Chloroplast movement is essential for plants to survive under various environmental light conditions. Photo- tropins--plant-specific blue-light-activated receptor kinases--mediate the response by perceiving light inte...Chloroplast movement is essential for plants to survive under various environmental light conditions. Photo- tropins--plant-specific blue-light-activated receptor kinases--mediate the response by perceiving light intensity and direction. Recently, novel chloroplast actin （cp-actin） filaments have been identified as playing a pivotal role in the directional chloroplast photorelocation movement. Encouraging progress has recently been made in this field of research through molecular genetics and cell biological analyses. This review describes factors that have been identified as being involved in chloroplast movement and their roles in the regulation of cp-actin filaments, thus providing a basis for reflection on their biochemical activities and functions.展开更多
Chloroplast photo-relocation movement is crucial for plant survival; however, the mechanism of this phenome- non is still poorly understood. Especially, the signal that goes from photoreceptor to chloroplast is unknow...Chloroplast photo-relocation movement is crucial for plant survival; however, the mechanism of this phenome- non is still poorly understood. Especially, the signal that goes from photoreceptor to chloroplast is unknown, although the photoreceptors （phototropin 1 and 2） have been identified and an actin structure （chloroplast actin filaments） has been characterized that is specific for chloroplast movement. Here, in gametophytes of the fern Adiantum capillus-veneris, gametophores of the moss Physcomiterella patens, and leaves of the seed plant Arabidopsis thaliana, we sought to characterize the signaling system by measuring the lifetime of the induced response. Chloroplast movements were induced by microbeam irradiation with high-intensity blue light and recorded. The lifetime of the avoidance state was measured as a lag time between switching off the beam and the loss of avoidance behavior, and that of the accumulation state was measured as the duration of accumulation behavior following the extinction of the beam. The lifetime for the avoidance response state is approximately 3-4rain and that for the accumulation response is 19-28 rain. These data suggest that the two responses are based on distinct signals.展开更多
Chloroplast movement has been studied in many plants mainly in relation to the local light, mechanical or stress effects. Here we investigated possible systemic responses of chloroplast movement to local light or burn...Chloroplast movement has been studied in many plants mainly in relation to the local light, mechanical or stress effects. Here we investigated possible systemic responses of chloroplast movement to local light or burning stress in tobacco plants （Nicotisna tabacum cv. Samsun）. Chloroplast movement was measured using two independent methods： one with a SPAD 502 Chlorophyll meter and another by collimated transmittance at a selected wavelength （676 nm）. A sensitive periodic movement of chloroplasts was used in high or low （2 000 or 50 μmol/m2 per s photosynthetically active radiation, respectively） cold white light with periods of 50 or 130 min. Measurements were carried out in the irradiated area, in the non-irradisted area of the same leaf or in the leaf located on the stem below the irradiated or bumed one. No significant changes in systemic chloroplast movement in non-irradiated parts of the leaf and in the non-treated leaf were detected. Our data indicate that chloroplast movement in tobacco is dependent dominantly on the intensity and spectral composition of the incident light and on the local stimulation and state of the target tissue. No systemic signal was strong enough to evoke a detectable systemic response in chloroplast movement in distant untreated tissues of tobacco plants.展开更多
在植物中,叶绿体运动以光依赖的方式来调节光合作用,该过程对于植物有效捕获光能和避免光损伤至关重要,虽然引起叶绿体运动的蛋白质已经有过报道,但是他们之间的相互作用尚不清楚。Plastid Movement Impaired2(PMI2)是经鉴定的调节叶绿...在植物中,叶绿体运动以光依赖的方式来调节光合作用,该过程对于植物有效捕获光能和避免光损伤至关重要,虽然引起叶绿体运动的蛋白质已经有过报道,但是他们之间的相互作用尚不清楚。Plastid Movement Impaired2(PMI2)是经鉴定的调节叶绿体运动的蛋白质。PMI2在结构上具有长卷曲螺旋区域,该区域往往被认为是能够介导蛋白质与蛋白质之间相互作用的结构域。主要讲述了PMI2的基因、定位、表达、互作蛋白以及叶绿体运动等方面,并对以后的研究进行展望。展开更多
