Leaves are important‘source’organs that synthesize organic matter,providing carbon sources for plant growth.Here,we used Populus talassica×Populus euphratica,the dominant species in ecological and timber forest...Leaves are important‘source’organs that synthesize organic matter,providing carbon sources for plant growth.Here,we used Populus talassica×Populus euphratica,the dominant species in ecological and timber forests,to simulate carbon limitation through artificial 25%,50%,and 75%defoliation treatments and explore the effects on root,stem,and leaf morphology,biomass accumulation,and carbon allocation strategies.At the 60th d after treat-ment,under 25%defoliation treatment,the plant height,specific leaf weight,root surface area and volume,and concentrations of non-structural carbohydrates in stem and root were significantly increased by 9.13%,20.00%,16.60%,31.95%,5.12%,and 9.34%,respectively,relative to the control.There was no significant change in the growth indicators under 50%defoliation treatment,but the concentrations of non-structural carbohydrates in the leaf and stem significantly decreased,showing mostly a negative correlation between them.The opposite was observed in the root.Under 75%defoliation treatment,the plant height,ground diameter,leaf number,single leaf area,root,stem,and total biomass were significantly reduced by 14.15%,10.24%,14.86%,11.31%,11.56%,21.87%,and 16.82%,respectively,relative to the control.The concentrations of non-structural carbohydrates in various organs were significantly reduced,particularly in the consumption of the starch concentrations in the stem and root.These results indicated that carbon allocation strategies can be adjusted to increase the con-centration of non-structural carbohydrates in root and meet plant growth needs under 25%and 50%defoliation.However,75%defoliation significantly limited the distribution of non-structural carbohydrates to roots and stems,reduced carbon storage,and thus inhibited plant growth.Defoliation-induced carbon limitation altered the carbon allocation pattern of P.talassica×P.euphratica,and the relationship between carbon reserves in roots and tree growth recovery after defoliation was greater.This study provides a theoretical basis for the comprehen-sive management of P.talassica×P.euphratica plantations,as well as a reference for the study of plantation car-bon allocation strategies in the desert and semi-desert regions of Xinjiang under carbon-limitation conditions.展开更多
We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) ...We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.展开更多
The authors used suspension cells of Populus euphratica to isolate protoplast in the present study. Protoplasts were successfully obtained after 4 hours incubation in enzyme solution containing 1 0% cellulase “o...The authors used suspension cells of Populus euphratica to isolate protoplast in the present study. Protoplasts were successfully obtained after 4 hours incubation in enzyme solution containing 1 0% cellulase “onozuka” R\|10, 0\^01% pectolyase Y\|23,0\^15% macerozyme R\|10 and 0\^1% hemicellulase at 25℃. Outward and inward single channels in plasma membrane were observed using cell\|attached recording of patch\|clamp technique. In this study, single channel records showed that more than one species of channel were obtained. These attempts in protoplast isolation and ion channel recording offers the opportunity to characterize cellular mechanisms of salt tolerance in tree species.展开更多
Tonoplast-enriched vesicles were prepared from suspension-cultured Populus euphratica Oliv. cells by differential centrifugation and discontinuous sucrose density gradient centrifugation. The properties of the proton ...Tonoplast-enriched vesicles were prepared from suspension-cultured Populus euphratica Oliv. cells by differential centrifugation and discontinuous sucrose density gradient centrifugation. The properties of the proton pumping activity of H+-ATPases in tonoplast vesicles were studied by acridine orange fluorescent quenching measured at 22 degreesC. The proton pumping activity of ATPase was ATP-dependent with apparent Michaelis-Menten Constant (K-m) for ATP about 0.65 mmol/L. The optimal pH for H+-ATPases activity was 7.5. The proton pumping activity of H+-ATPase could be initiated by some divalent cations, Mg2+ being highly efficient, much more than Fe2+; and Ca2+, Cu2+ and Zn2+ were inefficient under the experimental condition. The proton translocation could be stimulated by halide anions, with potencies decreasing in the order Cl- > Br- > I- > F-. The proton pumping activity was greatly inhibited by N-ethylmaleimide (NEM), N, N'-dicyclohexylcarbodiimide (DCCD), NO3- and Bafilomycin A(1), but not by orthovanadate and azide. These results demonstrated that the H+-ATPase in the tonoplast of Populus euphratica belonged to vacuolar type ATPase. This work was the first time that tonoplast-enriched vesicles were isolated from Populus euphratica cells.展开更多
