Glucose-6-phosphate dehydrogenase (G6PDH,EC 1.1.1.49) is the first and main regulated enzyme of oxidative pentose phosphate pathway (OPPP),catalyzing the conversion of glucose-6-phosphate to 6-phospho-gluconolactone a...Glucose-6-phosphate dehydrogenase (G6PDH,EC 1.1.1.49) is the first and main regulated enzyme of oxidative pentose phosphate pathway (OPPP),catalyzing the conversion of glucose-6-phosphate to 6-phospho-gluconolactone and playing important roles in the growth and development of plants. It is preciously reported that the enhancement of freezing resistance of Populus suaveolenscuttings is clear related to the distinct increase in cytosolic G6PDH activity. Here,a 1697 bp cDNA fragment (PsG6PDH) is amplified by RT-PCR from cold-induced total RNA of the freezing-tolerant P. suaveolens. A sequence analysis showed that PsG6PDH coding region had 1 530 bp and encoded 510 predicted amino acid residues. Genomic Southern analysis revealed that the isoform is encoded by a few copies of the gene in the poplar genome. The cloned gene PsG6PDHis cloned into binary vector pBI121 and used to transform tobacco. PCR and Southern blotting results verified integration of this gene into the genome of tobacco. Moreover,cold treatment experiments and membrane defense enzymeactivity analysis confirmed that overexpression of the PsG6PDHgene could enhance the tolerance to cold or frigid stresses in transgenic plants.展开更多
Freezing injury in winter is an important abiotic stress that seriously affects plant growth and development.Deciduous fruit trees resist freezing injury by inducing dormancy.However,different cultivars of the same sp...Freezing injury in winter is an important abiotic stress that seriously affects plant growth and development.Deciduous fruit trees resist freezing injury by inducing dormancy.However,different cultivars of the same species have different cold resistance strategies.Little is known about the molecular mechanism of apple trees in response to freezing injury during winter dormancy.Therefore,in this study,1-year-old branches of the cold-resistant cultivar‘Hanfu’(HF)and the cold-sensitive cultivar‘Changfuji No.2’(CF)were used to explore their cold resistance through physiological,biochemical,transcriptomics,and metabolomics analyses.Combining physiological and biochemical data,we found that HF had a stronger osmotic regulation ability and antioxidant enzyme activity than CF,as well as stronger cold resistance.The functional enrichment analysis showed that both cultivars were significantly enriched in pathways related to signal transduction,hormone regulation,and sugar metabolism under freezing stress.In addition,the differentially expressed genes(DEGs)encoding galactinol synthase,raffinose synthase,and stachyose synthetase in raffinose family oligosaccharides(RFOs)metabolic pathways were upregulated in HF,and raffinose and stachyose were accumulated,while their contents in CF were lower.HF accumulated 4-aminobutyric acid,spermidine,and ascorbic acid to scavenge reactive oxygen species(ROS).While the contents of oxidized glutathione,vitamin C,glutathione,and spermidine in CF decreased under freezing stress,consequently,the ability to scavenge ROS was low.Furthermore,the transcription factors apetala 2/ethylene responsive factor(AP2/ERF)and WRKY were strongly induced under freezing stress.In summary,the difference in key metabolic components of HF and CF under freezing stress is the major factor affecting their difference in cold resistance.The obtained results deepen our understanding of the cold resistance mechanism in apple trees in response to freezing injury during dormancy.展开更多
Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, ...Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, the mRNA and metabolome sequencing of P. hopeiensis flower organs exposed to different low temperatures were performed to identify changes of genes and metabolites in response to low-temperature stress. A total of 4 851 differentially expressed genes(DEGs) were identified. Trend analysis showed that these DEGs were significantly enriched in profiles 19, 18, 7, 14, 1, 4 and 11. And the KEGG enrichment analysis showed that the DEGs in profile 18 were significantly enriched in flavone and flavonol biosynthesis. Besides, the expressed trends as well as GO and KEGG functional enrichment analyses of DEGs under cold and freezing stress showed significantly difference. Analyses of flavonoid-related pathways indicated that flavonoid structural genes had undergone significant changes. Correlation analysis showed that b HLH and MYB TFs may affect flavonoid biosynthesis by regulating structural gene expression. And PhMYB308 and PhMYB330 were likely candidate repressors of flavonoid biosynthesis by binding to a specific site in bHLH proteins. In total, 92 differentially accumulated metabolites(DAMs) were identified in P. hopeiensis flowers including 12 flavonoids. WGCNA results showed that coral 1, pink and brown 4 modules were closely associated with flavonoids and 11 MYBs and 15 bHLHs among the three modules may activate or inhibit the expression of 23 structural genes of flavonoid biosynthesis. Taken together, the results of this study provided a theoretical basis for further exploration of the molecular mechanisms of flavonoid biosynthesis and cold resistance of P. hopeiensis flower organs and our findings laid a foundation for further molecular breeding in cold-resistant pear varieties.展开更多
