Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a di...Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a distinct endomembrane organization, in particular, the structural associations of the endoplasmic reticulum (ER) with other membrane systems. The striking findings are that some ER elements were in connection with the nuclear envelopes of two adjacent cells through plasmodesmata, and many ER elements were also associated with mitochondria, plastids, Golgi bodies or the plasma membrane (PM), forming a bridge_like continuum among various endomembrane systems or between nucleus to nucleus. A great number of plasmodesmata existed between cells, indicating a perfectly integrated symplasmic structure in poplar apical bud meristem grown in a long day environment. During the short day_induced dormancy, ER contracted, leading to its disassociation between nuclei, and between the nucleus and organelles/plasmalemma in many cells. After dormancy broke and shoots growth resumed, contracted ER was no longer observed in the apical bud cells. The ER associations with other endomembrane systems and the intercellular communication channels were re_established similar to that of plants before dormancy induction. These observations suggest that ER may play an important role in linking_up between the nucleus and organelles, and between the nucleus and the nucleus (or cell_to_cell), and seemingly coordinating various physiological processes by the bridging_like associations. And the contraction of ER under short_day may result in the growth cessation and the development of dormancy in poplar.展开更多
Polygalacturonase-inhibiting proteins （PGIPs） are extracellular proteins that belong to the leucine-rich repeat （LRR） protein superfamily. PGIPs inhibit fungal polygalacturonases （PGs） and promote accumulation o...Polygalacturonase-inhibiting proteins （PGIPs） are extracellular proteins that belong to the leucine-rich repeat （LRR） protein superfamily. PGIPs inhibit fungal polygalacturonases （PGs） and promote accumulation of oligogalacturonides, which activate plant defense responses. PGIPs play important roles in resistance to infection of pathogens. In this study, reverse transcriptase-polymerase chain reaction （RT-PCR） and RNA ligase-mediated rapid amplification of cDNA ends （RLM-RACE） were used to isolate the full-length PGIP cDNA from Populus deltoides （GenBank accession no. of PdPGIP2 and PdPGIP4：EF684913 and EF684912）. Domain analysis revealed that the deduced amino acid sequences of PdPGIP2 and PdPGIP4 had a typical PGIP topology. Phylogenetic analysis of known PGIPs indicated that the two PdPGIPs were clustered to the defense-related PGIP clade. Using real-time RT-PCR, the expression patterns of the two PdPGIPs following treatment with a fungal pathogen and defense-related signaling molecules were studied. The expression levels of PdPGIP2 and PdPGIP4 were both up-regulated when inoculated with the phytopathogenic fungus Marssonina brunnea. Therefore, it was proposed that the two PGIPs might be involved in the resistance to Marssonina brunnea in P. deltoides.展开更多
Plasma membrane （PM） Ca2+-ATPase activity in poplar apical bud meristematic cells during short-day （SD）-induced dormancy development was examined by a cerium precipitation EM-cytochemical method. Ca2+-ATPase activ...Plasma membrane （PM） Ca2+-ATPase activity in poplar apical bud meristematic cells during short-day （SD）-induced dormancy development was examined by a cerium precipitation EM-cytochemical method. Ca2+-ATPase activity, indicated by the status of cerium phosphate precipitated grains, was localized mainly on the interior face （cytoplasmic side） of the PM when plants were grown under long days and reached a deep dormancy. A few reaction products were also observed on the nuclear envelope.When plant buds were developing dormancy after 28 to 42 d of SD exposure, almost no reaction products were present on the interior face of the PM. In contrast, a large number of cerium phosphate precipitated grains were distributed on the exterior face of the PM. After 70 d of SD exposure, when buds had developed a deep dormancy, the reaction products of Ca2+-ATPase activity again appeared on the interior face of the PM. The results seemed suggesting that two kinds of Ca2+-ATPases may be present on the PM during the SD-induced dormancy in poplar.One is the Ca2+-punlping ATPase, which is located on the interior face of the PM, for maintaining and restoring the Ca2+homeostasis. The other might be an ecto-Ca2+-ATPase, which is located on the exterior face of the PM, for the exocytosis of cell wall materials as suggested by the fact of the cell wall thickening during the dormancy developlnent in poplar.展开更多
