2012 Vol. 30 No. 4
2012, 30(4): 327-336.
DOI: 10.3724/SP.J.1142.2012.40327
Abstract：
The floral anatomical morphology of Glycosmis (Rutaceae) including nine species and eleven samples from China,was studied by using paraffin section and microdissection.Results showed that: the projected appendage and oil glands were found at the tip of the anther and there were one to a few oil glands on the back of the anther in many species,except one species (G.cochinchinensis) with sparse long hairs; the gynophore was divided into sub-sphaeroidal,cushion-like and elongated types based on the swollen degree;the shape of the ovary was sub-spheroidicity and slightly swollen cylindricity;the outer wall of the ovary was smooth,with salient oil glands or with irregular tubercles;the number of locule was four (three) or five;the shape of style was terete or attenuately columnar;characters of stigma were thicke-ned slightly or non-obvious;the style was persistent in most species,except G.esquirolii.It was concluded that the anatomical morphology of the flowers was characterized with high diversity between species in Glycosmis.Therefore,the floral morphology and anatomical features of Glycosmis could be used as evidence for inter- and intra-specific taxonomy and showed great systematic value.
The floral anatomical morphology of Glycosmis (Rutaceae) including nine species and eleven samples from China,was studied by using paraffin section and microdissection.Results showed that: the projected appendage and oil glands were found at the tip of the anther and there were one to a few oil glands on the back of the anther in many species,except one species (G.cochinchinensis) with sparse long hairs; the gynophore was divided into sub-sphaeroidal,cushion-like and elongated types based on the swollen degree;the shape of the ovary was sub-spheroidicity and slightly swollen cylindricity;the outer wall of the ovary was smooth,with salient oil glands or with irregular tubercles;the number of locule was four (three) or five;the shape of style was terete or attenuately columnar;characters of stigma were thicke-ned slightly or non-obvious;the style was persistent in most species,except G.esquirolii.It was concluded that the anatomical morphology of the flowers was characterized with high diversity between species in Glycosmis.Therefore,the floral morphology and anatomical features of Glycosmis could be used as evidence for inter- and intra-specific taxonomy and showed great systematic value.
2012, 30(4): 337-351.
DOI: 10.3724/SP.J.1142.2012.40337
Abstract：
The leaves from fifteen populations of Pteroceltis tatarinowii Maxim.in eight provin-ces of China were compared and analyzed by the paraffin method and leaf epidermal maceration.Results showed that there were significant differences between leaf anatomical characteristics of populations,and the palisade tissue cell generally formed two layers.The shapes of the adaxial epidermal cells were polygonal or irregular,while abaxial epidermal cells were irregular.There were many types of anticlinal walls of adaxial surfaces,including flat,round,and shallow and deep wavy.Wavy was the only shape found in anticlinal walls of abaxial surfaces.Distribution of the epidermal hairs in these populations was significantly different,while the types of epidermal hair showed the stabilization in all populations,and the epidermal hair formed floral hoops with cells all around them in most populations.The types of stomatal apparatus in all the populations were irregular,and the stomatal apparatus was only found on the abaxial surface with a random distribution.Characteristics such as size and density of stomatal apparatus were different in these populations.There was a certain correlation between climate factors and the features of leaves from different populations.These results showed that the differences in anatomical structure of leaves from different populations were diverse.Leaf epidermal characteristics such as density of stomatal apparatus were also different,while the types of stomatal apparatus and shapes of epidermal hair in different populations showed stabilization,which may be regarded as evidence for the division of the species.
The leaves from fifteen populations of Pteroceltis tatarinowii Maxim.in eight provin-ces of China were compared and analyzed by the paraffin method and leaf epidermal maceration.Results showed that there were significant differences between leaf anatomical characteristics of populations,and the palisade tissue cell generally formed two layers.The shapes of the adaxial epidermal cells were polygonal or irregular,while abaxial epidermal cells were irregular.There were many types of anticlinal walls of adaxial surfaces,including flat,round,and shallow and deep wavy.Wavy was the only shape found in anticlinal walls of abaxial surfaces.Distribution of the epidermal hairs in these populations was significantly different,while the types of epidermal hair showed the stabilization in all populations,and the epidermal hair formed floral hoops with cells all around them in most populations.The types of stomatal apparatus in all the populations were irregular,and the stomatal apparatus was only found on the abaxial surface with a random distribution.Characteristics such as size and density of stomatal apparatus were different in these populations.There was a certain correlation between climate factors and the features of leaves from different populations.These results showed that the differences in anatomical structure of leaves from different populations were diverse.Leaf epidermal characteristics such as density of stomatal apparatus were also different,while the types of stomatal apparatus and shapes of epidermal hair in different populations showed stabilization,which may be regarded as evidence for the division of the species.
