Salinity is an abiotic stress that substantially limits crop production worldwide. To identify salt stress tolerance determinants, we screened for Arabidopsis mutants that are hypersensitive to salt stress and designa...Salinity is an abiotic stress that substantially limits crop production worldwide. To identify salt stress tolerance determinants, we screened for Arabidopsis mutants that are hypersensitive to salt stress and designated these mutants as short root in salt medium （rsa）. One of these mutants, rsa3-1, is hypersensitive to NaCI and LiCI but not to CsCI or to general osmotic stress. Reactive oxygen species （ROS） over-accumulate in rsa3-1 plants under salt stress. Gene expression profiling with Affymetrix microarray analysis revealed that RSA3 controls expression of many genes including genes encoding proteins for ROS detoxification under salt stress. Map-based cloning showed that RSA3 encodes a xyloglucan galactosyltransferase, which is allelic to a gene previously named MUR3/KAM1. The RSA3/ MUR3/KAMl-encoded xylogluscan galactosyltransferase regulates actin microfilament organization （and thereby con- tributes to endomembrane distribution） and is also involved in cell wall biosynthesis. In rsa3-1, actin cannot assemble and form bundles as it does in the wild-type but instead aggregates in the cytoplasm. Furthermore, addition of phal- Ioidin, which prevents actin depolymerization, can rescue salt hypersensitivity of rsa3-1. Together, these results sug- gest that RSA3/MUR3/KAM1 along with other cell wall-associated proteins plays a critical role in salt stress tolerance by maintaining the proper organization of actin microfilaments in order to minimize damage caused by excessive ROS.展开更多
Hyperosmotic stress caused by drought is a detrimental threat to plant growth and agricultural productivity due to limited water availability.Stomata are gateways of transpiration and gas exchange,the swift adjustment...Hyperosmotic stress caused by drought is a detrimental threat to plant growth and agricultural productivity due to limited water availability.Stomata are gateways of transpiration and gas exchange,the swift adjustment of stomatal aperture has a strong influence on plant drought resistance.Despite intensive investigations of stomatal closure during drought stress in past decades,little is known about how sequential signals are integrated during complete processes.Here,we discovered that the rapid Ca^(2+) signaling and subsequent abscisic acid(ABA)signaling contribute to the kinetics of both F-actin reorganizations and stomatal closure in Arabidopsis thaliana,while STOMATAL CLOSURE-RELATED ACTIN BINDING PROTEIN1(SCAB1)is the molecular switch for this entire process.During the early stage of osmotic shock responses,swift elevated calcium signaling promotes SCAB1 phosphorylation through calcium sensors CALCIUM DEPENDENT PROTEIN KINASE3(CPK3)and CPK6.The phosphorylation restrained the microfilament binding affinity of SCAB1,which bring about the Factin disassembly and stomatal closure initiation.As the osmotic stress signal continued,both the kinase activity of CPK3 and the phosphorylation level of SCAB1 attenuated significantly.We further found that ABA signaling is indispensable for these attenuations,which presumably contributed to the actin filament reassembly process as well as completion of stomatal closure.Notably,the dynamic changes of SCAB1 phosphorylation status are crucial for the kinetics of stomatal closure.Taken together,our results support a model in which SCAB1 works as a molecular switch,and directs the microfilament rearrangement through integrating the sequentially generated Ca^(2+) and ABA signals during osmotic stress induced stomatal closure.展开更多
The beginning of a mammalian life commences with a fertilized oocyte.The study of oocytes is certainly one of the most intriguing scientific questions of our time.Herein,we studied oocytes from a mechanical perspectiv...The beginning of a mammalian life commences with a fertilized oocyte.The study of oocytes is certainly one of the most intriguing scientific questions of our time.Herein,we studied oocytes from a mechanical perspective and characterized the typical life activities of oocytes by nanomechanical vibrations.During the development of oocytes from the germinal vesicle(GV)stage to the zygotes,the GV stage oocytes induced a significant nanomechanical vibration,compared with the oocytes in meiosis I(MI)and meiosis II(MII)stages and zygotes.We analyzed the characteristics of mechanical vibrations of oocytes,including the amplitude as well as the frequency.It showed that the amplitude and frequency of nanomechanical vibrations induced by oocytes were caused by the cytoskeleton(microfilaments)and the distribution of metabolic characteristics(mitochondria)within oocytes.This work provides a new perspective for clinical quality assessment and basic research of oocytes,and can open new doors for development of life science.展开更多