We evaluated the growth and crown traits of 36 poplar clones at two distinct agro-climatic regions of Punjab （Ludhiana and Bathinda） in northwestern India, following randomized block design with three replications a...We evaluated the growth and crown traits of 36 poplar clones at two distinct agro-climatic regions of Punjab （Ludhiana and Bathinda） in northwestern India, following randomized block design with three replications and plot size of four trees. Significant differences among clones （p〈0.001） were observed for diameter at breast height （DBH）, tree height, volume, crown width and number of branches under both the site conditions. Clones ‘G-3’, ‘25-N’ and ‘41-N’ at Ludhiana and ‘G-3’, ‘RD-01’ and ‘S7C8’ at Bathinda were found to be superior for volume production. All growth and crown traits registered significantly higher values at Ludhiana in comparison to those at Bathinda. Clone site interaction was also significant （p〈0.001）. For volume, clones ‘L-62/84’, ‘113520’, ‘25-N’ and ‘S4C2’ witnessed huge fluctuations in ranking between sites. The correlations between growth traits were positive and highly significant （p〈0.001） at both sites. The clonal mean heritability was moderate for DBH and volume both at Ludhiana （0.61–0.66） and Bathinda （0.61–0.62）. Across sites, the genetic advance was the highest for volume （49.76%） and the lowest （6.50%） in case of height.展开更多
clones of Populus deltoides and P. ?euramericana were introduced from Italy, Turkey and domestic in 1986 and 1987 with the agreement of FAO. A completely random block design was applied and the seedling test and contr...clones of Populus deltoides and P. ?euramericana were introduced from Italy, Turkey and domestic in 1986 and 1987 with the agreement of FAO. A completely random block design was applied and the seedling test and controlled afforestation trials had been held at Jinan City, Gaotang County and Juxian County, Shandong Province respectively. The results showed that two clones, namely S307-26 (P. deltoides cv.慡307-26? and PE-19-66 (P. deltoides cv. 慞E-19-66? performed well both in terms of adaptability and growth characteristics. The mean growth volumes (V) of single tree of S307-26 and PE-19-66 were 0.181 2 m3 and 0.164 9 m3, which were 42.0 % and 29.2 % larger than that of I-69 (P. deltoides cv. 慙ux?I-69/55) (CK), respectively, at the age of 5 years at three experimental sites. Results of variance analyses and T test (LSD) for variables showed that above mentioned two clones were significantly different with I-69 (CK). Further analyses found that both clones could be propagated easily and showed high resistance to poplar diseases, pests, drought, cold as well as strong wind, and had long growing period. Furthermore, mechanical properties were also better and fiber length was longer than that of I-69 (CK). It was concluded that both S307-26 and PE-19-66 were ideal varieties for the establishment of fast growing poplar plantations, especially of the wood pulp forest plantations in the region.展开更多
The uredinial stage in the life cycle of Melampsora larici-populina on poplar leaves is the most important pathogenic phase. We captured partial phases of uredinial infection in the wild, aiming to reconstruct the pro...The uredinial stage in the life cycle of Melampsora larici-populina on poplar leaves is the most important pathogenic phase. We captured partial phases of uredinial infection in the wild, aiming to reconstruct the process of uredinial ontogeny by using scanning and transmission electron microscope. At the initial infection stage, germ tubes germinated from the echinulate urediniospores. Germ tubes were frequently seen to merge with the leaf surface and cuticle breakage was observed, indicating direct hyphal penetration. Stomata penetration occurred commonly, sometimes with more than one germ tube penetrating the same stoma. Melampsora larici-populina did not form appressoria in the infection process,implying that infectious behavior of this pathogen may differ from the other rust pathogens. In general, germ tubes branched randomly, and no distinct evidence indicated that stoma could induce or orient germ tube branches. However, oriented germ tube growth has been occasionally observed in other studies. The urediniospores collapsed and finally wizened when they became nutrient stressed. At the last stage of infection, the uredinia erupted from the leaf epidermis and appeared as orange pustules on the leaf surface.展开更多
Leaves are of fundamental importance to plants, representing their facility to generate power and are the sensing units of plants towards the environment. An attempt was made to characterize and compare the variations...Leaves are of fundamental importance to plants, representing their facility to generate power and are the sensing units of plants towards the environment. An attempt was made to characterize and compare the variations of leaf morphology of various Populus deltoides Bartr. clones by studying the winter buds and other leaf parameters of fully developed leaves. To achieve these objectives, forty-three exotic and indigenous clones ofP. deltoides Bartr. were evaluated for different parameters. On the basis of various morphological characteristics the results reveal that each clone has a distinct color pattern of leaves. Different colors observed in these clones varied from light green through green to dark green. Two distinct lengths of the leaf apex were found, i.e., short and long; as well both acuminate and acute apex types were found. Erratic distribution of serration of leaves was also found. In this study, the morphological traits of leaves provided discriminatory grounds for separating various populations of P. deltoides Bartr. clones. Winter bud studies indicate that different clones vary considerably with regard to shape, color, shape of leaf scars and exudation.展开更多
