Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However,the immaturity of its stable transformation system and its low transformation ...Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However,the immaturity of its stable transformation system and its low transformation efficiency limit gene function research on non-heading Chinese cabbage. Agrobacterium rhizogenes-mediated(ARM) transgenic technology is a rapid and effective transformation method that has not yet been established for non-heading Chinese cabbage plants. Here, we optimized conventional ARM approaches(one-step and two-step transformation methods) suitable for living non-heading Chinese cabbage plants in nonsterile environments. Transgenic roots in composite non-heading Chinese cabbage plants were identified using phenotypic detection, fluorescence observation, and PCR analysis. The transformation efficiency of a two-step method on four five-day-old non-heading Chinese cabbage seedlings(Suzhouqing, Huangmeigui, Wuyueman, and Sijiu Caixin) was 43.33%-51.09%, whereas using the stout hypocotyl resulted in a transformation efficiency of 54.88% for the 30-day-old Sijiu Caixin.The one-step method outperformed the two-step method;the transformation efficiency of different varieties was above 60%, and both methods can be used to obtain transgenic roots for functional studies within one month. Finally, optimized ARM transformation methods can easily,quickly, and effectively produce composite non-heading Chinese cabbage plants with transgenic roots, providing a reliable foundation for gene function research and non-heading Chinese cabbage genetic improvement breeding.展开更多
Pitting corrosion often occurs due to the presence of various corrosive substances,such as CO_(2) and H_(2)S,in the pipe service environment.As a result of this process,the residual strength of oil pipes is reduced an...Pitting corrosion often occurs due to the presence of various corrosive substances,such as CO_(2) and H_(2)S,in the pipe service environment.As a result of this process,the residual strength of oil pipes is reduced and this can compromise the integrity of the entire pipe string.In the present work,a model is introduced on the basis of the API579 standard to determine the so-called stress concentration coefficient.The model accounts for pitting corrosion shapes such as shallow semi-circles,semi-circles,and deep semi-circles.The relationship between the corrosion pit depth and opening diameter and the residual strength of the oil casing is obtained.The results show that the influence of the pit opening diameter on the stress concentration coefficient is smaller than that of the pit depth.For a constant pit opening diameter,the coefficient increases gradually with increasing the pit depth.The compressive strength and internal pressure strength of the carbon steel oil casing decrease accordingly.When the depth of the corrosion pit is relatively small,the growth of the coefficient is slower;when the depth of the corrosion pit increases to a certain value,the increase in stress concentration coefficient becomes obvious.展开更多
[ Objectives ] This study was conducted to investigate the genetic diversity of 20 lotus （Nelumbo nucifera Gaertn） samples. [ Methods ] On this optimal ISSR amplification system, 16 primers were screened with good p...[ Objectives ] This study was conducted to investigate the genetic diversity of 20 lotus （Nelumbo nucifera Gaertn） samples. [ Methods ] On this optimal ISSR amplification system, 16 primers were screened with good polymorphism, and the DNA was used to amplify the 20 plant samples. [ R^ults] The 16 primers produced 225 loci, of which 170 were polymorphic, and the polymorphic loci percentage was up to 75.56%. The genetic similarity coefficients between the 20 vari- eties ranged from 0. 577 8 to 0.951 1, which were calculated by POPGENE32. The 20 varieties by UPMGA analysis could be clustered into 2 groups, the first of which included Baiyangdian red lotus and Donggua lotus, and other varieties was included in the second group. [ Conchmions] ISSR molecular markers could be effectively used in genetic diversity and fingerprint analysis for different lotus varieties.展开更多
Dendrocalamus latiflorus Munro is a woody clumping bamboo with rapid shoot growth.Both genetic transformation and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)gene...Dendrocalamus latiflorus Munro is a woody clumping bamboo with rapid shoot growth.Both genetic transformation and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)gene editing techniques are available for D.latiflorus,enabling reverse genetic approaches.Thus,D.latiflorus has the potential to be a model bamboo species.However,the genome sequence of D.latiflorus has remained unreported due to its polyploidy and large genome size.Here,we sequenced the D.latiflorus genome and assembled it into three allele-aware subgenomes(AABBCC),representingthe largest genome of a major bamboo species.We assembled 70 allelic chromosomes(2,737 Mb)for hexaploid D.latiflorus using both singlemolecule sequencing from the Pacific Biosciences(Pac Bio)Sequel platform and chromosome conformation capture sequencing(Hi-C).Repetitive sequences comprised 52.65%of the D.latiflorus genome.We annotated 135231 protein-coding genes in the genome based on transcriptomes from eight different tissues.Transcriptome sequencing using RNA-Seq and Pac Bio singlemolecule real-time long-read isoform sequencing revealed highly differential alternative splicing(AS)between non-abortive and abortive shoots,suggesting that AS regulates the abortion rate of bamboo shoots.This high-quality hexaploid genome and comprehensive strand-specific transcriptome datasets for this Poaceae family member will pave the way for bamboo research using D.latiflorus as a model species.展开更多
