Rapid and dynamic change in hydrogen peroxide （H2O2） levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production a...Rapid and dynamic change in hydrogen peroxide （H2O2） levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production and scavenging rates, in which membrane-associated NADPH oxidases are known to play a crucial role. Functioning independently from NADPH oxidases, glycolate oxidase （GLO） was recently demonstrated as an aitemative source for H2O2 production during both germ-for-germ and non-host resistance in plants. In this study, we show that GLO physically interacts with catalase （CAT） in rice leaves, and that the interaction can be deregulated by salicylic acid （SA）. Furthermore, the GLO-mediated H2O2 accumulation is synergistically enhanced by SA. Based on the well-known mechanism of substrate channeling in enzyme complexes, SA-induced H2O2 accumulation likely results from SA-induced GLO-CAT dissociation. In the GLO-CAT complex, GLO-mediated H2O2 production during photorespiration is very high, whereas the affinity of CAT for H2O2 （measured Km ≈ 43 raM） is extraordinarily low. This unique combination can further potentiate the increase in H2O2 when GLO is dissociated from CAT. Taken together, we propose that the physical association-dissociation of GLO and CAT, in response to environmental stress or stimuli, seems to serve as a specific mechanism to modulate H2O2 levels in rice.展开更多
High oleic acid rapeseed oil offers superior nutritional and health benefits,but its mass production is limited due to poor resistance and slightly lower yield.Photosynthesis serves as the foundation of biological sur...High oleic acid rapeseed oil offers superior nutritional and health benefits,but its mass production is limited due to poor resistance and slightly lower yield.Photosynthesis serves as the foundation of biological survival and closely correlates with crop resistance to stresses,yield,and quality.To identify photosynthesis-related genes,transcriptome sequencing was conducted on high oleic acid rapeseed Gaoyousuan No.1 and low oleic acid rapeseed Xiangyou 15 resulting in the identification of a total of 9396 differentially expressed genes(4669 upregulated and 4727 down-regulated).From these genes nine candidate genes were screened using GO and KEGG analysis with BnGLO4 being selected for cloning purposes.The BnGLO4 gene fragment has a length of 1161 bp with an ORF sequence of 1092 bp encoding a theoretical isoelectric point of pI 7.60;it encodes an unstable lipid-soluble protein localized in peroxisomes without transmembrane structural domains or signal peptides.Its amino acid sequence homology was highest with that of BnaA01G0355200ZS,BnaA01G0355600ZS,BnaA05G0410400ZS,BnaC01G0441800ZS,and Brassica rapa(XP_009117145.1),Brassica napus(CDY39100.1),Brassica cretica(KAF3533604.1)and Brassica oleracea var.oleracea(XP_013610644.1)belonging to the same cruciferous family.The BnGLO4 gene may be associated with responses to abiotic stresses such as salt,drought,and temperature extremes along with photosynthesis and growth in rapeseed plants.The expression levels of the GLO4 gene(BnaA01G0355200 ZS)were highest in filaments while being higher at each stage in seeds and siliques with the highest expression level at day 14 in seeds.Expression was significantly upregulated after 3 h of salt stress treatment,reaching a maximum at 12 h before slightly decreasing at 24 h.The findings of this study lay a foundation for further investigation on photosynthesis and stress response in high oleic rapeseed.展开更多
The oxalate content was assessed in nine diverse genotypes of cherry tomato in ripened fruit,leaf and root tissues.The maximum oxalate accumulation was found in leaf lamina followed by mature fruit and root tissues am...The oxalate content was assessed in nine diverse genotypes of cherry tomato in ripened fruit,leaf and root tissues.The maximum oxalate accumulation was found in leaf lamina followed by mature fruit and root tissues among all genotypes where the lowest oxalate content was found in the genotype FB-3-5 and the highest content was recorded in the genotype RSC-4.Examining the leaf and root of nine cherry tomato genotypes at three developmental stages,the investigation into the biosynthesis of oxalates focused on the study of two enzymes,glycolate oxidase(GLO)and ascorbate peroxidase(APX).A positive correlation was observed between oxalate formation and enzyme specific activity of both enzymes.Examining the relative gene expression of oxalate biosynthesizing genes,SlGLO_(2) and SlAPX7,indicated that the gene SlGLO_(2) encoded the GLO enzyme and played a crucial role in oxalate biosynthesis in cherry tomatoes.Understanding oxalate biosynthetic pathways and gene expression will aid in developing mechanisms to enhance cherry tomato nutritional quality and improving breeding programmes.展开更多
Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two...Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two different plant cellular compartments has divergent effects on the plant transcriptome. Arabidopsis thaliana overexpressing glycolate oxidase in the chloroplast （Fahnenstich et al., 2008; Balazadeh et al., 2012） and plants deficient in peroxisomal catalase （Queval et al., 2007; Inze et al., 2012） were grown under non-photorespiratory conditions and then transferred to photorespiratory conditions to foster the production of H202 in both organelles. We show that H202 originating in a specific organelle induces two types of responses： one that integrates signals independently from the subcellular site of H202 production and another that is dependent on the H2O2 production site. H2O2 produced in peroxisomes induces transcripts involved in protein repair responses, while H2O2 produced in chloroplasts induces early signaling responses, including transcription factors and biosynthetic genes involved in production of secondary signaling messengers. There is a significant bias towards the induction of genes involved in responses to wounding and pathogen attack by chloroplas- tic-produced H202, including indolic glucosinolates-, camalexin-, and stigmasterol-biosynthetic genes. These transcriptional responses were accompanied by the accumulation of 4-methoxy-indol-3-ylmethyl glucosinolate and stigmasterol.展开更多
基金This work was supported by the National Natural Science Foundation of China （31170222, 31470343, U 1201212）.
