title: A salt-regulated peptide derived from the CAP superfamily protein negatively regulates salt-stress tolerance in Arabidopsis.
abstract: High salinity has negative impacts on plant growth through altered water uptake and ion-specific toxicities. Plants have therefore evolved an intricate regulatory network in which plant hormones play significant roles in modulating physiological responses to salinity. However, current understanding of the plant peptides involved in this regulatory network remains limited. Here, we identified a salt-regulated peptide in Arabidopsis. The peptide was 11 aa and was derived from the C terminus of a cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP) superfamily. This peptide was found by searching homologues in Arabidopsis using the precursor of a tomato CAP-derived peptide (CAPE) that was initially identified as an immune signal. In searching for a CAPE involved in salt responses, we screened CAPE precursor genes that showed salt-responsive expression and found that the PROAtCAPE1 (AT4G33730) gene was regulated by salinity. We confirmed the endogenous Arabidopsis CAP-derived peptide 1 (AtCAPE1) by mass spectrometry and found that a key amino acid residue in PROAtCAPE1 is critical for AtCAPE1 production. Moreover, although PROAtCAPE1 was expressed mainly in the roots, AtCAPE1 was discovered to be upregulated systemically upon salt treatment. The salt-induced AtCAPE1 negatively regulated salt tolerance by suppressing several salt-tolerance genes functioning in the production of osmolytes, detoxification, stomatal closure control, and cell membrane protection. This discovery demonstrates that AtCAPE1, a homologue of tomato immune regulator CAPE1, plays an important role in the regulation of salt stress responses. Our discovery thus suggests that the peptide may function in a trade-off between pathogen defence and salt tolerance.
authors.affiliation: Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan.
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Chien
authors.affiliation: Center for Plant Aging Research, Institute for Basic Science, and Department of New Biology, DGIST, Daegu 711-873, Republic of Korea.
authors.forename: Hong Gil
authors.initials: HG
authors.lastname: Nam
authors.affiliation: Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan yetran@gate.sinica.edu.tw.
authors.forename: Yet-Ran
authors.identifier: http://orcid.org/0000-0002-2409-6655
authors.initials: YR
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D010455:Peptides / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D029681:Arabidopsis Proteins; C000607731:CAP-derived peptide 1, Arabidopsis; D010455:Peptides; D012965:Sodium Chloride
keywords: CAP; Environmental regulation; negative regulator of salt resistance; plant peptide; proteolytic process; salinity.