An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) o...An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based day-time leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elected, but not at ambient CO2. Nighttime leaf Rd. and Rdm were unthected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 μmol m-2 s-1 in the spring and 3.5 to 4.5 μmol m-2 s-1 in the summer. Root Rda. was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.展开更多
In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormo...In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormones in the plants. At the same time, the factors that influenced the vitrification of the plant as well as de-vitrification method were also studied by changing medium’s component, which was to provide useful information for commercial propagation of good hybrid clones of aspen. The results were as follows: 1)The ABA and IAA contents in the vitrificated plants were higher than those in the non-vitrificated plants obviously, and the GA content was little lower than that of the non-vitrificated plants. Therefore, the higher IAA or ABA content in the vitrificated plants was possibly the main reason for the vitrification of the plant.2)The ratios of endogenous plant hormones such as ABA/GA and IAA/GA in the vitrificated plants of hybrid aspen by tissue culture were higher than those in the non-vitrificated plants, which indicated that the equilibrium relationship among different endogenous hormones in vitrificated plants was deviated from the normal, then possibly resulting in the vitrification of the plant.展开更多
In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and developm...In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and development of Arabidopsis, we transformed Arabidopsis plants with an overexpression vector containing an aspen SUS gene (PtrSUS1). The genomic PCR confirmed the successful integration of PtrSUS1 transgene in the Arabidopsis genome. PtrSUS1 expression in transgenic Arabidopsis plants was confirmed by RT-PCR. The SUS activity was dramatically increased in all transgenic lines examined. The three selected transgenic PtrSUS1 lines exhibited faster growth and flowered about 10 days earlier compared to untransformed controls, and also possessed 133%, 139%, and 143% SUS activity compared to controls. Both fresh weights and dry biomass yields of the whole plants from these three selected transgenic lines were significantly increased to 125% of the controls. Transgenic PtrSUS1 lines also had a higher tolerance to higher concentration of sucrose which was reflective of the increased SUS activity in transgenic versus wild-type plants. The growth differences between wild-type and transgenic plants, either in root and hypocotyl length or in fresh and dry weight of whole plant, became more pronounced on the media containing higher sucrose concentrations. Taken together, these results showed that the early flowering, faster growth and increased tolerance to higher sucrose in transgenic lines were caused by the genome integration and constitutive expression of the aspen PtrSUS1 gene in transgenic Arabidopsis.展开更多
基金the National institute for Global Environmental Change (DOENIGEC), Program for Ecosystem Research (DOE-PER Grant D E- FG O Z-9
文摘An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based day-time leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elected, but not at ambient CO2. Nighttime leaf Rd. and Rdm were unthected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 μmol m-2 s-1 in the spring and 3.5 to 4.5 μmol m-2 s-1 in the summer. Root Rda. was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.
文摘In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormones in the plants. At the same time, the factors that influenced the vitrification of the plant as well as de-vitrification method were also studied by changing medium’s component, which was to provide useful information for commercial propagation of good hybrid clones of aspen. The results were as follows: 1)The ABA and IAA contents in the vitrificated plants were higher than those in the non-vitrificated plants obviously, and the GA content was little lower than that of the non-vitrificated plants. Therefore, the higher IAA or ABA content in the vitrificated plants was possibly the main reason for the vitrification of the plant.2)The ratios of endogenous plant hormones such as ABA/GA and IAA/GA in the vitrificated plants of hybrid aspen by tissue culture were higher than those in the non-vitrificated plants, which indicated that the equilibrium relationship among different endogenous hormones in vitrificated plants was deviated from the normal, then possibly resulting in the vitrification of the plant.
文摘In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and development of Arabidopsis, we transformed Arabidopsis plants with an overexpression vector containing an aspen SUS gene (PtrSUS1). The genomic PCR confirmed the successful integration of PtrSUS1 transgene in the Arabidopsis genome. PtrSUS1 expression in transgenic Arabidopsis plants was confirmed by RT-PCR. The SUS activity was dramatically increased in all transgenic lines examined. The three selected transgenic PtrSUS1 lines exhibited faster growth and flowered about 10 days earlier compared to untransformed controls, and also possessed 133%, 139%, and 143% SUS activity compared to controls. Both fresh weights and dry biomass yields of the whole plants from these three selected transgenic lines were significantly increased to 125% of the controls. Transgenic PtrSUS1 lines also had a higher tolerance to higher concentration of sucrose which was reflective of the increased SUS activity in transgenic versus wild-type plants. The growth differences between wild-type and transgenic plants, either in root and hypocotyl length or in fresh and dry weight of whole plant, became more pronounced on the media containing higher sucrose concentrations. Taken together, these results showed that the early flowering, faster growth and increased tolerance to higher sucrose in transgenic lines were caused by the genome integration and constitutive expression of the aspen PtrSUS1 gene in transgenic Arabidopsis.
