OXR2 PROTEINS FROM Arabidopsis AND SUNFLOWER MODIFY ROOT ARCHITECTURE AND CONFER TOLERANCE TO UV-B DAMAGE IN Arabidopsis

MENCIA R; WELCHEN E; TORTI P

Congreso; LVI Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2020

Oxidation resistance (OXR) proteins are members of a protein family present in Eukaryotic organisms. Whilst the mechanismof their actions is unknown, OXR proteins are involved in alleviating stress, ageing, inflammatory responses, and DNA damagein mammals. We previously demonstrated that increased expression of OXR2 gene from Arabidopsis (AtOXR2) or theirsunflower homologous (HaOXR2) conferring tolerance to oxidative stress in Arabidopsis and maize. Arabidopsis plantsoverexpressing AtOXR2 or HaOXR2 (OE plants) showed alteration in the plant root system architecture (RSA), having shortermain root in comparison to Wild type (WT) plants. OE Arabidopsis plants exhibit smaller meristematic (MZ), transition (TZ)and differentiation (DZ) zone with fewer cells than WT plants. Mature-elongated root cells are also shorter. Lateral root (LR)initiation and emergence are important aspects of governing RSA. Arabidopsis AtOXR2 and HaOXR2 OE plants have anincreased number of LR in comparison to WT plants. It is known that H2O2 regulates auxins accumulation and redistribution,thus leading to changes in the RSA in Arabidopsis. In this sense, AtOXR2 and HaOXR2 plants produce higher levels of H2O2in roots and have increased tolerance to methyl viologen (MV) exposure, showing less affected and improved root developmentunder these grown conditions. Previous studies showed that human Oxr1 protein protects nuclear and mitochondrial DNAfrom oxidative damage. We explored if the same characteristics could be extended to OXR2 proteins in plants. We observedthat AtOXR2transcript levels increased after UV-B exposure. Moreover, Arabidopsis AtOXR2 and HaOXR2 rosette diameterand leaf area were not affected after repeated plant exposition to UV-B treatment. We also evaluated the effect of UV-B on theprimary root development and demonstrated that AtOXR2 and HaOXR2 plants were less affected in the root growth parameterscompared to WT plants, showing reduced levels of dead cells per root. In sum, our results suggest the presence of a protectiverole performed by the OXR2 plant proteins against DNA damage, exerting some positive effect, possibly regulating the cellularredox balance.