Molecular biological research into wood development and formation has been the focus in recent years, but the pace of discovery of related genes and their functions in the control of wood properties has been slow. The...Molecular biological research into wood development and formation has been the focus in recent years, but the pace of discovery of related genes and their functions in the control of wood properties has been slow. The microarray technique--with its advantages of high throughput capacity, sensitivity, and reliability over other tools developed for investigating genes expression patterns-is capable of rapidly assaying thousands of genes. In this study, a cDNA microarray prepared from two cDNA libraries of developing poplar xylem tissues was used to assay gene expression patterns in immature xylem tissues at different heights from the main stem of Populus deltoides （15 years old）, which was confirmed to have distinct wood properties （microfibrillar angle, woody density） by X-ray. Two hundred seventy-four transcripts with differ- ential expression profles between the chips were screened out, and the individual clones were subjected to 5＇ sequencing. Using bioinformatic analysis, we identified candidate genes that may influence poplar wood properties, many of which belong to various regulatory and signal transduction gene families, such as zinc finger protein transcription factor, DNA-binding transcription factor, ethylene response factors, and so on. The results suggest that these genes may regulate enzymes involved in wood formation. Further work will be performed to clone these genes and determine how they influence poplar wood properties.展开更多
In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were...In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were determined and analyzed. The results showed that there were significant differences in CSPG of wood between different clones of P. deltoides . The CSPG of the tested clones reached more than 41 MPa, which was higher than the average compressive strength of P. deltoides （32.94 MPa）. Similar to the changes of stem height, the CSPG of the clones gradually increased with the increase of stem height. However, there were significant differences in CSPG of an individual plant at different tree heights. The CSPG of P. deltoides clones was related with their growth traits, but not significantly. Therefore, it is expected to achieve simultaneous and independent improvement on CSPG and the growth of P. deltoides , so as to get excellent individuals with fast growth and high CSPG.展开更多
It is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity.In this study,both were evaluated for 338 Populus deltoides genotypes from six provenances.The...It is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity.In this study,both were evaluated for 338 Populus deltoides genotypes from six provenances.The plants were cultured under normal nitrogen(750μM NH_4 NO_3)and low nitrogen(5μM NH_4 NO_3)conditions for 3 months.Growth,chlorophyll content and glutamine synthetase activity of each genotype were measured.Under low nitrogen,heights,ground diameter,leaf area,leaf and root biomass,and chlorophyll contents were significantly lower than those under normal nitrogen level.Correlation analysis showed that nutrient distribution changed under different nitrogen treatments.There was a negative correlation between leaf traits and root biomass under normal nitrogen level,however,the correlation became positive in low nitrogen treatment.Moreover,with the decrease of nitrogen level,the negative correlation between leaf morphology and chlorophyll levels became weakened.The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy mathematical membership function;the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model.According to the results of comprehensive evaluation of plants under the two treatments,the 338 P.deltoides genotypes could be divided into nine categories,with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance.As a result,26 N-efficient genotypes and 24 N-inefficient genotypes were selected.By comparative analysis of their morphological and physiological traits under the two treatments,leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance,which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.展开更多
Linear risk programming was used to determine the optimum cultivation pattern to increase incomes of poplar farmers.Seven clones of Populus deltoides Bartr.ex Marsh.were examined in Guilan province,northern Iran.Growt...Linear risk programming was used to determine the optimum cultivation pattern to increase incomes of poplar farmers.Seven clones of Populus deltoides Bartr.ex Marsh.were examined in Guilan province,northern Iran.Growth and price data were taken from previous research at the Safrabaste Poplar Research Station and in interviews with farmers.The Lingo software was used to analyze the data in different forms of E.The results show that when risk was considered,the optimal solution included the clones Pd63/51-x1,-Pd72/51-x3,Pd73/51-x4 and Pd79/51-x6.There was a high growth fluctuations of the clones Pd69/55-x2,Pd77.51-x5,and Pd caroliniensis-x7 and were not included in cultivation plans.Furthermore,the existing farm plans executed by local farmers,is neither profitoriented nor efficient in terms of income risk management according to risk efficient frontier.These results could help farmers with different levels of risk-aversion to select proper planting plans.展开更多
