Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairme...Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes.Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions.This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants.Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,respectively.This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous exchange.However,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress.In particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,respectively.Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants.Overall,these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes.This stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.展开更多
While biochar amendment enhances plant productivity and water-use efficiency(WUE),particularly under waterlimited conditions,the specific mechanisms driving these benefits remain unclear.Thus,the present study aims to...While biochar amendment enhances plant productivity and water-use efficiency(WUE),particularly under waterlimited conditions,the specific mechanisms driving these benefits remain unclear.Thus,the present study aims to elucidate the synergistic effects of biochar and reduced irrigation on maize(Zea mays L.)plants,focusing on xylem composition,root-to-shoot signaling,stomatal behavior,and WUE.Maize plants were cultivated in splitroot pots filled with clay loam soil,amended by either wheat-straw biochar(WSB)or softwood biochar(SWB)at 2%(w/w).Plants received full irrigation(FI),deficit irrigation(DI),or partial root-zone drying rrigation(PRD)from the 4-leaf to the grain-filling stage.Our results revealed that the WSB amendment significantly enhanced plant water status,biomass accumulation,and WUE under reduced irrigation,particularly when combined with PRD.Although reduced irrigation inhibited photosynthesis,it enhanced WUE by modulating stomatal morphology and conductance.Biochar amendment combined with reduced rrigation significantly increased xylem K^(+),Ca^(2+),Mg^(2+),NO_(3)^(-),Cl^(-),PO_(4)^(3-),and SO_(4)^(2-)-but decreased Na+,which in turn lowered xylem pH.Moreover,biochar amendment and especially WSB amendment further increased abscisic acid(ABA)contents in both leaf and xylem sap under reduced irrigation conditions due to changes in xylem ionic constituents and pH.The synergistic interactions between xylem components and ABA led to refined adjustments in stomatal size and density,thereby affecting stomatal conductance and ultimately improving the WUE of maize plants at different scales.The combined application of WSB and PRD can,therefore,emerge as a promising approach for improving the overall plant performance of maize plants with increased stomatal adaptations and WUE,especially under water-limited conditions.展开更多
To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2...To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2000, with the LI 1600 Steady Porometer and the general weather information. The daily variation of transpiration in black locust forest ( Robinia pesudoacacia L.) is modeled by Penman Monteith equation. As a result of the model, a continuous daily transpiration in the growth season was calculated. The net radiation, intercepted by black locust forest canopy, was acquired from a semi empirical equation of measuring net radiation R n with the extinction coefficient k and leaf area index LAI . The canopy integral stomatic resistance is a mimesis with an empirical equation of measuring data. Compared with measuring data, the relative error of the modeled ones is less than 12% averagely. At last, the total transpiration of black locust forest during the period of 1998 and 2000 in the growth season of May to October, as an average transpiration of the different density stands, were 192 46, 187 07 and 195 59?mm respectively.展开更多
Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree spec...Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree species in boreal Eurasia,calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology.Here,we conducted a short-term rainfall(−60% ambient rainfall;three-year)and snowfall(−73% ambient snowfall;two-year)exclusions experiment in Larix gmelinii forest in northeastern China,and aimed to explore the responses of hydraulic(leaf pressure-volume traits,leaf and branch hydraulic conductivity and embolism resistance),stomatal(stomatal closure point and stomatal safety margin),and economic(photosynthetic rate,nutrient and non-structural carbohydrates contents)traits to rainfall and snowfall reductions.Despite the weak alternation of leaf and branch hydraulic traits,both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins(the difference between stomatal closure point and xylem embolism threshold,describing drought resistance by merging both hydraulic and stomatal strategies).Reductions in rainfall and snowfall induced water or/and low-temperature stress,resulting in more conservative leaf economic traits,including a reduced photosynthetic rate,lower leaf nitrogen concentration,and higher leaf density.In addition,larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem,which helps repair embolism or lower the freezing point acting as osmolytes.Overall,our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing,at the cost of carbon assimilation.展开更多