This study presented an improved CTAB method for extracting DNA from leaves of Populus euphratica Oliv. and Populus pruinosa Schrenk. based on the conventional CTAB method. The results showed that preventing DNA from ...This study presented an improved CTAB method for extracting DNA from leaves of Populus euphratica Oliv. and Populus pruinosa Schrenk. based on the conventional CTAB method. The results showed that preventing DNA from browning is a key step to obtain the high-quality DNA during DNA extraction, and under the condition of grinding in the presence of liquid nitrogen, adding such three antioxidants as PVP dry powder, Vc and β-mercaptoethanol could prevent DNA from browning effectively. The total DNA extracted by the improved CTAB method was subjected to PCR detection which proved that it totally satisfied the requirements of subsequent study.展开更多
[Objective] This study was to elucidate the cellular and molecular mechanism of the development of heteromorphic leaves of Populus euphratica Oliv. [Method] By employing SDS-PAGE and 2-demensional electrophoresis (2-D...[Objective] This study was to elucidate the cellular and molecular mechanism of the development of heteromorphic leaves of Populus euphratica Oliv. [Method] By employing SDS-PAGE and 2-demensional electrophoresis (2-DE) techniques,proteins in various heteromorphic leaves from the same adult tree of P. euphratica were isolated and separated to the electrophoresis technique suitable for the separation and analysis of proteins in leaves of P. euphratica tree. [Results] There were significant differences in the expressions of proteins in various heteromorphic leaves of P. euphratica tree. SDS-PAGE pattern showed that bands of proteins with molecular weight of 57.2,13.2,30.2,23.9 and 33.3 kDa were remarkably different. 2-D electrophoresis pattern presented that proteins in leaves of P. euphratica tree mainly belong to acidic proteins distributed at pH value of 5.0-6.5 and with molecular weight of 20-40 kDa; totally 73 different protein spots were observed,of which 51 were up expressed and other 22 were down expressed in the serrated ovate leaves. [Conclusion] Based on these results,we speculate that regulated gene expression in leaves of P. euphratica tree results in the generation of different shapes of leaves,in order to adapt to the surroundings better.展开更多
[Objective] This research was to study the correlation regional climatic characteristics and changing geographic distribution of Populus euphratica Oliv. (Salicaceae), as well as the adaption of Populus euphratica Oli...[Objective] This research was to study the correlation regional climatic characteristics and changing geographic distribution of Populus euphratica Oliv. (Salicaceae), as well as the adaption of Populus euphratica Oliv. to the climatic environment. [Method] The climatic characteristics, water source, groundwater and soil type in the distribution regions of Populus euphratica Oliv. and the effect of long-term human activities were comprehensively analyzed based an overview of Populus euphratica Oliv. and its distribution. [Result] Specific regional climatic characteristics and long term human activities are the principle determinants for the growth of Populus euphratica Oliv. The change of leaf shape is a distinct feature of Populus euphratica Oliv. in adapting to the climatic environment. Populus euphratica Oliv. withstands various environmental stresses by means of in vivo synthesis, transport and conversion of secondary phenolic metabolites. Effective protection and rehabilitation measures, and ecological water transport have obvious effect on the restoration and reconstruction of damaged ecological environment of Populus euphratica oasis. [Conclusion] This study is of great significance for the restoration of ecological environment in the arid inland regions, north-west China.展开更多
The microstructural and ultrastructural traits of three kinds of typical leaves of Populus euphratica Olive, including lanceolate, broad-ovate and dentate broad-ovate leaves, were studied by using electron microscope...The microstructural and ultrastructural traits of three kinds of typical leaves of Populus euphratica Olive, including lanceolate, broad-ovate and dentate broad-ovate leaves, were studied by using electron microscope and optical microscope. The re- sults showed that with the leaves changing from lanceolate shape to dentate broad-ovate shape, their structure obviously tended to be xeromorph: developed palisade tissue, undeveloped spongy tissue, thick cutin layer and sunken stomas. The amount of mitochondria tended to be increased, and the shape of chloroplasts varied from regular spindle to irregular rotundity or oval. The leaves were cov- ered with wax without cilium, and the stomas on the upper and lower epidermis of the leaves opened unevenly. The stomas on the lower epidermis were deeper than those on the upper epidermis under the scanning electron microscope. The results implied that the structural characteristics of the diversiform-leaves of P. euphratica are related to its eco-adaptability.展开更多
Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains l...Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling''method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.展开更多
Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a...Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphrafica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter （height means the height of a tree and diameter means the diameter at breast height （DBH） of a tree） relationship of trees in different vitality classes （i.e. healthy, good, medium, senesced, dying, dead and fallen）. Trees classified as healthy and good ac- counted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH （tree height） and DBH ranged from 0-19 m and 0-125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees by determining the height-diameter correlation coefficient, and the coefficient would be a new parameter for detecting degradation and assessing sustainable management of floodplain forests in arid regions. In addition, tree vitality should be taken into account to make an accurate height-diameter model for tree height prediction.展开更多
Populus euphratica Oliv. is widely distributed along the Tarim River. Maintaining stability of P. euphratica population is important to local development. This study explored the static life table, survivorship curves...Populus euphratica Oliv. is widely distributed along the Tarim River. Maintaining stability of P. euphratica population is important to local development. This study explored the static life table, survivorship curves and four function curves (survival rate, cumulative mortality rate, mortality density, and hazard rate), and development index of P. euphratica population in the middle reaches of Tarim River. The results indicated that the age structure of P. euphratica population belonged to positive pyramidal type, which meant young age-class individuals occupied most populations. The number ofⅠ-Ⅱage classes accounted for 66.2% of whole population, and this indicated that there were abundant subsequent seedlings resources to support the growth of P. euphratica population in the middle reaches of Tarim River. The survivorship curve of P. euphratica belonged to the Deevey Ⅲ (concave-type) and the development index was 47.72%. Four function curves revealed that the individuals of P. euphratica sharply decreased at the initial stage and then leveled off at the late stage of survival curve. Time sequence prediction models predicted that the number of midlife individuals would increase in future 10, 20, 30 years, and P. euphratica population grew steadily as a result of rich saplings.展开更多
We conducted an investigation into the germination of seeds from individual Populus euphratica trees of different ages and growing conditions in order to discover the effect of intraspecific factors on their sexual re...We conducted an investigation into the germination of seeds from individual Populus euphratica trees of different ages and growing conditions in order to discover the effect of intraspecific factors on their sexual reproduction in the Ejina Oasis, Inner Mongolia of China. By carrying out germination experiments of seeds collected at various seed dispersal periods, we found that P. euphratica seeds could be germinated intensively within 8 h from the start of the experiments, that the germination percentage decreased with the time of seed dispersal and that the germination percentage of seeds collected at the early stage of seed dispersal was 1.86 times greater than those collected at the final stage. There was no significant difference in the germination percentage or the germination index between seeds collected at the early and peak stages. The vitality of seeds from the mature forest was clearly higher than that of the half-mature and near-mature forests. The rate of branch dieback only affected seed germination at the final stage. Therefore, we conclude that the mature P. euphratica forest was the main contributor to reproduction. The results show that both the time of seed harvest and stand age were the main factors affecting the germination percentage of P. euphratica seeds.展开更多
