Contributors: State Key Laboratory of Soil and Sustainable Agriculture; Institute of Soil Science; Chinese Academy of Sciences Beijing (CAS)-Chinese Academy of Sciences Beijing (CAS); Institut des Sciences des Plantes de Montpellier (IPSIM); Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Montpellier; Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université de Montpellier (UM); Shandong Agricultural University (SDAU); Shandong Institute of Sericulture; National Key Laboratory of Crop Genetic Improvement China; Huazhong Agricultural University Wuhan (HZAU); Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP); Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro Montpellier; Département Systèmes Biologiques (Cirad-BIOS); Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad); University of Chinese Academy of Sciences Beijing (UCAS); Chinese Academy of Sciences Beijing (CAS); Jiangsu Academy of Agricultural Sciences; This work was supported by the National Natural Science Foundation of China (31672230), an ANR-DFG grant (ANR-20-CE92-0005 to A.-A.V.), a doctoral fellowship from the French Embassy in Vietnam (to T.H.N.), an ANR IA Grant (ANR-11-RSNR-0005 to E.G. and H.S.), and the Innovation Programs of the Institute of Soil Science (ISSASIP2201 and ISSAS2423).; ANR-20-CE92-0005,RiceKTrans,Rôle du transport du potassium dans l'obtention de rendements élevés chez le riz(2020); ANR-11-RSNR-0005,DEMETERRES,Développement de Méthodes bio-et Eco-Technologiques pour la Remédiation Raisonnée des Effluents et des Sols en appui à une stratégie de réhabilitation agricole post-accidentelle(2011)
نبذة مختصرة : International audience ; Significance: K+ transport from root to shoot is a critical process for sustaining physiological functions in aerial organs. We report here a short inward channel OsKAT1, localized in the root stele of rice, which contributes to root–shoot K+ translocation. Functional comparison between OsKAT1 and its C-terminal extended chimera OsKAT1-C1 in both Xenopus oocytes and Arabidopsis roots demonstrates that the short channel OsKAT1 mediates more efficient K+ transport than the chimera carrying a canonical C terminus. Under field conditions, OsKAT1 activity shows significant contributions to K+ accumulation in shoots and grain yield of rice, highlighting its agronomic importance.Abstract: Shaker potassium channels play essential roles in K+ uptake and distribution in plants. Studies on Shaker channels in Arabidopsis have provided a paradigmatic framework, but the rice genome encodes an additional member, OsKAT1, whose function remained poorly defined. OsKAT1-type channels are characterized by an innately short cytosolic C terminus, forming a unique clade of monocot-specific short Shakers that is prevalent in Poaceae species. In rice, OsKAT1 is predominantly expressed in the root stele. Disruption of OsKAT1 (KO mutation) leads to a significant reduction in K+ secretion into the xylem sap delivered to the shoot. Patch-clamp experiments on root stele protoplasts of WT and KO plants indicate that OsKAT1 functions as an inward channel. Functional analyses in Xenopus oocytes reveal that despite activating at weakly negative voltages, OsKAT1 is intrinsically incapable of mediating substantial outward currents—a property attributed to its truncated C terminus. Together with outward K+ channel activity, this feature enables stelar cells to remain significantly permeable to K+ around the K+ equilibrium potential. When expressed in Arabidopsis, OsKAT1 contributes to K+ transport in the xylem sap, but only in wild-type plants that express SKOR, a Shaker channel specialized for this role. These results ...
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