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A salt-regulated peptide derived from the CAP superfamily protein negatively regulates salt-stress tolerance in Arabidopsis.

Chien PS, Nam HG, Chen YR - J. Exp. Bot. (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.

No MeSH data available.


Related in: MedlinePlus

Expression of various salt-inducible genes is downregulated by AtCAPE1. Ten-day-old seedlings were treated without and with salt for 12h. The transcript levels of the selected salt-inducible genes in wild-type (Ler) and proatcape1 mutant seedlings were determined by qRT-PCR: ACTIN2 (A), AREB1 and ABI5 (B), and RD29B, RD20, ALDH7B4, GolS2, RD22, and P5CS1 (C). Zero hours means that the seedlings were subjected to the medium indicated and harvested immediately. For proatcape1, the mutants were subjected to either 125mM NaCl (proatcape1_Salt) or 125mM NaCl in the presence of 500nM AtCAPE1 peptide (proatcape1_Salt+AtCAPE1 peptide). The mean values from four biological repeats are shown. Error bars are means±SEM (proatcape1 versus Ler upon salt treatment; Student’s t-test: **P≤0.01, *P≤0.05).
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Figure 5: Expression of various salt-inducible genes is downregulated by AtCAPE1. Ten-day-old seedlings were treated without and with salt for 12h. The transcript levels of the selected salt-inducible genes in wild-type (Ler) and proatcape1 mutant seedlings were determined by qRT-PCR: ACTIN2 (A), AREB1 and ABI5 (B), and RD29B, RD20, ALDH7B4, GolS2, RD22, and P5CS1 (C). Zero hours means that the seedlings were subjected to the medium indicated and harvested immediately. For proatcape1, the mutants were subjected to either 125mM NaCl (proatcape1_Salt) or 125mM NaCl in the presence of 500nM AtCAPE1 peptide (proatcape1_Salt+AtCAPE1 peptide). The mean values from four biological repeats are shown. Error bars are means±SEM (proatcape1 versus Ler upon salt treatment; Student’s t-test: **P≤0.01, *P≤0.05).

Mentions: We further confirmed some of the salt-inducible genes regulated by AtCAPE1. The ACTIN2 transcript was used as an internal control in this experiment as its expression did not respond to salinity (Fig. 5A). ABA-responsive element binding protein 1 (AREB1) (Fujita et al., 2005) and ABA-INSENSITIVE 5 (ABI5) (Finkelstein and Lynch, 2000) are well-characterized basic leucine zipper transcription factors involved in ABA signalling under drought and high-salinity conditions (Uno et al., 2000; Nakashima and Yamaguchi-Shinozaki, 2013 m). The expression level of the AREB1 gene was highly upregulated by salt by around 13-fold in the wild type (Fig. 5B), which is in agreement with previous reports (Uno et al., 2000; Fujita et al., 2005). The proatcape1 mutation resulted in a further increase in AREB1 of around 2-fold compared with that in the wild type under salinity. However, the increased expression of AREB1 in the mutant was completely restored to the wild-type level by exogenous treatment with AtCAPE1 (Fig. 5B). A similar trend was found in the regulation of the ABI5 gene (Fig. 5B), although the ABI5 expression was low after seedling establishment (Nakashima and Yamaguchi-Shinozaki, 2013). AtCAPE1 also negatively regulated the expression of high-salt-inducible downstream genes, including the genes for the enzymes involved in osmoprotectant biosynthesis [Δ1-PYRROLINE-5-CARBOXYLATE SYNTHASE 1 (P5CS1) (Yoshiba et al., 1999); and GALACTINOL SYNTHASE (GolS2) (Taji et al., 2002)], for detoxification [ALDEHYDE DEHYDROGENASES 7B4 (ALDH7B4) (Kirch et al., 2004; Kotchoni et al., 2006)], and for the dehydration response [RD22, RD20 (also known as CLO3), and RD29B (Yamaguchi-Shinozaki and Shinozaki, 1993; Ingram and Bartels, 1996; Takahashi et al., 2000)] (Fig. 5C). Taken together, these results indicated that the negative role of AtCAPE1 in salt tolerance is through downregulation of the salt-tolerance genes involved in salt-stress resistance. A further investigation of the levels of RD29B transcripts regulated by various concentrations of AtCAPE1 (0.5, 5, 50, and 500nM and 5 μM) in proatcape1 mutants upon salinity indicated that, when introducing 50–500nM AtCAPE1 to the mutants, the induced RD29B genes in mutant lines were suppressed to the same level as that of the wild type upon salt stress (Supplementary Fig. S4, available at JXB online). However, an increasing peptide concentration (5 μM) did not show more suppression (Supplementary Fig. S4). This result suggested that the AtCAPE1 level in wild-type plants in response to salinity may have reached the maximum suppression efficacy for RD29B expression.


