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Background <p>Drought stress is a major constraint limiting tomato (<i>Solanum lycopersicum</i> L.) productivity worldwide. In vitro selection using polyethylene glycol (PEG)-induced osmotic stress provides a controlled approach for identifying stress-responsive genotypes.</p> Methods <p>This study aimed to select local tomato varieties using an in vitro selection system based on PEG 6000-induced osmotic stress (0–8%). Callus cultures were induced from root explants and grown on MS medium supplemented with 2&#xa0;mg/L BAP and 0.2&#xa0;mg/L NAA. Physiological responses were assessed using relative growth rate (RGR), cell viability (TTC reduction), proline accumulation, and tolerance index. Sub-lethal PEG concentrations (4%, 6%, and 8%) were determined based on approximately 50% reduction in growth and viability and were used for plant regeneration on MS medium supplemented with zeatin and GA₃. Regenerated plants were evaluated for drought tolerance based on key morphological traits relative to their donor plants.</p> Results <p>Increasing PEG concentration significantly reduced callus growth and viability while increasing proline accumulation in all genotypes. Among the studied varieties, Daraa and Brieh exhibited higher tolerance, as measured by RGR, viability, and tolerance index, than Daher-Aljabal and Baskanta. Four regenerant lines (DH1, BR1, DA1, and DA2) were obtained under selection pressure. These regenerants showed improved performance under PEG stress compared with their respective parental plants, particularly in root length, plant height, root-to-shoot ratio, and dry biomass. However, the extent of improvement varied among lines and stress levels.</p> Conclusion <p>The study demonstrates that in vitro PEG-based selection can be used to identify drought-responsive tomato callus lines and regenerate plants with improved physiological performance under osmotic stress. The regenerated lines represent putative stress-tolerant variants; however, molecular validation and field evaluation are required to confirm the stability and agronomic relevance of these responses.</p>

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Physiological responses of tomato callus and regenerated plants under PEG-induced stress during in vitro selection for drought tolerance

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月26日

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  • Ola Alnaddaf,
  • Wasim Mohsen,
  • Abdel Razzaq Al-Tawaha,
  • Abdel Rahman Mohammad Al-Tawaha,
  • Ibrahim Mohammad Al-Rawashdeh,
  • Arun Karnwal

摘要

Background

Drought stress is a major constraint limiting tomato (Solanum lycopersicum L.) productivity worldwide. In vitro selection using polyethylene glycol (PEG)-induced osmotic stress provides a controlled approach for identifying stress-responsive genotypes.

Methods

This study aimed to select local tomato varieties using an in vitro selection system based on PEG 6000-induced osmotic stress (0–8%). Callus cultures were induced from root explants and grown on MS medium supplemented with 2 mg/L BAP and 0.2 mg/L NAA. Physiological responses were assessed using relative growth rate (RGR), cell viability (TTC reduction), proline accumulation, and tolerance index. Sub-lethal PEG concentrations (4%, 6%, and 8%) were determined based on approximately 50% reduction in growth and viability and were used for plant regeneration on MS medium supplemented with zeatin and GA₃. Regenerated plants were evaluated for drought tolerance based on key morphological traits relative to their donor plants.

Results

Increasing PEG concentration significantly reduced callus growth and viability while increasing proline accumulation in all genotypes. Among the studied varieties, Daraa and Brieh exhibited higher tolerance, as measured by RGR, viability, and tolerance index, than Daher-Aljabal and Baskanta. Four regenerant lines (DH1, BR1, DA1, and DA2) were obtained under selection pressure. These regenerants showed improved performance under PEG stress compared with their respective parental plants, particularly in root length, plant height, root-to-shoot ratio, and dry biomass. However, the extent of improvement varied among lines and stress levels.

Conclusion

The study demonstrates that in vitro PEG-based selection can be used to identify drought-responsive tomato callus lines and regenerate plants with improved physiological performance under osmotic stress. The regenerated lines represent putative stress-tolerant variants; however, molecular validation and field evaluation are required to confirm the stability and agronomic relevance of these responses.