文摘Rapid and dynamic change in hydrogen peroxide （H2O2） levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production and scavenging rates, in which membrane-associated NADPH oxidases are known to play a crucial role. Functioning independently from NADPH oxidases, glycolate oxidase （GLO） was recently demonstrated as an aitemative source for H2O2 production during both germ-for-germ and non-host resistance in plants. In this study, we show that GLO physically interacts with catalase （CAT） in rice leaves, and that the interaction can be deregulated by salicylic acid （SA）. Furthermore, the GLO-mediated H2O2 accumulation is synergistically enhanced by SA. Based on the well-known mechanism of substrate channeling in enzyme complexes, SA-induced H2O2 accumulation likely results from SA-induced GLO-CAT dissociation. In the GLO-CAT complex, GLO-mediated H2O2 production during photorespiration is very high, whereas the affinity of CAT for H2O2 （measured Km ≈ 43 raM） is extraordinarily low. This unique combination can further potentiate the increase in H2O2 when GLO is dissociated from CAT. Taken together, we propose that the physical association-dissociation of GLO and CAT, in response to environmental stress or stimuli, seems to serve as a specific mechanism to modulate H2O2 levels in rice.
基金This work was financially supported by China Agriculture Research System of MOF and MARA(CARS-13)Hunan Agriculture Research System of DARA.
文摘High oleic acid rapeseed oil offers superior nutritional and health benefits,but its mass production is limited due to poor resistance and slightly lower yield.Photosynthesis serves as the foundation of biological survival and closely correlates with crop resistance to stresses,yield,and quality.To identify photosynthesis-related genes,transcriptome sequencing was conducted on high oleic acid rapeseed Gaoyousuan No.1 and low oleic acid rapeseed Xiangyou 15 resulting in the identification of a total of 9396 differentially expressed genes(4669 upregulated and 4727 down-regulated).From these genes nine candidate genes were screened using GO and KEGG analysis with BnGLO4 being selected for cloning purposes.The BnGLO4 gene fragment has a length of 1161 bp with an ORF sequence of 1092 bp encoding a theoretical isoelectric point of pI 7.60;it encodes an unstable lipid-soluble protein localized in peroxisomes without transmembrane structural domains or signal peptides.Its amino acid sequence homology was highest with that of BnaA01G0355200ZS,BnaA01G0355600ZS,BnaA05G0410400ZS,BnaC01G0441800ZS,and Brassica rapa(XP_009117145.1),Brassica napus(CDY39100.1),Brassica cretica(KAF3533604.1)and Brassica oleracea var.oleracea(XP_013610644.1)belonging to the same cruciferous family.The BnGLO4 gene may be associated with responses to abiotic stresses such as salt,drought,and temperature extremes along with photosynthesis and growth in rapeseed plants.The expression levels of the GLO4 gene(BnaA01G0355200 ZS)were highest in filaments while being higher at each stage in seeds and siliques with the highest expression level at day 14 in seeds.Expression was significantly upregulated after 3 h of salt stress treatment,reaching a maximum at 12 h before slightly decreasing at 24 h.The findings of this study lay a foundation for further investigation on photosynthesis and stress response in high oleic rapeseed.
文摘The oxalate content was assessed in nine diverse genotypes of cherry tomato in ripened fruit,leaf and root tissues.The maximum oxalate accumulation was found in leaf lamina followed by mature fruit and root tissues among all genotypes where the lowest oxalate content was found in the genotype FB-3-5 and the highest content was recorded in the genotype RSC-4.Examining the leaf and root of nine cherry tomato genotypes at three developmental stages,the investigation into the biosynthesis of oxalates focused on the study of two enzymes,glycolate oxidase(GLO)and ascorbate peroxidase(APX).A positive correlation was observed between oxalate formation and enzyme specific activity of both enzymes.Examining the relative gene expression of oxalate biosynthesizing genes,SlGLO_(2) and SlAPX7,indicated that the gene SlGLO_(2) encoded the GLO enzyme and played a crucial role in oxalate biosynthesis in cherry tomatoes.Understanding oxalate biosynthetic pathways and gene expression will aid in developing mechanisms to enhance cherry tomato nutritional quality and improving breeding programmes.
文摘Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two different plant cellular compartments has divergent effects on the plant transcriptome. Arabidopsis thaliana overexpressing glycolate oxidase in the chloroplast （Fahnenstich et al., 2008; Balazadeh et al., 2012） and plants deficient in peroxisomal catalase （Queval et al., 2007; Inze et al., 2012） were grown under non-photorespiratory conditions and then transferred to photorespiratory conditions to foster the production of H202 in both organelles. We show that H202 originating in a specific organelle induces two types of responses： one that integrates signals independently from the subcellular site of H202 production and another that is dependent on the H2O2 production site. H2O2 produced in peroxisomes induces transcripts involved in protein repair responses, while H2O2 produced in chloroplasts induces early signaling responses, including transcription factors and biosynthetic genes involved in production of secondary signaling messengers. There is a significant bias towards the induction of genes involved in responses to wounding and pathogen attack by chloroplas- tic-produced H202, including indolic glucosinolates-, camalexin-, and stigmasterol-biosynthetic genes. These transcriptional responses were accompanied by the accumulation of 4-methoxy-indol-3-ylmethyl glucosinolate and stigmasterol.