The dynamic changes in the malondialdehyde(MDA), superoxide dismutase(SOD), soluble sugar, proline, and soluble protein contents, as well as the relative electrolyte conductivity and the corresponding cold resistance,...The dynamic changes in the malondialdehyde(MDA), superoxide dismutase(SOD), soluble sugar, proline, and soluble protein contents, as well as the relative electrolyte conductivity and the corresponding cold resistance, of Cinnamomum bodinieri Level., C. camphora L., and C. caudiferum Kisterm were investigated during the winter months of October 2009 to April 2010. During the short period of temperature decline that lasted until mid-December, the changes in the relative electrolyte conductivity and MDA content with temperature were insignificant. In January, SOD activity continued to increase and then peaked as a result of rapid increases in soluble sugar, proline, soluble protein, as well as the inhibition of the relative electrolyte conductivity and decrease in MDA content. These physiological changes protected the camphor trees from cold damage during winter. From February to March, SOD activity and the soluble protein and proline contents increased with the increase in temperature. However, the relative electrolyte conductivity and MDA content decreased, indicating that the cell membrane damaged by low temperature was gradually being repaired. The cold dip in April led to slight increases in the relative electrolyte conductivity and MDA content. Using a fuzzy mathematics method, the cold resistance adaptability of the camphor trees was divided into three periods namely, the enhancement setting stage, the vigorous stage, and the reducing stage. The cold tolerance abilities were ranked as the following order: C. bodinieri Level>C. camphora L.>C. caudiferum Kisterm.展开更多
This paper aimed to study the change in MDA content and antioxidant enzyme activity of roots in wintering period under single sowing of alfalfa and mixed sowing of alfalfa and Bromus inermis Leyss.By the single sowing...This paper aimed to study the change in MDA content and antioxidant enzyme activity of roots in wintering period under single sowing of alfalfa and mixed sowing of alfalfa and Bromus inermis Leyss.By the single sowing of 4 alfalfa varieties with different cold resistance and mixed sowing of alfalfa varieties and Bromus inermis Leyss,the changes in MDA content,SOD,POD and CAT activity of alfalfa roots throughout the wintering period were measured.Results indicated that after single sowing of alfalfa and mixed sowing of alfalfa and Bromus inermis Leyss,the MDA content of roots showed an up-down-up trend with temperature; the CAT activity increased with the decreasing temperature but decreased when the temperature rose in the spring of the following year; the SOD and POD activity showed an increasing trend with sharp decline in temperature,and decreased when the temperature continued to decline,but increased with alfalfa reviving in the following year.The enzymic activity of the same variety under mixed sowing was higher than under single sowing.The membership function was used for comprehensive evaluation of cold resistance,and the cold resistance under different treatments was in the order of Wega7F + Bromus inermis Leyss >Wega7F > Xunlu + Bromus inermis Leyss > Xunlu > Aohan + Bromus inermis Leyss > Aohan > WL319HQ + Bromus inermis Leyss > WL319HQ.This was of great significance to the study on cold resistant alfalfa breeding and cultivation in cold areas of northern China.展开更多
The Asian citrus psyllid,Diaphorina citri,is the vector of the pathogenic bacteria that causes Huanglongbing,the most devasting disease affecting citrus worldwide.As cultivation of citrus tends to expand northward,the...The Asian citrus psyllid,Diaphorina citri,is the vector of the pathogenic bacteria that causes Huanglongbing,the most devasting disease affecting citrus worldwide.As cultivation of citrus tends to expand northward,the tolerance of psyllids to freezing temperatures needs to be investigated.While mortality of D.citri to cold temperature has been previously studied,much less is known regarding the acclimation potential of psyllids to cold temperatures.We first evaluated cold resistance of D.citri depending on color morph and sex.Subsequently,we compared mortality of D.citri at−4°C for 10 hours between unacclimated psyllids,psyllids that were gradually acclimated to cold over 1 or 2 weeks,and psyllids intermittently acclimated also for 1 or 2 weeks.We did not find major differences in cold resistance between color morphs and sex.We found that after 1 week of gradual acclimation,the survival of psyllids at−4°C increased to 86%,compared to 20%in the control group.Survival did not increase after the second week of gradual acclimation.Although intermittent acclimation improved survival compared to the control group,it was less effective than gradual acclimation with a survival at 30%and 70%after 1 and 2 weeks of acclimation,respectively,although this difference with gradual acclimation was not significant at week 2.These data show that gradual cold acclimation allows D.citri to survive brief periods below freezing.It may serve as a mechanism responsible for increasing northern establishment of this pest.展开更多
基金supported by the National Natural Science Foundation of China (No .30271093)
文摘Glucose-6-phosphate dehydrogenase (G6PDH,EC 1.1.1.49) is the first and main regulated enzyme of oxidative pentose phosphate pathway (OPPP),catalyzing the conversion of glucose-6-phosphate to 6-phospho-gluconolactone and playing important roles in the growth and development of plants. It is preciously reported that the enhancement of freezing resistance of Populus suaveolenscuttings is clear related to the distinct increase in cytosolic G6PDH activity. Here,a 1697 bp cDNA fragment (PsG6PDH) is amplified by RT-PCR from cold-induced total RNA of the freezing-tolerant P. suaveolens. A sequence analysis showed that PsG6PDH coding region had 1 530 bp and encoded 510 predicted amino acid residues. Genomic Southern analysis revealed that the isoform is encoded by a few copies of the gene in the poplar genome. The cloned gene PsG6PDHis cloned into binary vector pBI121 and used to transform tobacco. PCR and Southern blotting results verified integration of this gene into the genome of tobacco. Moreover,cold treatment experiments and membrane defense enzymeactivity analysis confirmed that overexpression of the PsG6PDHgene could enhance the tolerance to cold or frigid stresses in transgenic plants.