2012, 30(4): 352-357.
DOI: 10.3724/SP.J.1142.2012.40352
Abstract：
The micro-morphological characteristics of nut epidermis of 11 species of Scirpus from Shandong were studied under light microscope and scanning electron microscope (SEM).The micro-morphological characteristics of the nut epidermis were divided into four types: Ⅰ Waveform reticulate sculpture,Ⅱ Tuberculate-reticulate sculpture, Ⅲ Smooth sculpture,and Ⅳ reticulate sculpture.The evidence supported that section Sect.Bolboschoenus Ascheron,Sect.Scirpus & Sect.Trichophorum (Pers.) Darl.,which belongs to Subgen.Scirpus should be promoted to Bolboschoenus (Ascheron) Palla,Scirpus L..Sect.Schoenoplectus Reichb.& Sect.Actaeogeton Reichb,which belongs to Subgen.Isolepis should be promoted to Schoenoplectus (Rchb.) Palla.Sect.Schoenoplectus (Reichb.) F.Z.Li & L.N.Liu,Sect.Ac-taeogeton (Reichb.) F.Z.Li & L.N.Liu,Sect.Ehrenbergii F.Z.Li & L.N.Liu should be retained in Schoenoplectus (Rchb.) Palla.Evidence of the micromorphological characteristics of the fruits supported that Scirpus trisetosus Tang et Wang should be treated as a synonym of Scirpus triqueter L.Eight species of plants names of Scirpus from Shandong have been amended.
The micro-morphological characteristics of nut epidermis of 11 species of Scirpus from Shandong were studied under light microscope and scanning electron microscope (SEM).The micro-morphological characteristics of the nut epidermis were divided into four types: Ⅰ Waveform reticulate sculpture,Ⅱ Tuberculate-reticulate sculpture, Ⅲ Smooth sculpture,and Ⅳ reticulate sculpture.The evidence supported that section Sect.Bolboschoenus Ascheron,Sect.Scirpus & Sect.Trichophorum (Pers.) Darl.,which belongs to Subgen.Scirpus should be promoted to Bolboschoenus (Ascheron) Palla,Scirpus L..Sect.Schoenoplectus Reichb.& Sect.Actaeogeton Reichb,which belongs to Subgen.Isolepis should be promoted to Schoenoplectus (Rchb.) Palla.Sect.Schoenoplectus (Reichb.) F.Z.Li & L.N.Liu,Sect.Ac-taeogeton (Reichb.) F.Z.Li & L.N.Liu,Sect.Ehrenbergii F.Z.Li & L.N.Liu should be retained in Schoenoplectus (Rchb.) Palla.Evidence of the micromorphological characteristics of the fruits supported that Scirpus trisetosus Tang et Wang should be treated as a synonym of Scirpus triqueter L.Eight species of plants names of Scirpus from Shandong have been amended.
2012, 30(4): 358-365.
DOI: 10.3724/SP.J.1142.2012.40358
Abstract：
Mountain barriers was expected to interrupt habitats and have significant effects on the genetic structure,genetic biodiversity,and gene flow of plants.Using AFLP markers,we tested the genetic variation and differentiation of four populations of Cercidiphyllum japonicum Sieb.et Zucc.(Cercidiphyllaceae) along four riparian rivers in the northern and southern slopes of the Shennongjia region.The effect of the Shennongjia Mountain as a natural barrier to genetic structure and gene flow of the species was investigated.The Nei’s gene diversity (h) and Shannon index (I) were 0.116 and 0.173,respectively.Despite the low genetic differentiation between the two slopes (FST=0.075),the Neighbor-Joining Tree(NJ) and PCA data divided the four populations into two clusters corresponding to the northern and southern slopes.STRUCTURE analysis showed that the gene flow between populations within the same slope was higher than those in different slopes.Our results suggested that large mountains may have served as physical barriers to gene flow between plant populations.The low level of genetic differentiation of populations between the southern and northern slope may have resulted from the internal characters of long distance pollen and seed dispersal ability of the species.Our results suggested that large mountain may have served as physical barriers to gene flow between plant populations.