基金National Science Foundation (NSF) grants IOS0919745 and MCB0950242 to J.Z.and by NSF grant DB10922650
文摘Salinity is an abiotic stress that substantially limits crop production worldwide. To identify salt stress tolerance determinants, we screened for Arabidopsis mutants that are hypersensitive to salt stress and designated these mutants as short root in salt medium （rsa）. One of these mutants, rsa3-1, is hypersensitive to NaCI and LiCI but not to CsCI or to general osmotic stress. Reactive oxygen species （ROS） over-accumulate in rsa3-1 plants under salt stress. Gene expression profiling with Affymetrix microarray analysis revealed that RSA3 controls expression of many genes including genes encoding proteins for ROS detoxification under salt stress. Map-based cloning showed that RSA3 encodes a xyloglucan galactosyltransferase, which is allelic to a gene previously named MUR3/KAM1. The RSA3/ MUR3/KAMl-encoded xylogluscan galactosyltransferase regulates actin microfilament organization （and thereby con- tributes to endomembrane distribution） and is also involved in cell wall biosynthesis. In rsa3-1, actin cannot assemble and form bundles as it does in the wild-type but instead aggregates in the cytoplasm. Furthermore, addition of phal- Ioidin, which prevents actin depolymerization, can rescue salt hypersensitivity of rsa3-1. Together, these results sug- gest that RSA3/MUR3/KAM1 along with other cell wall-associated proteins plays a critical role in salt stress tolerance by maintaining the proper organization of actin microfilaments in order to minimize damage caused by excessive ROS.
基金This work was supported by the National Natural Science Foundation of China(31921001).
文摘Hyperosmotic stress caused by drought is a detrimental threat to plant growth and agricultural productivity due to limited water availability.Stomata are gateways of transpiration and gas exchange,the swift adjustment of stomatal aperture has a strong influence on plant drought resistance.Despite intensive investigations of stomatal closure during drought stress in past decades,little is known about how sequential signals are integrated during complete processes.Here,we discovered that the rapid Ca^(2+) signaling and subsequent abscisic acid(ABA)signaling contribute to the kinetics of both F-actin reorganizations and stomatal closure in Arabidopsis thaliana,while STOMATAL CLOSURE-RELATED ACTIN BINDING PROTEIN1(SCAB1)is the molecular switch for this entire process.During the early stage of osmotic shock responses,swift elevated calcium signaling promotes SCAB1 phosphorylation through calcium sensors CALCIUM DEPENDENT PROTEIN KINASE3(CPK3)and CPK6.The phosphorylation restrained the microfilament binding affinity of SCAB1,which bring about the Factin disassembly and stomatal closure initiation.As the osmotic stress signal continued,both the kinase activity of CPK3 and the phosphorylation level of SCAB1 attenuated significantly.We further found that ABA signaling is indispensable for these attenuations,which presumably contributed to the actin filament reassembly process as well as completion of stomatal closure.Notably,the dynamic changes of SCAB1 phosphorylation status are crucial for the kinetics of stomatal closure.Taken together,our results support a model in which SCAB1 works as a molecular switch,and directs the microfilament rearrangement through integrating the sequentially generated Ca^(2+) and ABA signals during osmotic stress induced stomatal closure.
基金the National Natural Science Foundation of China(Nos.11627803,32061160475,and 11872355).
文摘The beginning of a mammalian life commences with a fertilized oocyte.The study of oocytes is certainly one of the most intriguing scientific questions of our time.Herein,we studied oocytes from a mechanical perspective and characterized the typical life activities of oocytes by nanomechanical vibrations.During the development of oocytes from the germinal vesicle(GV)stage to the zygotes,the GV stage oocytes induced a significant nanomechanical vibration,compared with the oocytes in meiosis I(MI)and meiosis II(MII)stages and zygotes.We analyzed the characteristics of mechanical vibrations of oocytes,including the amplitude as well as the frequency.It showed that the amplitude and frequency of nanomechanical vibrations induced by oocytes were caused by the cytoskeleton(microfilaments)and the distribution of metabolic characteristics(mitochondria)within oocytes.This work provides a new perspective for clinical quality assessment and basic research of oocytes,and can open new doors for development of life science.
