Attention is given to the role of Ca^2＋ at the interface between the cell wall and the cytoplast, especially as seen in pollen tubes. While the cytoplasm directs the synthesis and deposition of the wall, it is less w...Attention is given to the role of Ca^2＋ at the interface between the cell wall and the cytoplast, especially as seen in pollen tubes. While the cytoplasm directs the synthesis and deposition of the wall, it is less well appreciated that the wall exerts considerable self control and influences activities of the cytoplasm. Ca^2＋ participates as a crucial factor in this two way communication. In the cytoplasm, a [Ca^2＋] above 0.1 μM, regulates myriad processes, including secretion of cell wall components. In the cell wall Ca^2＋ , at 10μM to 10 mM, binds negative charges on pectins and imparts structural rigidity to the wall. The plasma membrane occupies a pivotal position between these two compartments, where selective channels regulate influx of Ca^2＋ , and specific carriers pump the ion back into the wall. In addition we draw attention to different factors, which either respond to the wall or are present in the wall, and usually generate elevated[Ca^2＋ ] in the cytoplasm. These factors include： （i） stretch activated channels; （ii） calmodulin; （iii） annexins; （iv） wall associated kinases; （v） oligogalacturonides; and （vi） extracellular adenosine 5＇-triphosphate. Together they provide evidence for a rich and multifaceted system of communication between the cytoplast and cell wall, with Ca^2＋ as a carrier of information.展开更多
Since the first plant cyclic nucleotide-gated ion channel （CNGC）, HvCBT1, was identified as a calmodulin bind- ing protein, more than a decade has passed and a substantial amount of work has been done to understand ...Since the first plant cyclic nucleotide-gated ion channel （CNGC）, HvCBT1, was identified as a calmodulin bind- ing protein, more than a decade has passed and a substantial amount of work has been done to understand the molecular nature and function of these channel proteins. Based on electrophysiological and heterologous expression analyses, plant CNGCs function as non-selective cation channels and, so far, their biological roles have been reported in defense responses, development, and ion homeostasis. Forward genetic approaches identified four AtCNGCs （AtCNGC2, 4, 11, and 12） to be involved in plant immunity, as null mutants for AtCNGC2, 4, 11, and 12 as well as a gain-of- function mutant for AtCNGC11 and 12 exhibited alterations in defense responses. Since ion flux changes have been reported as one of the early events upon pathogen recognition and also are an essential component for the activation of defense responses, the involvement of CNGCs in these ion flux changes has been suggested. However, the recent detailed characterization of null mutants suggested a more complex involvement of this channel family. In this review, we focus on the discoveries and character- ization of these CNGC mutants and discuss possible roles of CNGCs as components in plant immunity.展开更多
The genetic identities of Ca2+ channels in root hair (RH) tips essential for constitutive RH growth have remained elusive for decades. Here, we report the identification and characterization of three cyclicnucleotide-...The genetic identities of Ca2+ channels in root hair (RH) tips essential for constitutive RH growth have remained elusive for decades. Here, we report the identification and characterization of three cyclicnucleotide-gated channel (CNGC) family members, CNGC5, CNGC6, and CNGC9, as Ca2+ channels essential for constitutive RH growth in Arabidopsis. We found that the cngc5-1cngc6-2cngc9-1 triple mutant(designated shrh1) showed significantly shorter and branching RH phenotypes as compared with thewild type. The defective RH growth phenotype of shrh1 could be rescued by either the expression ofCNGC5, CNGC6, or CNGC9 single gene or by the supply of high external Ca2+, but could not be rescuedby external K+ supply. Cytosolic Ca2+ imaging and patch-clamp data in HEK293T cells showed that thesethree CNGCs all function as Ca2+-permeable channels. Cytosolic Ca2+ imaging in growing RHs furthershowed that the Ca2+ gradients and their oscillation in RH tips were dramatically attenuated in shrh1compared with those in the wild type. Phenotypic analysis revealed that these three CNGCs are Ca2+ channels essential for constitutive RH growth, with different roles in RHs from the conditional player CNGC14.Moreover, we found that these three CNGCs are involved in auxin signaling in RHs. Taken together, ourstudy identified CNGC5, CNGC6, and CNGC9 as three key Ca2+ channels essential for constitutive RHgrowth and auxin signaling in Arabidopsis.展开更多