Riparian vegetation belts in arid regions of Central Asia are endangered to lose their ecosystem services due to intensified land use.For the development of sustained land use,management knowledge of plant performance...Riparian vegetation belts in arid regions of Central Asia are endangered to lose their ecosystem services due to intensified land use.For the development of sustained land use,management knowledge of plant performance in relation to resource supply is needed.We estimated productivity related functional traits at the edges of the habitat of Populus euphratica Oliv.Specific leaf area （SLA） and carbon/nitrogen （C/N） ratio of P.euphratica leaves growing near a former river bank and close to moving sand dunes in the Ebinur Lake National Nature Reserve in Xinjiang,Northwest China （near Kazakhstan） were determined and daily courses of CO2 net assimilation （PN）,transpiration （E）,and stomatal conductance （gs） of two consecutive seasons were measured during July-August 2007 and June-July 2008.Groundwater level was high （1.5-2.5 m below ground） throughout the years and no flooding occurred at the two tree stands.SLA was slightly lower near the desert than at the former river bank and leaves contained less N in relation to C.Highest E and gs of P.euphratica were reached in the morning before noon on both stands and a second low maximum occurred in the afternoon despite of the unchanged high levels of air to leaf water vapor pressure deficit （ALVPD）.Decline of gs in P.euphratica was followed by decrease of E.Water use efficiency （WUE） of leaves near the desert were higher in the morning and the evening,in contrast to leaves from the former river bank that maintained an almost stable level throughout the day.High light compensation points and high light saturation levels of PN indicated the characteristics of leaves well-adapted to intensive irradiation at both stands.In general,leaves of P.euphratica decreased their gs beyond 20 Pa/kPa ALVPD in order to limit water losses.Decrease of E did not occur in both stands until 40 Pa/kPa ALVPD was reached.Full stomatal closure of P.euphratica was achieved at 60 Pa/kPa ALVPD in both stands.E through the leaf surface amounted up to 30％ of the highest E rates,indicating dependence on water recharge from the ground despite of obviously closed stomata.A distinct leaf surface temperature （Tleaf） threshold of around 30℃ also existed before stomata started to close.Generally,the differences in gas exchange between both stands were small,which led to the conclusion that micro-climatic constraints to E and photosynthesis were not the major factors for declining tree density with increasing distance from the river.展开更多
Riparian vegetation in the lower reaches of Heihe River serves important ecological functions. However, the riparian ecosystems have been constantly deteriorating in the past 30 years simply due to water interception ...Riparian vegetation in the lower reaches of Heihe River serves important ecological functions. However, the riparian ecosystems have been constantly deteriorating in the past 30 years simply due to water interception for oasis agricultural irrigation in the middle reaches of the river. This study pays a particular attention to Populus eu- phratica Oily. forest because it is a dominant component of the riparian ecosystem in the lower reaches of Heihe River where the depth of groundwater table is the controlling factor in sustaining riparian ecosystems. To reveal leaf-related physiological responses of Populus euphratica Oliv. forest to groundwater table variations, we analyzed the relationships between the depth of groundwater table （DG） and three leaf-related parameters, i.e. leaf stomatal density （SD）, specific leaf area （SLA）, and stable carbon isotopic composition （6~SC）. Our results show that the relationship between DG and leaf SD is a bi-mode one shaped by both salt stress and water stress. That is, salt stress appeared in shallow groundwater conditions and water stress happened in deep groundwater conditions, and the thin layer around 2.7 m of DG is a stress-free layer. Leaf SD fluctuated according to the DG variation, first de- creased with increasing DG, then increased at depths ranging 2.7-3.7 m, and after a relatively stable plateau of SD at depths ranging 3.7-5.2 m, decreased again with increasing DG. Our results also show that SLA decreased ex- ponentially with increasing DG and foliar 6130 values are also strongly dependent on DG, further demonstrating that these two parameters are sensitive indicators of water stress. The exponential curve suggests that SLA is more sensitive to DG when groundwater table is shallow and 3 m seems to be a threshold beyond which SLA becomes less sensitive to DG. Foliar 613C becomes more sensitive when the groundwater table is deep and 7 m seems to be a threshold below which the 6130 signature becomes more sensitive to DG. These findings should be helpful in monitoring the growth and development of Populus euphratica Oliv. forests and also in providing protection measures （i.e. DG related） for Heihe River riparian forests.展开更多
基金funded by the Talents ans its Youth Project of Xinjiang Production and Construction Corps(38000020924,380000358).
