The chloroplast is a critical battleground in the arms race between plants and pathogens.Among microbe-secreted mycotoxins,tenuazonic acid(TeA),produced by the genus Alternaria and other phytopathogenic fungi,inhibits...The chloroplast is a critical battleground in the arms race between plants and pathogens.Among microbe-secreted mycotoxins,tenuazonic acid(TeA),produced by the genus Alternaria and other phytopathogenic fungi,inhibits photosynthesis,leading to a burst of photosynthetic singlet oxygen(1O2)that is implicated in damage and chloroplast-to-nucleus retrograde signaling.Despite the signicant crop damage caused by Alternaria pathogens,our understanding of the molecular mechanism by which TeA promotes pathoge-nicity and cognate plant defense responses remains fragmentary.We now reveal that A.alternata induces necrotrophic foliar lesions by harnessing EXECUTER1(EX1)/EX2-mediated chloroplast-to-nucleus retro-grade signaling activated by TeA toxin–derived photosynthetic 1O2 in Arabidopsis thaliana.Mutation of the 1O2-sensitive EX1-W643 residue or complete deletion of the EX1 singlet oxygen sensor domain compro-mises expression of 1O2-responsive nuclear genes and foliar lesions.We also found that TeA toxin rapidly induces nuclear genes implicated in jasmonic acid(JA)synthesis and signaling,and EX1-mediated retro-grade signaling appears to be critical for establishing a signaling cascade from 1O2 to JA.The present study sheds new light on the foliar pathogenicity of A.alternata,during which EX1-dependent 1O2 signaling in-duces JA-dependent foliar cell death.展开更多
Chloroplasts overproduce reactive oxygen species(ROS)under unfavorable environmental conditions,and these ROS are implicated in both signaling and oxidative damage.There is mounting evidence for their roles in transla...Chloroplasts overproduce reactive oxygen species(ROS)under unfavorable environmental conditions,and these ROS are implicated in both signaling and oxidative damage.There is mounting evidence for their roles in translating environmental fluctuations into distinct physiological responses,but their targets,signaling cascades,and mutualism and antagonism with other stress signaling cascades and within ROS signaling remain poorly understood.Great efforts made in recent years have shed new light on chloroplast ROS-directed plant stress responses,from ROS perception to plant responses,in conditional mutants of Arabidopsis thaliana or under various stress conditions.Some articles have also reported the mechanisms underlying the complexity of ROS signaling pathways,with an emphasis on spatiotemporal regulation.ROS and oxidative modification of affected target proteins appear to induce retrograde signaling pathways to maintain chloroplast protein quality control and signaling at a whole-cell level using stress hormones.This review focuses on these seemingly interconnected chloroplast-to-nucleus retrograde signaling pathways initiated by ROS and ROS-modified target molecules.We also discuss future directions in chloroplast stress research to pave the way for discovering new signaling molecules and identifying intersectional signaling components that interact in multiple chloroplast signaling pathways.展开更多
Carbon materials are widely used for supercapacitor applications thanks to their high surface area, good rate capability, and excellent cycling stability. However, the development of high energy density carbon superca...Carbon materials are widely used for supercapacitor applications thanks to their high surface area, good rate capability, and excellent cycling stability. However, the development of high energy density carbon supercapacitors still remains a challenge. In this work, hollow Co3O4 nanoboxes have been embedded into three-dimensional macroporous laser-scribed graphene （LSG） to produce composite electrodes with improved electrochemical performance. Here, Co3O4 provides high capacity through fast and reversible redox reactions, while LSG serves as a conductive network to maintain high power. The open nanobox morphology is a unique solution for extracting the maximum capacity from Co3O4, resulting in electrodes whose surfaces, both internal and external, are accessible to the electrolyte. The electrochemical performance of the composite material is promising with a volumetric capacity of 60.0 C/cm^3 and a specific capacity of 542.3 C/g, corresponding to 682.0 C/g of the constituent Co3O4. With a low equivalent series resistance of 0.9 Ω, the Co3O4/LSG electrode is able to maintain 113.1% of its original capacity after 10,000 cycles. This work provides new insights into the design of high-performance carbon/metal oxide nano- composites for next-generation energy storage devices.展开更多
Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(...Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(1)O_(2))sensor,undergoes tryptophan(Trp)643 oxidation by^(1)O_(2),a chloroplast-derived and light-dependent reactive oxygen species.The indole side chain of Trp is vulnerable to^(1)O_(2),leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease.The perception of^(1)O_(2)via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling.In this study,we discovered that the EX1-like protein EX2 also undergoes^(1)O_(2)-dependent Trp530 oxidation and FtsH-dependent turnover,which attenuates^(1)O_(2)signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation.Consistent with this finding,the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis,whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of-function mutants of EX2.Intriguingly,phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward^(1)O_(2).Collectively,these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own^(1)O_(2)-dependent oxidation,providing a new mechanistic insight into the regulation of EX1-mediated^(1)O_(2)signaling.展开更多
基金funded by the National Key R&D Program (2021YFD1700100,2017YFD0201304)the Jiangsu Agricultural Science and Technology Innovation Fund (CX (21)3093)to S.C.+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB27040102)the National Natural Science Foundation of China (NSFC) (31871397)to C.K.
