IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CYTOCHROME c AS A MITOCHONDRIAL REGULATOR OF Arabidopsis DEVELOPMENT
Autor/es:
GRAS D; CANAL, M VICTORIA; GONZALEZ DH; MANSILLA N; WELCHEN E
Reunión:
Congreso; LVI Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2020
Resumen:
Mitochondrial respiration is essential for energy production by most living organisms. Cytochrome c (CYTc) is a soluble hemeprotein of the inner mitochondrial membrane, which delivers electrons to Complex IV during the last step of aerobic cellularrespiration. In addition to their central role in ATP production, increasing evidence suggests that mitochondria also act assensing and signaling organelles, orchestrating growth and development through different regulatory pathways. We previouslyreported that Arabidopsis thaliana plants with lower CYTc levels show decreased biomass and delayed vegetative growth andthat these phenotypes are explained by alterations in carbohydrate metabolism and gibberellin homeostasis, thus linkingmitochondria with a hormonal regulatory pathway. In this work, we used different loss-of-function and overexpressor lines toexplore possible connections between CYTc and the Target of Rapamycin (TOR) pathway, involved in growth regulationaccording to energy availability. Detailed analysis of plants with decreased CYTc levels revealed phenotypic similarities withmutants affected in the TOR pathway, mainly those affected in the TOR component RAPTOR. These similarities includeddelayed germination, decreased root and hypocotyl growth, and delayed vegetative development. Increasing CYTc levels inraptor mutants partially restored germination rates and ABA responses of plants with defects in the TOR pathway. CYTc alsorestored the root growth defects of raptor mutants, including total root length and the size and number of cells in themeristematic and elongation zones. In turn, the growth of raptor hypocotyls was only rescued by overexpressing CYTc underillumination conditions, but not under darkness. On the other hand, increasing CYTc levels caused accelerated vegetativegrowth in a wild-type background but failed to modify vegetative growth in a raptor mutant background. These results suggestthat CYTc can regulate seedling growth either downstream or independently of TOR, but it requires TOR activity to affectvegetative development. This indicates the existence of complex interactions between the mitochondrial energy-producingpathway and growth regulation by the TOR complex, which may be related to the metabolic, hormonal and energyrequirements at different plant development stages