Sondersammlungen

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Should we delay leaf water potential measurements after excision? Dehydration or equilibration?
(2024) Perera‐Castro, Alicia V.; Puértolas, Jaime; Fernández-Marín, Beatriz; González-Rodríguez, Águeda M.; Perera-Castro, Alicia V.; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; Puértolas, Jaime; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; Fernández-Marín, Beatriz; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; González-Rodríguez, Águeda M.; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain
Background: Accurate leaf water potential (Ψw) determination is crucial in studying plant responses to water deficit. After excision, water potential decreases, even under low evaporative demand conditions, which has been recently attributed to the equilibration of pre-excision Ψw gradients across the leaf. We assessed the influence of potential re-equilibration on water potential determination by monitoring leaf Ψw and relative water content decline after excision using different storage methods. Results: Even though leaf Ψw declined during storage under low evaporative demand conditions, this was strongly reduced when covering the leaf with a hydrophobic layer (vaseline) and explained by changes in relative water content. However, residual water loss was variable between species, possibly related to morpho-physiological leaf traits. Provided water loss was minimized during storage, pre-excision leaf transpiration rate did not affect to the magnitude of leaf Ψw decline after excision, confirming that transpiration-driven Ψw gradients have no effect on leaf Ψw determination. Conclusions: Disequilibrium in water potentials across a transpiring leaf upon excision is dissipated very quickly, well within the elapsed time between excision and pressurization, therefore, not resulting in overestimation of leaf Ψw measured immediately after excision. When leaf storage is required, the effectiveness of a storage under low evaporative demand varied among species. Covering with a hydrophobic layer is an acceptable alternative.
The tale of two Ions Na⁺ and Cl⁻: unraveling onion plant responses to varying salt treatments
(2024) Romo-Pérez, Maria Luisa; Weinert, C. H.; Egert, B.; Kulling, S. E.; Zörb, Christian; Romo-Pérez, M. L.; University of Hohenheim, Institute of Crop Science, Quality of Plant Products 340e, Schloss Westflügel, 70599, Stuttgart, Germany; Weinert, C. H.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Egert, B.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Kulling, S. E.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Zörb, C.; University of Hohenheim, Institute of Crop Science, Quality of Plant Products 340e, Schloss Westflügel, 70599, Stuttgart, Germany
Background: Exploring the adaptive responses of onions ( Allium cepa L.) to salinity reveals a critical challenge for this salt-sensitive crop. While previous studies have concentrated on the effects of sodium (Na⁺), this research highlights the substantial yet less-explored impact of chloride (Cl⁻) accumulation. Two onion varieties were subjected to treatments with different sodium and chloride containing salts to observe early metabolic responses without causing toxicity. Results: The initial effects of salinity on onions showed increased concentrations of both ions, with Cl⁻ having a more pronounced impact on metabolic profiles than Na⁺. Onions initially adapt to salinity by first altering their organic acid concentrations, which are critical for essential functions such as energy production and stress response. The landrace Birnförmige exhibited more effective regulation of its Na⁺/K⁺ balance and a milder response to Cl⁻ compared to the hybrid Hytech. Metabolic alterations were analyzed using advanced techniques, revealing specific responses in leaves and bulbs to Cl⁻ accumulation, with significant changes observed in organic acids involved in the TCA cycle, such as fumaric acid, and succinic acid, in both varieties. Additionally, there was a variety-specific increase in ethanolamine in Birnförmige and lysine in Hytech in response to Cl⁻ accumulation. Conclusion: This comprehensive study offers new insights into onion ion regulation and stress adaptation during the initial stages of salinity exposure, emphasizing the importance of considering both Na⁺ and Cl⁻ when assessing plant responses to salinity.

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