Secondary salinization is a major environmental factor that causes a stress response and growth inhibition in plants in protected agriculture.The positive effect of a low red to far-red light ratio(R:FR)in salt tolera...Secondary salinization is a major environmental factor that causes a stress response and growth inhibition in plants in protected agriculture.The positive effect of a low red to far-red light ratio(R:FR)in salt tolerance through antioxidant defense has been reported,while the underlying model remains obscure.In this study,we used physiological and genetic approaches to investigate the relationship between H_(2)O_(2) signaling and low R:FR-induced salt tolerance and antioxidant capacity in tomato seedlings.This study found that low R:FR treatment with calcium nitrate stress(SL treatment)enhanced the growth of plants and increased the net photosynthetic rate 5 days after stress compared with a higher R:FR ratio and calcium nitrate stress(S treatment).With transcriptomic analysis of tomato leaves at 5 d,compared with CK,most of glutaredoxin genes and antioxidant enzymes were upregulated by S treatment,which were upregulated further by SL treatment.Compared to the S treatment,within 5 days,the H_(2)O_(2) level was increased faster before 24 h and it was slowed down after 24 h by SL treatment,with less H_(2)O_(2) accumulation at 5 d than that of S treatment.The enhancement of gene expression of RBOH genes were also shown at 24 h under SL.It was found that stomatal conductance followed the dynamic change of H_(2)O_(2),with a rapid closure of stomata of a decrease at 3 h and an increase after 9 h in SL treatment compared to S treatment,respectively.There was same trend of stomata opening degrees of tomato leaves observed by optical microscope.However,the inhibitor of H_(2)O_(2) production(DPI pretreatment)weakened the positive effect of low R:FR on the regulation of stomatal movement.In addition,SL treatment increased the antioxidant enzyme activities and proline content and decreased the MDA content as compared to the S treatment,while the enhancement of ROS homeostasis was reduced by the DPI pretreatment.In conclusion,low R:FR improved redox homeostasis and stomatal status under calcium nitrate stress through H_(2)O_(2)signaling,improving the adaptation of tomato seedlings to soil salinization stress.展开更多
5-Aminolevulinic acid(ALA)is a novel plant growth regulator that has shown outstanding capability to promote stomatal opening.Starch degradation,catalyzed byβ-amylase(EC3.2.1.2,BAM),plays an important role in stomata...5-Aminolevulinic acid(ALA)is a novel plant growth regulator that has shown outstanding capability to promote stomatal opening.Starch degradation,catalyzed byβ-amylase(EC3.2.1.2,BAM),plays an important role in stomatal opening.However,whether the starch breakdown is involved in ALA-regulating stomatal movement is unclear.In the current study,we found that exogenous ALA effectively stimulated the starch breakdown in guard cells,increasedβ-amylase activity and promoted stomatal opening in leaves of apple(Malus×domestica).Based on genome-wide identification,we identified a total of 119 members of BAM gene family in ten commonly Rosaceae crops.Analyses of gene structure,motif identification,and gene pair collinearity revealed relative conservation among members within the same group or subgroup.Among these genes,MdBAM17 and other 12 genes were identified as the orthologous genes of AtBAM1,which is responsible for starch degradation to modulate the stomatal movement in Arabidopsis.qRT-PCR analysis revealed a positive correlation between the expressions of MdBAM17 and stomatal aperture,as well asβ-amylase activity,whereas a negative correlation was observed with the starch content.Subcellular localization analysis confirmed that MdBAM17 is a chloroplast protein,consistent with the AtBAM1.MdBAM17 was mainly expressed in guard cells and responsive to exogenous ALA.Overexpressing MdBAM17 increasedβ-amylase activity and promoted starch breakdown,leading to stomatal opening,which was further strengthened by ALA.RNA-interfering MdBAM17 decreasedβ-amylase activity,resulting in starch accumulation,and impairing the stomatal opening by ALA.However,modulation of MdBAM17 expression did not affect the levels of flavonols and H_(2)O_(2)in guard cells,suggesting that MdBAM17-promoted starch degradation may function at downstream of ROS signaling in the ALAregulated stomatal opening.Our findings provide new insights into the mechanisms of ALA-regulated stomatal movement.展开更多
