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
Microbe communities in rhizosphere ecosystems are important for plant health but there is limited knowledge of them in the rhizospheres of genetically modified（GM） plants, especial for tree species. We used the ampl...Microbe communities in rhizosphere ecosystems are important for plant health but there is limited knowledge of them in the rhizospheres of genetically modified（GM） plants, especial for tree species. We used the amplitude sequencing method to analyze the V4 regions of the 16 S r RNA gene to identify changes in bacterial diversity and community structure in two GM lines（D520 and D521）, one non-genetically modified（nonGM） line and in uncultivated soil. After chimera filtering,468.133 sequences in the domain Bacteria remained. There were ten dominant taxonomic groups（with [1 % of all sequences） across the samples. 241 of 551 genera（representing a ratio of 97.33 %） were common to all samples.A Venn diagram showed that 1.926 operational taxonomic units（OTUs） were shared by all samples. We found a specific change, a reduction in Chloroflexi, in the microorganisms in the rhizosphere soil planted with poplars. Taken together, the results showed few statistical differences in the bacterial diversity and community structure between the GM line and non-GM line, this suggests that there was no or very limited impact of this genetic modification on the bacterial communities in the rhizosphere.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
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.
基金financially supported by the National High-Tech Research and Development Program of China,863Program(Grant No.2011AA100201)the National Forestry Public Welfare Research Project of China(Grant No.201004004)
文摘Microbe communities in rhizosphere ecosystems are important for plant health but there is limited knowledge of them in the rhizospheres of genetically modified（GM） plants, especial for tree species. We used the amplitude sequencing method to analyze the V4 regions of the 16 S r RNA gene to identify changes in bacterial diversity and community structure in two GM lines（D520 and D521）, one non-genetically modified（nonGM） line and in uncultivated soil. After chimera filtering,468.133 sequences in the domain Bacteria remained. There were ten dominant taxonomic groups（with [1 % of all sequences） across the samples. 241 of 551 genera（representing a ratio of 97.33 %） were common to all samples.A Venn diagram showed that 1.926 operational taxonomic units（OTUs） were shared by all samples. We found a specific change, a reduction in Chloroflexi, in the microorganisms in the rhizosphere soil planted with poplars. Taken together, the results showed few statistical differences in the bacterial diversity and community structure between the GM line and non-GM line, this suggests that there was no or very limited impact of this genetic modification on the bacterial communities in the rhizosphere.
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.
