Rice(Oryza sativa)provides>20%of the consumed calories in the human diet.However,rice is also a leading source of dietary cadmium(Cd)that seriously threatens human health.Deciphering the genetic network that underl...Rice(Oryza sativa)provides>20%of the consumed calories in the human diet.However,rice is also a leading source of dietary cadmium(Cd)that seriously threatens human health.Deciphering the genetic network that underlies the grain-Cd accumulation will benefit the development of low-Cd rice and mitigate the effects of Cd accumulation in the rice grain.In this study,we identified a QTL gene,OsCS1,which is allelic to OsMTP11 and encodes a protein sequestering Cd in the leaf during vegetative growth and preventing Cd from being translocated to the grain after heading in rice.OsCS1 is predominantly expressed in leaf vascular parenchyma cells,where it binds to a vacuole-sorting receptor protein OsVSR2 and is translocated intracellularly from the trans-Golgi network to pre-vacuolar compartments and then to the vacuole.In this trafficking process,OsCS1 actively transports Cd into the endomembrane system and sequesters it in the vacuoles.There are natural variations in the promoter of OsCS1 between the indica and japonica rice subspecies.Duplication of a G-box-like motif in the promoter region of the superior allele of OsCS1 from indica rice enhances the binding of the transcription factor OsIRO2 to the OsCS1 promoter,thereby promoting OsCS1 expression.Introgression of this allele into commercial rice varieties could significantly lower grain-Cd levels compared to the inferior allele present in japonica rice.Collectively,our findings offer new insights into the genetic control of leaf-to-grain Cd translocation and provide a novel gene and its superior allele for the genetic improvement of low-Cd variety in rice.展开更多
Plant sensitive factor attachment protein receptors （SNAREs） encoded by genes of the same sub-family are generally considered as redundant in promoting vesicle-associated membrane fusion events. Nonetheless, the app...Plant sensitive factor attachment protein receptors （SNAREs） encoded by genes of the same sub-family are generally considered as redundant in promoting vesicle-associated membrane fusion events. Nonetheless, the application of innovative experimental approaches highlighted that members of the same gene sub-family often have different functional specificities. In this work, two closely related Qc-SNAREs--the AtSYP51 and the AtSYP52--are compared in their ability to influence different secretory pathways. Their role in the vesicle sorting to the central vacuole has been revised and they were found to have a novel inhibitory function. When transiently overexpressed, the SYP51 and the SYP52 distributed between the TGN and the tonoplast. Our data demonstrate that these SYPs （syntaxin of plants） act as t-SNARE when present on the membrane of TGN/PVC, whereas they behave as inhibitory or interfering SNAREs （i-SNAREs） when they accumulate on the tonoplast. Moreover, the performed functional analysis indicated that the AtSYP51 and the AtSYP52 roles differ in the traffic to the vacuole. The findings are a novel contribution to the functional characterization of plant SNAREs that reveals additional non-fusogenic roles.展开更多
The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by...The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein （GFP） （smGFP） with the pH-sensing capabil- ity of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin （plant-solubility-modified ecliptic pHluorin） gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin （plant- solubility-modified ratiomatric pHluorin）, a dual-excitation sensor, allowing for precise measurements. Compartment- specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar （pH 7.3 and 7.2）, while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum （ER） to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network （TGN） and mul- tivesicular body （MVB） is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H＋-ATPase （V-ATPase） with concanamycin A （ConcA） caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.展开更多
基金jointly supported by the Strategic Priority Research Program of the CAS(XDA24010404)the National Natural Science Foundation of ChinaNational Natural Science Foundation of China(U19A2026 and 31972490)+1 种基金the Major Program of Natural Science Foundation of Hunan Province(2021JC0007)the Hunan Key Technologies R&D Program Hunan Key Technologies R&D Program(2023NK1010).
文摘Rice(Oryza sativa)provides>20%of the consumed calories in the human diet.However,rice is also a leading source of dietary cadmium(Cd)that seriously threatens human health.Deciphering the genetic network that underlies the grain-Cd accumulation will benefit the development of low-Cd rice and mitigate the effects of Cd accumulation in the rice grain.In this study,we identified a QTL gene,OsCS1,which is allelic to OsMTP11 and encodes a protein sequestering Cd in the leaf during vegetative growth and preventing Cd from being translocated to the grain after heading in rice.OsCS1 is predominantly expressed in leaf vascular parenchyma cells,where it binds to a vacuole-sorting receptor protein OsVSR2 and is translocated intracellularly from the trans-Golgi network to pre-vacuolar compartments and then to the vacuole.In this trafficking process,OsCS1 actively transports Cd into the endomembrane system and sequesters it in the vacuoles.There are natural variations in the promoter of OsCS1 between the indica and japonica rice subspecies.Duplication of a G-box-like motif in the promoter region of the superior allele of OsCS1 from indica rice enhances the binding of the transcription factor OsIRO2 to the OsCS1 promoter,thereby promoting OsCS1 expression.Introgression of this allele into commercial rice varieties could significantly lower grain-Cd levels compared to the inferior allele present in japonica rice.Collectively,our findings offer new insights into the genetic control of leaf-to-grain Cd translocation and provide a novel gene and its superior allele for the genetic improvement of low-Cd variety in rice.
文摘Plant sensitive factor attachment protein receptors （SNAREs） encoded by genes of the same sub-family are generally considered as redundant in promoting vesicle-associated membrane fusion events. Nonetheless, the application of innovative experimental approaches highlighted that members of the same gene sub-family often have different functional specificities. In this work, two closely related Qc-SNAREs--the AtSYP51 and the AtSYP52--are compared in their ability to influence different secretory pathways. Their role in the vesicle sorting to the central vacuole has been revised and they were found to have a novel inhibitory function. When transiently overexpressed, the SYP51 and the SYP52 distributed between the TGN and the tonoplast. Our data demonstrate that these SYPs （syntaxin of plants） act as t-SNARE when present on the membrane of TGN/PVC, whereas they behave as inhibitory or interfering SNAREs （i-SNAREs） when they accumulate on the tonoplast. Moreover, the performed functional analysis indicated that the AtSYP51 and the AtSYP52 roles differ in the traffic to the vacuole. The findings are a novel contribution to the functional characterization of plant SNAREs that reveals additional non-fusogenic roles.
文摘The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein （GFP） （smGFP） with the pH-sensing capabil- ity of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin （plant-solubility-modified ecliptic pHluorin） gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin （plant- solubility-modified ratiomatric pHluorin）, a dual-excitation sensor, allowing for precise measurements. Compartment- specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar （pH 7.3 and 7.2）, while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum （ER） to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network （TGN） and mul- tivesicular body （MVB） is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H＋-ATPase （V-ATPase） with concanamycin A （ConcA） caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.