To cope with fluctuating light conditions,terrestrial plants have evolved precise regulation mechanisms to help optimize light capture and increase photosynthetic efficiency.Upon blue light-triggered autophosphorylati...To cope with fluctuating light conditions,terrestrial plants have evolved precise regulation mechanisms to help optimize light capture and increase photosynthetic efficiency.Upon blue light-triggered autophosphorylation,acti-vated phototropin(PHOT1 and PHOT2)photoreceptors function solely or redundantly to regulate diverse responses,including phototropism,chloroplast movement,stomatal opening,and leaf positioning and flattening in plants.These responses enhance light capture under low-light conditions and avoid photodamage under high-light conditions.NON-PHOTOTROPIC HYPOCOTYL 3(NPH3)and ROOT PHOTOTROPISM 2(RPT2)are signal transducers that function in the PHOT1-and PHOT2-mediated response.NPH3 is required for phototropism,leaf expansion and positioning.RPT2 regulates chloroplast accumulation as well as NPH3-mediated responses.NRL PROTEIN FOR CHLOROPLAST MOVE-MENT 1(NCH1)was recently identified as a PHOT1-interacting protein that functions redundantly with RPT2 to medi-ate chloroplast accumulation.The PHYTOCHROME KINASE SUBSTRATE(PKS)proteins(PKS1,PKS2,and PKS4)interact with PHOT1 and NPH3 and mediate hypocotyl phototropic bending.This review summarizes advances in phototropic growth and chloroplast movement induced by light.We also focus on how crosstalk in signaling between phototro-pism and chloroplast movement enhances weak light capture,providing a basis for future studies aiming to delineate the mechanism of light-trapping plants to improve light-use efficiency.展开更多
Does the ER subdomain that associates with the chloroplast in vivo, hereafter referred to as the chloroplast/ER nexus, play a role in protein flow within the ER？ In studies of tobacco cells either constitutively or t...Does the ER subdomain that associates with the chloroplast in vivo, hereafter referred to as the chloroplast/ER nexus, play a role in protein flow within the ER？ In studies of tobacco cells either constitutively or transiently expressing ER-retained luminal, GFP-HDEL, or trans-membrane, YFP-RHD3, fluorescent fusion proteins, brief 405-nm （3-6-mW） laser stimulation of the nexus causes a qualitative difference in the movement and behavior of proteins in the ER. Photostimulating the nexus produces fluorescent protein punctate aggregates （boluses） within the lumen and membrane of the ER. The aggregation propagates through the membrane network throughout the cell, but within minutes can revert to normal, with disaggregation propagating back toward the originally photostimulated nexus. In the meantime, the ER grows and anastomoses around the chloroplast, forming a dense cisternal and tubular network. If this network is again photostimulated, bolus formation does not recur and, if the photostimulation results in photobleaching, fluorescence recovery after photobleaching occurs as it would typically in areas away from the nexus. Bolus propagation is not mediated by the actin cytoskeleton, but can be reversed by pre-conditioning the cells for 30 min with high, 40-45℃, temperature （heat stress）. Because it is not reversed with heat stress, the reorganization of the ER at the nexus following photostimulation is a separate event.展开更多
文摘Chloroplast movement is essential for plants to survive under various environmental light conditions. Photo- tropins--plant-specific blue-light-activated receptor kinases--mediate the response by perceiving light intensity and direction. Recently, novel chloroplast actin （cp-actin） filaments have been identified as playing a pivotal role in the directional chloroplast photorelocation movement. Encouraging progress has recently been made in this field of research through molecular genetics and cell biological analyses. This review describes factors that have been identified as being involved in chloroplast movement and their roles in the regulation of cp-actin filaments, thus providing a basis for reflection on their biochemical activities and functions.
基金supported in part by Grants-in-Aid for scientific research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (23120523 to M. W.)the Japan Society for the Promotion of Science (20227001, 25120721, and 25251033 to M. W.)
文摘Chloroplast photo-relocation movement is crucial for plant survival; however, the mechanism of this phenome- non is still poorly understood. Especially, the signal that goes from photoreceptor to chloroplast is unknown, although the photoreceptors （phototropin 1 and 2） have been identified and an actin structure （chloroplast actin filaments） has been characterized that is specific for chloroplast movement. Here, in gametophytes of the fern Adiantum capillus-veneris, gametophores of the moss Physcomiterella patens, and leaves of the seed plant Arabidopsis thaliana, we sought to characterize the signaling system by measuring the lifetime of the induced response. Chloroplast movements were induced by microbeam irradiation with high-intensity blue light and recorded. The lifetime of the avoidance state was measured as a lag time between switching off the beam and the loss of avoidance behavior, and that of the accumulation state was measured as the duration of accumulation behavior following the extinction of the beam. The lifetime for the avoidance response state is approximately 3-4rain and that for the accumulation response is 19-28 rain. These data suggest that the two responses are based on distinct signals.
基金Supported by the Ministry of Education of the Czech Republic (MSM6198959215).
