentration in <italic>A. thaliana</italic>. These data suggested that HaCRT1 may contribute to the pathogenicity of <italic>H. avenae</italic> by suppressing host basal defense.</p>