Partially modified Bt Cry1Ac gene and the arrowhead proteinase inhibitor (API) gene were used to construct a plant transformation vector pBtiA and this construct was transferred into the genome of the hybrid popla...Partially modified Bt Cry1Ac gene and the arrowhead proteinase inhibitor (API) gene were used to construct a plant transformation vector pBtiA and this construct was transferred into the genome of the hybrid poplar 741 [ Populus alba L.×( P. davidiana Dode+ P. simonii Carr.)× P. tomentosa Carr.] by Agrobacterium _ mediated transformation. Ten kanamycin resistant plants have been regenerated. Upon insect bioassay using Clostera anachoreta (Fabricius), three of the examined plants were demonstrated to be highly resistant to the testing insects. The mortality of insect larvae on one plant was higher than 90% in 6 days after infestation and the growth of the survival larvae were seriously inhibited. Results of PCR and Southern blot analysis indicated that both Bt Cry1Ac gene and API gene were integrated as a single copy into the genomes of these three plants when Cry1Ac gene fragment was used as the probe. Protein dot blot immunoassay and ELISA analysis revealed that at least the Cry1Ac protein was produced in these three transgenic plants and the expression levels were estimated to be approximately 0.015% of the leaf total soluble protein. This is the first report on insect resistant transgenic hybrid poplar 741 that expresses two insecticidal protein genes.展开更多
The cDNA fragment encoding caffeic acid 3_O_methyltransferase (COMT) in Chinese white poplar ( Populus tomentosa Carr.) was isolated and cloned by RT_PCR technique. The size of the cDNA fragment is 1 080 bp, which alm...The cDNA fragment encoding caffeic acid 3_O_methyltransferase (COMT) in Chinese white poplar ( Populus tomentosa Carr.) was isolated and cloned by RT_PCR technique. The size of the cDNA fragment is 1 080 bp, which almost covers the whole cDNA_encoding region. Authors’ cDNA fragment in P. tomentosa shares 98.7% homology with the reported corresponding cDNA in the P. tremuloids at nucleotide level, 99.4% homology at amino acid level, respectively. The analysis of Northern dot hybridization showed that COMT is expressed specifically in the developing secondary xylem of stem during the season of xylem differentiation, which means the linkage between the gene expression for a monolignol biosynthetic enzyme and seasonal regulation of xylem development in woody plant.展开更多
cDNA encoding caffeoyl CoA O-methyltransferase (CCoAOMT) from Chinese white poplar ( Populus tomentosa Carr.) was cloned by RT-PCR and sequenced. Northern analysis displayed that the CCoAOMT was expressed specifically...cDNA encoding caffeoyl CoA O-methyltransferase (CCoAOMT) from Chinese white poplar ( Populus tomentosa Carr.) was cloned by RT-PCR and sequenced. Northern analysis displayed that the CCoAOMT was expressed specifically in the developing secondary xylem and its expression was coincident with lignification. The antisense CCoAOMT cDNA was transformed into P. tremula x P. alba mediated by Agrobacterium tumefaciens ( Smith et Townsend) Conn. Transgenic plants were identified with PCR, PCR-Southern and Southern analysis. Lignin content in 5- to 6-month-old transgenic plants was measured. One of the transgenic lines had significant reduction of 17.9% in Klason lignin content as compared with that of untransformed poplar. The results demonstrate that antisense repression of CCoAOMT is an efficient way to reduce lignin content for improving pulping property in engineered trees.展开更多
Wood is the product of cambial activity in trees, and the seasonal activity style of cambium directly influences wood biomass production, structures and properties. The seasonal changes in the ultrastructure of the va...Wood is the product of cambial activity in trees, and the seasonal activity style of cambium directly influences wood biomass production, structures and properties. The seasonal changes in the ultrastructure of the vascular cambium activity of Populus tonientosa Carr. planted in Beijing area were examined in shoot tissues collected during 15 months by means of transmission electron microscopy. Before xylem mother cells reactivated completely, the dividing fusiform cells in cambium and new phloem cells had appeared at the same time. The initiation of cambial activity may be related to the bud sprouting and the young leaf growth in shoots. More details about the ultrastructural changes of cambial cells at the onset of cambial activity have been gained. When the large vacuole in active cambial cells divided into smaller ones during the dormant phase, proteinaceous material that disappeared in active cambial cells refilled many of these small vactioles. In addition, lipid droplets and starch granules had the same cycles as proteinaceous material. The plasmalemma invaginations of fusiform cells were observed not only in active phase but also in dormancy. The endomembrane system consisting of nuclear membrane, endoplasmic reticulum (ER), dictyosomes and their secretory vesicles, changed in form and distribution at different phases during a cycle and performed important roles at the onset of active cambium and during the wall formation process of secondary xylem cells. The tangential walls remained relatively thin throughout the year but the radial walls thickened markedly when the cambium was dormant. During the transition from dormancy to activity, a partial autolysis occurred in the radial walls of the cambial cells, especially at the cell wall junctions. A notable feature of the cells at the onset of cambial activity was the thinning of the radial walls.展开更多
Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzy...Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzymes that has been described previously in most of the plants. In silico cloning is a new method that utilizes the bioinformatics on the complete genome and available EST database. In this study, a full-length cDNA clone of PtFATB gene was isolated from Populus tomentosa using this approach. It is 1,450 bp in length and the open reading frame encodes a peptide of 421 amino acids. The predicted amino acid sequence shows significant homology with those from other plant species, which contain typical domains owned by FATB proteins. The transcripts of PtFATB were abundant in leaves, and less in roots detected by using semiquantitative RT-PCR. When the shoots were subjected to the stress treatments （cold, dry, NaC1） and ABA （Abscisic acid）, the expression of PtFATB was only slightly reduced under the treatment of low temperature. This suggests that the expression of PtFATB is in a constitutive fashion. This study provides the basis not only for the identification and characterization of this gene but also for the improvement of cold tolerance by controlling the expression of the PtFATB gene in trees in near future.展开更多
Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru...Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base,which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp,is reported.The introduction of Cs_(2)CO_(3) led to the generation of C2 side‐chained phenols through the cleavage of C_(β)–O and C_(β)–C_(γ) bonds inβ–O–4 units in addition to C3 side‐chained phenols;the relationship between C2 and C3 was dependent on the base dosage.The reaction conditions,including base species,temperature,time,and H_(2) pressure,were optimized in terms of phenolic product distribution,delignification degree,and carbohydrate retention.The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs_(2)CO_(3) were more amenable to enzymatic hydrolysis,indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.展开更多
The main morphological characteristics, producing area and growth characteristics of sixteen new varieties of Chinese white poplar （Populus tomentosa Carr. ） are reported, aiming at providing reference for breeding ...The main morphological characteristics, producing area and growth characteristics of sixteen new varieties of Chinese white poplar （Populus tomentosa Carr. ） are reported, aiming at providing reference for breeding and extension of new varieties.展开更多
基金ThePresidentialFoundationofTheChineseAcademyofSciences NaturalScienceFoundationofHebeiProvince China
文摘Partially modified Bt Cry1Ac gene and the arrowhead proteinase inhibitor (API) gene were used to construct a plant transformation vector pBtiA and this construct was transferred into the genome of the hybrid poplar 741 [ Populus alba L.×( P. davidiana Dode+ P. simonii Carr.)× P. tomentosa Carr.] by Agrobacterium _ mediated transformation. Ten kanamycin resistant plants have been regenerated. Upon insect bioassay using Clostera anachoreta (Fabricius), three of the examined plants were demonstrated to be highly resistant to the testing insects. The mortality of insect larvae on one plant was higher than 90% in 6 days after infestation and the growth of the survival larvae were seriously inhibited. Results of PCR and Southern blot analysis indicated that both Bt Cry1Ac gene and API gene were integrated as a single copy into the genomes of these three plants when Cry1Ac gene fragment was used as the probe. Protein dot blot immunoassay and ELISA analysis revealed that at least the Cry1Ac protein was produced in these three transgenic plants and the expression levels were estimated to be approximately 0.015% of the leaf total soluble protein. This is the first report on insect resistant transgenic hybrid poplar 741 that expresses two insecticidal protein genes.
文摘The cDNA fragment encoding caffeic acid 3_O_methyltransferase (COMT) in Chinese white poplar ( Populus tomentosa Carr.) was isolated and cloned by RT_PCR technique. The size of the cDNA fragment is 1 080 bp, which almost covers the whole cDNA_encoding region. Authors’ cDNA fragment in P. tomentosa shares 98.7% homology with the reported corresponding cDNA in the P. tremuloids at nucleotide level, 99.4% homology at amino acid level, respectively. The analysis of Northern dot hybridization showed that COMT is expressed specifically in the developing secondary xylem of stem during the season of xylem differentiation, which means the linkage between the gene expression for a monolignol biosynthetic enzyme and seasonal regulation of xylem development in woody plant.
