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

Background: Arabidopsis thaliana 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. Objective: 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). Methodology: 75-day-old A. thaliana 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. Results: A. thaliana 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 Arabidopsis 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. Implications: 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. Conclusion: 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.