Optimized theophylline administration across diverse model organisms: insights from Nicotiana tabacum L. comparison to Escherichia coli and Chlamydomonas reinhardtii

Theophylline, a rare xanthine alkaloid, has recently gained more interest in molecular and synthetic biology research due to its high selectivity, strong affinity to its aptamer, cost-effectiveness, availability, and non-toxicity. Despite its non-toxic nature, it is however crucial to establish the threshold limit of its application across different organisms, along with the minimum amount necessary for biotechnological applications. In the current study, various theophylline application methods were investigated at the diverse developmental stages of the model plant Nicotiana tabacum L., exponential growth phases of the bacterium Escherichia coli, and microalga Chlamydomonas reinhardtii. The growth behavior showed that while both plants and bacteria absorbed theophylline, the microalgae demonstrated a higher tolerance, suggesting a probable inefficient uptake of the substance into the cells or metabolization of it within the cell. Accordingly, C. reinhardtii, E. coli, and in vitro-grown tobacco explants showed relative tolerance to theophylline, respectively. Regarding the experiments done with tobacco, a range of theophylline tolerance between 1.5 and 2.5 mM was observed in different in vitro tissues with root development showing more sensitivity than seed germination or shoot regenerations. Remarkably, the greenhouse-grown tobacco plants could tolerate up to 15 mM theophylline when irrigated with the solution. Based on the analysis of the molecular metabolic processes, theophylline exposure did not remarkably affect the total RNA and protein qualities, and also the profiles of two main plastid membrane lipids, in treated tobacco. These findings on theophylline application in three different model organisms offer valuable insights into the protocols for the biological and biotechnological use of this agent.