To date, research on the adverse effects of continuous cropping has focused on field crops;forest plantations, despite their very significant economic and ecological value, have received less attention. The evolution ...To date, research on the adverse effects of continuous cropping has focused on field crops;forest plantations, despite their very significant economic and ecological value, have received less attention. The evolution of microbial community in the rhizosphere of forest plantations, in particular, has rarely been examined. In this study, changes in the size, composition, and structure of bacterial and fungal communities in the rhizosphere of different generations of poplar (Populus deltoides) plantations were studied using real-time polymerase chain reaction (PCR) and PCR-denaturing gradient gel electrophoresis and compared with the composition of the microbial community in a bare land (control) adjacent to the plantation sites through sequencing analysis and by constructing phylogenetic trees. The numbers of bacteria and fungi increased significantly with successive poplar generations, although the increases in the two groups were not parallel. When compared with the control, the bacterial community increased greatly in the second generation, and the most significant increase occurred in the third generation. In contrast, the most significant increase in the fungal community occurred in the first generation, and the increase in the third generation was insignificant. In terms of community composition, the first generation showed little change in either community;however, the second generation showed remarkable changes in the bacterial community, and the third in the fungal community. The numbers of Gammaproteobacteria,Alphaproteobacteria, and Actinobacteria increased by 10.92%, 7.38%, and 5.46%, respectively, whereas those of Acidobacteria decreased by 18.38%in the second generation. These changes in the number and composition of microbial communities in the rhizosphere could be one of the reasons for the decline in yield and quality associated with long-term monoculture.展开更多
文摘Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a distinct endomembrane organization, in particular, the structural associations of the endoplasmic reticulum (ER) with other membrane systems. The striking findings are that some ER elements were in connection with the nuclear envelopes of two adjacent cells through plasmodesmata, and many ER elements were also associated with mitochondria, plastids, Golgi bodies or the plasma membrane (PM), forming a bridge_like continuum among various endomembrane systems or between nucleus to nucleus. A great number of plasmodesmata existed between cells, indicating a perfectly integrated symplasmic structure in poplar apical bud meristem grown in a long day environment. During the short day_induced dormancy, ER contracted, leading to its disassociation between nuclei, and between the nucleus and organelles/plasmalemma in many cells. After dormancy broke and shoots growth resumed, contracted ER was no longer observed in the apical bud cells. The ER associations with other endomembrane systems and the intercellular communication channels were re_established similar to that of plants before dormancy induction. These observations suggest that ER may play an important role in linking_up between the nucleus and organelles, and between the nucleus and the nucleus (or cell_to_cell), and seemingly coordinating various physiological processes by the bridging_like associations. And the contraction of ER under short_day may result in the growth cessation and the development of dormancy in poplar.
基金the National Basic Research Program of China (No 2007CB116307)Forestry Scientific and Technical Supporting Programs (No 2006BAD01A15-3)
文摘Polygalacturonase-inhibiting proteins （PGIPs） are extracellular proteins that belong to the leucine-rich repeat （LRR） protein superfamily. PGIPs inhibit fungal polygalacturonases （PGs） and promote accumulation of oligogalacturonides, which activate plant defense responses. PGIPs play important roles in resistance to infection of pathogens. In this study, reverse transcriptase-polymerase chain reaction （RT-PCR） and RNA ligase-mediated rapid amplification of cDNA ends （RLM-RACE） were used to isolate the full-length PGIP cDNA from Populus deltoides （GenBank accession no. of PdPGIP2 and PdPGIP4：EF684913 and EF684912）. Domain analysis revealed that the deduced amino acid sequences of PdPGIP2 and PdPGIP4 had a typical PGIP topology. Phylogenetic analysis of known PGIPs indicated that the two PdPGIPs were clustered to the defense-related PGIP clade. Using real-time RT-PCR, the expression patterns of the two PdPGIPs following treatment with a fungal pathogen and defense-related signaling molecules were studied. The expression levels of PdPGIP2 and PdPGIP4 were both up-regulated when inoculated with the phytopathogenic fungus Marssonina brunnea. Therefore, it was proposed that the two PGIPs might be involved in the resistance to Marssonina brunnea in P. deltoides.
