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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

Levels of PROAtCAPE1 transcripts under salinity. (A) Ten-day-old wild-type (Ler) seedlings were subjected to 150mM NaCl, 150mM KCl, 30mM LiCl, 300mM mannitol, and 100 μM abscisic acid (ABA). Relative transcripts indicate the normalized PROAtCAPE1 level (PROAtCAPE1/ACTIN2) from each sample compared with that in wild type in medium alone (1/2MS) at 0h. The bar shown here is the mean of three biological repeats. Error bars indicate means±SEM (stress-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P≤0.01, *P≤0.05). (B) Ten-day-old wild-type seedlings were treated without (1/2MS) or with 125mM NaCl. Zero hours means that the seedlings were subjected to medium alone and harvested immediately. The bars shown here are the means from four biological repeats. Error bars indicate means±SEM (salt-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P,≤0.01, *P,≤0.05).
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Figure 2: Levels of PROAtCAPE1 transcripts under salinity. (A) Ten-day-old wild-type (Ler) seedlings were subjected to 150mM NaCl, 150mM KCl, 30mM LiCl, 300mM mannitol, and 100 μM abscisic acid (ABA). Relative transcripts indicate the normalized PROAtCAPE1 level (PROAtCAPE1/ACTIN2) from each sample compared with that in wild type in medium alone (1/2MS) at 0h. The bar shown here is the mean of three biological repeats. Error bars indicate means±SEM (stress-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P≤0.01, *P≤0.05). (B) Ten-day-old wild-type seedlings were treated without (1/2MS) or with 125mM NaCl. Zero hours means that the seedlings were subjected to medium alone and harvested immediately. The bars shown here are the means from four biological repeats. Error bars indicate means±SEM (salt-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P,≤0.01, *P,≤0.05).

Mentions: Having confirmed the endogenous presence of AtCAPE1, we further validated that expression of the precursor gene, PROAtCAPE1, was regulated by salt stress via qRT-PCR (Fig. 2A). In comparison with normal growth condition, the transcripts of PROAtCAPE1 were significantly reduced by around 3- to 4- fold (P≤0.01) after 3 and 6h treatment with 150mM NaCl and KCl, as well as 6h treatment with 30mM LiCl (Fig. 2A). However, incubation with 300mM mannitol or 100 μM abscisic acid (ABA) for 3 and 6h showed no significant effect on the expression of the PROAtCAPE1 gene (Fig. 2A). As expression of the PROAtCAPE1 gene was significantly reduced upon incubation with three different salts, NaCl, KCl, and LiCl, but with not mannitol, we propose that the reduced expression of PROAtCAPE1 under high salinity is mainly due to ionic stress, not osmotic stress. In addition, ABA showed much less effect on expression of PROAtCAPE1 in comparison with the effect derived from salt ions, and the reduction in expression of the PROAtCAPE1 gene was still observed in the ABA biosynthesis mutants (Supplementary Fig. S1, available at JXB online) nced3, aba2, and aba3 (Nambara and Marion-Poll, 2005). These findings indicated that the PROAtCPAE1 gene may not be regulated by an ABA-dependent pathway under salinity. A comparison of the expression level at 3 and 6h of incubation with 150mM NaCl revealed that the expression of PROAtCAPE1 showed a kinetic response to salt stress. Therefore, more detailed kinetics of the expression of PROAtCAPE1 were examined upon incubation with a slightly reduced salt concentration (125mM NaCl) (Fig. 2B). We found that the transcript level of PROAtCAPE1 started to show a noticeable decrease in the first 1h, reaching a minimum at 3h (Fig. 2B). This result showed that the downregulation of PROAtCAPE1 is an early cellular response to salt stress. Interestingly, the expression level remained low up to 12h but recovered to a level close to that of wild type at 24h (Fig. 2B; see Discussion).


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)

Levels of PROAtCAPE1 transcripts under salinity. (A) Ten-day-old wild-type (Ler) seedlings were subjected to 150mM NaCl, 150mM KCl, 30mM LiCl, 300mM mannitol, and 100 μM abscisic acid (ABA). Relative transcripts indicate the normalized PROAtCAPE1 level (PROAtCAPE1/ACTIN2) from each sample compared with that in wild type in medium alone (1/2MS) at 0h. The bar shown here is the mean of three biological repeats. Error bars indicate means±SEM (stress-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P≤0.01, *P≤0.05). (B) Ten-day-old wild-type seedlings were treated without (1/2MS) or with 125mM NaCl. Zero hours means that the seedlings were subjected to medium alone and harvested immediately. The bars shown here are the means from four biological repeats. Error bars indicate means±SEM (salt-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P,≤0.01, *P,≤0.05).
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Figure 2: Levels of PROAtCAPE1 transcripts under salinity. (A) Ten-day-old wild-type (Ler) seedlings were subjected to 150mM NaCl, 150mM KCl, 30mM LiCl, 300mM mannitol, and 100 μM abscisic acid (ABA). Relative transcripts indicate the normalized PROAtCAPE1 level (PROAtCAPE1/ACTIN2) from each sample compared with that in wild type in medium alone (1/2MS) at 0h. The bar shown here is the mean of three biological repeats. Error bars indicate means±SEM (stress-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P≤0.01, *P≤0.05). (B) Ten-day-old wild-type seedlings were treated without (1/2MS) or with 125mM NaCl. Zero hours means that the seedlings were subjected to medium alone and harvested immediately. The bars shown here are the means from four biological repeats. Error bars indicate means±SEM (salt-treated wild-type versus untreated wild-type at different time points; Student’s t-test: **P,≤0.01, *P,≤0.05).
Mentions: Having confirmed the endogenous presence of AtCAPE1, we further validated that expression of the precursor gene, PROAtCAPE1, was regulated by salt stress via qRT-PCR (Fig. 2A). In comparison with normal growth condition, the transcripts of PROAtCAPE1 were significantly reduced by around 3- to 4- fold (P≤0.01) after 3 and 6h treatment with 150mM NaCl and KCl, as well as 6h treatment with 30mM LiCl (Fig. 2A). However, incubation with 300mM mannitol or 100 μM abscisic acid (ABA) for 3 and 6h showed no significant effect on the expression of the PROAtCAPE1 gene (Fig. 2A). As expression of the PROAtCAPE1 gene was significantly reduced upon incubation with three different salts, NaCl, KCl, and LiCl, but with not mannitol, we propose that the reduced expression of PROAtCAPE1 under high salinity is mainly due to ionic stress, not osmotic stress. In addition, ABA showed much less effect on expression of PROAtCAPE1 in comparison with the effect derived from salt ions, and the reduction in expression of the PROAtCAPE1 gene was still observed in the ABA biosynthesis mutants (Supplementary Fig. S1, available at JXB online) nced3, aba2, and aba3 (Nambara and Marion-Poll, 2005). These findings indicated that the PROAtCPAE1 gene may not be regulated by an ABA-dependent pathway under salinity. A comparison of the expression level at 3 and 6h of incubation with 150mM NaCl revealed that the expression of PROAtCAPE1 showed a kinetic response to salt stress. Therefore, more detailed kinetics of the expression of PROAtCAPE1 were examined upon incubation with a slightly reduced salt concentration (125mM NaCl) (Fig. 2B). We found that the transcript level of PROAtCAPE1 started to show a noticeable decrease in the first 1h, reaching a minimum at 3h (Fig. 2B). This result showed that the downregulation of PROAtCAPE1 is an early cellular response to salt stress. Interestingly, the expression level remained low up to 12h but recovered to a level close to that of wild type at 24h (Fig. 2B; see Discussion).

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