A novel switchgrass (Panicum virgatum) extract mediated green process was demonstrated for the synthesis of silver nanoparticles from silver nitrate solution at ambient temperature. UV-visible spectroscopic analysis i...A novel switchgrass (Panicum virgatum) extract mediated green process was demonstrated for the synthesis of silver nanoparticles from silver nitrate solution at ambient temperature. UV-visible spectroscopic analysis indicates the rapid reduction of silver (Ag+) ions by swithgrass extract. The silver nanoparticles began to form at 15 min and the reduction reaction was completed within 2 hours. Synthesized silver nanoparticles were subjected to x-ray diffraction (XRD) for structural characterization, which confirms the FCC symmetry of silver nanoparticles with the lattice parameter of 4.0962 ?. The particle size of bio-synthesized silver nanoparticles was identified through transmission electron microscopic (TEM) analysis and found to be in the range of 20 - 40 nm.展开更多
Switchgrass is native to the tallgrass prairie of North America. It is self-incompatible and has varied ploidy levels from diploid（2x） to dodecaploid（12x） with tetraploid and octoploid being the most common. The h...Switchgrass is native to the tallgrass prairie of North America. It is self-incompatible and has varied ploidy levels from diploid（2x） to dodecaploid（12x） with tetraploid and octoploid being the most common. The high yielding potential and the ability to grow well in marginal lands make switchgrass an ideal species as a dedicated biomass producer for lignocellulosic ethanol production. Genetic transformation is an important tool for studying gene function and for germplasm improvement in switchgrass, the genome of which has been sequenced recently. This paper intends to provide a comprehensive review on plant regeneration and genetic transformation in switchgrass. We first reviewed the effect of explants, basal medium and plant growth regulators on plant regeneration in switchgrass, which is a prerequisite for genetic transformation. We then reviewed the progresses on genetic transformation with either the biolistic or Agrobacterium-mediated method in switchgrass, and discussed various techniques employed to improve the transformation efficiency. Finally we reviewed the recent progresses on the use of genetic transformation in improving biomass quality such as the reduction of lignin, and in increasing biomass yield in switchgrass. We also provided a future perspective on the use of new genome editing technologies in switchgrass and its potential impact on regulatory processes.展开更多
Genes encoding enzymes involved in the lignin biosynthesis through phenylpropanoid pathway were not only associated with the lignin content, but also related to the abiotic stress resistances. As far as the production...Genes encoding enzymes involved in the lignin biosynthesis through phenylpropanoid pathway were not only associated with the lignin content, but also related to the abiotic stress resistances. As far as the production of liquid biofuels and cultivation within the marginal land are concerned, switchgrass could be the better candidate to determine the relationship between lower lignin content and physiological function under stress. Caffeoyl-coenzyme A 3-O-methyltransferase（CCoAOMT） is a key enzyme for the methylation reaction of lignin biosynthesis. For this purpose, we cloned a CCoAOMT gene from switchgrass and identified its expression patterns under abiotic stresses. The full-length CCoAOMT gene, designated PvCCoAOMT（Gen Bank accession no. KF041775）, was 1 005-bp in length, has an opening reading frame of 777 nucleotides encoding a 258-amino acid protein. The deduced amino acid sequence of PvCCoAOMT shared a high degree of similarity（up to 98%） with CCoAOMTs from Panicum virgatum allele（BAO20881）, Sorghum bicolor（XP002436550） and Zea mays（NP001131288）. Using quantitative real-time PCR（qRT-PCR）, the significant upregulation of PvCCoAOMT was observed in stem tissues at a later stage（24 h） after drought treatment, with the transcript level increasing 33-fold compared that of the controls. Moderate and insignificant inductions of PvCCoAOMT were also observed in both stems and leaves during the later stages after cold（48 h in stems, 12 h in leaves） and mechanical wounding（48 h in stems, 12 h in leaves） treatments, respectively. Our results showed the different expression patterns of PvCCoAOMT in drought, cold and mechanical wounding stresses. PvCCoAOMT can be highly induced by drought and cold stresses, which indicates that it may play a role in plant abiotic stress resistance, particularly in the regulation of drought and cold resistance.展开更多
Caffeic acid O-methyltransferase(COMT) is a crucial enzyme that mainly methylates phenylpropanoid meta-hydroxyl of C5 in the biosynthesis of syringyl lignin in angiosperms. A putative COMT, named as PvCOMT1,was isolat...Caffeic acid O-methyltransferase(COMT) is a crucial enzyme that mainly methylates phenylpropanoid meta-hydroxyl of C5 in the biosynthesis of syringyl lignin in angiosperms. A putative COMT, named as PvCOMT1,was isolated from switchgrass(Panicum virgatum), a C4 warm-season dual-purpose forage and bioenergy crop. Our results showed that recombinant PvCOMT1 enzyme protein catalyzed the methylation of 5-OH coniferyl alcohol, 5-OH coniferaldehyde(CAld5H) and 5-OH ferulic acid. Further in vitro studies indicate that CAld5H can dominate COMT-mediated reactions by inhibiting the methylation of the other substrates. Transgenic switchgrass plants generated by an RNAi approach were further employed to study the function of COMT in internode lignification. A dramatic decrease in syringyl lignin units coupled with an obvious incorporation in 5-OH guaiacyl lignin units were observed in the COMT-RNAi transgenic plants. However, the constitutive suppression of COMT in switchgrass plants altered neither the pattern of lignin deposition along the stem nor the anatomical structure of internodes. Consistent with the biochemical characterization of PvCOMT1, a significant decrease in sinapaldehyde was found in the COMT-RNAi transgenic switchgrass plants, suggesting that CAld5H could be the optimal intermediate in the biosynthesis syringyl lignin.展开更多
文摘A novel switchgrass (Panicum virgatum) extract mediated green process was demonstrated for the synthesis of silver nanoparticles from silver nitrate solution at ambient temperature. UV-visible spectroscopic analysis indicates the rapid reduction of silver (Ag+) ions by swithgrass extract. The silver nanoparticles began to form at 15 min and the reduction reaction was completed within 2 hours. Synthesized silver nanoparticles were subjected to x-ray diffraction (XRD) for structural characterization, which confirms the FCC symmetry of silver nanoparticles with the lattice parameter of 4.0962 ?. The particle size of bio-synthesized silver nanoparticles was identified through transmission electron microscopic (TEM) analysis and found to be in the range of 20 - 40 nm.
