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The Wheat NAC Transcription Factor TaNAC2L Is Regulated at the Transcriptional and Post-Translational Levels and Promotes Heat Stress Tolerance in Transgenic Arabidopsis.

Guo W, Zhang J, Zhang N, Xin M, Peng H, Hu Z, Ni Z, Du J - PLoS ONE (2015)

Bottom Line: In this study, we examine the wheat (Triticum aestivum) NAC transcription factor gene TaNAC2L.High temperature induced TaNAC2L expression in wheat and overexpression of TaNAC2L in Arabidopsis thaliana enhanced acquired heat tolerance without causing obvious alterations in phenotype compared with wild type under normal conditions.Notably, TaNAC2L is also regulated at the post-translational level and might be degraded via a proteasome-mediated pathway.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193, China; National Plant Gene Research Centre (Beijing), Beijing, 100193, China.

ABSTRACT
Heat stress poses a serious threat to global crop production. In efforts that aim to mitigate the adverse effects of heat stress on crops, a variety of genetic tools are being used to develop plants with improved thermotolerance. The characterization of important regulators of heat stress tolerance provides essential information for this aim. In this study, we examine the wheat (Triticum aestivum) NAC transcription factor gene TaNAC2L. High temperature induced TaNAC2L expression in wheat and overexpression of TaNAC2L in Arabidopsis thaliana enhanced acquired heat tolerance without causing obvious alterations in phenotype compared with wild type under normal conditions. TaNAC2L overexpression also activated the expression of heat-related genes in the transgenic Arabidopsis plants, suggesting that TaNAC2L may improve heat tolerance by regulating the expression of stress-responsive genes. Notably, TaNAC2L is also regulated at the post-translational level and might be degraded via a proteasome-mediated pathway. Thus, this wheat transcription factor may have potential uses in enhancing thermotolerance in crops.

No MeSH data available.


Related in: MedlinePlus

Protein levels of TaNAC2L in TaNAC2L-OX transgenic lines.A. TaNAC2L protein and transcript levels in TaNAC2L-overexpressing lines (#2, #9 and #13) under normal conditions and 38°C heat stress. Western blot analyses were performed with the anti-HA monoclonal antibody. B. Seven-day-old wild-type (WT) and TaNAC2L-OX-#13 seedlings were treated at 38°C for 2 h. After heat treatment, seedlings were transferred to dimethylsulfoxide (DMSO) for 0.5, 1, 2, 3, 4, 6, or 8 h; or DMSO with 50 μM MG132 for 1, 3, 4, 6, 8, 12, or 24 h before harvesting. The HA antibody was used for the immunoblot analyses.
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pone.0135667.g004: Protein levels of TaNAC2L in TaNAC2L-OX transgenic lines.A. TaNAC2L protein and transcript levels in TaNAC2L-overexpressing lines (#2, #9 and #13) under normal conditions and 38°C heat stress. Western blot analyses were performed with the anti-HA monoclonal antibody. B. Seven-day-old wild-type (WT) and TaNAC2L-OX-#13 seedlings were treated at 38°C for 2 h. After heat treatment, seedlings were transferred to dimethylsulfoxide (DMSO) for 0.5, 1, 2, 3, 4, 6, or 8 h; or DMSO with 50 μM MG132 for 1, 3, 4, 6, 8, 12, or 24 h before harvesting. The HA antibody was used for the immunoblot analyses.

Mentions: In wheat, heat stress induces TaNAC2L expression; however, in the transgenic Arabidopsis lines, TaNAC2L was expressed from the constitutive 35S promoter. These transgenic lines exhibited clear transcription of TaNAC2L, driven by the constitutive 35S promoter under both normal and heat stress conditions (Fig 4A). To test whether these high, stable TaNAC2L transcript levels would affect the abundance of TaNAC2L protein in Arabidopsis, we determined the TaNAC2L protein levels by performing HA immunoblot assays on the three TaNAC2L-OX transgenic lines with and without exposure to heat stress. The immunoblot analysis demonstrated that under normal conditions, the TaNAC2L protein was absent in the transgenic lines TaNAC2L-OX #2 and #9, and only expressed at a low level in the transgenic line TaNAC2L-OX #13. By contrast, after heat stress, the immunoblotting detected a strong protein band in these three independent TaNAC2L-OX transgenic lines in the corresponding size range (Fig 4A). Thus, these transgenic lines exhibited clear transcription of TaNAC2L, driven by the constitutive 35S promoter, under both normal and heat stress conditions (Fig 4A), but showed high levels of TaNAC2L protein only in response to heat stress. These results suggest that the level of TaNAC2L protein is regulated post-translationally. We further evaluated the TaNAC2L protein level during recovery from 2 h of heat stress. The results indicate that TaNAC2L levels increased in response to the 38°C treatment and decreased gradually with recovery from heat stress (Fig 4B). To further test if TaNAC2L degradation in Arabidopsis was ubiquitination-dependent, we treated the TaNAC2L-OX transgenic lines with the 26S proteasome inhibitor MG132. MG132 treatment blocked TaNAC2L protein degradation during recovery from heat stress, suggesting that TaNAC2L might be degraded via a proteasome-mediated pathway.