文摘Plasma membrane （PM） Ca2+-ATPase activity in poplar apical bud meristematic cells during short-day （SD）-induced dormancy development was examined by a cerium precipitation EM-cytochemical method. Ca2+-ATPase activity, indicated by the status of cerium phosphate precipitated grains, was localized mainly on the interior face （cytoplasmic side） of the PM when plants were grown under long days and reached a deep dormancy. A few reaction products were also observed on the nuclear envelope.When plant buds were developing dormancy after 28 to 42 d of SD exposure, almost no reaction products were present on the interior face of the PM. In contrast, a large number of cerium phosphate precipitated grains were distributed on the exterior face of the PM. After 70 d of SD exposure, when buds had developed a deep dormancy, the reaction products of Ca2+-ATPase activity again appeared on the interior face of the PM. The results seemed suggesting that two kinds of Ca2+-ATPases may be present on the PM during the SD-induced dormancy in poplar.One is the Ca2+-punlping ATPase, which is located on the interior face of the PM, for maintaining and restoring the Ca2+homeostasis. The other might be an ecto-Ca2+-ATPase, which is located on the exterior face of the PM, for the exocytosis of cell wall materials as suggested by the fact of the cell wall thickening during the dormancy developlnent in poplar.
基金the funding agency ‘Forest Research Institute, Dehradun for providing necessary funds and supplying the clonesused in the study
文摘We evaluated the growth and crown traits of 36 poplar clones at two distinct agro-climatic regions of Punjab （Ludhiana and Bathinda） in northwestern India, following randomized block design with three replications and plot size of four trees. Significant differences among clones （p〈0.001） were observed for diameter at breast height （DBH）, tree height, volume, crown width and number of branches under both the site conditions. Clones ‘G-3’, ‘25-N’ and ‘41-N’ at Ludhiana and ‘G-3’, ‘RD-01’ and ‘S7C8’ at Bathinda were found to be superior for volume production. All growth and crown traits registered significantly higher values at Ludhiana in comparison to those at Bathinda. Clone site interaction was also significant （p〈0.001）. For volume, clones ‘L-62/84’, ‘113520’, ‘25-N’ and ‘S4C2’ witnessed huge fluctuations in ranking between sites. The correlations between growth traits were positive and highly significant （p〈0.001） at both sites. The clonal mean heritability was moderate for DBH and volume both at Ludhiana （0.61–0.66） and Bathinda （0.61–0.62）. Across sites, the genetic advance was the highest for volume （49.76%） and the lowest （6.50%） in case of height.
文摘clones of Populus deltoides and P. ?euramericana were introduced from Italy, Turkey and domestic in 1986 and 1987 with the agreement of FAO. A completely random block design was applied and the seedling test and controlled afforestation trials had been held at Jinan City, Gaotang County and Juxian County, Shandong Province respectively. The results showed that two clones, namely S307-26 (P. deltoides cv.慡307-26? and PE-19-66 (P. deltoides cv. 慞E-19-66? performed well both in terms of adaptability and growth characteristics. The mean growth volumes (V) of single tree of S307-26 and PE-19-66 were 0.181 2 m3 and 0.164 9 m3, which were 42.0 % and 29.2 % larger than that of I-69 (P. deltoides cv. 慙ux?I-69/55) (CK), respectively, at the age of 5 years at three experimental sites. Results of variance analyses and T test (LSD) for variables showed that above mentioned two clones were significantly different with I-69 (CK). Further analyses found that both clones could be propagated easily and showed high resistance to poplar diseases, pests, drought, cold as well as strong wind, and had long growing period. Furthermore, mechanical properties were also better and fiber length was longer than that of I-69 (CK). It was concluded that both S307-26 and PE-19-66 were ideal varieties for the establishment of fast growing poplar plantations, especially of the wood pulp forest plantations in the region.