基金supported by a grant from the Bill Melinda Gates FoundationNational Institute of Food and Agriculture of the United States Department of Agriculture for support (Award number 2013-33522-21091)
文摘Switchgrass is native to the tallgrass prairie of North America. It is self-incompatible and has varied ploidy levels from diploid（2x） to dodecaploid（12x） with tetraploid and octoploid being the most common. The high yielding potential and the ability to grow well in marginal lands make switchgrass an ideal species as a dedicated biomass producer for lignocellulosic ethanol production. Genetic transformation is an important tool for studying gene function and for germplasm improvement in switchgrass, the genome of which has been sequenced recently. This paper intends to provide a comprehensive review on plant regeneration and genetic transformation in switchgrass. We first reviewed the effect of explants, basal medium and plant growth regulators on plant regeneration in switchgrass, which is a prerequisite for genetic transformation. We then reviewed the progresses on genetic transformation with either the biolistic or Agrobacterium-mediated method in switchgrass, and discussed various techniques employed to improve the transformation efficiency. Finally we reviewed the recent progresses on the use of genetic transformation in improving biomass quality such as the reduction of lignin, and in increasing biomass yield in switchgrass. We also provided a future perspective on the use of new genome editing technologies in switchgrass and its potential impact on regulatory processes.
基金provided by the Ministry of Science and Technology, China (2012AA101801, 2014BAD23B00)the National Natural Science Foundation of China(31272493)China Agricultural University (2014FG062)
文摘Genes encoding enzymes involved in the lignin biosynthesis through phenylpropanoid pathway were not only associated with the lignin content, but also related to the abiotic stress resistances. As far as the production of liquid biofuels and cultivation within the marginal land are concerned, switchgrass could be the better candidate to determine the relationship between lower lignin content and physiological function under stress. Caffeoyl-coenzyme A 3-O-methyltransferase（CCoAOMT） is a key enzyme for the methylation reaction of lignin biosynthesis. For this purpose, we cloned a CCoAOMT gene from switchgrass and identified its expression patterns under abiotic stresses. The full-length CCoAOMT gene, designated PvCCoAOMT（Gen Bank accession no. KF041775）, was 1 005-bp in length, has an opening reading frame of 777 nucleotides encoding a 258-amino acid protein. The deduced amino acid sequence of PvCCoAOMT shared a high degree of similarity（up to 98%） with CCoAOMTs from Panicum virgatum allele（BAO20881）, Sorghum bicolor（XP002436550） and Zea mays（NP001131288）. Using quantitative real-time PCR（qRT-PCR）, the significant upregulation of PvCCoAOMT was observed in stem tissues at a later stage（24 h） after drought treatment, with the transcript level increasing 33-fold compared that of the controls. Moderate and insignificant inductions of PvCCoAOMT were also observed in both stems and leaves during the later stages after cold（48 h in stems, 12 h in leaves） and mechanical wounding（48 h in stems, 12 h in leaves） treatments, respectively. Our results showed the different expression patterns of PvCCoAOMT in drought, cold and mechanical wounding stresses. PvCCoAOMT can be highly induced by drought and cold stresses, which indicates that it may play a role in plant abiotic stress resistance, particularly in the regulation of drought and cold resistance.
基金supported by the "100-Talent Program of the Chinese Academy of Sciences" foundationthe National Natural Science Foundation of China (31470390)the National Key Technologies Research & Development Program-Seven Major Crop Breeding Project (2016YFD0101803)
文摘Caffeic acid O-methyltransferase(COMT) is a crucial enzyme that mainly methylates phenylpropanoid meta-hydroxyl of C5 in the biosynthesis of syringyl lignin in angiosperms. A putative COMT, named as PvCOMT1,was isolated from switchgrass(Panicum virgatum), a C4 warm-season dual-purpose forage and bioenergy crop. Our results showed that recombinant PvCOMT1 enzyme protein catalyzed the methylation of 5-OH coniferyl alcohol, 5-OH coniferaldehyde(CAld5H) and 5-OH ferulic acid. Further in vitro studies indicate that CAld5H can dominate COMT-mediated reactions by inhibiting the methylation of the other substrates. Transgenic switchgrass plants generated by an RNAi approach were further employed to study the function of COMT in internode lignification. A dramatic decrease in syringyl lignin units coupled with an obvious incorporation in 5-OH guaiacyl lignin units were observed in the COMT-RNAi transgenic plants. However, the constitutive suppression of COMT in switchgrass plants altered neither the pattern of lignin deposition along the stem nor the anatomical structure of internodes. Consistent with the biochemical characterization of PvCOMT1, a significant decrease in sinapaldehyde was found in the COMT-RNAi transgenic switchgrass plants, suggesting that CAld5H could be the optimal intermediate in the biosynthesis syringyl lignin.
