Enhancing UV-C and perchlorate resistance in Arabidopsis thaliana through the introduction of microbial genes from hypersaline environment

Ultraviolet (UV) radiation reaching the Earth's surface affects all living organisms. Recent reports show a trend of increasing exposure levels due to stratospheric ozone depletion and contamination. UV-B radiation (280–315 nm), previously largely absorbed by the ozone layer, now reaches the surface in higher doses, posing a particular threat to plants, which are sessile organisms and cannot escape adverse conditions. The intrinsic protective and repair mechanisms in plants may be insufficient to counteract this increase, potentially impacting crop productivity, distribution, and quality, with serious implications for agriculture and ecological stability. This study aims to enhance plant resistance to UV radiation by introducing genes derived from extremophilic microorganism, which have previously shown to confer UV-protective effects in UV resistance to a radiation-sensitive Escherichia coli strain ( recA mutant). Extremophile microorganisms have been discovered in high-irradiation environments, such as hypersaline lakes, where survival relies on unique genetic adaptations. In our laboratory, four genes were selected from metagenomic libraries derived from high-altitude hypersaline lakes in Argentina (Diamante and Ojo Seco, at 4,589 m and 3,200 m respectively) and from the Es Trenc salt flat (Mallorca, Spain). Based on these promising results, the genes were introduced into Arabidopsis thaliana to evaluate their potential to enhance UV-B tolerance in plants. The selected genes included one encoding a TATA-box binding protein, and three hypothetical proteins. Each gene was independently transformed into Arabidopsis thaliana lines and subjected to UV-B and UV-C irradiation (4.5 kJ·m −2 ), with UV-C (100–280 nm) ultimately chosen for its higher damaging potential to test the limits of plant tolerance. Additionally, cross-resistance was evaluated using sodium perchlorate, a common soil contaminant and oxidative stressor. Plants were exposed to concentrations between 3.67 and 7.34 g/L, exceeding those used in previous studies. As a result, the plants obtained were more resistant to UV radiation and were also capable of growing in environments containing higher levels of perchlorate in the growth medium. Thus, the expression of these genes in the plant appears to contribute to enhanced stress resistance.