N6-methyladenosine(m^(6)A)is a prevalent modification in messenger RNAs and circular RNAs that play important roles in regulating various aspects of RNA metabolism.However,the occurrence of the m^(6)A modification in ...N6-methyladenosine(m^(6)A)is a prevalent modification in messenger RNAs and circular RNAs that play important roles in regulating various aspects of RNA metabolism.However,the occurrence of the m^(6)A modification in plant circular RNAs has not been reported.A widely used method to identify m^(6)A modifications relies on m^(6)A-specific antibodies followed by next-generation sequencing of precipitated RNAs(MeRIP-Seq).However,one limitation of MeRIP-Seq is that it does not provide the precise location of m^(6)A at single-nucleotide resolution.Although more recent sequencing techniques such as Nanopore-based direct RNA sequencing(DRS)can overcome such limitations,the technology does not allow sequencing of circular RNAs,as these molecules lack a poly(A)tail.Here,we developed a novel method to detect the precise location of m^(6)A modifications in circular RNAs using Nanopore DRS.We first enriched our samples for circular RNAs,which we then fragmented and sequenced on the Nanopore platform with a customized protocol.Using this method,we identified 470 unique circular RNAs from DRS reads based on the back-spliced junction region.Among exonic circular RNAs,about 10%contained m^(6)A sites,which mainly occurred around acceptor and donor splice sites.This study demonstrates the utility of our antibody-independent method in identifying total and methylated circular RNAs using Nanopore DRS.This method has the additional advantage of providing the exact location of m^(6)A sites at single-base resolution in circular RNAs or linear transcripts from non-coding RNA without poly(A)tails.展开更多
基金funded by National Natural Science Foundation of China (Grant No.32072575)Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No.KYCX20_0588)National Vegetable Industry Technology System (Grant No.CARS-23-A16)。
文摘Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However,the immaturity of its stable transformation system and its low transformation efficiency limit gene function research on non-heading Chinese cabbage. Agrobacterium rhizogenes-mediated(ARM) transgenic technology is a rapid and effective transformation method that has not yet been established for non-heading Chinese cabbage plants. Here, we optimized conventional ARM approaches(one-step and two-step transformation methods) suitable for living non-heading Chinese cabbage plants in nonsterile environments. Transgenic roots in composite non-heading Chinese cabbage plants were identified using phenotypic detection, fluorescence observation, and PCR analysis. The transformation efficiency of a two-step method on four five-day-old non-heading Chinese cabbage seedlings(Suzhouqing, Huangmeigui, Wuyueman, and Sijiu Caixin) was 43.33%-51.09%, whereas using the stout hypocotyl resulted in a transformation efficiency of 54.88% for the 30-day-old Sijiu Caixin.The one-step method outperformed the two-step method;the transformation efficiency of different varieties was above 60%, and both methods can be used to obtain transgenic roots for functional studies within one month. Finally, optimized ARM transformation methods can easily,quickly, and effectively produce composite non-heading Chinese cabbage plants with transgenic roots, providing a reliable foundation for gene function research and non-heading Chinese cabbage genetic improvement breeding.
基金supported by CNPC Forward-Looking Basic Strategic Technology Research Projects(Nos.2021DJ6504,2021DJ6501,2021DJ6502&2021DJ0806)received by Bo Zhang.
文摘Pitting corrosion often occurs due to the presence of various corrosive substances,such as CO_(2) and H_(2)S,in the pipe service environment.As a result of this process,the residual strength of oil pipes is reduced and this can compromise the integrity of the entire pipe string.In the present work,a model is introduced on the basis of the API579 standard to determine the so-called stress concentration coefficient.The model accounts for pitting corrosion shapes such as shallow semi-circles,semi-circles,and deep semi-circles.The relationship between the corrosion pit depth and opening diameter and the residual strength of the oil casing is obtained.The results show that the influence of the pit opening diameter on the stress concentration coefficient is smaller than that of the pit depth.For a constant pit opening diameter,the coefficient increases gradually with increasing the pit depth.The compressive strength and internal pressure strength of the carbon steel oil casing decrease accordingly.When the depth of the corrosion pit is relatively small,the growth of the coefficient is slower;when the depth of the corrosion pit increases to a certain value,the increase in stress concentration coefficient becomes obvious.