文摘Leaves are important‘source’organs that synthesize organic matter,providing carbon sources for plant growth.Here,we used Populus talassica×Populus euphratica,the dominant species in ecological and timber forests,to simulate carbon limitation through artificial 25%,50%,and 75%defoliation treatments and explore the effects on root,stem,and leaf morphology,biomass accumulation,and carbon allocation strategies.At the 60th d after treat-ment,under 25%defoliation treatment,the plant height,specific leaf weight,root surface area and volume,and concentrations of non-structural carbohydrates in stem and root were significantly increased by 9.13%,20.00%,16.60%,31.95%,5.12%,and 9.34%,respectively,relative to the control.There was no significant change in the growth indicators under 50%defoliation treatment,but the concentrations of non-structural carbohydrates in the leaf and stem significantly decreased,showing mostly a negative correlation between them.The opposite was observed in the root.Under 75%defoliation treatment,the plant height,ground diameter,leaf number,single leaf area,root,stem,and total biomass were significantly reduced by 14.15%,10.24%,14.86%,11.31%,11.56%,21.87%,and 16.82%,respectively,relative to the control.The concentrations of non-structural carbohydrates in various organs were significantly reduced,particularly in the consumption of the starch concentrations in the stem and root.These results indicated that carbon allocation strategies can be adjusted to increase the con-centration of non-structural carbohydrates in root and meet plant growth needs under 25%and 50%defoliation.However,75%defoliation significantly limited the distribution of non-structural carbohydrates to roots and stems,reduced carbon storage,and thus inhibited plant growth.Defoliation-induced carbon limitation altered the carbon allocation pattern of P.talassica×P.euphratica,and the relationship between carbon reserves in roots and tree growth recovery after defoliation was greater.This study provides a theoretical basis for the comprehen-sive management of P.talassica×P.euphratica plantations,as well as a reference for the study of plantation car-bon allocation strategies in the desert and semi-desert regions of Xinjiang under carbon-limitation conditions.
文摘We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.
文摘The authors used suspension cells of Populus euphratica to isolate protoplast in the present study. Protoplasts were successfully obtained after 4 hours incubation in enzyme solution containing 1 0% cellulase “onozuka” R\|10, 0\^01% pectolyase Y\|23,0\^15% macerozyme R\|10 and 0\^1% hemicellulase at 25℃. Outward and inward single channels in plasma membrane were observed using cell\|attached recording of patch\|clamp technique. In this study, single channel records showed that more than one species of channel were obtained. These attempts in protoplast isolation and ion channel recording offers the opportunity to characterize cellular mechanisms of salt tolerance in tree species.
文摘Tonoplast-enriched vesicles were prepared from suspension-cultured Populus euphratica Oliv. cells by differential centrifugation and discontinuous sucrose density gradient centrifugation. The properties of the proton pumping activity of H+-ATPases in tonoplast vesicles were studied by acridine orange fluorescent quenching measured at 22 degreesC. The proton pumping activity of ATPase was ATP-dependent with apparent Michaelis-Menten Constant (K-m) for ATP about 0.65 mmol/L. The optimal pH for H+-ATPases activity was 7.5. The proton pumping activity of H+-ATPase could be initiated by some divalent cations, Mg2+ being highly efficient, much more than Fe2+; and Ca2+, Cu2+ and Zn2+ were inefficient under the experimental condition. The proton translocation could be stimulated by halide anions, with potencies decreasing in the order Cl- > Br- > I- > F-. The proton pumping activity was greatly inhibited by N-ethylmaleimide (NEM), N, N'-dicyclohexylcarbodiimide (DCCD), NO3- and Bafilomycin A(1), but not by orthovanadate and azide. These results demonstrated that the H+-ATPase in the tonoplast of Populus euphratica belonged to vacuolar type ATPase. This work was the first time that tonoplast-enriched vesicles were isolated from Populus euphratica cells.
基金Supported by Natural Science Foundation of China(31160110)Open Project of Key Laboratory of Biological Resource Protection and Utilization of Tarim Basin(BRYB1003)the Principle Fund of Tarim University(TDZKSS201419)~~
文摘This study presented an improved CTAB method for extracting DNA from leaves of Populus euphratica Oliv. and Populus pruinosa Schrenk. based on the conventional CTAB method. The results showed that preventing DNA from browning is a key step to obtain the high-quality DNA during DNA extraction, and under the condition of grinding in the presence of liquid nitrogen, adding such three antioxidants as PVP dry powder, Vc and β-mercaptoethanol could prevent DNA from browning effectively. The total DNA extracted by the improved CTAB method was subjected to PCR detection which proved that it totally satisfied the requirements of subsequent study.