Recurrent aphthous stomatitis(RAS)is a very frequent condition in developed countries whose basic symptom is a lesion referred to as an aphthous ulcer.High levels of interleukin(IL)-1 and IL-6 and low salivary levels ...Recurrent aphthous stomatitis(RAS)is a very frequent condition in developed countries whose basic symptom is a lesion referred to as an aphthous ulcer.High levels of interleukin(IL)-1 and IL-6 and low salivary levels of IL-10 are the basis of RAS pathogenesis.Sublingual supplements based on IL-10 can be very useful in reducing the phenomenon of aphthous recurrence in patients with RAS.An observational clinical experience with a group of 5 patients with RAS receiving a commercially available IL-10-based supplement was reported by the authors.The findings revealed a subsequent reduction in the incidence of mouth ulcers.展开更多
Soil water content(SWC)and meteorological conditions,as key environmental variables influencing tree water use,vary highly within the growing season,hindering a better understanding of environmental control mechanisms...Soil water content(SWC)and meteorological conditions,as key environmental variables influencing tree water use,vary highly within the growing season,hindering a better understanding of environmental control mechanisms on canopy transpiration(Ec).Disentangling the effects of these variables on Ec across growing-season stages is crucial for Ec estimation and forest management.In this study,43-year-old Pinus tabuliformis Carr.and 31-yearold Platycladus orientalis(L.)Franco plantations in the semiarid Chinese Loess Plateau were monitored for Ec during the growing season of 2015-2020.The contributions of environmental factors to Ec were assessed using the boosted regression tree(BRT)model.Results showed that the contributions of SWC to Ec were greater at the early(May-June)and late(September)stages,while the contributions of vapor pressure deficit(VPD)and total solar radiation(Rs)to Ec increased at the middle(July-August)stage due to high soil water availability.Overall,Ec in both plantations was dominated by SWC(20.4%≤contributions≤48.8%)and Rs(22.7%≤contributions≤35.8%).Both species exhibited strong stomatal regulation of Ec.Specifically,stomatal opening was significantly inhibited by VPD at the early stage and strongly affected by SWC at the late stage.This study highlights that soil water conditions in artificial forests should be adjusted according to changes in influencing factors on Ec.Particularly during the early and late stages,measures(e.g.,land preparation,thinning,and pruning)can be implemented to improve soil moisture in such dryland forests.展开更多
Rhizosheath development benefits drought resistance in many upland crops.Although water-saving irrigation techniques induce rice rhizosheath formation,how and whether root hairs and different root types influence rice...Rhizosheath development benefits drought resistance in many upland crops.Although water-saving irrigation techniques induce rice rhizosheath formation,how and whether root hairs and different root types influence rice rhizosheath development and shoot water relations at seedling stage in drying soil are unclear.Wild-type(WT)seedlings with root hairs and its root hairless mutant rth2 were watered every 2 or 4 d,with root hair,whole root and shoot traits determined.Less frequent irrigation significantly increased rhizosheath of both genotypes by 14%during the seedling stage.Although root exudates from rth2 adhered 54%more soil than WT,facilitating rhizosheath development,root hairs and 25%greater lateral root proliferation of WT seedlings allowed 48%more rhizosheath especially in older seedlings.Greater root hair length,root hair length density and root hair number/root surface area on lateral than axial roots especially enhanced WT rhizosheath development.Soil water deficit increased root and leaf ABA concentrations especially in WT seedlings,causing stomatal closure that contributed to increased leaf water potential.In 36-d-old seedlings,10%greater shoot biomass of WT plants than rth2 accompanied 15%higher root and 36%higher foliar ABA concentrations and ultimately lower stomatal conductance.Higher ABA concentrations of WT plants at the same soil moisture suggested root hairs may be important in mediating shoot water status of rice seedlings.展开更多
