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Pepper pathogenesis‐related protein 4c is a plasma membrane‐localized cysteine protease inhibitor that is required for plant cell death and defense signaling
Author(s) -
Kim Nak Hyun,
Hwang Byung Kook
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12709
Subject(s) - biology , programmed cell death , hypersensitive response , pseudomonas syringae , microbiology and biotechnology , biochemistry , gene , apoptosis
Summary Xanthomonas campestris pv. vesicatoria ( Xcv ) type III effector AvrBsT triggers programmed cell death ( PCD ) and activates the hypersensitive response ( HR ) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis‐related ( PR ) protein 4c gene ( Ca PR 4c ) from pepper ( Capsicum annuum ) leaves undergoing AvrBsT‐triggered HR cell death. Ca PR 4c encodes a protein with a signal peptide and a Barwin domain. Recombinant Ca PR 4c protein expressed in Escherichia coli exhibited cysteine protease‐inhibitor activity and ribonuclease ( RN ase) activity. Subcellular localization analyses revealed that Ca PR 4c localized to the plasma membrane in plant cells. Ca PR 4c expression was rapidly and specifically induced by avirulent Xcv ( avrBsT ) infection. Transient expression of Ca PR 4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H 2 O 2 and significant induction of some defense‐response genes. Deletion of the signal peptide from Ca PR 4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of Ca PR 4c for HR cell death. Ca PR 4c silencing in pepper disrupted both basal and AvrBsT‐triggered resistance responses, and enabled Xcv proliferation in infected leaves. H 2 O 2 accumulation, cell‐death induction, and defense‐response gene expression were distinctly reduced in Ca PR 4c‐ silenced pepper. Ca PR 4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis . These results collectively suggest that Ca PR 4c plays an important role in plant cell death and defense signaling.