环核苷酸门控离子通道(Cyclic nucleotide-gated ion channels,CNGC)是非选择性的阳离子通道,受细胞内信使小分子环核苷酸(cAMP和cGMP)以及Ca^(2+)/CaM调控。哺乳动物CNGC功能的变构调节机制受到CaM结合影响,哺乳动物CNGC在胞质N和/或C...环核苷酸门控离子通道(Cyclic nucleotide-gated ion channels,CNGC)是非选择性的阳离子通道,受细胞内信使小分子环核苷酸(cAMP和cGMP)以及Ca^(2+)/CaM调控。哺乳动物CNGC功能的变构调节机制受到CaM结合影响,哺乳动物CNGC在胞质N和/或C末端具有CaMBD。在植物方面,研究大多集中于与植物CNGC的环核苷酸结合结构域重叠的C端CaM结合结构域(CaMBD)。然而近期对模式植物拟南芥CNGC12的研究提供了单个植物CNGC同种型具有多个CaMBD的证据。重点总结了动植物钙调蛋白多个结合位点调控环核苷酸门控离子通道的研究进展。展开更多
基金supported by a grant from the USA National Science Foundation (MCB-0846876)
文摘Attention is given to the role of Ca^2＋ at the interface between the cell wall and the cytoplast, especially as seen in pollen tubes. While the cytoplasm directs the synthesis and deposition of the wall, it is less well appreciated that the wall exerts considerable self control and influences activities of the cytoplasm. Ca^2＋ participates as a crucial factor in this two way communication. In the cytoplasm, a [Ca^2＋] above 0.1 μM, regulates myriad processes, including secretion of cell wall components. In the cell wall Ca^2＋ , at 10μM to 10 mM, binds negative charges on pectins and imparts structural rigidity to the wall. The plasma membrane occupies a pivotal position between these two compartments, where selective channels regulate influx of Ca^2＋ , and specific carriers pump the ion back into the wall. In addition we draw attention to different factors, which either respond to the wall or are present in the wall, and usually generate elevated[Ca^2＋ ] in the cytoplasm. These factors include： （i） stretch activated channels; （ii） calmodulin; （iii） annexins; （iv） wall associated kinases; （v） oligogalacturonides; and （vi） extracellular adenosine 5＇-triphosphate. Together they provide evidence for a rich and multifaceted system of communication between the cytoplast and cell wall, with Ca^2＋ as a carrier of information.
文摘Since the first plant cyclic nucleotide-gated ion channel （CNGC）, HvCBT1, was identified as a calmodulin bind- ing protein, more than a decade has passed and a substantial amount of work has been done to understand the molecular nature and function of these channel proteins. Based on electrophysiological and heterologous expression analyses, plant CNGCs function as non-selective cation channels and, so far, their biological roles have been reported in defense responses, development, and ion homeostasis. Forward genetic approaches identified four AtCNGCs （AtCNGC2, 4, 11, and 12） to be involved in plant immunity, as null mutants for AtCNGC2, 4, 11, and 12 as well as a gain-of- function mutant for AtCNGC11 and 12 exhibited alterations in defense responses. Since ion flux changes have been reported as one of the early events upon pathogen recognition and also are an essential component for the activation of defense responses, the involvement of CNGCs in these ion flux changes has been suggested. However, the recent detailed characterization of null mutants suggested a more complex involvement of this channel family. In this review, we focus on the discoveries and character- ization of these CNGC mutants and discuss possible roles of CNGCs as components in plant immunity.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB27020102)the National Natural Science Foundation of China(91635301,31570262,and 31770292).
文摘The genetic identities of Ca2+ channels in root hair (RH) tips essential for constitutive RH growth have remained elusive for decades. Here, we report the identification and characterization of three cyclicnucleotide-gated channel (CNGC) family members, CNGC5, CNGC6, and CNGC9, as Ca2+ channels essential for constitutive RH growth in Arabidopsis. We found that the cngc5-1cngc6-2cngc9-1 triple mutant(designated shrh1) showed significantly shorter and branching RH phenotypes as compared with thewild type. The defective RH growth phenotype of shrh1 could be rescued by either the expression ofCNGC5, CNGC6, or CNGC9 single gene or by the supply of high external Ca2+, but could not be rescuedby external K+ supply. Cytosolic Ca2+ imaging and patch-clamp data in HEK293T cells showed that thesethree CNGCs all function as Ca2+-permeable channels. Cytosolic Ca2+ imaging in growing RHs furthershowed that the Ca2+ gradients and their oscillation in RH tips were dramatically attenuated in shrh1compared with those in the wild type. Phenotypic analysis revealed that these three CNGCs are Ca2+ channels essential for constitutive RH growth, with different roles in RHs from the conditional player CNGC14.Moreover, we found that these three CNGCs are involved in auxin signaling in RHs. Taken together, ourstudy identified CNGC5, CNGC6, and CNGC9 as three key Ca2+ channels essential for constitutive RHgrowth and auxin signaling in Arabidopsis.
文摘环核苷酸门控离子通道(Cyclic nucleotide-gated ion channels,CNGC)是非选择性的阳离子通道,受细胞内信使小分子环核苷酸(cAMP和cGMP)以及Ca^(2+)/CaM调控。哺乳动物CNGC功能的变构调节机制受到CaM结合影响,哺乳动物CNGC在胞质N和/或C末端具有CaMBD。在植物方面,研究大多集中于与植物CNGC的环核苷酸结合结构域重叠的C端CaM结合结构域(CaMBD)。然而近期对模式植物拟南芥CNGC12的研究提供了单个植物CNGC同种型具有多个CaMBD的证据。重点总结了动植物钙调蛋白多个结合位点调控环核苷酸门控离子通道的研究进展。
