Abscisic acid (ABA) is an important phytohormone that functions in seed germination, plant development, and multiple stress responses. Arabidopsis Peroxisome defective 2 (AtPED2) (also known as AtPEXOXIN14, AtPEX14),...Abscisic acid (ABA) is an important phytohormone that functions in seed germination, plant development, and multiple stress responses. Arabidopsis Peroxisome defective 2 (AtPED2) (also known as AtPEXOXIN14, AtPEX14), is involved in the intracellular transport of thiolase from the cytosol to glyoxysomes, and perosisomal matrix protein import in plants. In this study, we assigned a new role for AtPED2 in drought stress resistance. The transcript level of AtPED2 was downregulated by ABA and abiotic stress treatments. AtPED2 knockout mutants were insensitive to ABA-mediated seed germination, primary root elongation, and stomatal response, while AtPED2 over-expressing plants were sensitive to ABA in comparison to wide type (WT). AtPED2 also positively regulated drought stress resistance, as evidenced by the changes of water loss rate, electrolyte leakage, and survival rate. Notably, AtPED2 positively modulated expression of several stress-responsive genes (RAB18, RD22, RD29A, and RD29B), positively affected underlying antioxidant enzyme activities and negatively regulated reactive oxygen species (ROS) level under drought stress conditions. Moreover, multiple carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines were also positively regulated by AtPED2. Taken together, these results indicated a positive role for AtPED2 in drought resistance, through modulation of stress-responsive genes expression, ROS metabolism, and metabolic homeostasis, at least partially.展开更多
Maintenance of root elongation is beneficial for the growth and survival of plants under salt stress,but currently the cellular components involved in the regulation of root growth under high salinity are not fully un...Maintenance of root elongation is beneficial for the growth and survival of plants under salt stress,but currently the cellular components involved in the regulation of root growth under high salinity are not fully understood.In this study,we identified an Arabidopsis mutant,rres1,which exhibited reduced root elongation under treatment of a variety of salts,including NaCl,NaNO3,KCl,and KNO3.RRES1 encodes a novel mitochondrial protein and its molecular function is still unknown.Under salt stress,the root meristem length was shorter in the rres1 mutant compared to the wild type,which was correlated with a reduced auxin accumulation in the mutant.Reactive oxygen species(ROS),as important signals that regulate root elongation,were accumulated to higher levels in the rres1 mutant than the wild type after salt treatment.Measurement of monosaccharides in the cell wall showed that arabinose and xylose contents were decreased in the rres1 mutant under salt stress,and application of boric acid,which is required for the crosslinking of pectic polysaccharide rhamnogalacturonan-II(RG-II),largely rescued the root growth arrest of the rres1 mutant,suggesting that RRES1 participates in the maintenance of cell wall integrity under salt stress.GUS staining assay indicated that the RRES1 gene was expressed in leaves and weakly in root tip under normal conditions,but its expression was dramatically increased in leaves and roots after salt treatment.Together,our study reveals a novel mitochondrial protein that regulates root elongation under salt stress via the modulation of cell wall integrity,auxin accumulation,and ROS homeostasis.展开更多
Proanthocyanidins （PAs） as the end products of flavonoid biosynthetic pathway mainly accumulate in seed coat but their biological function is largely unknown. We studied the anti-oxidation ability in seed coat and g...Proanthocyanidins （PAs） as the end products of flavonoid biosynthetic pathway mainly accumulate in seed coat but their biological function is largely unknown. We studied the anti-oxidation ability in seed coat and germination changes under externally applied oxidative stresses in PAs-deficient mutants of Arabidopsis. Germination of PAs-deficient mutant seeds was faster than that of wild-type under low or no oxidative stress, suggesting a PAs-induced inhibition of germination. When the applied oxidative stress was high, germination of PAs-deficient mutants was lower than that of wild-type, suggesting a loss of PAs-related anti-oxidation ability in the mutants. Using ABA signaling mutants, our studies demonstrated that both ABA signaling pathway and PAs were important for the response to serve oxidative stress during seed germination. However, the discrepancy of the response between abi mutants and PAs mutants to oxidative stress suggests that ABA signaling pathway may not play