UP AND DOWN, THE EFFECT OF THE OSOXR-Q12 PROTEIN ON DEVELOPMENT AND SALT STRESS RESPONSE IN RICE SEEDLINGS

BECERRA-AGUDELO, EVELYN; TORTI, PABLO; WELCHEN, ELINA

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

The OXR (OXidation Resistance) protein family was characterized by the presence of the TLDc domain in the C-terminal portion of the protein. Members of the OXR/TLDc family were firstly identified in mammals for their protective effect against oxidative stress. In Arabidopsis thaliana, we identified six members whose expression profile is differentially regulated on different plant tissues and during situations that generate oxidative stress. Arabidopsis plants overexpressing AtOXR2 show higher biomass and seed production and are more tolerant to biotic and abiotic stresses. In addition, we observed that Arabidopsis lines overexpressing the chimeric AtOXR-Q12 protein are plants with increased root and aerial development, photosynthetic efficiency, and seed production. In order to characterize the role of TLDc proteins in monocots, we obtained rice plants (Oryza sativa var. Kitaake) with high ectopic expression of this AtOXR-Q12 chimeric protein (OsOXR-Q12). The biometric parameters of 6-day-old seedlings grown on 0.5x liquid MS medium were measured. OsOXR-Q12 lines showed 150% more height in the aerial part, while the root was 160% longer than WT. Thus, OsOXR-Q12 plants produced 50% more aerial and 20% more root biomass. In addition, histological analysis of transversal root sections of 30-day-old plants grown under these conditions was performed. As we expected, due to the root diameter quantified, the OsOXR-Q12 lines showed an increase of about 50% in the number of parenchyma cells. Rice photosynthetic parameters suggest enhanced vegetative and radicle development in OsOXR-Q12 plants under normal growth conditions. We then evaluated the behaviour of these plants under salt stress imposed by the addition of 90 mM NaCl during the first six growing days. OsOXR-Q12 seedlings showed beneficial characteristics in parameters such as height and total biomass, increased by about 50% and 100%, respectively. Since the expression of the AtOXR-Q12 protein in Arabidopsis shows increased resistance to oxidative stress, we are evaluating the levels of ROS and phenolic compounds, as well as the activity of these antioxidant enzymes and stress pathway marker genes. All the results will allow us to characterize the mechanisms by which OsOXR-Q12 plants show beneficial characteristics and to find candidates for generating plants of interest and usefulness from the Agrobiotechnological view.