基金Supported by the Education Department Project of Fujian Province(JB11039)
文摘[ Objectives ] This study was conducted to investigate the genetic diversity of 20 lotus （Nelumbo nucifera Gaertn） samples. [ Methods ] On this optimal ISSR amplification system, 16 primers were screened with good polymorphism, and the DNA was used to amplify the 20 plant samples. [ R^ults] The 16 primers produced 225 loci, of which 170 were polymorphic, and the polymorphic loci percentage was up to 75.56%. The genetic similarity coefficients between the 20 vari- eties ranged from 0. 577 8 to 0.951 1, which were calculated by POPGENE32. The 20 varieties by UPMGA analysis could be clustered into 2 groups, the first of which included Baiyangdian red lotus and Donggua lotus, and other varieties was included in the second group. [ Conchmions] ISSR molecular markers could be effectively used in genetic diversity and fingerprint analysis for different lotus varieties.
基金supported by the National Key Research and Development Program of China(2018YFD0600104)the National Natural Science Foundation of China Grant(31971734)+3 种基金the Natural Science Foundation of Fujian Province(Grant No.2021J02027)the Distinguished Young Scholar Program of Fujian Agriculture and Forestry University(Grant No.xjq202017)the Technological Innovation Team at the University of Fujian provincethe Forestry Peak Discipline Construction Project from Fujian Agriculture and Forestry University。
文摘Dendrocalamus latiflorus Munro is a woody clumping bamboo with rapid shoot growth.Both genetic transformation and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)gene editing techniques are available for D.latiflorus,enabling reverse genetic approaches.Thus,D.latiflorus has the potential to be a model bamboo species.However,the genome sequence of D.latiflorus has remained unreported due to its polyploidy and large genome size.Here,we sequenced the D.latiflorus genome and assembled it into three allele-aware subgenomes(AABBCC),representingthe largest genome of a major bamboo species.We assembled 70 allelic chromosomes(2,737 Mb)for hexaploid D.latiflorus using both singlemolecule sequencing from the Pacific Biosciences(Pac Bio)Sequel platform and chromosome conformation capture sequencing(Hi-C).Repetitive sequences comprised 52.65%of the D.latiflorus genome.We annotated 135231 protein-coding genes in the genome based on transcriptomes from eight different tissues.Transcriptome sequencing using RNA-Seq and Pac Bio singlemolecule real-time long-read isoform sequencing revealed highly differential alternative splicing(AS)between non-abortive and abortive shoots,suggesting that AS regulates the abortion rate of bamboo shoots.This high-quality hexaploid genome and comprehensive strand-specific transcriptome datasets for this Poaceae family member will pave the way for bamboo research using D.latiflorus as a model species.
基金This work was supported by the National Key Researchand Development Program of China(2018YFD0600101)the National Natural Science Foundation of China Grant(Grant No.31971734)and Program for scientific andtechnological innovation team in University of Fujianprovince(No.118/KLA18069A).
文摘N6-methyladenosine(m^(6)A)is a prevalent modification in messenger RNAs and circular RNAs that play important roles in regulating various aspects of RNA metabolism.However,the occurrence of the m^(6)A modification in plant circular RNAs has not been reported.A widely used method to identify m^(6)A modifications relies on m^(6)A-specific antibodies followed by next-generation sequencing of precipitated RNAs(MeRIP-Seq).However,one limitation of MeRIP-Seq is that it does not provide the precise location of m^(6)A at single-nucleotide resolution.Although more recent sequencing techniques such as Nanopore-based direct RNA sequencing(DRS)can overcome such limitations,the technology does not allow sequencing of circular RNAs,as these molecules lack a poly(A)tail.Here,we developed a novel method to detect the precise location of m^(6)A modifications in circular RNAs using Nanopore DRS.We first enriched our samples for circular RNAs,which we then fragmented and sequenced on the Nanopore platform with a customized protocol.Using this method,we identified 470 unique circular RNAs from DRS reads based on the back-spliced junction region.Among exonic circular RNAs,about 10%contained m^(6)A sites,which mainly occurred around acceptor and donor splice sites.This study demonstrates the utility of our antibody-independent method in identifying total and methylated circular RNAs using Nanopore DRS.This method has the additional advantage of providing the exact location of m^(6)A sites at single-base resolution in circular RNAs or linear transcripts from non-coding RNA without poly(A)tails.