Mountain barriers was expected to interrupt habitats and have significant effects on the genetic structure,genetic biodiversity,and gene flow of plants.Using AFLP markers,we tested the genetic variation and differentiation of four populations of Cercidiphyllum japonicum Sieb.et Zucc.(Cercidiphyllaceae) along four riparian rivers in the northern and southern slopes of the Shennongjia region.The effect of the Shennongjia Mountain as a natural barrier to genetic structure and gene flow of the species was investigated.The Nei’s gene diversity (h) and Shannon index (I) were 0.116 and 0.173,respectively.Despite the low genetic differentiation between the two slopes (FST=0.075),the Neighbor-Joining Tree(NJ) and PCA data divided the four populations into two clusters corresponding to the northern and southern slopes.STRUCTURE analysis showed that the gene flow between populations within the same slope was higher than those in different slopes.Our results suggested that large mountains may have served as physical barriers to gene flow between plant populations.The low level of genetic differentiation of populations between the southern and northern slope may have resulted from the internal characters of long distance pollen and seed dispersal ability of the species.Our results suggested that large mountain may have served as physical barriers to gene flow between plant populations.
2012, 30(4): 366-373.
DOI: 10.3724/SP.J.1142.2012.40366
Abstract：
Solidago canadensis (Asteraceae),a noxious invasive plant in central and eastern China,has invaded woodland in Lushan Natural Reserve of Jiangxi Province,central China.To reveal the spread pattern of S.canadensis and the possible effects on biodiversity in this woodland,we investigated the seasonal dynamics of S.canadensis over two years and the species diversity of the main native plants by establishing seven plots.Results showed that low sunlight and predominance of foggy weather of the Lushan Nature Reserve were not suitable for the growth of S.canadensis,while S.canadensis was always the dominant species in the herb layer and caused a significant decline in species diversity in this layer,especially in autumn (October).Although low sunlight in the woodland inhibited the growth and the further spread of S.canadensis,this plant invader was able to survive and regenerate by sexual and clonal reproduction.Therefore,the invasion of S.canadensis into the woodlands and nearby habitats in Lushan Natural Reserve remains a possibility and deserves further study.
Solidago canadensis (Asteraceae),a noxious invasive plant in central and eastern China,has invaded woodland in Lushan Natural Reserve of Jiangxi Province,central China.To reveal the spread pattern of S.canadensis and the possible effects on biodiversity in this woodland,we investigated the seasonal dynamics of S.canadensis over two years and the species diversity of the main native plants by establishing seven plots.Results showed that low sunlight and predominance of foggy weather of the Lushan Nature Reserve were not suitable for the growth of S.canadensis,while S.canadensis was always the dominant species in the herb layer and caused a significant decline in species diversity in this layer,especially in autumn (October).Although low sunlight in the woodland inhibited the growth and the further spread of S.canadensis,this plant invader was able to survive and regenerate by sexual and clonal reproduction.Therefore,the invasion of S.canadensis into the woodlands and nearby habitats in Lushan Natural Reserve remains a possibility and deserves further study.
2012, 30(4): 374-384.
DOI: 10.3724/SP.J.1142.2012.40374
Abstract：
The Fenhe Source is located in the hinterland of the Guancen Mountains of northern L黮iang Mountain Range.This area belongs to the warm temperate zone and has the largest larch and spruce forest in North China.With great ecological function,the flora in the Fenhe Source is complex and diverse.In this study,875 species of seed plants belonging to 398 genera and 94 families were found in the Fenhe Source.The gymnosperms included 12 species in 7 genera and 3 families,and angiosperms included 863 species in 391 genera and 91 families.Among these species,four were National Key Protected Plants and 24 were Key Protected Plants of Shanxi Province.The percentage of areal types of seed plants in families,ge-nera,and species had no obvious relevance,and the endemic types were also unbalanced.In the areal types of family,Cosmopolitan,Pantropic,and Temperate types included 40 families,19 families,and 30 families,respectively.However,no Endemic to China type was found.For areal types of genera,the temperate elements included 264 genera,in which North Temperate was the dominant type.Furthermore,Endemic to China type included 4 genera.The areal types of genera reflected temperate characteristics of the flora.In areal types of species,Endemic to China type included 501 species,which constituted the majority of the flora.The Temperate Asia and East Asia types included 236 and 97 species,respectively.These two types were the main constituents of constructive and dominant species of forest and shrubbery in Fenhe Source.
