2012 Vol. 30 No. 5
2012, 30(5): 431-436.
DOI: 10.3724/SP.J.1142.2012.50431
Abstract：
Based on previous study of Orobanchaceae,we added sequence data of the genus Cistanche,used maximum parsimony,maximum likelihood and Bayesian inference to perform phylogenetic analysis,and investigated the systematic position of Cistanche in Orobanchaceae, as well as the generic relationships within Orobanchaceae. The phylogenetic trees respectively basing on sequences of rps16 and rps16+ITS revealed that Cistanche,Orobanche,and Boschniakia formed a one single clade,Cistanche was a sister to Orobanche,and holoparasi-tic,semiparasitic and non-parasitic taxon in Orobanchaceae fell into three separate clades.
Based on previous study of Orobanchaceae,we added sequence data of the genus Cistanche,used maximum parsimony,maximum likelihood and Bayesian inference to perform phylogenetic analysis,and investigated the systematic position of Cistanche in Orobanchaceae, as well as the generic relationships within Orobanchaceae. The phylogenetic trees respectively basing on sequences of rps16 and rps16+ITS revealed that Cistanche,Orobanche,and Boschniakia formed a one single clade,Cistanche was a sister to Orobanche,and holoparasi-tic,semiparasitic and non-parasitic taxon in Orobanchaceae fell into three separate clades.
2012, 30(5): 437-442.
DOI: 10.3724/SP.J.1142.2012.50437
Abstract：
Anatomy of the Cycas revoluta seed coat showed that the episperm included sarcotesta,mesotesta and endotesta layers.The sarcotesta layer contained horny epidermis cells,parenchyma cells,as well as a few cells with thickened walls and idioblasts,resin canals,air chambers,and four big vascular bundles.The mesotesta was comprised of sclereids and lignified fiber,with a suture at one end and three holes at the other end.The endotesta had layers of wizened parenchyma cells and veining vascular bundles,and an elliptic membrane preserving its micropyle.Obvious differences were observed between the vascular bundles of the sarcotesta and endotesta.The vascular bundles of sarcotesta appeared to move in an arc along the seed from the hilum side down to the micropyle side.The vascular bundles of endotesta formed the veining net.There were a variety of vessels in both.
Anatomy of the Cycas revoluta seed coat showed that the episperm included sarcotesta,mesotesta and endotesta layers.The sarcotesta layer contained horny epidermis cells,parenchyma cells,as well as a few cells with thickened walls and idioblasts,resin canals,air chambers,and four big vascular bundles.The mesotesta was comprised of sclereids and lignified fiber,with a suture at one end and three holes at the other end.The endotesta had layers of wizened parenchyma cells and veining vascular bundles,and an elliptic membrane preserving its micropyle.Obvious differences were observed between the vascular bundles of the sarcotesta and endotesta.The vascular bundles of sarcotesta appeared to move in an arc along the seed from the hilum side down to the micropyle side.The vascular bundles of endotesta formed the veining net.There were a variety of vessels in both.
2012, 30(5): 443-458.
DOI: 10.3724/SP.J.1142.2012.50443
Abstract：
Grimmia and Racomitrium are two important genera of the family Grimmiaceae (Musci,Bryophyta).To predict and compare their potential distribution regions in relation to climatic conditions in China,and thereby help their conservation and subsequent field investigations,we modeled the geographical distribution at the genus level by using a maximum entropy algorithm modeling program (MaxEnt) based on 172 presence-only data for Grimmia and 181 data for Racomitrium,as well as 19 bioclimatic variables.We found Grimmia had higher habitat suitability in Zhejiang (0.7099,integrated habitat suitability index),Jiangsu (0.6212),Beijing (0.5987),Tianjin (0.5648),Yunnan (0.5532),Liaoning (0.5515),Taiwan (0.5422),Anhui (0.5398),and Jilin (0.4945),while Racomitrium had higher habitat suitability in Zhejiang (0.889),Shanghai (0.6564),Hong Kong (0.5897),Taiwan (0.5858),Guizhou (0.5354),Hubei (0.5039),Yunnan (0.4885),Chongqing (0.4871),Jiangsu (0.4793),and Anhui (0.4552).Comparison between the predicted distribution of Racomitrium and that of Grimmia showed that Racomitrium had higher distribution probability in Hong Kong,Chongqing,Guizhou,Guangdong,Guangxi,Hubei,Hainan,and Taiwan than Grimmia,similar distribution probability to that of Grimmia in Jiangxi,Fujian,Hunan,and lower than Grimmia in the other provinces (municipality autonomous regions).Grimmia belonged to the typical moderate geographical element,mainly in the high altitude and cold districts.