文摘The chloroplast is a critical battleground in the arms race between plants and pathogens.Among microbe-secreted mycotoxins,tenuazonic acid(TeA),produced by the genus Alternaria and other phytopathogenic fungi,inhibits photosynthesis,leading to a burst of photosynthetic singlet oxygen(1O2)that is implicated in damage and chloroplast-to-nucleus retrograde signaling.Despite the signicant crop damage caused by Alternaria pathogens,our understanding of the molecular mechanism by which TeA promotes pathoge-nicity and cognate plant defense responses remains fragmentary.We now reveal that A.alternata induces necrotrophic foliar lesions by harnessing EXECUTER1(EX1)/EX2-mediated chloroplast-to-nucleus retro-grade signaling activated by TeA toxin–derived photosynthetic 1O2 in Arabidopsis thaliana.Mutation of the 1O2-sensitive EX1-W643 residue or complete deletion of the EX1 singlet oxygen sensor domain compro-mises expression of 1O2-responsive nuclear genes and foliar lesions.We also found that TeA toxin rapidly induces nuclear genes implicated in jasmonic acid(JA)synthesis and signaling,and EX1-mediated retro-grade signaling appears to be critical for establishing a signaling cascade from 1O2 to JA.The present study sheds new light on the foliar pathogenicity of A.alternata,during which EX1-dependent 1O2 signaling in-duces JA-dependent foliar cell death.
基金Research in the Kim laboratory has been supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant XDB27040102)the 100-Talent Program of the Chinese Academy of Sciences,and the National Natural Science Foundation of China(grant 31871397 to C.K.).
文摘Chloroplasts overproduce reactive oxygen species(ROS)under unfavorable environmental conditions,and these ROS are implicated in both signaling and oxidative damage.There is mounting evidence for their roles in translating environmental fluctuations into distinct physiological responses,but their targets,signaling cascades,and mutualism and antagonism with other stress signaling cascades and within ROS signaling remain poorly understood.Great efforts made in recent years have shed new light on chloroplast ROS-directed plant stress responses,from ROS perception to plant responses,in conditional mutants of Arabidopsis thaliana or under various stress conditions.Some articles have also reported the mechanisms underlying the complexity of ROS signaling pathways,with an emphasis on spatiotemporal regulation.ROS and oxidative modification of affected target proteins appear to induce retrograde signaling pathways to maintain chloroplast protein quality control and signaling at a whole-cell level using stress hormones.This review focuses on these seemingly interconnected chloroplast-to-nucleus retrograde signaling pathways initiated by ROS and ROS-modified target molecules.We also discuss future directions in chloroplast stress research to pave the way for discovering new signaling molecules and identifying intersectional signaling components that interact in multiple chloroplast signaling pathways.
文摘Carbon materials are widely used for supercapacitor applications thanks to their high surface area, good rate capability, and excellent cycling stability. However, the development of high energy density carbon supercapacitors still remains a challenge. In this work, hollow Co3O4 nanoboxes have been embedded into three-dimensional macroporous laser-scribed graphene （LSG） to produce composite electrodes with improved electrochemical performance. Here, Co3O4 provides high capacity through fast and reversible redox reactions, while LSG serves as a conductive network to maintain high power. The open nanobox morphology is a unique solution for extracting the maximum capacity from Co3O4, resulting in electrodes whose surfaces, both internal and external, are accessible to the electrolyte. The electrochemical performance of the composite material is promising with a volumetric capacity of 60.0 C/cm^3 and a specific capacity of 542.3 C/g, corresponding to 682.0 C/g of the constituent Co3O4. With a low equivalent series resistance of 0.9 Ω, the Co3O4/LSG electrode is able to maintain 113.1% of its original capacity after 10,000 cycles. This work provides new insights into the design of high-performance carbon/metal oxide nano- composites for next-generation energy storage devices.
基金This research was supported by the Strategic Priority Research Program from the Chinese Academy of Sciences(grant no.XDB27040102)the 100-Talent Program of the Chinese Academy of Sciences and the National Natural Science Foundation of China(NSFC)(grant no.31871397)to C.K.Support from a President's International Fellowship Initiative(PIFI)postdoctoral fellowship from the Chinese Academy of Sciences(no.2019PB0066)to V.D.is also acknowledged.
文摘Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(1)O_(2))sensor,undergoes tryptophan(Trp)643 oxidation by^(1)O_(2),a chloroplast-derived and light-dependent reactive oxygen species.The indole side chain of Trp is vulnerable to^(1)O_(2),leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease.The perception of^(1)O_(2)via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling.In this study,we discovered that the EX1-like protein EX2 also undergoes^(1)O_(2)-dependent Trp530 oxidation and FtsH-dependent turnover,which attenuates^(1)O_(2)signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation.Consistent with this finding,the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis,whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of-function mutants of EX2.Intriguingly,phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward^(1)O_(2).Collectively,these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own^(1)O_(2)-dependent oxidation,providing a new mechanistic insight into the regulation of EX1-mediated^(1)O_(2)signaling.
