Data Sheet 1_Enhancing UV-C and perchlorate resistance in Arabidopsis thaliana through the introduction of microbial genes from hypersaline environment.pdf

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.

抵达地球表面的紫外线（UV, Ultraviolet）辐射会对所有生物体造成影响。近期研究显示，受平流层臭氧耗竭与环境污染影响，紫外线暴露水平呈上升趋势。此前大部分可被臭氧层吸收的UV-B辐射（280–315 nm），如今以更高剂量抵达地表，对固着且无法逃避不良环境的植物构成了特殊威胁。植物自身的保护与修复机制或许不足以应对这种辐射水平的提升，可能会对作物产量、分布与品质造成影响，进而对农业生产与生态稳定性产生严重危害。本研究旨在通过引入源自嗜极微生物（extremophilic microorganism）的基因，提升植物对紫外线辐射的抗性——此前已有研究表明，这类基因可在对辐射敏感的大肠杆菌recA突变体（recA mutant）中赋予紫外线防护效果。嗜极微生物多生存于高辐射环境中，例如高盐湖，其存活依赖独特的遗传适应性。在本实验室中，研究人员从阿根廷海拔4589米的迪亚曼特湖与3200米的奥霍塞科湖，以及西班牙马略卡岛埃特伦奇盐滩的宏基因组文库（metagenomic libraries）中，筛选出了4个基因。基于上述颇具前景的实验结果，研究人员将这些基因导入拟南芥（Arabidopsis thaliana）中，以评估其提升植物UV-B耐受性的潜力。筛选得到的基因包括1个编码TATA盒结合蛋白（TATA-box binding protein）的基因，以及3个假定蛋白（hypothetical proteins）。每个基因均被独立转化至拟南芥株系中，并分别接受UV-B与UV-C辐射（4.5 kJ·m⁻²）处理；最终选择UV-C（100–280 nm）开展实验，因其具备更强的损伤潜力，可用于测试植物的耐受极限。此外，本研究还使用高氯酸钠（sodium perchlorate）——一种常见的土壤污染物与氧化应激源（oxidative stressor）——评估了交叉抗性。实验中将植物暴露于3.67~7.34 g/L的浓度区间内，该浓度高于此前研究中使用的剂量。实验结果显示，所得转基因植株对紫外线辐射具有更强的抗性，同时也能够在生长培养基含更高浓度高氯酸盐的环境中存活生长。由此可见，这些基因在植物中的表达，有助于提升植株的逆境抗性。