Grimmia and Racomitrium are two important genera of the family Grimmiaceae (Musci,Bryophyta).To predict and compare their potential distribution regions in relation to climatic conditions in China,and thereby help their conservation and subsequent field investigations,we modeled the geographical distribution at the genus level by using a maximum entropy algorithm modeling program (MaxEnt) based on 172 presence-only data for Grimmia and 181 data for Racomitrium,as well as 19 bioclimatic variables.We found Grimmia had higher habitat suitability in Zhejiang (0.7099,integrated habitat suitability index),Jiangsu (0.6212),Beijing (0.5987),Tianjin (0.5648),Yunnan (0.5532),Liaoning (0.5515),Taiwan (0.5422),Anhui (0.5398),and Jilin (0.4945),while Racomitrium had higher habitat suitability in Zhejiang (0.889),Shanghai (0.6564),Hong Kong (0.5897),Taiwan (0.5858),Guizhou (0.5354),Hubei (0.5039),Yunnan (0.4885),Chongqing (0.4871),Jiangsu (0.4793),and Anhui (0.4552).Comparison between the predicted distribution of Racomitrium and that of Grimmia showed that Racomitrium had higher distribution probability in Hong Kong,Chongqing,Guizhou,Guangdong,Guangxi,Hubei,Hainan,and Taiwan than Grimmia,similar distribution probability to that of Grimmia in Jiangxi,Fujian,Hunan,and lower than Grimmia in the other provinces (municipality autonomous regions).Grimmia belonged to the typical moderate geographical element,mainly in the high altitude and cold districts.
2012, 30(5): 459-467.
DOI: 10.3724/SP.J.1142.2012.50459
Abstract：
Two quadrat scales,1 m?1 m and 25 cm?25 cm,were established to investigate the vegetation of the Jinchuan Peatland.Interspecific correlations among 9 bryophytes and 30 main vascular plants were analyzed by X2-test,Pearson correlation,and Spearman rank correlation quantitatively.There were significantly negative associations among three main peatmosses: Sphagnum subsecundum,S.palustre,and S.capillifolium,each of which occupied different habitats.Accordingly,four ecological species groups were classified.Spearman rank correlation analysis showed that positive association amounted to 49.53% of the 741 species pairs in the large quadrats,and more than 41.14% of the 666 species pairs in the small quadrats.This study suggests that quadrat size played a crucial role in analyzing interspecific associations in peatlands,with great disparity in body size of different plant groups.It appears more suitable to analyze interspecific associations among bryophytes and among bryophytes and vascular plants with small and large quadrats, respectively.
Two quadrat scales,1 m?1 m and 25 cm?25 cm,were established to investigate the vegetation of the Jinchuan Peatland.Interspecific correlations among 9 bryophytes and 30 main vascular plants were analyzed by X2-test,Pearson correlation,and Spearman rank correlation quantitatively.There were significantly negative associations among three main peatmosses: Sphagnum subsecundum,S.palustre,and S.capillifolium,each of which occupied different habitats.Accordingly,four ecological species groups were classified.Spearman rank correlation analysis showed that positive association amounted to 49.53% of the 741 species pairs in the large quadrats,and more than 41.14% of the 666 species pairs in the small quadrats.This study suggests that quadrat size played a crucial role in analyzing interspecific associations in peatlands,with great disparity in body size of different plant groups.It appears more suitable to analyze interspecific associations among bryophytes and among bryophytes and vascular plants with small and large quadrats, respectively.
2012, 30(5): 468-475.
DOI: 10.3724/SP.J.1142.2012.50468
Abstract：
Garden species are the main component in the construction of ecological garden cities.Quantitative studies on their ecological functions provide an important basis for selection,configuration,and management of garden species.In this study,we estimated water use efficiency (WUE),and the capacities of carbon fixation (WCO2) and oxygen release (WO2),temperature reduction (ΔT) and dust detention (Wdust) of 65 garden species in Wuhan City by measuring the diurnal changes of photosynthesis and transpiration,and the crown width and leaf area index.The results showed there were significant differences in WUE,WCO2,WO2,ΔT,and Wdust among species,shrubs and trees,and deciduous and evergreen species.Based on the values of these ecological functions,the species studied were divided into five functional groups: low carbon fixation and low dust detention species (26 species),high carbon fixation and high temperature reduction species (8 species),high dust detention and low temperature reduction species (9 species),low water use and high transpiration species (11 species),and high water use species (11 species).