The Fenhe Source is located in the hinterland of the Guancen Mountains of northern L黮iang Mountain Range.This area belongs to the warm temperate zone and has the largest larch and spruce forest in North China.With great ecological function,the flora in the Fenhe Source is complex and diverse.In this study,875 species of seed plants belonging to 398 genera and 94 families were found in the Fenhe Source.The gymnosperms included 12 species in 7 genera and 3 families,and angiosperms included 863 species in 391 genera and 91 families.Among these species,four were National Key Protected Plants and 24 were Key Protected Plants of Shanxi Province.The percentage of areal types of seed plants in families,ge-nera,and species had no obvious relevance,and the endemic types were also unbalanced.In the areal types of family,Cosmopolitan,Pantropic,and Temperate types included 40 families,19 families,and 30 families,respectively.However,no Endemic to China type was found.For areal types of genera,the temperate elements included 264 genera,in which North Temperate was the dominant type.Furthermore,Endemic to China type included 4 genera.The areal types of genera reflected temperate characteristics of the flora.In areal types of species,Endemic to China type included 501 species,which constituted the majority of the flora.The Temperate Asia and East Asia types included 236 and 97 species,respectively.These two types were the main constituents of constructive and dominant species of forest and shrubbery in Fenhe Source.
2012, 30(4): 385-393.
DOI: 10.3724/SP.J.1142.2012.40385
Abstract：
Heat shock proteins (Hsp),representing an important molecular chaperone in eukaryotic cells,is a common response to development,stress resistance,signal transduction and evolution of plants.The relationship between the structure and functional roles was elucidated in Hsp90 based on the generation of full-length cDNAs from Senecio scandens Buch.-Ham.ex D.Don.Sequence analysis of Hsp90-3 gene indicated that it shared 93.71% identity with Arabidopsis thaliana (GenBank accession: NP_200412.1),encoding a protein composed of 699 amino acid residues with the predicted molecular weight of 79.78 kD and theoretical isoelectric point of 5.08.Moreover,the distribution of Hsp90-3 was involved in the endomembrane system such as nuclei,peroxisomes,chloroplast thylakoid membranes,and chloroplast matrices in the present study.Three-dimensional measurement revealed that the Hsp90-3 protein was composed of three structural domains and one link region.These results suggested that Hsp90-3 played a critical role in molecular chaperone,signal transduction,transcriptional regulation and stress-response in higher plants.
Heat shock proteins (Hsp),representing an important molecular chaperone in eukaryotic cells,is a common response to development,stress resistance,signal transduction and evolution of plants.The relationship between the structure and functional roles was elucidated in Hsp90 based on the generation of full-length cDNAs from Senecio scandens Buch.-Ham.ex D.Don.Sequence analysis of Hsp90-3 gene indicated that it shared 93.71% identity with Arabidopsis thaliana (GenBank accession: NP_200412.1),encoding a protein composed of 699 amino acid residues with the predicted molecular weight of 79.78 kD and theoretical isoelectric point of 5.08.Moreover,the distribution of Hsp90-3 was involved in the endomembrane system such as nuclei,peroxisomes,chloroplast thylakoid membranes,and chloroplast matrices in the present study.Three-dimensional measurement revealed that the Hsp90-3 protein was composed of three structural domains and one link region.These results suggested that Hsp90-3 played a critical role in molecular chaperone,signal transduction,transcriptional regulation and stress-response in higher plants.
2012, 30(4): 394-401.
DOI: 10.3724/SP.J.1142.2012.40394
Abstract：
The full-length cDNA sequence of the PPa1 gene was obtained by the RACE method based on the cDNA library of Picea wilsonii.Bioinformatic analysis was used to predict the physicochemical properties,hydrophobicity,secondary structure,and tertiary structure of PwPPa1.Multiple sequences alignment and phylogenetic trees were also constructed to predict the conserved domain and genetic relationship with other species.The RT-qPCR assays were used to identify the tissue expression level of PPa1 in Picea wilsonii.The results showed that PwPPa1 consisted of 216 amino acids.The molecular weight was 24.55 kD and theoretical PI was 5.83.The PPa1 was a hydrophilic protein and the secondary structure of PPa1 was mainly composed of alpha helix,random coil,and extended strand.The expression level of PPa1 was highest in the pollen.This research provides the foundation for further studies on the functions of PwPPa1.
