AtOXR2: a new mitochondrial protein connected with hormonal control of plant defense and development.

COLOMBATTI F; CECCOLI G; WELCHEN E; MENCIA R; GONZALEZ DH

Congreso; International Conference Plant Mitochondrial Biology (ICPMB); 2017

Among the efforts to elucidate the defense lines established by the cell to counteract the oxidative damage caused by an excessive ROS production under stress situations, a new family of eukaryotic proteins called OXR (Oxidation Resistance) was identified. The most highly conserved region of OXR proteins is the carboxyl-terminal half, which contains a TLDc (TBC, LysM, Domain catalytic) domain. Although the structure-function connection is unknown, the TLDc domain was implicated in the prevention of oxidative DNA damage. Heretofore, it was shown that disruption in TLDc-containing genes originates a reduction in lifespan in mice, Drosophila, C. elegans and Anopheles, or causes severe neurological disorders in humans. Moreover, mouse OXR1 was proposed as a neuroprotective factor in neurodegenerative disorders by, at least in part, regulating mitochondrial morphology. We analyzed the existence of OXR family members in plants and identified five members in Arabidopsis thaliana. In order to elucidate the role of this family in plants, we studied one of the family members, AtOXR2. AtOXR2 is a mitochondrial protein and the corresponding gene is induced by heat, high light intensity, UV-B and pathogen treatments. Induction was also observed after treatments with salicylic acid (SA) and 3-aminotriazol. Overexpression of AtOXR2 in plants causes an increase in biomass, seed production and photosynthetic performance and a delay in senescence compared to wild type. Plants with modified levels of AtOXR2 show differential responses to hemibiotrophic pathogens and altered levels of SA, cytokinins and abscisic acid. AtOXR2 constitutes a new example of a mitochondrial protein able to influence hormone homeostasis, growth and stress responses.