The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and...The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.展开更多
Cupressus sempervirens is a relevant species in the Mediterranean for its cultural,economic and landscape value.This species is threatened by Seiridium cardinale,the causal agent of the cypress canker disease(CCD).The...Cupressus sempervirens is a relevant species in the Mediterranean for its cultural,economic and landscape value.This species is threatened by Seiridium cardinale,the causal agent of the cypress canker disease(CCD).The effects of biotic stressors on O_(3)risk assessment are unknown and a comprehensive O_(3)risk assessment in C.sempervirens is missing.To fill these gaps,two clones of C.sempervirens,one resistant(Clone R)and one susceptible to CCD(Clone S),were subjected to three levels of O_(3)(Ambient Air-AA;1.5×AA;2.0×AA)for two consecutive years in an O_(3)-free-air controlled exposure facility and artificially inoculated with S.cardinale.Both the exposure-(AOT40)and flux-based(PODy)indices were tested.We found that PODy performed better than AOT40 to assess O_(3)effects on biomass and the critical level for a 4%biomass loss was 2.51 mmol/m^(2)POD2.However,significant O_(3)dose-response relationships were not found for the inoculated cypresses because the combination of middle level O_(3)(1.5×AA)and inoculation stimulated a biomass growth in Clone S as hormetic response.Moreover,we found a different inter-clonal response to both stressors with a statistically significant reduction of total and belowground biomass following O_(3),and lower root biomass in Clone S than in Clone R following pathogen infection.In summary,Clone R was more resistant to O_(3),and inoculation altered O_(3)risk via an hormetic effect on biomass.These results warrant further studies on how biotic stressors affect O_(3)responses and risk assessment.展开更多
Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tio...Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tions:full light(CK),70%light(L1),50%light(L2),and 30%light(L3)to investigate variations in morphology,photosynthetic responses,stomatal ultrastructure as well as the mechanisms through which these saplings adapt to differing lighting environments.The results indicate that L2 leaves exhibit significantly greater length,width,and petiole development compared to other treatments across varying intensities.Over time,chlorophyll content and PSII levels in L2-treated saplings surpass those observed in other treatments;Proline(PRO),malondialdehyde(MDA),and soluble protein(SP)contents are markedly lower under L2 treatment.Catalase(CAT)and superoxide dismutase(SOD)demonstrate significant correlations across various light con-ditions but respond differently among treatments,indicat-ing distinct species sensitivities to light intensity while both contribute to environmental stress resistance mechanisms.Findings reveal that R.micranthum saplings at 50%light intensity benefit from enhanced protection via antioxidant enzymes,and shading reduces osmotic adjustment sub-stances yet increases chlorophyll content.Stomatal length/width along with conductance rates and net photosynthesis rates for L2 exceed those of CK,suggesting an improved photosynthetic structure conducive to efficient photosynthe-sis under this condition.Thus,moderate shading represents optimal growth at 50%illumination,a critical factor promot-ing sapling development.This research elucidates the ideal environment for R.micranthum adaptation to varying light conditions supporting future conservation initiatives.展开更多
Thalidomide,an immunomodulatory drug,is widely recommended for the treatment of recurrent aphthous stomatitis(RAS).This review aimed to assess the reliability of thalidomide for managing RAS,oro-genital ulcers associa...Thalidomide,an immunomodulatory drug,is widely recommended for the treatment of recurrent aphthous stomatitis(RAS).This review aimed to assess the reliability of thalidomide for managing RAS,oro-genital ulcers associated with Behçet’s disease(BD),and RAS in individuals with HIV infection.A systematic review was conducted following PICOS(Patient,Intervention,Control,Outcome,Study design)principles.Given the heterogeneity across studies,a qualitative analysis was performed in place of a meta-analysis.Eight randomized controlled trials(RCTs)were deemed