Garden species are the main component in the construction of ecological garden cities.Quantitative studies on their ecological functions provide an important basis for selection,configuration,and management of garden species.In this study,we estimated water use efficiency (WUE),and the capacities of carbon fixation (WCO2) and oxygen release (WO2),temperature reduction (ΔT) and dust detention (Wdust) of 65 garden species in Wuhan City by measuring the diurnal changes of photosynthesis and transpiration,and the crown width and leaf area index.The results showed there were significant differences in WUE,WCO2,WO2,ΔT,and Wdust among species,shrubs and trees,and deciduous and evergreen species.Based on the values of these ecological functions,the species studied were divided into five functional groups: low carbon fixation and low dust detention species (26 species),high carbon fixation and high temperature reduction species (8 species),high dust detention and low temperature reduction species (9 species),low water use and high transpiration species (11 species),and high water use species (11 species).
2012, 30(5): 476-483.
DOI: 10.3724/SP.J.1142.2012.50476
Abstract：
Ultrastructural and cytochemical methods were used to study egg development of the liverwort Marchantia polymorpha L.Egg development of M.polymorpha was divided into young egg,middle egg,and mature egg stages.Well-developed plasmodesmata existed between the egg,the ventral canal and the neck canal cells in the young egg stage.However,the plasmodesmata between the egg and the ventral canal cells degenerated soon after the egg was formed.At this stage,the egg cell contained numerous transparent vesicles distributed evenly in the cytoplasm.In the middle egg stage,lipid bodies were found in the vesicles of the cytoplasm.The ventral canal cell degenerated obviously.Mucilaginous materials accumulated in the vesicles and resembled that in the chamber around the egg.The mucilaginous materials showed a PAS positive reaction and were most likely polysaccharide.In the mature stage of the egg,the ventral canal cell and the neck canal cell degenerated completely.A layer of mucilaginous polysaccharide encompassed the matured egg.The nucleus showed an irregular profile and apparent nuclear evaginations were produced.The nucleus appeared to show blebbing,because a numerous small vesicles occurred close the nucleus.The lipid bodies formed clusters around the nucleus,while other organelles were indistinguishable.During egg development,the plastids possessed no starch granules;the mitochondria degenerated,while and the Golgi bodies became more abundant.The features of the egg development of M.polymorpha were different from those in pteridophytes.
Ultrastructural and cytochemical methods were used to study egg development of the liverwort Marchantia polymorpha L.Egg development of M.polymorpha was divided into young egg,middle egg,and mature egg stages.Well-developed plasmodesmata existed between the egg,the ventral canal and the neck canal cells in the young egg stage.However,the plasmodesmata between the egg and the ventral canal cells degenerated soon after the egg was formed.At this stage,the egg cell contained numerous transparent vesicles distributed evenly in the cytoplasm.In the middle egg stage,lipid bodies were found in the vesicles of the cytoplasm.The ventral canal cell degenerated obviously.Mucilaginous materials accumulated in the vesicles and resembled that in the chamber around the egg.The mucilaginous materials showed a PAS positive reaction and were most likely polysaccharide.In the mature stage of the egg,the ventral canal cell and the neck canal cell degenerated completely.A layer of mucilaginous polysaccharide encompassed the matured egg.The nucleus showed an irregular profile and apparent nuclear evaginations were produced.The nucleus appeared to show blebbing,because a numerous small vesicles occurred close the nucleus.The lipid bodies formed clusters around the nucleus,while other organelles were indistinguishable.During egg development,the plastids possessed no starch granules;the mitochondria degenerated,while and the Golgi bodies became more abundant.The features of the egg development of M.polymorpha were different from those in pteridophytes.
2012, 30(5): 484-493.
