Grasslands are one of the major biomes on Earth,covering approximately 25%of the terrestrial planet.Human history is deeply intertwined with grassland biomes,where we,as a natural species,first walked upright 2 millio...Grasslands are one of the major biomes on Earth,covering approximately 25%of the terrestrial planet.Human history is deeply intertwined with grassland biomes,where we,as a natural species,first walked upright 2 million years ago.Today,grassland ecosystems continue to play an important role in people's livelihoods by producing meat and dairy products,providing habitats for biodiversity,and delivering essential ecosystem services such as climate regulation and cultural heritage.展开更多
In the present study, the phosphorus-absorption capacity of transgenic Arabidopsis plants ectopically ex- pressing a novel phytase gene from Medicago truncatula Barrel Medic was evaluated. A full-length cDNA encoding ...In the present study, the phosphorus-absorption capacity of transgenic Arabidopsis plants ectopically ex- pressing a novel phytase gene from Medicago truncatula Barrel Medic was evaluated. A full-length cDNA encoding an extracellular form of phytase was isolated from the model legume M. truncatula. The phytase gene (MtPHY1) has an open reading frame of I 632 bp predicted to encode 543 amino acids, including an N- terminal signal peptide of 27 amino acids. The genomic sequence of the MtPHY1 gene is 5 151 bp, containing seven exons interrupted by six introns. Under high-Pi (2 mmol/L) growth conditions, higher levels of MtPHY1 transcripts accumulated in the leaf and stem than in the root. The transcript level was reduced in the stem and increased in the root, with no obvious changes in the hybridization signal detected in the leaf under IowPi (10 pmol/L) conditions. Chimeric transgenes were constructed by placing MtPHY1 under the control of the constitutive CaMV35S promoter and the root-specific MtPT1 promoter. Phytase activities in root apoplast of transgenic Arabidopsis were 12.3- to 16.2-fold of that in control plants. The phytase expressed was secreted into the rhizosphere, as demonstrated by HPLC analysis of phytate degradation by root exudates. Ectopic expression of MtPHY1 in Arabidopsis, leading to significant improvement in organic phosphorus absorption and plant growth, indicated that MtPHY1 has great potential for improving plant phosphorus absorption and phytoremediation.展开更多
A novel purple acid phosphatase gene (MtPAP1) was Isolated from the model legume Medicago truncatula Barrel Medic. The cDNA was 1 698 bp In length with an open reading frame (ORF) of 1 398 bp capable of encoding a...A novel purple acid phosphatase gene (MtPAP1) was Isolated from the model legume Medicago truncatula Barrel Medic. The cDNA was 1 698 bp In length with an open reading frame (ORF) of 1 398 bp capable of encoding an N-terminal signal peptlde of 23 amino acids. The transcripts of MtPAP1 were mainly detected In leaves under high-phosphate conditions, whereas under low-phosphate conditions the transcript level was reduced In leaves and Increased In roots, with the strongest hybridization signal detected In roots. A chimeric gene construct fusing MtPAP1 and GFPwas made In which the fusion was driven by the CaMV35S promoter. Transgenlc Arabidopsis plants carrying the chimeric gene constructs showed that the fusion protein was mainly located at the apoplast based on confocal mlcroecoplc analysis, showing that MtPAP1 could be secreted to the outside of the cell directed by the signal peptlde at the N-terminal. The coding region of MtPAP1 without signal peptlde was Inserted Into the prokaryotlc expression vector pET-30a (+) and overexpressed In Escherichla coil BL21 (DE3). The acid phosphatase (APase) proteins extracted from bacterial culture were found largely based on sodium dodecyl sulfate-polyecrylamlde gel electrophoresls. An enzyme activity assay demonstrated that the APase activity In the transformed bacteria was 3.16-fold higher than that of control. The results Imply that MtPAP1 functions to Improve phosphorus acquisition In plants under conditions of phosphorus (P) stress.展开更多
Chloroplasts most likely originated from the endosymbiosis of cyanobacterial ancestors,entering the eukaryotic lineage about 1.0-1.5 billion years ago(Parfrey et al.,2011;Archibald,2015).Consequently,their biogenesis ...Chloroplasts most likely originated from the endosymbiosis of cyanobacterial ancestors,entering the eukaryotic lineage about 1.0-1.5 billion years ago(Parfrey et al.,2011;Archibald,2015).Consequently,their biogenesis depends on genetic information from both the nuclear and chloroplast genomes.Photosynthetic housekeeping genes of core components in photosystemsⅠandⅡ(PSI and PSII)are encoded by the plastid genome。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
Genome editing is an advanced genetic modification tool that facilitates the removal,insertion,or substitution of nucleotides in the genome of an organism for mutation induction.CRISPR/Cas9(clustered regularly intersp...Genome editing is an advanced genetic modification tool that facilitates the removal,insertion,or substitution of nucleotides in the genome of an organism for mutation induction.CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9)is the most widely used genome editing tool that can precisely modify the specific sequence of a genome.Significant progress has been made in the use of CRISPR/Cas9 for the genetic improvement of food crops.However,in forage crops,the use of CRISPR/Cas9 is still in the infant stage with limited understanding and application.This article reviews current advances in the establishment and application of the CRISPR/Cas9 system in alfalfa,summarizes the application of CRISPR/Cas9 in several other forage legume and grass species,and discusses the prospects of CRISPR/Cas9 in the genetic improvement of forage crops.展开更多
文摘Grasslands are one of the major biomes on Earth,covering approximately 25%of the terrestrial planet.Human history is deeply intertwined with grassland biomes,where we,as a natural species,first walked upright 2 million years ago.Today,grassland ecosystems continue to play an important role in people's livelihoods by producing meat and dairy products,providing habitats for biodiversity,and delivering essential ecosystem services such as climate regulation and cultural heritage.