文摘[Objective] This study was to elucidate the cellular and molecular mechanism of the development of heteromorphic leaves of Populus euphratica Oliv. [Method] By employing SDS-PAGE and 2-demensional electrophoresis (2-DE) techniques,proteins in various heteromorphic leaves from the same adult tree of P. euphratica were isolated and separated to the electrophoresis technique suitable for the separation and analysis of proteins in leaves of P. euphratica tree. [Results] There were significant differences in the expressions of proteins in various heteromorphic leaves of P. euphratica tree. SDS-PAGE pattern showed that bands of proteins with molecular weight of 57.2,13.2,30.2,23.9 and 33.3 kDa were remarkably different. 2-D electrophoresis pattern presented that proteins in leaves of P. euphratica tree mainly belong to acidic proteins distributed at pH value of 5.0-6.5 and with molecular weight of 20-40 kDa; totally 73 different protein spots were observed,of which 51 were up expressed and other 22 were down expressed in the serrated ovate leaves. [Conclusion] Based on these results,we speculate that regulated gene expression in leaves of P. euphratica tree results in the generation of different shapes of leaves,in order to adapt to the surroundings better.
文摘[Objective] This research was to study the correlation regional climatic characteristics and changing geographic distribution of Populus euphratica Oliv. (Salicaceae), as well as the adaption of Populus euphratica Oliv. to the climatic environment. [Method] The climatic characteristics, water source, groundwater and soil type in the distribution regions of Populus euphratica Oliv. and the effect of long-term human activities were comprehensively analyzed based an overview of Populus euphratica Oliv. and its distribution. [Result] Specific regional climatic characteristics and long term human activities are the principle determinants for the growth of Populus euphratica Oliv. The change of leaf shape is a distinct feature of Populus euphratica Oliv. in adapting to the climatic environment. Populus euphratica Oliv. withstands various environmental stresses by means of in vivo synthesis, transport and conversion of secondary phenolic metabolites. Effective protection and rehabilitation measures, and ecological water transport have obvious effect on the restoration and reconstruction of damaged ecological environment of Populus euphratica oasis. [Conclusion] This study is of great significance for the restoration of ecological environment in the arid inland regions, north-west China.
文摘The microstructural and ultrastructural traits of three kinds of typical leaves of Populus euphratica Olive, including lanceolate, broad-ovate and dentate broad-ovate leaves, were studied by using electron microscope and optical microscope. The re- sults showed that with the leaves changing from lanceolate shape to dentate broad-ovate shape, their structure obviously tended to be xeromorph: developed palisade tissue, undeveloped spongy tissue, thick cutin layer and sunken stomas. The amount of mitochondria tended to be increased, and the shape of chloroplasts varied from regular spindle to irregular rotundity or oval. The leaves were cov- ered with wax without cilium, and the stomas on the upper and lower epidermis of the leaves opened unevenly. The stomas on the lower epidermis were deeper than those on the upper epidermis under the scanning electron microscope. The results implied that the structural characteristics of the diversiform-leaves of P. euphratica are related to its eco-adaptability.
