<p><i>Plumbago auriculata</i> L., a tropical evergreen, developed enhanced cold tolerance through long-term field acclimation, yet its molecular mechanisms remained unclear. Here, we identified <i>PaMYBS3</i>, a MYB transcription factor, as a key dual-function regulator during cold acclimation. Short-term artificial cold treatment induced <i>PaMYBS3</i> expression and improved cold resistance. Overexpression of <i>PaMYBS3</i> in <i>Arabidopsis</i> promoted growth but reduced freezing tolerance, while domain-mutant and VIGS-silenced lines exhibited inhibited growth and enhanced cold adaptation. Physiological assays revealed that <i>PaMYBS3</i> enhances cold tolerance by modulating ROS balance, photosynthetic performance, and osmotic regulators, while suppressing growth through downregulation of auxin- and sugar-related genes, supporting a cold acclimation strategy that prioritizes survival over growth. Notably, <i>PaMYBS3</i> regulated cold-responsive pathways independently of the classical CBF/DREB1-COR module, suggesting a CBF-independent cold tolerance mechanism. Our findings highlight <i>PaMYBS3</i> as a central integrator of cold response and growth restraint, offering new insights into the adaptive strategies of tropical perennials under prolonged low temperature.</p>

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PaMYBS3 balances cold tolerance and growth inhibition as a cold acclimation strategy in Plumbago auriculata L.

  • Yirui Li,
  • Zi-an Zhao,
  • Dan Jiang,
  • Wenji Li,
  • Ting Lei,
  • Lijuan Yang,
  • Jiani Li,
  • Xuan Liu,
  • Qinxiao Zeng,
  • Cailei Liu,
  • Long Guo,
  • Qibing Chen,
  • Suping Gao

摘要

Plumbago auriculata L., a tropical evergreen, developed enhanced cold tolerance through long-term field acclimation, yet its molecular mechanisms remained unclear. Here, we identified PaMYBS3, a MYB transcription factor, as a key dual-function regulator during cold acclimation. Short-term artificial cold treatment induced PaMYBS3 expression and improved cold resistance. Overexpression of PaMYBS3 in Arabidopsis promoted growth but reduced freezing tolerance, while domain-mutant and VIGS-silenced lines exhibited inhibited growth and enhanced cold adaptation. Physiological assays revealed that PaMYBS3 enhances cold tolerance by modulating ROS balance, photosynthetic performance, and osmotic regulators, while suppressing growth through downregulation of auxin- and sugar-related genes, supporting a cold acclimation strategy that prioritizes survival over growth. Notably, PaMYBS3 regulated cold-responsive pathways independently of the classical CBF/DREB1-COR module, suggesting a CBF-independent cold tolerance mechanism. Our findings highlight PaMYBS3 as a central integrator of cold response and growth restraint, offering new insights into the adaptive strategies of tropical perennials under prolonged low temperature.