Plasma membrane-associated abscisic acid(ABA)signal transduction is an integral part of ABA signaling.The C2-domain ABA-related(CAR)proteins play important roles in the recruitment of ABA receptors to the plasma membr...Plasma membrane-associated abscisic acid(ABA)signal transduction is an integral part of ABA signaling.The C2-domain ABA-related(CAR)proteins play important roles in the recruitment of ABA receptors to the plasma membrane to facilitate ABA signaling.However,how CAR proteins are regulated remains unclear.In this study,we conducted a genetic screen for mutants with altered leaf transpiration and identified an uncharacterized protein,LOWER TEMPERATURE 1(LOT1),which regulates the dynamic localization and stability of CAR proteins.The lotimutant had a lower leaf temperature as compared with the wild type due to higher transpiration.We found that LOT1 physically interacts with CAR9,and ABA reduces LOT1-CAR9 interaction in the nucleus,likely via Ca^2+,resulting in increased localization of CAR9 to the plasma membrane.We further found that the stability of CAR9 is affected by LOT1 less CAR9 proteins were accumulated and more were ubiquitinated in lot1.While the lot1 car9 and/of f car9 mutants were hyposerisitive to ABA,the hyposensitive phenotype of loticould be rescued by CAR9 overexpression.Collectively,our study reveals that LOT1 regulates plant tolerance to drought stress by affecting ABA signaling through regulating the stability and dynamic localization of CAR9.展开更多
文摘Plasma membrane-associated abscisic acid(ABA)signal transduction is an integral part of ABA signaling.The C2-domain ABA-related(CAR)proteins play important roles in the recruitment of ABA receptors to the plasma membrane to facilitate ABA signaling.However,how CAR proteins are regulated remains unclear.In this study,we conducted a genetic screen for mutants with altered leaf transpiration and identified an uncharacterized protein,LOWER TEMPERATURE 1(LOT1),which regulates the dynamic localization and stability of CAR proteins.The lotimutant had a lower leaf temperature as compared with the wild type due to higher transpiration.We found that LOT1 physically interacts with CAR9,and ABA reduces LOT1-CAR9 interaction in the nucleus,likely via Ca^2+,resulting in increased localization of CAR9 to the plasma membrane.We further found that the stability of CAR9 is affected by LOT1 less CAR9 proteins were accumulated and more were ubiquitinated in lot1.While the lot1 car9 and/of f car9 mutants were hyposerisitive to ABA,the hyposensitive phenotype of loticould be rescued by CAR9 overexpression.Collectively,our study reveals that LOT1 regulates plant tolerance to drought stress by affecting ABA signaling through regulating the stability and dynamic localization of CAR9.
