Improved resistance to UV radiation resistance of Arabidopsis thaliana by expressing genes isolated from hyperhalophilic microorganisms
Sara Gómez De Frutos  1, *@  , Carolina González De Figueras  1@  , María Lamprecht-Grandío  1@  , José Eduardo González-Pastor  1@  
1 : Centro de Astrobiología
* : Corresponding author

Ultraviolet (UV) radiation is an important natural component of solar radiation that influence on organism functions and ecosystem interactions. However, the flux of UV radiation is substantially higher and different in extraterrestrial environments compared from those experienced on Earth. Terrestrial organisms such as plants have not the skills to deal with that levels of UV radiation thus, to survive outside the biosphere, they must be protected by exterior shielding or increasing its inherent resistance.

Therefore, the main goal is to generate plants which are more capable of surviving in space conditions by improving its resistance to UV radiation. In a previous work of our laboratory, five genes involved in resistance to UV radiation were isolated by a functional metagenomics approach of microorganisms from hypersaline environments that are highly exposed to high doses of UV-B radiation: hypersaline lakes of the Andean highlands (4.300 m altitude, Argentina) and Es Trenc salterns (Spain). In addition, all these genes were also resistant to 4-nitroquinoline 1-oxide (4-NQO), a compound that mimics the DNA damage effect produced by UV-B radiation, so it was concluded that they could play a role in the repair of DNA damage. Those genes were introduced in the genomes of different plants: a putative endonuclease (pML84-orf1), a putative ribonuclease III (pML56-orf1), a transcription factor (pML56-orf2), and conserved hypothetical proteins (pML6-orf1 and pML105-orf1). Afterwards, all the genes were cloned in the plasmid pCAMBIA 3500 (from Carlos Alonso, CNB), then the recombinant plasmids were used to transform Agrobacterium tumefaciens, and the plants were infected with these bacteria (floral dipping) to transfer the UV resistant genes to the genome of Arabidopsis thaliana ecotype Columbia-0. Several independent transgenic lines were obtained for each construction, and the third generation of plants expressing the pML84-orf1 and pML6-orf1 were tested for resistance to UV and 4-NQO. Results indicate that both constructions improve their resistance to UV radiation, although only pML84-orf1 exhibited more resistance to 4-NQO. Further analysis are being made for the remaining transgenic plants lines. Plants with enhance UV resistance could be used for Life Support Systems in extraterrestrial environments.

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