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Background <p>Saline-alkali stress severely impacts global crop productivity, while basic leucine zipper (bZIP) transcription factors (TFs) are known regulators of abiotic stress responses, the specific mechanisms of <i>StbZIP1</i> in potato saline-alkaline tolerance remains unclear.</p> Methods <p>We cloned <i>StbZIP1</i> from tetraploid potato ‘Favorita’, analyzed its sequence characteristics, and generated overexpression lines. <i>StbZIP1</i>-overexpressing (OE) and wild-type (WT) plants were subjected to saline-alkaline stress (NaCl: NaHCO<sub>3</sub> = 1:1) to assess physiological and molecular responses.</p> Results <p>StbZIP1 encodes a 16.61&#xa0;kDa protein with conserved bZIP domains. Secondary structure prediction revealed that the protein comprises 55.48% α-helix and 44.52% random coil, consistent with the structural characteristics of typical bZIP family features. Physicochemical characterization revealed StbZIP1 was a highly hydrophilic protein (GRAVY index: −0.882) with no transmembrane region, and it harbors 27 predicted phosphorylation sites. Subcellular localization analysis using GFP-tagged StbZIP1 via confocal microscopy confirmed its exclusive nuclear localization, classifying it as a nuclear-targeted transcription factor. Under saline-alkaline stress, WT plants displayed severe wilting and complete desiccation of lower leaves, whereas <i>StbZIP1</i>-OE plants exhibited delayed wilting, no death and retained greener apical leaves. Quantitative analysis revealed that <i>StbZIP1</i>-OE plants showed a 33%–50% increase in chlorophyll content compared to WT (<i>p</i> &lt; 0.01). Notably, <i>StbZIP1</i>-OE plants exhibited a more pronounced increase in Pro content (28%&#xa0;~&#xa0;46%) higher than WT, while their MDA content was significantly reduced compared to WT. Furthermore, the activities of antioxidant enzymes (SOD, POD, and APX) were markedly elevated in <i>StbZIP1</i>-OE plants, showing increases of 81% ~ 100%, 81% ~ 104%, and 20% ~ 43%, respectively, relative to WT. Analysis of stress-related gene expression showed that after 12 d of saline-alkaline stress, the OE plants exhibited significantly increased expression of all six genes (<i>StNCED</i>, <i>StRD29B</i>, <i>StABI5</i>, <i>StP5CS</i>, <i>StSOD</i>, and <i>StCAT</i>) compared with WT (<i>p</i> &lt; 0.05).</p> Conclusions <p><i>StbZIP1</i> positively regulates saline-alkaline tolerance by enhancing antioxidant capacity, providing a reference for the further cultivation of new stress-resistant potatoes.</p> Graphical Abstract <p></p>

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Molecular mechanisms of potato (Solanum tuberosum L.) transcription factor StbZIP1 in regulating saline-alkaline stress response through enhanced antioxidant capacity

  • 期刊论文

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  • 发表日期：

    2025年10月7日

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  • Shujuan Jiao,
  • Xiongliang Hu,
  • Yong Wang,
  • Ruyan Zhang,
  • Xingxing Wang,
  • Yuan Lu,
  • Weina Zhang,
  • Yuhui Liu,
  • Shuhao Qin,
  • Yichen Kang

摘要

Background

Saline-alkali stress severely impacts global crop productivity, while basic leucine zipper (bZIP) transcription factors (TFs) are known regulators of abiotic stress responses, the specific mechanisms of StbZIP1 in potato saline-alkaline tolerance remains unclear.

Methods

We cloned StbZIP1 from tetraploid potato ‘Favorita’, analyzed its sequence characteristics, and generated overexpression lines. StbZIP1-overexpressing (OE) and wild-type (WT) plants were subjected to saline-alkaline stress (NaCl: NaHCO3 = 1:1) to assess physiological and molecular responses.

Results

StbZIP1 encodes a 16.61 kDa protein with conserved bZIP domains. Secondary structure prediction revealed that the protein comprises 55.48% α-helix and 44.52% random coil, consistent with the structural characteristics of typical bZIP family features. Physicochemical characterization revealed StbZIP1 was a highly hydrophilic protein (GRAVY index: −0.882) with no transmembrane region, and it harbors 27 predicted phosphorylation sites. Subcellular localization analysis using GFP-tagged StbZIP1 via confocal microscopy confirmed its exclusive nuclear localization, classifying it as a nuclear-targeted transcription factor. Under saline-alkaline stress, WT plants displayed severe wilting and complete desiccation of lower leaves, whereas StbZIP1-OE plants exhibited delayed wilting, no death and retained greener apical leaves. Quantitative analysis revealed that StbZIP1-OE plants showed a 33%–50% increase in chlorophyll content compared to WT (p < 0.01). Notably, StbZIP1-OE plants exhibited a more pronounced increase in Pro content (28% ~ 46%) higher than WT, while their MDA content was significantly reduced compared to WT. Furthermore, the activities of antioxidant enzymes (SOD, POD, and APX) were markedly elevated in StbZIP1-OE plants, showing increases of 81% ~ 100%, 81% ~ 104%, and 20% ~ 43%, respectively, relative to WT. Analysis of stress-related gene expression showed that after 12 d of saline-alkaline stress, the OE plants exhibited significantly increased expression of all six genes (StNCED, StRD29B, StABI5, StP5CS, StSOD, and StCAT) compared with WT (p < 0.05).

Conclusions

StbZIP1 positively regulates saline-alkaline tolerance by enhancing antioxidant capacity, providing a reference for the further cultivation of new stress-resistant potatoes.

Graphical Abstract