DOI: 10.3724/SP.J.1142.2012.50484
Abstract：
To investigate drought adaptation of evergreen and deciduous fig species occurring in dry karst forests, we compared anatomical traits, stem hydraulic conductivity, leaf water relation traits, photosynthesis, drought-resistance, and seasonal changes in physiology in evergreen Ficus orthoneura and deciduous F.pisocarpa, both of which belong to F.subgen. urostigma. Results showed that the two fig species have adapted to drought in different ways. Both have typical xeromorphic leaf structures, as shown by their two-layered palisade cells, highly-defused sponge cells and cystolith in leaves. They have a low cuticular evaporation (gmin) and stomatal conductance (gs) to alleviate water loss. However, F.orthoneura possesses a xylem structure more resistant to cavitation and lower gmin and adopts conserved water use to adapt to drought stress and maintains its leaves all year. In contrast, F.pisocarpa escapes from extreme drought stress by shedding leaves at the beginning of the dry season. To compensate the loss of carbon gain in the leafless period, F.pisocarpa has a particularly high rate in hydraulic and photosynthesis during the rainy season.The diversification of drought adaptation and water use reduces their competition for water and makes it possible for these fig species to coexist in the karst topography.
To investigate drought adaptation of evergreen and deciduous fig species occurring in dry karst forests, we compared anatomical traits, stem hydraulic conductivity, leaf water relation traits, photosynthesis, drought-resistance, and seasonal changes in physiology in evergreen Ficus orthoneura and deciduous F.pisocarpa, both of which belong to F.subgen. urostigma. Results showed that the two fig species have adapted to drought in different ways. Both have typical xeromorphic leaf structures, as shown by their two-layered palisade cells, highly-defused sponge cells and cystolith in leaves. They have a low cuticular evaporation (gmin) and stomatal conductance (gs) to alleviate water loss. However, F.orthoneura possesses a xylem structure more resistant to cavitation and lower gmin and adopts conserved water use to adapt to drought stress and maintains its leaves all year. In contrast, F.pisocarpa escapes from extreme drought stress by shedding leaves at the beginning of the dry season. To compensate the loss of carbon gain in the leafless period, F.pisocarpa has a particularly high rate in hydraulic and photosynthesis during the rainy season.The diversification of drought adaptation and water use reduces their competition for water and makes it possible for these fig species to coexist in the karst topography.
2012, 30(5): 494-500.
DOI: 10.3724/SP.J.1142.2012.50494
Abstract：
The NPR1 (nonexpressor of pathogenesis-related genes 1) gene plays an important role in SA-depended defense response processes in model plants such as Arabidopsis and rice.However,the function and underlying mechanism of this gene in non-model plants,including pepper (Capsicum annuum) and other Solanaceae,remain poorly understood.Here,we report on the functional characterization of CaNPR1 from pepper.Our data showed that the full-length cDNA of CaNPR1 was isolated and overexpression of CaNPR1 was construed in tobacco K326.Compared to wild type K326,CaNPR1-OE lines did not exhibit any phenotypic differences,but exhibited higher resistance to Ralstonia solanacearum inoculation.In addition,this was coupled with enhanced transcript levels of defense-related marker genes,suggesting that CaNPR1 possessed higher conservative function in cross species.
The NPR1 (nonexpressor of pathogenesis-related genes 1) gene plays an important role in SA-depended defense response processes in model plants such as Arabidopsis and rice.However,the function and underlying mechanism of this gene in non-model plants,including pepper (Capsicum annuum) and other Solanaceae,remain poorly understood.Here,we report on the functional characterization of CaNPR1 from pepper.Our data showed that the full-length cDNA of CaNPR1 was isolated and overexpression of CaNPR1 was construed in tobacco K326.Compared to wild type K326,CaNPR1-OE lines did not exhibit any phenotypic differences,but exhibited higher resistance to Ralstonia solanacearum inoculation.In addition,this was coupled with enhanced transcript levels of defense-related marker genes,suggesting that CaNPR1 possessed higher conservative function in cross species.
2012, 30(5): 501-510.