a major role in PAs＂ action in alleviating oxidative stress. Under low or no oxidative stress, germination was mainly determined by the ABA content in seed and the PAs-deficient mutant seeds germinated faster due to their lower ABA content than wild-type. However, oxidative injury inhibited germination when PAs-deficient seeds germinated under high oxidative stress, Wild-type exhibited higher germination under the high ox- idative stress due to the PAs＇ anti-oxidation ability. Oxidative stress applied externally led to changes in endogenous PAs contents that coincided with the expression changes of PAs biogenesis genes. PAs modulated the activities of some key enzymes that controlled the levels of reactive oxygen species and the anti-oxidation capacity during the seed germination. This work suggests that PAs contribute to the adaptive mechanism that helps germination under environmental stresses by playing dual roles in both germination control and anti-oxidation reaction.展开更多
Aquaporins are water channel proteins that mediate the fine-tuning of cell membrane water permeability during development or in response to environmental stresses. The present work focuses on the oxidative stress-indu...Aquaporins are water channel proteins that mediate the fine-tuning of cell membrane water permeability during development or in response to environmental stresses. The present work focuses on the oxidative stress-induced redistribution of plasma membrane intrinsic protein （PIP） aquaporins from the plasma membrane （PM） to intracellular membranes. This process was investigated in the Arabidopsis root. Su- crose density gradient centrifugation showed that exposure of roots to 0.5 mM H2O2 induces significant depletion in PM fractions of several abundant PIP homologs after 15 rain. Analyses by single-particle tracking and fluorescence correlative spectroscopy showed that, in the PM of epidermal cells, H2O2 treat- ment induces an increase in lateral motion and a reduction in the density of a fluorescently tagged form of the prototypal AtPIP2;1 isoform, respectively. Co-expression analyses of AtPIP2;1 with endomembrane markers revealed that H2O2 triggers AtPIP2;1 accumulation in the late endosomal compartments. Life- time analyses established that the high stability of PIPs was maintained under oxidative stress conditions, suggesting that H2O2 triggers a mechanism for intracellular sequestration of PM aquaporins without further degradation. In addition to information on cellular regulation of aquaporins, this study provides novel and complementary insights into the dynamic remodeling of plant internal membranes during oxida- tive stress responses.展开更多
基金supported by the National Natural Science Foundation of China (31370302)" the Hundred Talents Program " (54Y154761O01076 and 29Y329631O0263) to Zhulong Chanby the Youth Innovation Promotion Association of Chinese Academy of Sciences (No. 29Y429371O0437) to H. S
文摘Abscisic acid (ABA) is an important phytohormone that functions in seed germination, plant development, and multiple stress responses. Arabidopsis Peroxisome defective 2 (AtPED2) (also known as AtPEXOXIN14, AtPEX14), is involved in the intracellular transport of thiolase from the cytosol to glyoxysomes, and perosisomal matrix protein import in plants. In this study, we assigned a new role for AtPED2 in drought stress resistance. The transcript level of AtPED2 was downregulated by ABA and abiotic stress treatments. AtPED2 knockout mutants were insensitive to ABA-mediated seed germination, primary root elongation, and stomatal response, while AtPED2 over-expressing plants were sensitive to ABA in comparison to wide type (WT). AtPED2 also positively regulated drought stress resistance, as evidenced by the changes of water loss rate, electrolyte leakage, and survival rate. Notably, AtPED2 positively modulated expression of several stress-responsive genes (RAB18, RD22, RD29A, and RD29B), positively affected underlying antioxidant enzyme activities and negatively regulated reactive oxygen species (ROS) level under drought stress conditions. Moreover, multiple carbon metabolites including amino acids, organic acids, sugars, sugar alcohols, and aromatic amines were also positively regulated by AtPED2. Taken together, these results indicated a positive role for AtPED2 in drought resistance, through modulation of stress-responsive genes expression, ROS metabolism, and metabolic homeostasis, at least partially.
基金supported by Shanghai Pujiang Program,Grant 20PJ1414800(to C.Z.)National Natural Science Foundation of China,Grant 32070295(to C.Z.)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences,Grant XDB27040101(to J-K.Z.)Shanghai Agriculture Applied Technology Development Program,Grant G2020-01-01(to C.Z.).