基金financially supported by the Key Forestry Public Welfare Project(201304102)the National Natural Science Foundation(No.31400563)+3 种基金the Key Project of Jiangsu Foundation of Natural Sciences for High Education(10KJA180018)the Natural Science Foundation of Jiangsu Province(BK20130968)supported by the program for Innovative Research Teams in the Universities of Jiangsu Province and the Educational Department of Chinathe Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions
文摘The uredinial stage in the life cycle of Melampsora larici-populina on poplar leaves is the most important pathogenic phase. We captured partial phases of uredinial infection in the wild, aiming to reconstruct the process of uredinial ontogeny by using scanning and transmission electron microscope. At the initial infection stage, germ tubes germinated from the echinulate urediniospores. Germ tubes were frequently seen to merge with the leaf surface and cuticle breakage was observed, indicating direct hyphal penetration. Stomata penetration occurred commonly, sometimes with more than one germ tube penetrating the same stoma. Melampsora larici-populina did not form appressoria in the infection process,implying that infectious behavior of this pathogen may differ from the other rust pathogens. In general, germ tubes branched randomly, and no distinct evidence indicated that stoma could induce or orient germ tube branches. However, oriented germ tube growth has been occasionally observed in other studies. The urediniospores collapsed and finally wizened when they became nutrient stressed. At the last stage of infection, the uredinia erupted from the leaf epidermis and appeared as orange pustules on the leaf surface.
文摘Leaves are of fundamental importance to plants, representing their facility to generate power and are the sensing units of plants towards the environment. An attempt was made to characterize and compare the variations of leaf morphology of various Populus deltoides Bartr. clones by studying the winter buds and other leaf parameters of fully developed leaves. To achieve these objectives, forty-three exotic and indigenous clones ofP. deltoides Bartr. were evaluated for different parameters. On the basis of various morphological characteristics the results reveal that each clone has a distinct color pattern of leaves. Different colors observed in these clones varied from light green through green to dark green. Two distinct lengths of the leaf apex were found, i.e., short and long; as well both acuminate and acute apex types were found. Erratic distribution of serration of leaves was also found. In this study, the morphological traits of leaves provided discriminatory grounds for separating various populations of P. deltoides Bartr. clones. Winter bud studies indicate that different clones vary considerably with regard to shape, color, shape of leaf scars and exudation.
基金supported by the State Key Basic Research Program of China(No.2012CB114506)
文摘Molecular biological research into wood development and formation has been the focus in recent years, but the pace of discovery of related genes and their functions in the control of wood properties has been slow. The microarray technique--with its advantages of high throughput capacity, sensitivity, and reliability over other tools developed for investigating genes expression patterns-is capable of rapidly assaying thousands of genes. In this study, a cDNA microarray prepared from two cDNA libraries of developing poplar xylem tissues was used to assay gene expression patterns in immature xylem tissues at different heights from the main stem of Populus deltoides （15 years old）, which was confirmed to have distinct wood properties （microfibrillar angle, woody density） by X-ray. Two hundred seventy-four transcripts with differ- ential expression profles between the chips were screened out, and the individual clones were subjected to 5＇ sequencing. Using bioinformatic analysis, we identified candidate genes that may influence poplar wood properties, many of which belong to various regulatory and signal transduction gene families, such as zinc finger protein transcription factor, DNA-binding transcription factor, ethylene response factors, and so on. The results suggest that these genes may regulate enzymes involved in wood formation. Further work will be performed to clone these genes and determine how they influence poplar wood properties.