基金funded by the National Key Research and Development Program of China(Grant No.2020YFD1000201)China Agriculture Research System of MOF and MARA(Grant No.CARS-27)+1 种基金the National Natural Science Foundation of China(Grant No.31972359)the Agricultural Research and Industrialization Project of Liaoning Province(Grant No.2020JH2/10200028).
文摘Freezing injury in winter is an important abiotic stress that seriously affects plant growth and development.Deciduous fruit trees resist freezing injury by inducing dormancy.However,different cultivars of the same species have different cold resistance strategies.Little is known about the molecular mechanism of apple trees in response to freezing injury during winter dormancy.Therefore,in this study,1-year-old branches of the cold-resistant cultivar‘Hanfu’(HF)and the cold-sensitive cultivar‘Changfuji No.2’(CF)were used to explore their cold resistance through physiological,biochemical,transcriptomics,and metabolomics analyses.Combining physiological and biochemical data,we found that HF had a stronger osmotic regulation ability and antioxidant enzyme activity than CF,as well as stronger cold resistance.The functional enrichment analysis showed that both cultivars were significantly enriched in pathways related to signal transduction,hormone regulation,and sugar metabolism under freezing stress.In addition,the differentially expressed genes(DEGs)encoding galactinol synthase,raffinose synthase,and stachyose synthetase in raffinose family oligosaccharides(RFOs)metabolic pathways were upregulated in HF,and raffinose and stachyose were accumulated,while their contents in CF were lower.HF accumulated 4-aminobutyric acid,spermidine,and ascorbic acid to scavenge reactive oxygen species(ROS).While the contents of oxidized glutathione,vitamin C,glutathione,and spermidine in CF decreased under freezing stress,consequently,the ability to scavenge ROS was low.Furthermore,the transcription factors apetala 2/ethylene responsive factor(AP2/ERF)and WRKY were strongly induced under freezing stress.In summary,the difference in key metabolic components of HF and CF under freezing stress is the major factor affecting their difference in cold resistance.The obtained results deepen our understanding of the cold resistance mechanism in apple trees in response to freezing injury during dormancy.
基金supported by the National Key Research and Development Plan“Research on protection and restoration of typical small populations of wild plants”(Grant No.2016YFC0503106)。
文摘Low temperature is among the most restrictive factors to limit the yield and distribution of pear. Pyrus hopeiensis is a valuable wild resource.PCA showed that P. hopeiensis had strong cold resistance. In this study, the mRNA and metabolome sequencing of P. hopeiensis flower organs exposed to different low temperatures were performed to identify changes of genes and metabolites in response to low-temperature stress. A total of 4 851 differentially expressed genes(DEGs) were identified. Trend analysis showed that these DEGs were significantly enriched in profiles 19, 18, 7, 14, 1, 4 and 11. And the KEGG enrichment analysis showed that the DEGs in profile 18 were significantly enriched in flavone and flavonol biosynthesis. Besides, the expressed trends as well as GO and KEGG functional enrichment analyses of DEGs under cold and freezing stress showed significantly difference. Analyses of flavonoid-related pathways indicated that flavonoid structural genes had undergone significant changes. Correlation analysis showed that b HLH and MYB TFs may affect flavonoid biosynthesis by regulating structural gene expression. And PhMYB308 and PhMYB330 were likely candidate repressors of flavonoid biosynthesis by binding to a specific site in bHLH proteins. In total, 92 differentially accumulated metabolites(DAMs) were identified in P. hopeiensis flowers including 12 flavonoids. WGCNA results showed that coral 1, pink and brown 4 modules were closely associated with flavonoids and 11 MYBs and 15 bHLHs among the three modules may activate or inhibit the expression of 23 structural genes of flavonoid biosynthesis. Taken together, the results of this study provided a theoretical basis for further exploration of the molecular mechanisms of flavonoid biosynthesis and cold resistance of P. hopeiensis flower organs and our findings laid a foundation for further molecular breeding in cold-resistant pear varieties.