文摘cDNA encoding caffeoyl CoA O-methyltransferase (CCoAOMT) from Chinese white poplar ( Populus tomentosa Carr.) was cloned by RT-PCR and sequenced. Northern analysis displayed that the CCoAOMT was expressed specifically in the developing secondary xylem and its expression was coincident with lignification. The antisense CCoAOMT cDNA was transformed into P. tremula x P. alba mediated by Agrobacterium tumefaciens ( Smith et Townsend) Conn. Transgenic plants were identified with PCR, PCR-Southern and Southern analysis. Lignin content in 5- to 6-month-old transgenic plants was measured. One of the transgenic lines had significant reduction of 17.9% in Klason lignin content as compared with that of untransformed poplar. The results demonstrate that antisense repression of CCoAOMT is an efficient way to reduce lignin content for improving pulping property in engineered trees.
文摘Wood is the product of cambial activity in trees, and the seasonal activity style of cambium directly influences wood biomass production, structures and properties. The seasonal changes in the ultrastructure of the vascular cambium activity of Populus tonientosa Carr. planted in Beijing area were examined in shoot tissues collected during 15 months by means of transmission electron microscopy. Before xylem mother cells reactivated completely, the dividing fusiform cells in cambium and new phloem cells had appeared at the same time. The initiation of cambial activity may be related to the bud sprouting and the young leaf growth in shoots. More details about the ultrastructural changes of cambial cells at the onset of cambial activity have been gained. When the large vacuole in active cambial cells divided into smaller ones during the dormant phase, proteinaceous material that disappeared in active cambial cells refilled many of these small vactioles. In addition, lipid droplets and starch granules had the same cycles as proteinaceous material. The plasmalemma invaginations of fusiform cells were observed not only in active phase but also in dormancy. The endomembrane system consisting of nuclear membrane, endoplasmic reticulum (ER), dictyosomes and their secretory vesicles, changed in form and distribution at different phases during a cycle and performed important roles at the onset of active cambium and during the wall formation process of secondary xylem cells. The tangential walls remained relatively thin throughout the year but the radial walls thickened markedly when the cambium was dormant. During the transition from dormancy to activity, a partial autolysis occurred in the radial walls of the cambial cells, especially at the cell wall junctions. A notable feature of the cells at the onset of cambial activity was the thinning of the radial walls.
基金This work was supported by project "Regulation of Composition and Saturation of Fatty Acid in Trees by Genetic Engineering", Introduction of Foreign Advanced Agricultural Science and Technology into China (No. 2005-4-52).
文摘Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzymes that has been described previously in most of the plants. In silico cloning is a new method that utilizes the bioinformatics on the complete genome and available EST database. In this study, a full-length cDNA clone of PtFATB gene was isolated from Populus tomentosa using this approach. It is 1,450 bp in length and the open reading frame encodes a peptide of 421 amino acids. The predicted amino acid sequence shows significant homology with those from other plant species, which contain typical domains owned by FATB proteins. The transcripts of PtFATB were abundant in leaves, and less in roots detected by using semiquantitative RT-PCR. When the shoots were subjected to the stress treatments （cold, dry, NaC1） and ABA （Abscisic acid）, the expression of PtFATB was only slightly reduced under the treatment of low temperature. This suggests that the expression of PtFATB is in a constitutive fashion. This study provides the basis not only for the identification and characterization of this gene but also for the improvement of cold tolerance by controlling the expression of the PtFATB gene in trees in near future.
文摘Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base,which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp,is reported.The introduction of Cs_(2)CO_(3) led to the generation of C2 side‐chained phenols through the cleavage of C_(β)–O and C_(β)–C_(γ) bonds inβ–O–4 units in addition to C3 side‐chained phenols;the relationship between C2 and C3 was dependent on the base dosage.The reaction conditions,including base species,temperature,time,and H_(2) pressure,were optimized in terms of phenolic product distribution,delignification degree,and carbohydrate retention.The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs_(2)CO_(3) were more amenable to enzymatic hydrolysis,indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.
基金Henan Provincial Science and Technology Key Project (024050019)~~
文摘The main morphological characteristics, producing area and growth characteristics of sixteen new varieties of Chinese white poplar （Populus tomentosa Carr. ） are reported, aiming at providing reference for breeding and extension of new varieties.