The full-length cDNA sequence of the PPa1 gene was obtained by the RACE method based on the cDNA library of Picea wilsonii.Bioinformatic analysis was used to predict the physicochemical properties,hydrophobicity,secondary structure,and tertiary structure of PwPPa1.Multiple sequences alignment and phylogenetic trees were also constructed to predict the conserved domain and genetic relationship with other species.The RT-qPCR assays were used to identify the tissue expression level of PPa1 in Picea wilsonii.The results showed that PwPPa1 consisted of 216 amino acids.The molecular weight was 24.55 kD and theoretical PI was 5.83.The PPa1 was a hydrophilic protein and the secondary structure of PPa1 was mainly composed of alpha helix,random coil,and extended strand.The expression level of PPa1 was highest in the pollen.This research provides the foundation for further studies on the functions of PwPPa1.
2012, 30(4): 402-406.
DOI: 10.3724/SP.J.1142.2012.40402
Abstract：
Studies on the phylogenetic relationship among species are the theoretical basis of hybridization breeding.Wild Citrullus species play important roles in Citrullus lanatus breeding.However,research on relationships among C.lanatus and its close relatives are limited.Moreover,there are disagreements on the taxonomy of the genus Citrullus.Comparative genomic in situ hybridization is an effective method to analyze phylogenetic relationships.The mitotic metaphase chromosomes of Citrullus ecirrhosus,Citrullus rehmii, Citrullus colocynthis and Citrullus naudinianus were hybridized with labeled genome DNA from C.lanatus.The phylogenetic relationship was revealed among species and a close relationship between C.naudinianus and Cucumis melo was found by comparative genomic in situ hybridization with labeled genome DNA from C.melo.This research will provide a theoretical basis for hybridization breeding between watermelon and its close relatives.
Studies on the phylogenetic relationship among species are the theoretical basis of hybridization breeding.Wild Citrullus species play important roles in Citrullus lanatus breeding.However,research on relationships among C.lanatus and its close relatives are limited.Moreover,there are disagreements on the taxonomy of the genus Citrullus.Comparative genomic in situ hybridization is an effective method to analyze phylogenetic relationships.The mitotic metaphase chromosomes of Citrullus ecirrhosus,Citrullus rehmii, Citrullus colocynthis and Citrullus naudinianus were hybridized with labeled genome DNA from C.lanatus.The phylogenetic relationship was revealed among species and a close relationship between C.naudinianus and Cucumis melo was found by comparative genomic in situ hybridization with labeled genome DNA from C.melo.This research will provide a theoretical basis for hybridization breeding between watermelon and its close relatives.
2012, 30(4): 407-414.
DOI: 10.3724/SP.J.1142.2012.40407
Abstract：
Interspecific hybridizations between different varieties of Brassica rapa L.ssp.peki-nensis (Lour.) Olsson and Brassica oleracea var.capitata L.were carried out. The hybrids were obtained by successive bud pollination and ovule culture and tested by means of identification by cytology.Results showed that 57 plants were obtained by interspecific hybridization between B.rapa L.ssp.pekinensis and B.oleracea var.capitata L.Cytological identification and pollen characteristics survey revealed that 47 of the hybrids had the anticipated chromosomes (2n=19) and pollen fertility was aborted; while 6 hybrids had 38chromosomes and were fertile.The BC1 plants were obtained through back cross between fertile hybrids F1 and B.rapa L.ssp.pekinensis.Field investigation showed that all F1 hybrids had many characteristics from both parents,the BC1 plants had obvious heading and were similar to B.rapa L.ssp.pekinensis.
Interspecific hybridizations between different varieties of Brassica rapa L.ssp.peki-nensis (Lour.) Olsson and Brassica oleracea var.capitata L.were carried out. The hybrids were obtained by successive bud pollination and ovule culture and tested by means of identification by cytology.Results showed that 57 plants were obtained by interspecific hybridization between B.rapa L.ssp.pekinensis and B.oleracea var.capitata L.Cytological identification and pollen characteristics survey revealed that 47 of the hybrids had the anticipated chromosomes (2n=19) and pollen fertility was aborted; while 6 hybrids had 38chromosomes and were fertile.The BC1 plants were obtained through back cross between fertile hybrids F1 and B.rapa L.ssp.pekinensis.Field investigation showed that all F1 hybrids had many characteristics from both parents,the BC1 plants had obvious heading and were similar to B.rapa L.ssp.pekinensis.
2012, 30(4): 415-422.
