Fruit taste quality is greatly influenced by the content of soluble sugars,which are predominantly stored in the vacuolar lumen.However,the accumulation and regulation mechanisms of sugars in most fruits remain unclea...Fruit taste quality is greatly influenced by the content of soluble sugars,which are predominantly stored in the vacuolar lumen.However,the accumulation and regulation mechanisms of sugars in most fruits remain unclear.Recently,we established the citrus fruit vacuole proteome and discovered the major transporters localized in the vacuole membrane.Here,we demonstrated that the expression of tonoplast sugar transporter 2(CsTST2)is closely associated with sugar accumulation during sweet orange(Citrus sinensis)ripening.It was further demonstrated that CsTST2 had the function of transporting hexose and sucrose into the vacuole.Overexpression of CsTST2 resulted in an elevation of sugar content in citrus juice sac,calli,and tomato fruit,whereas the downregulation of its expression led to the reduction in sugar levels.CsTST2 was identified as interacting with CsCIPK23,which binds to the upstream calcium signal sensor protein CsCBL1.The phosphorylation of the three serine residues(Ser277,Ser337,and Ser354)in the loop region of CsTST2 by CsCIPK23 is crucial for maintaining the sugar transport activity of CsTST2.Additionally,the expression of CsCIPK23 is positively correlated with sugar content.Genetic evidence further confirmed that calcium and CsCIPK23-mediated increase in sugar accumulation depends on CsTST2 and its phosphorylation level.These findings not only unveil the functional mechanism of CsTST2 in sugar accumulation,but also explore a vital calcium signal regulation module of CsCBL1/CIPK23 for citrus sweetness quality.展开更多
Phosphorus(P)is an indispensable macronutrient required for plant growth and development.Natural phosphate(Pi)reserves are finite,and a better understanding of Pi utilization by crops is therefore vital for worldwide ...Phosphorus(P)is an indispensable macronutrient required for plant growth and development.Natural phosphate(Pi)reserves are finite,and a better understanding of Pi utilization by crops is therefore vital for worldwide food security.Ammonium has long been known to enhance Pi acquisition efficiency in agriculture;however,the molecular mechanisms coordinating Pi nutrition and ammonium remains unclear.Here,we reveal that ammonium is a novel initiator that stimulates the accumulation of a key regulatory protein,STOP1,in the nuclei of Arabidopsis root cells under Pi deficiency.We show that Pi deficiency promotes ammonium uptake mediated by AMT1 transporters and causes rapid acidification of the root surface.Rhizosphere acidification-triggered STOP1 accumulation activates the excretion of organic acids,which help to solubilize Pi from insoluble iron or calcium phosphates.Ammonium uptake by AMT1 transporters is downregulated by a CIPK23 protein kinase whose expression is directly modulated by STOP1 when ammonium reaches toxic levels.Taken together,we have identified a STOP1-centered regulatory network that links external ammonium with efficient Pi acquisition from insoluble phosphate sources.These findings provide a framework for developing possible strategies to improve crop production by enhancing the utilization of non-bioavailable nutrients in soil.展开更多
基金supported by National Key Research and Development Program of China(2023YFD2300603,2022YFF1003100)the National Natural Science Foundation of China(32322073)+2 种基金Foundation of Hubei Hongshan Laboratory(2021hszd016)Fundamental Research Funds for the Central Universities(2662023PY011)the Huazhong Agricultural University(start-up funding to C.L.)。
文摘Fruit taste quality is greatly influenced by the content of soluble sugars,which are predominantly stored in the vacuolar lumen.However,the accumulation and regulation mechanisms of sugars in most fruits remain unclear.Recently,we established the citrus fruit vacuole proteome and discovered the major transporters localized in the vacuole membrane.Here,we demonstrated that the expression of tonoplast sugar transporter 2(CsTST2)is closely associated with sugar accumulation during sweet orange(Citrus sinensis)ripening.It was further demonstrated that CsTST2 had the function of transporting hexose and sucrose into the vacuole.Overexpression of CsTST2 resulted in an elevation of sugar content in citrus juice sac,calli,and tomato fruit,whereas the downregulation of its expression led to the reduction in sugar levels.CsTST2 was identified as interacting with CsCIPK23,which binds to the upstream calcium signal sensor protein CsCBL1.The phosphorylation of the three serine residues(Ser277,Ser337,and Ser354)in the loop region of CsTST2 by CsCIPK23 is crucial for maintaining the sugar transport activity of CsTST2.Additionally,the expression of CsCIPK23 is positively correlated with sugar content.Genetic evidence further confirmed that calcium and CsCIPK23-mediated increase in sugar accumulation depends on CsTST2 and its phosphorylation level.These findings not only unveil the functional mechanism of CsTST2 in sugar accumulation,but also explore a vital calcium signal regulation module of CsCBL1/CIPK23 for citrus sweetness quality.
基金This work was supported by the Ministry of Science and Tech no logy of the People's Republic of China(2015CB942903,2016YFD0100700)the Ministry of Education and Bureau of Foreign Experts of China(B14027)the Fundamental Research Funds for the Central Universities.
文摘Phosphorus(P)is an indispensable macronutrient required for plant growth and development.Natural phosphate(Pi)reserves are finite,and a better understanding of Pi utilization by crops is therefore vital for worldwide food security.Ammonium has long been known to enhance Pi acquisition efficiency in agriculture;however,the molecular mechanisms coordinating Pi nutrition and ammonium remains unclear.Here,we reveal that ammonium is a novel initiator that stimulates the accumulation of a key regulatory protein,STOP1,in the nuclei of Arabidopsis root cells under Pi deficiency.We show that Pi deficiency promotes ammonium uptake mediated by AMT1 transporters and causes rapid acidification of the root surface.Rhizosphere acidification-triggered STOP1 accumulation activates the excretion of organic acids,which help to solubilize Pi from insoluble iron or calcium phosphates.Ammonium uptake by AMT1 transporters is downregulated by a CIPK23 protein kinase whose expression is directly modulated by STOP1 when ammonium reaches toxic levels.Taken together,we have identified a STOP1-centered regulatory network that links external ammonium with efficient Pi acquisition from insoluble phosphate sources.These findings provide a framework for developing possible strategies to improve crop production by enhancing the utilization of non-bioavailable nutrients in soil.
