STUDY OF THE MORPHOLOGY AND PHYSIOLOGY OF Arabidopsis thaliana COLUMBIA ECOTYPE DURING INDIVIDUAL AND COMBINED STRESS: DROUGHT AND HEAT

<p><strong>Background:</strong> <em>Arabidopsis thaliana</em> is the most widely used plant organism as a study model, due to its short life cycle and small genome. Among the most used accessions, the Columbia (Col-0) ecotype is widely used for molecular and genetic research, however the physiological response of this model plant to abiotic factors is relatively unknown. <strong>Objective:</strong> Given its relevance in studying gene functionality, it is essential to understand its physiology and morphology under individual stress conditions: water deficit stress (WDS), thermal shock (50 °C for 2 hours), and under the combined effect of both stress types (WDS + 50 °C for 2 hours). <strong>Methodology:</strong> 75-day-old <em>A. thaliana</em> Col-0 plants were used for the 3 stress treatments: 14d of WDS, 50 °C/2 h, and 14d WDS + 50 °C/2 h. The survival percentage, water potential, electrolyte leakage, PSII status, and gas exchange were evaluated. <strong>Results:</strong> <em>A. thaliana</em> plants exhibited susceptibility to prolonged levels of stress, demonstrating different physiological mechanisms to cope with individual and combined stresses. The analysis of the photochemical state of PSII indicated that <em>Arabidopsis</em> is more vulnerable to the 50 °C/2 h stress and to the combined WDS + 50 °C/2 h stress, than to water deficit stress. The WDS + 50 °C/2 h treatment caused greater membrane damage, more negative water potential, and lower gas exchange compared to the individual stress. <strong>Implications:</strong> This system is proposed for future molecular analyses involving the overexpression of cloned transcription factor genes from tolerant species, with the aim of extrapolating these findings to commercially relevant crops. <strong>Conclusion:</strong> The differential response observed under different types of stress in this model plant, may facilitate the elucidation of underlying molecular mechanisms, which should be a central focus in future research aiming to increase resilience to climate change factors in commercially important agricultural crops.</p>