The lemon(Citrus limon;family Rutaceae)is one of the most important and popular fruits worldwide.Lemon also tolerates huan-glongbing(HLB)disease,which is a devastating citrus disease.Here we produced a gap-free and ha...The lemon(Citrus limon;family Rutaceae)is one of the most important and popular fruits worldwide.Lemon also tolerates huan-glongbing(HLB)disease,which is a devastating citrus disease.Here we produced a gap-free and haplotype-resolved chromosome-scale genome assembly of the lemon by combining Pacific Biosciences circular consensus sequencing,Oxford Nanopore 50-kb ultra-long,and high-throughput chromatin conformation capture technologies.The assembly contained nine-pair chromosomes with a contig N50 of 35.6 Mb and zero gaps,while a total of 633.0 Mb genomic sequences were generated.The origination analysis identified 338.5Mb genomic sequences originating from citron(53.5%),147.4Mb frommandarin(23.3%),and 147.1Mb frompummelo(23.2%).The genome included 30528 protein-coding genes,and most of the assembled sequences were found to be repetitive sequences.Several significantly expanded gene families were associated with plant-pathogen interactions,plant hormone signal transduction,and the biosynthesis of major active components,such as terpenoids and f lavor compounds.Most HLB-tolerant genes were expanded in the lemon genome,such as 2-oxoglutarate(2OG)/Fe(II)-dependent oxygenase and constitutive disease resistance 1,cell wall-related genes,and lignin synthesis genes.Comparative transcriptomic analysis showed that phloem regeneration and lower levels of phloem plugging are the elements that contribute to HLB tolerance in lemon.Our results provide insight into lemon genome evolution,active component biosynthesis,and genes associated with HLB tolerance.展开更多
In order to study the effect of copper ion implantation on the aqueous corrosion behavior of ZIRLO alloy, specimens were implanted with copper ions with fluences ranging from 1×10^16 to 1×10^ ions/cm^2, usin...In order to study the effect of copper ion implantation on the aqueous corrosion behavior of ZIRLO alloy, specimens were implanted with copper ions with fluences ranging from 1×10^16 to 1×10^ ions/cm^2, using a metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV, The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the copper ion implantation. The potcntiodynamic polarization technique was used to evaluate the aqueous corrosion resistance of implanted ZIRLO alloy in a 1 mol/L H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of ZIRLO alloy implanted with copper ions when the fluence is 5×10^16 ions/cm^2. When the fluence is 1×10^16 or 1×10^17 ions/cm^2, the corrosion resistance of implanted sanaples was bad. Finally, the mechanism of the corrosion behavior of copper-implanted ZIRLO alloy was discussed.展开更多
Soil organic nitrogen(ON)accounts for more than 90%of the total nitrogen(TN)in paddy soils.Inadequate understanding of the different ON fractions in paddy soils and their corresponding bioavailability under different ...Soil organic nitrogen(ON)accounts for more than 90%of the total nitrogen(TN)in paddy soils.Inadequate understanding of the different ON fractions in paddy soils and their corresponding bioavailability under different climatic conditions has constrained the development of appropriate nutrient management strategies for rice production.In this study,we applied a modified Bremner method coupled with high-performance liquid chromatography to characterize how soil ON fractions and amino acid chirality varied under different climatic conditions at five typical rice production sites along a latitudinal gradient.According to the results,climate had no obvious influence on TN,nitrogen(N)form,and individual amino acid contents.However,the proportions of various N forms in TN had linear relationships with annual mean temperature(AMT),with high correlation coefficient(r)values.Amino acid components also exhibited similar trends,with r as high as 0.85.Most notably,consistent linear relationships were observed between the D/L ratios of several amino acids and AMT in paddy soils(r=0.18–0.92).Findings of this study provide insights into ON and amino acid dynamics in paddy soil systems under intensive production along climate gradients.展开更多
基金supported by the Guangxi Major Project of Science and Technology(Guike AA18118027)the Postdoctoral Project of Hainan Yazhou Bay Seed Laboratory Program(B21Y10203)the Scientific Research and Development Fund of the College of Agriculture,Guangxi University(EE101731).
文摘The lemon(Citrus limon;family Rutaceae)is one of the most important and popular fruits worldwide.Lemon also tolerates huan-glongbing(HLB)disease,which is a devastating citrus disease.Here we produced a gap-free and haplotype-resolved chromosome-scale genome assembly of the lemon by combining Pacific Biosciences circular consensus sequencing,Oxford Nanopore 50-kb ultra-long,and high-throughput chromatin conformation capture technologies.The assembly contained nine-pair chromosomes with a contig N50 of 35.6 Mb and zero gaps,while a total of 633.0 Mb genomic sequences were generated.The origination analysis identified 338.5Mb genomic sequences originating from citron(53.5%),147.4Mb frommandarin(23.3%),and 147.1Mb frompummelo(23.2%).The genome included 30528 protein-coding genes,and most of the assembled sequences were found to be repetitive sequences.Several significantly expanded gene families were associated with plant-pathogen interactions,plant hormone signal transduction,and the biosynthesis of major active components,such as terpenoids and f lavor compounds.Most HLB-tolerant genes were expanded in the lemon genome,such as 2-oxoglutarate(2OG)/Fe(II)-dependent oxygenase and constitutive disease resistance 1,cell wall-related genes,and lignin synthesis genes.Comparative transcriptomic analysis showed that phloem regeneration and lower levels of phloem plugging are the elements that contribute to HLB tolerance in lemon.Our results provide insight into lemon genome evolution,active component biosynthesis,and genes associated with HLB tolerance.
基金This work was financially supported by the National Natural Science Foundation of China (No.50501011), the Ministry of Science andTechnology of China for Research Founding (MSTC No.G 2000067207-1), and the Postdoctoral Research Foundation of China (37thbatch, No.2005037079).
文摘In order to study the effect of copper ion implantation on the aqueous corrosion behavior of ZIRLO alloy, specimens were implanted with copper ions with fluences ranging from 1×10^16 to 1×10^ ions/cm^2, using a metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV, The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the copper ion implantation. The potcntiodynamic polarization technique was used to evaluate the aqueous corrosion resistance of implanted ZIRLO alloy in a 1 mol/L H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of ZIRLO alloy implanted with copper ions when the fluence is 5×10^16 ions/cm^2. When the fluence is 1×10^16 or 1×10^17 ions/cm^2, the corrosion resistance of implanted sanaples was bad. Finally, the mechanism of the corrosion behavior of copper-implanted ZIRLO alloy was discussed.
基金supported by the National Natural Science Foundation of China(No.41671296)Special Project on the Basis of National Science and Technology of China(No.2015FY110700).
文摘Soil organic nitrogen(ON)accounts for more than 90%of the total nitrogen(TN)in paddy soils.Inadequate understanding of the different ON fractions in paddy soils and their corresponding bioavailability under different climatic conditions has constrained the development of appropriate nutrient management strategies for rice production.In this study,we applied a modified Bremner method coupled with high-performance liquid chromatography to characterize how soil ON fractions and amino acid chirality varied under different climatic conditions at five typical rice production sites along a latitudinal gradient.According to the results,climate had no obvious influence on TN,nitrogen(N)form,and individual amino acid contents.However,the proportions of various N forms in TN had linear relationships with annual mean temperature(AMT),with high correlation coefficient(r)values.Amino acid components also exhibited similar trends,with r as high as 0.85.Most notably,consistent linear relationships were observed between the D/L ratios of several amino acids and AMT in paddy soils(r=0.18–0.92).Findings of this study provide insights into ON and amino acid dynamics in paddy soil systems under intensive production along climate gradients.