eligible for inclusion.In three RCTs focused on RAS,a dosage of thalidomide at 100 mg/d demonstrated efficacy,while a lower dose of 25 mg/d helped prolong the recurrence interval of RAS.For oro-genital ulcers of BD,two RCTs indicated that both 300 mg/d for 24 weeks and 200 mg/d for 28 d,preceded by an initial dose of 400 mg/d for 5 d,were effective.In three RCTs investigating RAS in HIV-infected patients,thalidomide at 200 mg/d for either 4 or 7 weeks,with an initial dose of 400 mg/d for the first week,proved effective.However,a regimen of 100 mg three times per week failed to prevent the recurrence of oral ulcers.Adverse reactions to thalidomide were generally tolerable within the dosage ranges used in these studies.Overall,thalidomide showed promising efficacy for treating RAS,oro-genital ulcers in BD,and RAS in HIV-infected individuals.However,the variability in trial designs,dosages,and treatment durations makes it challenging to recommend an optimal dose and course of therapy.Further high-quality RCTs are necessary to establish more definitive guidelines.展开更多
【Objective】Jatropha curcas is a potential source of biodiesel plant grown on waste and unattended lands,and parts of the areas are often suffered from flooding.The present study was conducted to develop a model to c...【Objective】Jatropha curcas is a potential source of biodiesel plant grown on waste and unattended lands,and parts of the areas are often suffered from flooding.The present study was conducted to develop a model to calculate the net CO_(2)assimilation rate,transpiration rate and stomatal conductance with respect to leaf position,which affect the J.curcas productivity under soil flooding.【Method】The process of developing mathematical models for physiological responses associated with parameterization,optimization and validation.The concept was applied for the calculation of net CO 2 assimilation rate from transpiration rate and stomatal conductance,transpiration rate from net CO_(2)assimilation rate and stomatal conductance,and stomatal conductance from net CO_(2)assimilation rate and transpiration rate in different leaf positions of J.curcas.The models were tested under soil flooding and normal conditions to suffice its wider applicability.A model was proposed to calculate net CO 2 assimilation rate,transpiration rate and stomatal conductance responses from a known set of response function data by calculating a transformation characteristic constant between any two possible paired response functions.【Result】The mean deviations and root mean square errors(RMSE)of calculated physiological responses were low,which validated the proposed hypothesis and statistical models.The approach was applied for modeling physiological responses successfully in J.curcas.RMSE ranged from1.69%to 11.17%when transpiration rate and stomatal conductance were transformed to net CO_(2)assimilation rate,and from 1.70%to 11.61%in case net CO_(2)assimilation rate and stomatal conductance were transformed to transpiration rate,and from 3.87%to 13.21%if net CO_(2)assimilation rate and transpiration rate were transformed to stomatal conductance,respectively.【Conclusion】The model can be useful for calculating cumulative responses under different conditions from a basic known set of data.The key to successful physiological models is finding the better options that are realistic,easy to understand,interpretative and practical between adherence to reality,comprehensibility,interpretative value,and practical usefulness on sustainable agriculture in years to come.展开更多
Seasonal changes in the photosynthetic characteristics of Ammopiptantus mongolicus (Maxim. )Chen f. were studied. When the net photosynthetic rate decreased with the elevation of air temperature, thestomatal conductan...Seasonal changes in the photosynthetic characteristics of Ammopiptantus mongolicus (Maxim. )Chen f. were studied. When the net photosynthetic rate decreased with the elevation of air temperature, thestomatal conductance and stomatal limitation value tended to decline simultaneously, while the interoellularCO2 concentration was increased. According to the two criteria discriminating the stomatal limitation of Photosynthesis suggeSted by Fmrquhar and Sharkey, the seasonal changes in these parameters indicated that the decrease in Pn may not be due to stomatal factor. These studies proved that the relative contents of the large subunit of Rubisco and the photochemical activities correlated with the seasonal changes in the net photosyntheticrate, whieh may show that these two factors contribute primarily to the seasonal changeS in CO2 assimilation.展开更多