DOI: 10.3724/SP.J.1142.2012.50501
Abstract：
We investigated the effects of salicylic acid (SA) and methyl jasmonate (MeJA) foliar applications on photosynthesis and accumulation of non-structure sugar of Salvia miltiorrhiza Bunge seedlings.Results showed that SA treatment was favorable in developing leaf microstructure and increased leaf stomata density.Intercellular space in the mesophyll tissue,size of mesophyll cell,and number of chloroplast per mesophyll cell were also reduced,but the size of chloroplast and number of granum in the chloroplast were markedly increased.Correspondingly,contents of chlorophyll a and b in the leaves,net photosynthetic rate of the leaves,and contents of sucrose and soluble sugar in shoots of the SA-treated seedling were together significantly increased following decreased activity of acid invertase in both shoots and roots.The MeJA application to the seedlings resulted in contrary effects in decreasing density of leaf stomata,incurring a number of abnormal stomata,decreasing layer of palisade cell and increasing intercellular space in mesophyll tissue,while number and size of chloroplast was notably reduced and granum in the chloroplast was destroyed.The MeJA treatment also decreased contents of chlorophyll a and carotenoid in leaves but significantly increased activity of acid invertase in both shoots and roots of the seedlings;as a consequence leaf net photosynthetic rate,contents of sucrose and total amount of soluble sugar in roots of the seedlings were decreased. In conclusion,the SA application to S.miltiorrhiza seedling accelerated sucrose accumulation by promoting the development of leaf microstructure to accelerate photosynthesis and inhibiting sucrose hydrolysis,while MeJA application to the seedlings decreased sucrose accumulation by damaging leaf microstructure to impair photosynthesis and accelerating sucrose hydrolysis.
We investigated the effects of salicylic acid (SA) and methyl jasmonate (MeJA) foliar applications on photosynthesis and accumulation of non-structure sugar of Salvia miltiorrhiza Bunge seedlings.Results showed that SA treatment was favorable in developing leaf microstructure and increased leaf stomata density.Intercellular space in the mesophyll tissue,size of mesophyll cell,and number of chloroplast per mesophyll cell were also reduced,but the size of chloroplast and number of granum in the chloroplast were markedly increased.Correspondingly,contents of chlorophyll a and b in the leaves,net photosynthetic rate of the leaves,and contents of sucrose and soluble sugar in shoots of the SA-treated seedling were together significantly increased following decreased activity of acid invertase in both shoots and roots.The MeJA application to the seedlings resulted in contrary effects in decreasing density of leaf stomata,incurring a number of abnormal stomata,decreasing layer of palisade cell and increasing intercellular space in mesophyll tissue,while number and size of chloroplast was notably reduced and granum in the chloroplast was destroyed.The MeJA treatment also decreased contents of chlorophyll a and carotenoid in leaves but significantly increased activity of acid invertase in both shoots and roots of the seedlings;as a consequence leaf net photosynthetic rate,contents of sucrose and total amount of soluble sugar in roots of the seedlings were decreased. In conclusion,the SA application to S.miltiorrhiza seedling accelerated sucrose accumulation by promoting the development of leaf microstructure to accelerate photosynthesis and inhibiting sucrose hydrolysis,while MeJA application to the seedlings decreased sucrose accumulation by damaging leaf microstructure to impair photosynthesis and accelerating sucrose hydrolysis.
2012, 30(5): 511-518.
DOI: 10.3724/SP.J.1142.2012.50511
Abstract：
The compositions of bark fiber in 64 samples (2-3 year old branches) of wild Pteroceltis tatarinowii population in Daguisi National Forest Park,Hubei province were analyzed.Results showed that the average value of moisture,ash,cold water extraction,and hot water extraction was 8.267%,6.273%,24.025%,and 26.594%,respectively;of 1%NaOH extraction,benzene-alcohol extraction,holocellulose,and acid accumulator insoluble lignin was 60.904%,11.011%,56.759% and 9.698%,respectively;cellulose absorbance value was 0.373.The distribution of four indices,namely acid accumulator insoluble lignin,ash,cellulose absorbance,and 1%NaOH extraction,was near to normal distribution,but other variables had large skewness.The inter-correlations between moisture and 1%NaOH extraction,ash and acid accumulator insoluble lignin,holocellulose and acid accumulator insoluble lignin were significant (p < 0.05). The inter-correlations between moisture and ash,moisture and hot water extraction,moisture and holocellulose, benzene-alcohol extraction and holocellulose,benzene-alcohol extracts and acid accumulator insoluble lignin were highly significant (p < 0.01).The 64 samples could be divided into 23 groups with average linkage of 5.627,which showed high phenotypic diversity in the wild Pteroceltis tatarinowii population in Daguisi National Forest Park and its broad prospect of genetic improvement.
