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Background <p>Active de-acclimation, triggered by mid-winter warm spells, threatens winter wheat survival under freezing conditions. This study investigated the physiological and molecular mechanisms underlying the response to active de-acclimation in eight wheat accessions with contrasting tolerance levels.</p> Results <p>Phenotyping showed that tolerant accessions maintained high survival rates and photosynthetic efficiency after freezing in the de-acclimated state, whereas the same treatment was lethal to susceptible lines. Chlorophyll fluorescence parameters and principal component analysis clearly separated tolerant from sensitive accessions, indicating distinct genetic bases of freezing tolerance in cold-acclimated and de-acclimated states. RNA sequencing demonstrated that active de-acclimation is not merely the reversal of cold acclimation, as numerous genes were uniquely differentially expressed during this process. Susceptible accessions exhibited broader and more pronounced transcriptomic changes than tolerant ones, suggesting that tolerance involves a more controlled molecular response to warming. Gene ontology analyses showed enrichment of transcripts related to ethylene perception, hormone signalling, root development, and metal ion transport specifically associated with de-acclimation. Expression analysis and hormone profiling highlighted the role of abscisic acid (ABA), salicylic acid (SA), and selected cytokinins in differentiating tolerant and susceptible accessions. Notably, ABA hydroxylase expression and ABA levels were closely associated with tolerance. qPCR validation confirmed RNA-seq results for key hormone-related candidate genes.</p> Conclusions <p>Active de-acclimation in wheat is a complex response involving stress-related pathways, particularly hormone signalling. Cold acclimation capacity is critical for subsequent tolerance, and dual selection for freezing and de-acclimation tolerance is recommended in breeding programs. These findings identify ABA- and ethylene-related pathways as key targets for improving resilience to fluctuating winter temperatures.</p>

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Mid-winter de-acclimation triggers a stress-like response in leaves of cold-acclimated wheat (Triticum aestivum L.) at the tillering stage

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月2日

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  • Magdalena Wójcik-Jagła,
  • Ipsa Bani,
  • Martin Kovacik,
  • Ales Pecinka,
  • Piotr Waligórski,
  • Marcin Rapacz

摘要

Background

Active de-acclimation, triggered by mid-winter warm spells, threatens winter wheat survival under freezing conditions. This study investigated the physiological and molecular mechanisms underlying the response to active de-acclimation in eight wheat accessions with contrasting tolerance levels.

Results

Phenotyping showed that tolerant accessions maintained high survival rates and photosynthetic efficiency after freezing in the de-acclimated state, whereas the same treatment was lethal to susceptible lines. Chlorophyll fluorescence parameters and principal component analysis clearly separated tolerant from sensitive accessions, indicating distinct genetic bases of freezing tolerance in cold-acclimated and de-acclimated states. RNA sequencing demonstrated that active de-acclimation is not merely the reversal of cold acclimation, as numerous genes were uniquely differentially expressed during this process. Susceptible accessions exhibited broader and more pronounced transcriptomic changes than tolerant ones, suggesting that tolerance involves a more controlled molecular response to warming. Gene ontology analyses showed enrichment of transcripts related to ethylene perception, hormone signalling, root development, and metal ion transport specifically associated with de-acclimation. Expression analysis and hormone profiling highlighted the role of abscisic acid (ABA), salicylic acid (SA), and selected cytokinins in differentiating tolerant and susceptible accessions. Notably, ABA hydroxylase expression and ABA levels were closely associated with tolerance. qPCR validation confirmed RNA-seq results for key hormone-related candidate genes.

Conclusions

Active de-acclimation in wheat is a complex response involving stress-related pathways, particularly hormone signalling. Cold acclimation capacity is critical for subsequent tolerance, and dual selection for freezing and de-acclimation tolerance is recommended in breeding programs. These findings identify ABA- and ethylene-related pathways as key targets for improving resilience to fluctuating winter temperatures.