基金financially supported by the Key Research Program of Frontier Sciences CAS(QYZDJ-SSWDQC031)Key Project of the Chinese Academy of Sciences(KZZDEW-04-05)+1 种基金the National Natural Science Foundation of China(91025024)the ‘‘Western Light’’ project of the Chinese Academy of Science
文摘Evidence exists of nighttime transpiration and its potential impact on plant/water relations for species in a diversity of ecosystems. However, relevant data related to typical desert riparian forest species remains limited Accordingly, we measured sap flow velocity of Populus euphratica using the heat ratio method between 2012 and2014. Nocturnal stem sap flow was separated into nighttime and stem refilling using the ‘‘forecasted refilling''method. Nighttime transpiration was observed for each phenophase. The highest value was during the full foliation period but lowest during leaf expansion and defoliation periods. The contribution of nighttime transpiration to daytime transpiration was an average of 15% but this was comparatively higher during the defoliation period. Relationships between nighttime transpiration, vapor pressure deficits, and air temperatures were more closely associated than with wind speed in all phenophases. Moreover, we found that nighttime transpiration linearly correlated to vapour pressure deficit during the first and the full foliation periods, but nighttime transpiration showed exponential correlations to air temperatures during the same phenophases. Additionally, environmental drivers of transpiration were significantly different between nighttime and daytime(P \ 0.05). Driving forces behind nighttime transpiration were characterized by many factors, and integrated impacts between these multiple environmental factors were complex. Future studies should focus on these integrated impacts on nighttime transpiration, and the physiological mechanisms of nighttime transpiration should be investigated, given that this could also influence its occurrence and magnitude during different phenophases.
基金supported by International Science & Technology Cooperation Program of China (2010DFA92720-12)the National Natural Science Foundation of China (31360200)+1 种基金the German Volkswagen Foundation Eco CAR Project (Az88497)the German Federal Ministry of Education and Research (BMBF) within the framework of the Su Ma Ri O Project (01LL0918D)
文摘Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphrafica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter （height means the height of a tree and diameter means the diameter at breast height （DBH） of a tree） relationship of trees in different vitality classes （i.e. healthy, good, medium, senesced, dying, dead and fallen）. Trees classified as healthy and good ac- counted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH （tree height） and DBH ranged from 0-19 m and 0-125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees by determining the height-diameter correlation coefficient, and the coefficient would be a new parameter for detecting degradation and assessing sustainable management of floodplain forests in arid regions. In addition, tree vitality should be taken into account to make an accurate height-diameter model for tree height prediction.
基金the National Science and Technology Support Program Projects (2009BAC54B04) for financing this research
文摘Populus euphratica Oliv. is widely distributed along the Tarim River. Maintaining stability of P. euphratica population is important to local development. This study explored the static life table, survivorship curves and four function curves (survival rate, cumulative mortality rate, mortality density, and hazard rate), and development index of P. euphratica population in the middle reaches of Tarim River. The results indicated that the age structure of P. euphratica population belonged to positive pyramidal type, which meant young age-class individuals occupied most populations. The number ofⅠ-Ⅱage classes accounted for 66.2% of whole population, and this indicated that there were abundant subsequent seedlings resources to support the growth of P. euphratica population in the middle reaches of Tarim River. The survivorship curve of P. euphratica belonged to the Deevey Ⅲ (concave-type) and the development index was 47.72%. Four function curves revealed that the individuals of P. euphratica sharply decreased at the initial stage and then leveled off at the late stage of survival curve. Time sequence prediction models predicted that the number of midlife individuals would increase in future 10, 20, 30 years, and P. euphratica population grew steadily as a result of rich saplings.
基金supported by the National Natural Science Foundation of China (Grant Nos. 31070553, 30570332)the 11th Five-Year Plan of the National Scientific and Technological Support Projects of China (Grant No. 2008BAD-B0B05)
文摘We conducted an investigation into the germination of seeds from individual Populus euphratica trees of different ages and growing conditions in order to discover the effect of intraspecific factors on their sexual reproduction in the Ejina Oasis, Inner Mongolia of China. By carrying out germination experiments of seeds collected at various seed dispersal periods, we found that P. euphratica seeds could be germinated intensively within 8 h from the start of the experiments, that the germination percentage decreased with the time of seed dispersal and that the germination percentage of seeds collected at the early stage of seed dispersal was 1.86 times greater than those collected at the final stage. There was no significant difference in the germination percentage or the germination index between seeds collected at the early and peak stages. The vitality of seeds from the mature forest was clearly higher than that of the half-mature and near-mature forests. The rate of branch dieback only affected seed germination at the final stage. Therefore, we conclude that the mature P. euphratica forest was the main contributor to reproduction. The results show that both the time of seed harvest and stand age were the main factors affecting the germination percentage of P. euphratica seeds.