The compositions of bark fiber in 64 samples (2-3 year old branches) of wild Pteroceltis tatarinowii population in Daguisi National Forest Park,Hubei province were analyzed.Results showed that the average value of moisture,ash,cold water extraction,and hot water extraction was 8.267%,6.273%,24.025%,and 26.594%,respectively;of 1%NaOH extraction,benzene-alcohol extraction,holocellulose,and acid accumulator insoluble lignin was 60.904%,11.011%,56.759% and 9.698%,respectively;cellulose absorbance value was 0.373.The distribution of four indices,namely acid accumulator insoluble lignin,ash,cellulose absorbance,and 1%NaOH extraction,was near to normal distribution,but other variables had large skewness.The inter-correlations between moisture and 1%NaOH extraction,ash and acid accumulator insoluble lignin,holocellulose and acid accumulator insoluble lignin were significant (p < 0.05). The inter-correlations between moisture and ash,moisture and hot water extraction,moisture and holocellulose, benzene-alcohol extraction and holocellulose,benzene-alcohol extracts and acid accumulator insoluble lignin were highly significant (p < 0.01).The 64 samples could be divided into 23 groups with average linkage of 5.627,which showed high phenotypic diversity in the wild Pteroceltis tatarinowii population in Daguisi National Forest Park and its broad prospect of genetic improvement.
2012, 30(5): 519-527.
DOI: 10.3724/SP.J.1142.2012.50519
Abstract：
In this paper,chemical fingerprints were established by referring to the HPLC chromatography of ten batch samples from the Taihang Mountains.Phenomsil C18 (250×4.6 mm,5 μm) columns were used and methanol-water (0.5% phosphoric acid.) was chosen as the mobile phase.The column temperature was 30℃ and the fingerprints were detected at 238 nm.The flow rate was 0.8 mL/min.The quality of Rabdosia rubescens herba from different places was evaluated by similarity analysis and principal component analysis of chemical fingerprints.The results showed that R.rubescens had multiple germplasm,the diterpenoids from R.rubescens in different areas had significant differences,and the diterpenoids of different mutation types were changed,but showed no obvious trend.The results of this article provide a scientific basis for the protection and development of R.rubescens germplasm.
In this paper,chemical fingerprints were established by referring to the HPLC chromatography of ten batch samples from the Taihang Mountains.Phenomsil C18 (250×4.6 mm,5 μm) columns were used and methanol-water (0.5% phosphoric acid.) was chosen as the mobile phase.The column temperature was 30℃ and the fingerprints were detected at 238 nm.The flow rate was 0.8 mL/min.The quality of Rabdosia rubescens herba from different places was evaluated by similarity analysis and principal component analysis of chemical fingerprints.The results showed that R.rubescens had multiple germplasm,the diterpenoids from R.rubescens in different areas had significant differences,and the diterpenoids of different mutation types were changed,but showed no obvious trend.The results of this article provide a scientific basis for the protection and development of R.rubescens germplasm.
2012, 30(5): 528-544.
DOI: 10.3724/SP.J.1142.2012.50528
Abstract：
Gateway molecular cloning technology was developed by Invitrogen based on the mechanism of site-specific recombination between λ phage DNA and the Escherichia coli genome.Construction of an expression vector for a target gene via Gateway LR reaction does not need to use restriction enzymes and a ligase,and thus is time efficient. Recently,to expand the application of Gateway technology in plant genetic engineering,several research groups have constructed Gateway destination vectors for studies on constitutive,inducible or silence expression of target genes,promoter analyses,protein localization,protein/protein interaction,DNA fragment modular assembly and functional verification of genomic fragments.Here we review research progress on the development of these destination vectors.
Gateway molecular cloning technology was developed by Invitrogen based on the mechanism of site-specific recombination between λ phage DNA and the Escherichia coli genome.Construction of an expression vector for a target gene via Gateway LR reaction does not need to use restriction enzymes and a ligase,and thus is time efficient. Recently,to expand the application of Gateway technology in plant genetic engineering,several research groups have constructed Gateway destination vectors for studies on constitutive,inducible or silence expression of target genes,promoter analyses,protein localization,protein/protein interaction,DNA fragment modular assembly and functional verification of genomic fragments.Here we review research progress on the development of these destination vectors.