基金Supported by the Major Science and Technology Program of Hunan Province(2017NK1010)the Research on High Efficient Cultivation of Populus deltoids Industrial Resources in Dongting Lake Area,the Special Found for the Development and Efficient Utilization Technology Innovation of Forestry Resources during the"13th Five-Year Plan"(2016YFD0600402-2)the Research and Demonstration of Populus Engineering Structural Materials Directional Cultivation and Value-Added Key Technologies,the Science and Technology Planning Project for Forestry of Hunan Province(XLK201506)
文摘In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were determined and analyzed. The results showed that there were significant differences in CSPG of wood between different clones of P. deltoides . The CSPG of the tested clones reached more than 41 MPa, which was higher than the average compressive strength of P. deltoides （32.94 MPa）. Similar to the changes of stem height, the CSPG of the clones gradually increased with the increase of stem height. However, there were significant differences in CSPG of an individual plant at different tree heights. The CSPG of P. deltoides clones was related with their growth traits, but not significantly. Therefore, it is expected to achieve simultaneous and independent improvement on CSPG and the growth of P. deltoides , so as to get excellent individuals with fast growth and high CSPG.
基金financial support this research and the State Key Laboratory of Tree Genetics and Breeding,Research Institute of Forestry,Chinese Academy of Forestry for the instrument support。
文摘It is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity.In this study,both were evaluated for 338 Populus deltoides genotypes from six provenances.The plants were cultured under normal nitrogen(750μM NH_4 NO_3)and low nitrogen(5μM NH_4 NO_3)conditions for 3 months.Growth,chlorophyll content and glutamine synthetase activity of each genotype were measured.Under low nitrogen,heights,ground diameter,leaf area,leaf and root biomass,and chlorophyll contents were significantly lower than those under normal nitrogen level.Correlation analysis showed that nutrient distribution changed under different nitrogen treatments.There was a negative correlation between leaf traits and root biomass under normal nitrogen level,however,the correlation became positive in low nitrogen treatment.Moreover,with the decrease of nitrogen level,the negative correlation between leaf morphology and chlorophyll levels became weakened.The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy mathematical membership function;the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model.According to the results of comprehensive evaluation of plants under the two treatments,the 338 P.deltoides genotypes could be divided into nine categories,with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance.As a result,26 N-efficient genotypes and 24 N-inefficient genotypes were selected.By comparative analysis of their morphological and physiological traits under the two treatments,leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance,which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.
文摘Linear risk programming was used to determine the optimum cultivation pattern to increase incomes of poplar farmers.Seven clones of Populus deltoides Bartr.ex Marsh.were examined in Guilan province,northern Iran.Growth and price data were taken from previous research at the Safrabaste Poplar Research Station and in interviews with farmers.The Lingo software was used to analyze the data in different forms of E.The results show that when risk was considered,the optimal solution included the clones Pd63/51-x1,-Pd72/51-x3,Pd73/51-x4 and Pd79/51-x6.There was a high growth fluctuations of the clones Pd69/55-x2,Pd77.51-x5,and Pd caroliniensis-x7 and were not included in cultivation plans.Furthermore,the existing farm plans executed by local farmers,is neither profitoriented nor efficient in terms of income risk management according to risk efficient frontier.These results could help farmers with different levels of risk-aversion to select proper planting plans.
基金This work was supported by the Special Fund for Forest Scientific Research in the Public Welfare of China(No.201104068).
文摘To date, research on the adverse effects of continuous cropping has focused on field crops;forest plantations, despite their very significant economic and ecological value, have received less attention. The evolution of microbial community in the rhizosphere of forest plantations, in particular, has rarely been examined. In this study, changes in the size, composition, and structure of bacterial and fungal communities in the rhizosphere of different generations of poplar (Populus deltoides) plantations were studied using real-time polymerase chain reaction (PCR) and PCR-denaturing gradient gel electrophoresis and compared with the composition of the microbial community in a bare land (control) adjacent to the plantation sites through sequencing analysis and by constructing phylogenetic trees. The numbers of bacteria and fungi increased significantly with successive poplar generations, although the increases in the two groups were not parallel. When compared with the control, the bacterial community increased greatly in the second generation, and the most significant increase occurred in the third generation. In contrast, the most significant increase in the fungal community occurred in the first generation, and the increase in the third generation was insignificant. In terms of community composition, the first generation showed little change in either community;however, the second generation showed remarkable changes in the bacterial community, and the third in the fungal community. The numbers of Gammaproteobacteria,Alphaproteobacteria, and Actinobacteria increased by 10.92%, 7.38%, and 5.46%, respectively, whereas those of Acidobacteria decreased by 18.38%in the second generation. These changes in the number and composition of microbial communities in the rhizosphere could be one of the reasons for the decline in yield and quality associated with long-term monoculture.