The Wheat NAC Transcription Factor TaNAC2L Is Regulated at the Transcriptional and Post-Translational Levels and Promotes Heat Stress Tolerance in Transgenic Arabidopsis.

Guo W, Zhang J, Zhang N, Xin M, Peng H, Hu Z, Ni Z, Du J - PLoS ONE (2015)

Protein levels of TaNAC2L in TaNAC2L-OX transgenic lines.A. TaNAC2L protein and transcript levels in TaNAC2L-overexpressing lines (#2, #9 and #13) under normal conditions and 38°C heat stress. Western blot analyses were performed with the anti-HA monoclonal antibody. B. Seven-day-old wild-type (WT) and TaNAC2L-OX-#13 seedlings were treated at 38°C for 2 h. After heat treatment, seedlings were transferred to dimethylsulfoxide (DMSO) for 0.5, 1, 2, 3, 4, 6, or 8 h; or DMSO with 50 μM MG132 for 1, 3, 4, 6, 8, 12, or 24 h before harvesting. The HA antibody was used for the immunoblot analyses.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4549282&req=5

pone.0135667.g004: Protein levels of TaNAC2L in TaNAC2L-OX transgenic lines.A. TaNAC2L protein and transcript levels in TaNAC2L-overexpressing lines (#2, #9 and #13) under normal conditions and 38°C heat stress. Western blot analyses were performed with the anti-HA monoclonal antibody. B. Seven-day-old wild-type (WT) and TaNAC2L-OX-#13 seedlings were treated at 38°C for 2 h. After heat treatment, seedlings were transferred to dimethylsulfoxide (DMSO) for 0.5, 1, 2, 3, 4, 6, or 8 h; or DMSO with 50 μM MG132 for 1, 3, 4, 6, 8, 12, or 24 h before harvesting. The HA antibody was used for the immunoblot analyses.
Mentions: In wheat, heat stress induces TaNAC2L expression; however, in the transgenic Arabidopsis lines, TaNAC2L was expressed from the constitutive 35S promoter. These transgenic lines exhibited clear transcription of TaNAC2L, driven by the constitutive 35S promoter under both normal and heat stress conditions (Fig 4A). To test whether these high, stable TaNAC2L transcript levels would affect the abundance of TaNAC2L protein in Arabidopsis, we determined the TaNAC2L protein levels by performing HA immunoblot assays on the three TaNAC2L-OX transgenic lines with and without exposure to heat stress. The immunoblot analysis demonstrated that under normal conditions, the TaNAC2L protein was absent in the transgenic lines TaNAC2L-OX #2 and #9, and only expressed at a low level in the transgenic line TaNAC2L-OX #13. By contrast, after heat stress, the immunoblotting detected a strong protein band in these three independent TaNAC2L-OX transgenic lines in the corresponding size range (Fig 4A). Thus, these transgenic lines exhibited clear transcription of TaNAC2L, driven by the constitutive 35S promoter, under both normal and heat stress conditions (Fig 4A), but showed high levels of TaNAC2L protein only in response to heat stress. These results suggest that the level of TaNAC2L protein is regulated post-translationally. We further evaluated the TaNAC2L protein level during recovery from 2 h of heat stress. The results indicate that TaNAC2L levels increased in response to the 38°C treatment and decreased gradually with recovery from heat stress (Fig 4B). To further test if TaNAC2L degradation in Arabidopsis was ubiquitination-dependent, we treated the TaNAC2L-OX transgenic lines with the 26S proteasome inhibitor MG132. MG132 treatment blocked TaNAC2L protein degradation during recovery from heat stress, suggesting that TaNAC2L might be degraded via a proteasome-mediated pathway.

Bottom Line: In this study, we examine the wheat (Triticum aestivum) NAC transcription factor gene TaNAC2L.High temperature induced TaNAC2L expression in wheat and overexpression of TaNAC2L in Arabidopsis thaliana enhanced acquired heat tolerance without causing obvious alterations in phenotype compared with wild type under normal conditions.Notably, TaNAC2L is also regulated at the post-translational level and might be degraded via a proteasome-mediated pathway.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Agrobiotechnology, Key Laboratory of Crop Heterosis and Utilization (MOE), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing, 100193, China; National Plant Gene Research Centre (Beijing), Beijing, 100193, China.

ABSTRACT
Heat stress poses a serious threat to global crop production. In efforts that aim to mitigate the adverse effects of heat stress on crops, a variety of genetic tools are being used to develop plants with improved thermotolerance. The characterization of important regulators of heat stress tolerance provides essential information for this aim. In this study, we examine the wheat (Triticum aestivum) NAC transcription factor gene TaNAC2L. High temperature induced TaNAC2L expression in wheat and overexpression of TaNAC2L in Arabidopsis thaliana enhanced acquired heat tolerance without causing obvious alterations in phenotype compared with wild type under normal conditions. TaNAC2L overexpression also activated the expression of heat-related genes in the transgenic Arabidopsis plants, suggesting that TaNAC2L may improve heat tolerance by regulating the expression of stress-responsive genes. Notably, TaNAC2L is also regulated at the post-translational level and might be degraded via a proteasome-mediated pathway. Thus, this wheat transcription factor may have potential uses in enhancing thermotolerance in crops.

No MeSH data available.


Related in: MedlinePlus