Phosphate (Pi) remobilization in plants is critical to continuous growth and development. AtATL80 is a plasma membrane (PM)-localized RING E3 ubiquitin (Ub) ligase that belongs to the Arabidopsis Toxicos en Levadura (ATL) family. AtATL80 was upregulated by long-term low Pi (0-0.02 mM KH2PO4) conditions in Arabidopsis seedlings. AtATL80-overexpressing transgenic Arabidopsis plants (35S:AtATL80-sGFP) displayed increased phosphorus (P) accumulation in the shoots and lower biomass, as well as reduced Putilization efficiency (PUE) under high Pi (1 mM KH2PO4) conditions compared to wild-type plants. The loss-of-function atatl80 mutant line exhibited opposite phenotypic traits. The atatl80 mutant line bolted earlier than wild-type plants, whereas AtATL80-overexpressors bloomed significantly later and produced lower seed yields than wild-type plants under high Pi conditions. Thus, AtATL80 is negatively correlated not only with P content and PUE, but also with biomass and seed yield in Arabidopsis. In addition, AtATL80-overexpressors were significantly more sensitive to cold stress than wild-type plants, while the atatl80 mutant line exhibited an increased tolerance to cold stress. Taken together, our results suggest that AtATL80, a PM-localized ATL-type RING E3 Ub ligase, participates in the Pi mobilization and cold stress response as a negative factor in Arabidopsis. (C) 2015 Elsevier Inc. All rights reserved.