Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioen...Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for chan- nels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple stra- tegies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.展开更多
Potassium(K)is a major essential element in plant cells,and KUP/HAK/KT-type K+transporters participate in the absorption of K+into roots and in the long-distance transport to above-ground parts.In Arabidopsis thaliana...Potassium(K)is a major essential element in plant cells,and KUP/HAK/KT-type K+transporters participate in the absorption of K+into roots and in the long-distance transport to above-ground parts.In Arabidopsis thaliana,KUP9 is involved in the transport of K+and Cs+in roots.In this study,we investigated KUP9 function in relation to the K+status of the plant.The expression of KUP9 was upregulated in older leaves on K+-depleted medium,compared to the expression of the other 12 KUP genes in the KUP/HAK/KT family in Arabidopsis.When grown on low K+medium,the kup9 mutant had reduced chlorophyll content in seedlings and chlorosis in older rosette leaves.Tissue-specific expression of KUP9 determined by KUP9 promoter:GUS assay depended on the K+status of the plants:In K+sufficient medium,KUP9 was expressed in the leaf blade towards the leaf tip,whereas in K+depleted medium expression was mainly found in the petioles.In accordance with this,K+accumulated in the roots of kup9 plants.The short-term 43K+tracer measurement showed that 43K was transferred at a lower rate in roots and shoots of kup9,compared to the wild type.These data show that KUP9 participates in the distribution of K+in leaves and K+absorption in roots under low K+conditions.展开更多
基金partially supported by Grants-in-Aid for Scientific Research from the Ministry of Education,Culture,Sports,Science,and Technology(18H03762 and 21H04543 to Fumihito Arai and Nobuyuki Uozumi)。
文摘Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for chan- nels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple stra- tegies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.
基金supported by Grants-in-Aid for Scientific Research from the Ministry of Education,Culture,Sports,Science and Technology(20KK0127 and 21 K19060 to NU,21H0526621KK0268 and 22K19121 to YI and 20 K15447 to SS,respectively)Moonshot R&D(JPMJMS2033)from JST to NU.
文摘Potassium(K)is a major essential element in plant cells,and KUP/HAK/KT-type K+transporters participate in the absorption of K+into roots and in the long-distance transport to above-ground parts.In Arabidopsis thaliana,KUP9 is involved in the transport of K+and Cs+in roots.In this study,we investigated KUP9 function in relation to the K+status of the plant.The expression of KUP9 was upregulated in older leaves on K+-depleted medium,compared to the expression of the other 12 KUP genes in the KUP/HAK/KT family in Arabidopsis.When grown on low K+medium,the kup9 mutant had reduced chlorophyll content in seedlings and chlorosis in older rosette leaves.Tissue-specific expression of KUP9 determined by KUP9 promoter:GUS assay depended on the K+status of the plants:In K+sufficient medium,KUP9 was expressed in the leaf blade towards the leaf tip,whereas in K+depleted medium expression was mainly found in the petioles.In accordance with this,K+accumulated in the roots of kup9 plants.The short-term 43K+tracer measurement showed that 43K was transferred at a lower rate in roots and shoots of kup9,compared to the wild type.These data show that KUP9 participates in the distribution of K+in leaves and K+absorption in roots under low K+conditions.