基金Supported by the Samuel Roberts Noble Foundation and the Hebei Provincial Natural Science Foundation of China (300112).
文摘In the present study, the phosphorus-absorption capacity of transgenic Arabidopsis plants ectopically ex- pressing a novel phytase gene from Medicago truncatula Barrel Medic was evaluated. A full-length cDNA encoding an extracellular form of phytase was isolated from the model legume M. truncatula. The phytase gene (MtPHY1) has an open reading frame of I 632 bp predicted to encode 543 amino acids, including an N- terminal signal peptide of 27 amino acids. The genomic sequence of the MtPHY1 gene is 5 151 bp, containing seven exons interrupted by six introns. Under high-Pi (2 mmol/L) growth conditions, higher levels of MtPHY1 transcripts accumulated in the leaf and stem than in the root. The transcript level was reduced in the stem and increased in the root, with no obvious changes in the hybridization signal detected in the leaf under IowPi (10 pmol/L) conditions. Chimeric transgenes were constructed by placing MtPHY1 under the control of the constitutive CaMV35S promoter and the root-specific MtPT1 promoter. Phytase activities in root apoplast of transgenic Arabidopsis were 12.3- to 16.2-fold of that in control plants. The phytase expressed was secreted into the rhizosphere, as demonstrated by HPLC analysis of phytate degradation by root exudates. Ectopic expression of MtPHY1 in Arabidopsis, leading to significant improvement in organic phosphorus absorption and plant growth, indicated that MtPHY1 has great potential for improving plant phosphorus absorption and phytoremediation.
基金Supported by the Samuel Roberts Noble Foundation and the Hebei Provincial Natural Science Foundation of China (300112).
文摘A novel purple acid phosphatase gene (MtPAP1) was Isolated from the model legume Medicago truncatula Barrel Medic. The cDNA was 1 698 bp In length with an open reading frame (ORF) of 1 398 bp capable of encoding an N-terminal signal peptlde of 23 amino acids. The transcripts of MtPAP1 were mainly detected In leaves under high-phosphate conditions, whereas under low-phosphate conditions the transcript level was reduced In leaves and Increased In roots, with the strongest hybridization signal detected In roots. A chimeric gene construct fusing MtPAP1 and GFPwas made In which the fusion was driven by the CaMV35S promoter. Transgenlc Arabidopsis plants carrying the chimeric gene constructs showed that the fusion protein was mainly located at the apoplast based on confocal mlcroecoplc analysis, showing that MtPAP1 could be secreted to the outside of the cell directed by the signal peptlde at the N-terminal. The coding region of MtPAP1 without signal peptlde was Inserted Into the prokaryotlc expression vector pET-30a (+) and overexpressed In Escherichla coil BL21 (DE3). The acid phosphatase (APase) proteins extracted from bacterial culture were found largely based on sodium dodecyl sulfate-polyecrylamlde gel electrophoresls. An enzyme activity assay demonstrated that the APase activity In the transformed bacteria was 3.16-fold higher than that of control. The results Imply that MtPAP1 functions to Improve phosphorus acquisition In plants under conditions of phosphorus (P) stress.
基金supported by the National Natural Science Foundation of China(31671336 and 31972958)the Start-Up Funds for High Level Talents of Qingdao Agricultural University(663-1120001)the First Class Grassland Science Discipline Program of Shandong Province,China。
文摘Chloroplasts most likely originated from the endosymbiosis of cyanobacterial ancestors,entering the eukaryotic lineage about 1.0-1.5 billion years ago(Parfrey et al.,2011;Archibald,2015).Consequently,their biogenesis depends on genetic information from both the nuclear and chloroplast genomes.Photosynthetic housekeeping genes of core components in photosystemsⅠandⅡ(PSI and PSII)are encoded by the plastid genome。
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.
基金National Natural Science Foundation of China(U1906201).
文摘Genome editing is an advanced genetic modification tool that facilitates the removal,insertion,or substitution of nucleotides in the genome of an organism for mutation induction.CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9)is the most widely used genome editing tool that can precisely modify the specific sequence of a genome.Significant progress has been made in the use of CRISPR/Cas9 for the genetic improvement of food crops.However,in forage crops,the use of CRISPR/Cas9 is still in the infant stage with limited understanding and application.This article reviews current advances in the establishment and application of the CRISPR/Cas9 system in alfalfa,summarizes the application of CRISPR/Cas9 in several other forage legume and grass species,and discusses the prospects of CRISPR/Cas9 in the genetic improvement of forage crops.