A salt-regulated peptide derived from the CAP superfamily protein negatively regulates salt-stress tolerance in Arabidopsis.

Chien PS, Nam HG, Chen YR - J. Exp. Bot. (2015)

Expression of various salt-inducible genes is downregulated by AtCAPE1. Ten-day-old seedlings were treated without and with salt for 12h. The transcript levels of the selected salt-inducible genes in wild-type (Ler) and proatcape1 mutant seedlings were determined by qRT-PCR: ACTIN2 (A), AREB1 and ABI5 (B), and RD29B, RD20, ALDH7B4, GolS2, RD22, and P5CS1 (C). Zero hours means that the seedlings were subjected to the medium indicated and harvested immediately. For proatcape1, the mutants were subjected to either 125mM NaCl (proatcape1_Salt) or 125mM NaCl in the presence of 500nM AtCAPE1 peptide (proatcape1_Salt+AtCAPE1 peptide). The mean values from four biological repeats are shown. Error bars are means±SEM (proatcape1 versus Ler upon salt treatment; Student’s t-test: **P≤0.01, *P≤0.05).
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Figure 5: Expression of various salt-inducible genes is downregulated by AtCAPE1. Ten-day-old seedlings were treated without and with salt for 12h. The transcript levels of the selected salt-inducible genes in wild-type (Ler) and proatcape1 mutant seedlings were determined by qRT-PCR: ACTIN2 (A), AREB1 and ABI5 (B), and RD29B, RD20, ALDH7B4, GolS2, RD22, and P5CS1 (C). Zero hours means that the seedlings were subjected to the medium indicated and harvested immediately. For proatcape1, the mutants were subjected to either 125mM NaCl (proatcape1_Salt) or 125mM NaCl in the presence of 500nM AtCAPE1 peptide (proatcape1_Salt+AtCAPE1 peptide). The mean values from four biological repeats are shown. Error bars are means±SEM (proatcape1 versus Ler upon salt treatment; Student’s t-test: **P≤0.01, *P≤0.05).
Mentions: We further confirmed some of the salt-inducible genes regulated by AtCAPE1. The ACTIN2 transcript was used as an internal control in this experiment as its expression did not respond to salinity (Fig. 5A). ABA-responsive element binding protein 1 (AREB1) (Fujita et al., 2005) and ABA-INSENSITIVE 5 (ABI5) (Finkelstein and Lynch, 2000) are well-characterized basic leucine zipper transcription factors involved in ABA signalling under drought and high-salinity conditions (Uno et al., 2000; Nakashima and Yamaguchi-Shinozaki, 2013 m). The expression level of the AREB1 gene was highly upregulated by salt by around 13-fold in the wild type (Fig. 5B), which is in agreement with previous reports (Uno et al., 2000; Fujita et al., 2005). The proatcape1 mutation resulted in a further increase in AREB1 of around 2-fold compared with that in the wild type under salinity. However, the increased expression of AREB1 in the mutant was completely restored to the wild-type level by exogenous treatment with AtCAPE1 (Fig. 5B). A similar trend was found in the regulation of the ABI5 gene (Fig. 5B), although the ABI5 expression was low after seedling establishment (Nakashima and Yamaguchi-Shinozaki, 2013). AtCAPE1 also negatively regulated the expression of high-salt-inducible downstream genes, including the genes for the enzymes involved in osmoprotectant biosynthesis [Δ1-PYRROLINE-5-CARBOXYLATE SYNTHASE 1 (P5CS1) (Yoshiba et al., 1999); and GALACTINOL SYNTHASE (GolS2) (Taji et al., 2002)], for detoxification [ALDEHYDE DEHYDROGENASES 7B4 (ALDH7B4) (Kirch et al., 2004; Kotchoni et al., 2006)], and for the dehydration response [RD22, RD20 (also known as CLO3), and RD29B (Yamaguchi-Shinozaki and Shinozaki, 1993; Ingram and Bartels, 1996; Takahashi et al., 2000)] (Fig. 5C). Taken together, these results indicated that the negative role of AtCAPE1 in salt tolerance is through downregulation of the salt-tolerance genes involved in salt-stress resistance. A further investigation of the levels of RD29B transcripts regulated by various concentrations of AtCAPE1 (0.5, 5, 50, and 500nM and 5 μM) in proatcape1 mutants upon salinity indicated that, when introducing 50–500nM AtCAPE1 to the mutants, the induced RD29B genes in mutant lines were suppressed to the same level as that of the wild type upon salt stress (Supplementary Fig. S4, available at JXB online). However, an increasing peptide concentration (5 μM) did not show more suppression (Supplementary Fig. S4). This result suggested that the AtCAPE1 level in wild-type plants in response to salinity may have reached the maximum suppression efficacy for RD29B expression.

Bottom Line: 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.

View Article: PubMed Central - PubMed

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.

No MeSH data available.


Related in: MedlinePlus