基金Supported by Youth Science Foundation from Henan University of Science and Technology(2013)
文摘The dynamic changes in the malondialdehyde(MDA), superoxide dismutase(SOD), soluble sugar, proline, and soluble protein contents, as well as the relative electrolyte conductivity and the corresponding cold resistance, of Cinnamomum bodinieri Level., C. camphora L., and C. caudiferum Kisterm were investigated during the winter months of October 2009 to April 2010. During the short period of temperature decline that lasted until mid-December, the changes in the relative electrolyte conductivity and MDA content with temperature were insignificant. In January, SOD activity continued to increase and then peaked as a result of rapid increases in soluble sugar, proline, soluble protein, as well as the inhibition of the relative electrolyte conductivity and decrease in MDA content. These physiological changes protected the camphor trees from cold damage during winter. From February to March, SOD activity and the soluble protein and proline contents increased with the increase in temperature. However, the relative electrolyte conductivity and MDA content decreased, indicating that the cell membrane damaged by low temperature was gradually being repaired. The cold dip in April led to slight increases in the relative electrolyte conductivity and MDA content. Using a fuzzy mathematics method, the cold resistance adaptability of the camphor trees was divided into three periods namely, the enhancement setting stage, the vigorous stage, and the reducing stage. The cold tolerance abilities were ranked as the following order: C. bodinieri Level>C. camphora L.>C. caudiferum Kisterm.
基金Supported by Special Postdoctoral Funding in Heilongjiang Province(LBHTZ06020)
文摘This paper aimed to study the change in MDA content and antioxidant enzyme activity of roots in wintering period under single sowing of alfalfa and mixed sowing of alfalfa and Bromus inermis Leyss.By the single sowing of 4 alfalfa varieties with different cold resistance and mixed sowing of alfalfa varieties and Bromus inermis Leyss,the changes in MDA content,SOD,POD and CAT activity of alfalfa roots throughout the wintering period were measured.Results indicated that after single sowing of alfalfa and mixed sowing of alfalfa and Bromus inermis Leyss,the MDA content of roots showed an up-down-up trend with temperature; the CAT activity increased with the decreasing temperature but decreased when the temperature rose in the spring of the following year; the SOD and POD activity showed an increasing trend with sharp decline in temperature,and decreased when the temperature continued to decline,but increased with alfalfa reviving in the following year.The enzymic activity of the same variety under mixed sowing was higher than under single sowing.The membership function was used for comprehensive evaluation of cold resistance,and the cold resistance under different treatments was in the order of Wega7F + Bromus inermis Leyss >Wega7F > Xunlu + Bromus inermis Leyss > Xunlu > Aohan + Bromus inermis Leyss > Aohan > WL319HQ + Bromus inermis Leyss > WL319HQ.This was of great significance to the study on cold resistant alfalfa breeding and cultivation in cold areas of northern China.
基金the Citrus Research Board(Grant#5500-222)for funding.
文摘The Asian citrus psyllid,Diaphorina citri,is the vector of the pathogenic bacteria that causes Huanglongbing,the most devasting disease affecting citrus worldwide.As cultivation of citrus tends to expand northward,the tolerance of psyllids to freezing temperatures needs to be investigated.While mortality of D.citri to cold temperature has been previously studied,much less is known regarding the acclimation potential of psyllids to cold temperatures.We first evaluated cold resistance of D.citri depending on color morph and sex.Subsequently,we compared mortality of D.citri at−4°C for 10 hours between unacclimated psyllids,psyllids that were gradually acclimated to cold over 1 or 2 weeks,and psyllids intermittently acclimated also for 1 or 2 weeks.We did not find major differences in cold resistance between color morphs and sex.We found that after 1 week of gradual acclimation,the survival of psyllids at−4°C increased to 86%,compared to 20%in the control group.Survival did not increase after the second week of gradual acclimation.Although intermittent acclimation improved survival compared to the control group,it was less effective than gradual acclimation with a survival at 30%and 70%after 1 and 2 weeks of acclimation,respectively,although this difference with gradual acclimation was not significant at week 2.These data show that gradual cold acclimation allows D.citri to survive brief periods below freezing.It may serve as a mechanism responsible for increasing northern establishment of this pest.