基金funded by the German Academic Exchange Service,PPP-China(D/06/00362)
文摘Riparian vegetation belts in arid regions of Central Asia are endangered to lose their ecosystem services due to intensified land use.For the development of sustained land use,management knowledge of plant performance in relation to resource supply is needed.We estimated productivity related functional traits at the edges of the habitat of Populus euphratica Oliv.Specific leaf area （SLA） and carbon/nitrogen （C/N） ratio of P.euphratica leaves growing near a former river bank and close to moving sand dunes in the Ebinur Lake National Nature Reserve in Xinjiang,Northwest China （near Kazakhstan） were determined and daily courses of CO2 net assimilation （PN）,transpiration （E）,and stomatal conductance （gs） of two consecutive seasons were measured during July-August 2007 and June-July 2008.Groundwater level was high （1.5-2.5 m below ground） throughout the years and no flooding occurred at the two tree stands.SLA was slightly lower near the desert than at the former river bank and leaves contained less N in relation to C.Highest E and gs of P.euphratica were reached in the morning before noon on both stands and a second low maximum occurred in the afternoon despite of the unchanged high levels of air to leaf water vapor pressure deficit （ALVPD）.Decline of gs in P.euphratica was followed by decrease of E.Water use efficiency （WUE） of leaves near the desert were higher in the morning and the evening,in contrast to leaves from the former river bank that maintained an almost stable level throughout the day.High light compensation points and high light saturation levels of PN indicated the characteristics of leaves well-adapted to intensive irradiation at both stands.In general,leaves of P.euphratica decreased their gs beyond 20 Pa/kPa ALVPD in order to limit water losses.Decrease of E did not occur in both stands until 40 Pa/kPa ALVPD was reached.Full stomatal closure of P.euphratica was achieved at 60 Pa/kPa ALVPD in both stands.E through the leaf surface amounted up to 30％ of the highest E rates,indicating dependence on water recharge from the ground despite of obviously closed stomata.A distinct leaf surface temperature （Tleaf） threshold of around 30℃ also existed before stomata started to close.Generally,the differences in gas exchange between both stands were small,which led to the conclusion that micro-climatic constraints to E and photosynthesis were not the major factors for declining tree density with increasing distance from the river.
基金financially supported by the National Natural Science Foundation of China (91025015, 30770387)
文摘Riparian vegetation in the lower reaches of Heihe River serves important ecological functions. However, the riparian ecosystems have been constantly deteriorating in the past 30 years simply due to water interception for oasis agricultural irrigation in the middle reaches of the river. This study pays a particular attention to Populus eu- phratica Oily. forest because it is a dominant component of the riparian ecosystem in the lower reaches of Heihe River where the depth of groundwater table is the controlling factor in sustaining riparian ecosystems. To reveal leaf-related physiological responses of Populus euphratica Oliv. forest to groundwater table variations, we analyzed the relationships between the depth of groundwater table （DG） and three leaf-related parameters, i.e. leaf stomatal density （SD）, specific leaf area （SLA）, and stable carbon isotopic composition （6~SC）. Our results show that the relationship between DG and leaf SD is a bi-mode one shaped by both salt stress and water stress. That is, salt stress appeared in shallow groundwater conditions and water stress happened in deep groundwater conditions, and the thin layer around 2.7 m of DG is a stress-free layer. Leaf SD fluctuated according to the DG variation, first de- creased with increasing DG, then increased at depths ranging 2.7-3.7 m, and after a relatively stable plateau of SD at depths ranging 3.7-5.2 m, decreased again with increasing DG. Our results also show that SLA decreased ex- ponentially with increasing DG and foliar 6130 values are also strongly dependent on DG, further demonstrating that these two parameters are sensitive indicators of water stress. The exponential curve suggests that SLA is more sensitive to DG when groundwater table is shallow and 3 m seems to be a threshold beyond which SLA becomes less sensitive to DG. Foliar 613C becomes more sensitive when the groundwater table is deep and 7 m seems to be a threshold below which the 6130 signature becomes more sensitive to DG. These findings should be helpful in monitoring the growth and development of Populus euphratica Oliv. forests and also in providing protection measures （i.e. DG related） for Heihe River riparian forests.