DOI: 10.3724/SP.J.1142.2012.40415
Abstract：
As a traditional Chinese medicinal herb,epimedii has effects on toning kidney,strengthening bones and muscles,and treating rheumatism.Its bioactive ingredients are mainly prenylated flavonol glycosides,including icariin,epimedin A,B,and C.Two light conditions [Yao-yuan (Medicinal Herb Garden) of Wuhan Botanical Garden,Yuan-wai-yuan of Wuhan Botanical Garden] were used to study how light affected the biosynthesis of the major bioactive ingredients in Epimedium wushanense T.S.Ying and Epimedium sagittatum (Sieb.& Zucc.) Maxim.Results showed that the photosynthesis rate was higher in Yao-yuan than in Yuan-wai-yuan for both species.The four bioactive ingredients of E.sagittatum were higher in Yao-yuan than in Yuan-wai-yuan,but the opposite was found for E.wushanense. Photosynthesis rate had significant positive correlation with the content of epimedin A,B and icariin,but had significant negative correlation with epimedin C.The relationship between photosynthesis rate and accumulation of bioactive ingredients was discussed.Suggestions were also proposed for cultivating different Epimedium species.
As a traditional Chinese medicinal herb,epimedii has effects on toning kidney,strengthening bones and muscles,and treating rheumatism.Its bioactive ingredients are mainly prenylated flavonol glycosides,including icariin,epimedin A,B,and C.Two light conditions [Yao-yuan (Medicinal Herb Garden) of Wuhan Botanical Garden,Yuan-wai-yuan of Wuhan Botanical Garden] were used to study how light affected the biosynthesis of the major bioactive ingredients in Epimedium wushanense T.S.Ying and Epimedium sagittatum (Sieb.& Zucc.) Maxim.Results showed that the photosynthesis rate was higher in Yao-yuan than in Yuan-wai-yuan for both species.The four bioactive ingredients of E.sagittatum were higher in Yao-yuan than in Yuan-wai-yuan,but the opposite was found for E.wushanense. Photosynthesis rate had significant positive correlation with the content of epimedin A,B and icariin,but had significant negative correlation with epimedin C.The relationship between photosynthesis rate and accumulation of bioactive ingredients was discussed.Suggestions were also proposed for cultivating different Epimedium species.
2012, 30(4): 423-430.
DOI: 10.3724/SP.J.1142.2012.40423
Abstract：
Water-soluble crude polysaccharide (wPNP) was extracted from cultured mycelium of the fungus Pholiota nameko by hot water extraction.The extraction rates of polysaccharide were 2.463%.The content of total polysaccharide was determined by the phenol-sulphuric acid method,and the value was 64.98%.The crude polysaccharides were purified by CTAB and Sephadex-150 in sequence,with the obtained one designated as wPNP-a1.The structure of wPNP-a1 was analysed by HPLC,FTIR,GC,NMR,ESEM,and AFM.The results showed that the average molecular weight of wPNP-a1 was 419310 Da.It had the general characteristics of polysaccharide absorption peaks,β-glycoside linkage,and no acetyl.The GC analysis indicated wPNP-a1 was composed of xylose,mannose,galactose,and glucose in molar ratios of 3.91∶2.77∶1.91∶1.The repelling forces between the molecules were stronger than the attractive forces. The wPNP-a1 formed a linear chain on the surface of mica,the width was 23 nm,and the height was 0.7-0.8 nm.
Water-soluble crude polysaccharide (wPNP) was extracted from cultured mycelium of the fungus Pholiota nameko by hot water extraction.The extraction rates of polysaccharide were 2.463%.The content of total polysaccharide was determined by the phenol-sulphuric acid method,and the value was 64.98%.The crude polysaccharides were purified by CTAB and Sephadex-150 in sequence,with the obtained one designated as wPNP-a1.The structure of wPNP-a1 was analysed by HPLC,FTIR,GC,NMR,ESEM,and AFM.The results showed that the average molecular weight of wPNP-a1 was 419310 Da.It had the general characteristics of polysaccharide absorption peaks,β-glycoside linkage,and no acetyl.The GC analysis indicated wPNP-a1 was composed of xylose,mannose,galactose,and glucose in molar ratios of 3.91∶2.77∶1.91∶1.The repelling forces between the molecules were stronger than the attractive forces. The wPNP-a1 formed a linear chain on the surface of mica,the width was 23 nm,and the height was 0.7-0.8 nm.