文摘Chloroplast movement has been studied in many plants mainly in relation to the local light, mechanical or stress effects. Here we investigated possible systemic responses of chloroplast movement to local light or burning stress in tobacco plants （Nicotisna tabacum cv. Samsun）. Chloroplast movement was measured using two independent methods： one with a SPAD 502 Chlorophyll meter and another by collimated transmittance at a selected wavelength （676 nm）. A sensitive periodic movement of chloroplasts was used in high or low （2 000 or 50 μmol/m2 per s photosynthetically active radiation, respectively） cold white light with periods of 50 or 130 min. Measurements were carried out in the irradiated area, in the non-irradisted area of the same leaf or in the leaf located on the stem below the irradiated or bumed one. No significant changes in systemic chloroplast movement in non-irradiated parts of the leaf and in the non-treated leaf were detected. Our data indicate that chloroplast movement in tobacco is dependent dominantly on the intensity and spectral composition of the incident light and on the local stimulation and state of the target tissue. No systemic signal was strong enough to evoke a detectable systemic response in chloroplast movement in distant untreated tissues of tobacco plants.
文摘在植物中,叶绿体运动以光依赖的方式来调节光合作用,该过程对于植物有效捕获光能和避免光损伤至关重要,虽然引起叶绿体运动的蛋白质已经有过报道,但是他们之间的相互作用尚不清楚。Plastid Movement Impaired2(PMI2)是经鉴定的调节叶绿体运动的蛋白质。PMI2在结构上具有长卷曲螺旋区域,该区域往往被认为是能够介导蛋白质与蛋白质之间相互作用的结构域。主要讲述了PMI2的基因、定位、表达、互作蛋白以及叶绿体运动等方面,并对以后的研究进行展望。
基金support from the National Natural Science Foundation of China(grant nos.31871419,and 31570294)Central Plain Talent Scheme(Grants.ZYYCYU202012164)by the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(Grants.21IRTSTHN019).
文摘To cope with fluctuating light conditions,terrestrial plants have evolved precise regulation mechanisms to help optimize light capture and increase photosynthetic efficiency.Upon blue light-triggered autophosphorylation,acti-vated phototropin(PHOT1 and PHOT2)photoreceptors function solely or redundantly to regulate diverse responses,including phototropism,chloroplast movement,stomatal opening,and leaf positioning and flattening in plants.These responses enhance light capture under low-light conditions and avoid photodamage under high-light conditions.NON-PHOTOTROPIC HYPOCOTYL 3(NPH3)and ROOT PHOTOTROPISM 2(RPT2)are signal transducers that function in the PHOT1-and PHOT2-mediated response.NPH3 is required for phototropism,leaf expansion and positioning.RPT2 regulates chloroplast accumulation as well as NPH3-mediated responses.NRL PROTEIN FOR CHLOROPLAST MOVE-MENT 1(NCH1)was recently identified as a PHOT1-interacting protein that functions redundantly with RPT2 to medi-ate chloroplast accumulation.The PHYTOCHROME KINASE SUBSTRATE(PKS)proteins(PKS1,PKS2,and PKS4)interact with PHOT1 and NPH3 and mediate hypocotyl phototropic bending.This review summarizes advances in phototropic growth and chloroplast movement induced by light.We also focus on how crosstalk in signaling between phototro-pism and chloroplast movement enhances weak light capture,providing a basis for future studies aiming to delineate the mechanism of light-trapping plants to improve light-use efficiency.
文摘Does the ER subdomain that associates with the chloroplast in vivo, hereafter referred to as the chloroplast/ER nexus, play a role in protein flow within the ER？ In studies of tobacco cells either constitutively or transiently expressing ER-retained luminal, GFP-HDEL, or trans-membrane, YFP-RHD3, fluorescent fusion proteins, brief 405-nm （3-6-mW） laser stimulation of the nexus causes a qualitative difference in the movement and behavior of proteins in the ER. Photostimulating the nexus produces fluorescent protein punctate aggregates （boluses） within the lumen and membrane of the ER. The aggregation propagates through the membrane network throughout the cell, but within minutes can revert to normal, with disaggregation propagating back toward the originally photostimulated nexus. In the meantime, the ER grows and anastomoses around the chloroplast, forming a dense cisternal and tubular network. If this network is again photostimulated, bolus formation does not recur and, if the photostimulation results in photobleaching, fluorescence recovery after photobleaching occurs as it would typically in areas away from the nexus. Bolus propagation is not mediated by the actin cytoskeleton, but can be reversed by pre-conditioning the cells for 30 min with high, 40-45℃, temperature （heat stress）. Because it is not reversed with heat stress, the reorganization of the ER at the nexus following photostimulation is a separate event.