文摘Maintenance of root elongation is beneficial for the growth and survival of plants under salt stress,but currently the cellular components involved in the regulation of root growth under high salinity are not fully understood.In this study,we identified an Arabidopsis mutant,rres1,which exhibited reduced root elongation under treatment of a variety of salts,including NaCl,NaNO3,KCl,and KNO3.RRES1 encodes a novel mitochondrial protein and its molecular function is still unknown.Under salt stress,the root meristem length was shorter in the rres1 mutant compared to the wild type,which was correlated with a reduced auxin accumulation in the mutant.Reactive oxygen species(ROS),as important signals that regulate root elongation,were accumulated to higher levels in the rres1 mutant than the wild type after salt treatment.Measurement of monosaccharides in the cell wall showed that arabinose and xylose contents were decreased in the rres1 mutant under salt stress,and application of boric acid,which is required for the crosslinking of pectic polysaccharide rhamnogalacturonan-II(RG-II),largely rescued the root growth arrest of the rres1 mutant,suggesting that RRES1 participates in the maintenance of cell wall integrity under salt stress.GUS staining assay indicated that the RRES1 gene was expressed in leaves and weakly in root tip under normal conditions,but its expression was dramatically increased in leaves and roots after salt treatment.Together,our study reveals a novel mitochondrial protein that regulates root elongation under salt stress via the modulation of cell wall integrity,auxin accumulation,and ROS homeostasis.
文摘Proanthocyanidins （PAs） as the end products of flavonoid biosynthetic pathway mainly accumulate in seed coat but their biological function is largely unknown. We studied the anti-oxidation ability in seed coat and germination changes under externally applied oxidative stresses in PAs-deficient mutants of Arabidopsis. Germination of PAs-deficient mutant seeds was faster than that of wild-type under low or no oxidative stress, suggesting a PAs-induced inhibition of germination. When the applied oxidative stress was high, germination of PAs-deficient mutants was lower than that of wild-type, suggesting a loss of PAs-related anti-oxidation ability in the mutants. Using ABA signaling mutants, our studies demonstrated that both ABA signaling pathway and PAs were important for the response to serve oxidative stress during seed germination. However, the discrepancy of the response between abi mutants and PAs mutants to oxidative stress suggests that ABA signaling pathway may not play a major role in PAs＂ action in alleviating oxidative stress. Under low or no oxidative stress, germination was mainly determined by the ABA content in seed and the PAs-deficient mutant seeds germinated faster due to their lower ABA content than wild-type. However, oxidative injury inhibited germination when PAs-deficient seeds germinated under high oxidative stress, Wild-type exhibited higher germination under the high ox- idative stress due to the PAs＇ anti-oxidation ability. Oxidative stress applied externally led to changes in endogenous PAs contents that coincided with the expression changes of PAs biogenesis genes. PAs modulated the activities of some key enzymes that controlled the levels of reactive oxygen species and the anti-oxidation capacity during the seed germination. This work suggests that PAs contribute to the adaptive mechanism that helps germination under environmental stresses by playing dual roles in both germination control and anti-oxidation reaction.
文摘Aquaporins are water channel proteins that mediate the fine-tuning of cell membrane water permeability during development or in response to environmental stresses. The present work focuses on the oxidative stress-induced redistribution of plasma membrane intrinsic protein （PIP） aquaporins from the plasma membrane （PM） to intracellular membranes. This process was investigated in the Arabidopsis root. Su- crose density gradient centrifugation showed that exposure of roots to 0.5 mM H2O2 induces significant depletion in PM fractions of several abundant PIP homologs after 15 rain. Analyses by single-particle tracking and fluorescence correlative spectroscopy showed that, in the PM of epidermal cells, H2O2 treat- ment induces an increase in lateral motion and a reduction in the density of a fluorescently tagged form of the prototypal AtPIP2;1 isoform, respectively. Co-expression analyses of AtPIP2;1 with endomembrane markers revealed that H2O2 triggers AtPIP2;1 accumulation in the late endosomal compartments. Life- time analyses established that the high stability of PIPs was maintained under oxidative stress conditions, suggesting that H2O2 triggers a mechanism for intracellular sequestration of PM aquaporins without further degradation. In addition to information on cellular regulation of aquaporins, this study provides novel and complementary insights into the dynamic remodeling of plant internal membranes during oxida- tive stress responses.