Stomatal conductance was found to change from steady-state to a slate of oscillations during daytime when vapour pressure deficit (VPD) increased to a value of 1 kPa in Glycyrrhiza inflata Batalin grown under the cond...Stomatal conductance was found to change from steady-state to a slate of oscillations during daytime when vapour pressure deficit (VPD) increased to a value of 1 kPa in Glycyrrhiza inflata Batalin grown under the conditions of arid desert in north-west China. The injected metabolic inhibitors (NaN3 or carbonyl cyanide-m-chlorophenyl-hydrazone (CCCP)) slightly reduced the stomatal conductance but did not significantly decrease the intensity of stomatal oscillations (amplitude/average). The oscillation intensity was found to he significantly correlated with VPD and root resistance, but not with the respiration rate. There might exist a minimum threshold of VPD (0.8 kPa) and root resistance (1/4 relative value) that induced stomatal oscillations. These results suggested that stomatal oscillations induced by atmospheric drought stress and root resistance were mainly a type of hydropassive movement.展开更多
Water channels or aquaporins are the main pathways of water transport. Both the existence and function of aquaporins in die guard cells of Vicia faba L. were investigated both by using RD28 cDNA and RD28 antibody as p...Water channels or aquaporins are the main pathways of water transport. Both the existence and function of aquaporins in die guard cells of Vicia faba L. were investigated both by using RD28 cDNA and RD28 antibody as probes, and by controlling stomatal movement as a parameter combined with antibody and inhibitor of aquaporins respectively. The results revealed that RD28 mRNA, encoding a plasma membrane aquaporin, expressed in ale mesophyll cells and vascular tissues of V. faba, especially in guard cells. And the location of RD28-like proteins was mainly on plasma membrane of guard cells. The addition of 25 mumol/L HgCl2, an aquaporin blocker, and antibody of RD28 as well, greatly suppressed the stomatal opening or guardcell protoplast swelling induced by fusicoccin and light, and closing induced by abscisic acid. However, 5 mmol/L, beta-mercaptoethanol, a reverse reagent of aquaporin blocker, reversed the inhibitory effect of HgCl2 Pretreatment oil stomatal opening ( i.e., HgCl2 was removed after HgCl2 pretreatment for 10 min). The results suggest that the aquaporins in V. faba are associated with stomatal movement.展开更多
Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer con...Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer conductance. Leuning in his revised Ball's model replaced relative humidity with VPD s (the vapor pressure deficit from stomatal pore to leaf surface) and thereby made the relation with transpiration more straightforward, and made it possible for the regulation of transpiration and the influence of boundary layer conductance to be integrated into the combined model. If the differences in water vapor and CO 2 concentration between leaf and ambient air are considered, VPD s , the evaporative demand, is influenced by stomatal and boundary layer conductance. The physiological responses of photosynthesis, transpiration, and stomatal function, and the changes of intercellular CO 2 and water use efficiency to environmental factors, such as wind speed, photon flux density, leaf temperature and ambient CO 2, are analyzed. It is shown that if the boundary layer conductance drops to a level comparable with stomatal conductance, the results of simulation by the model presented here differ significantly from those by the previous model, and, in some cases, are more realistic than the latter.展开更多
For finding valuable systematic characters, leaf epidermis of 77 taxa, representing 12 sections of the genus Clematis and three related genera in the Ranunculaceae, were examined mainly by means of light microscop...For finding valuable systematic characters, leaf epidermis of 77 taxa, representing 12 sections of the genus Clematis and three related genera in the Ranunculaceae, were examined mainly by means of light microscopy (LM), and partially by scanning electron microscopy (SEM). It was shown that the leaf epidermal cells were usually irregular or polygonal in shape. The patterns of anticlinal walls were straight, arched or undulate. The stomatal apparatus is anomocytic and exists in abaxial epidermis of all species, and in the adaxial epidermis of some species. Under SEM observation, the leaf epidermis was often striated, seldom nearly smooth, and often with flakes attached. Evidence from leaf epidermis serves as a criterion for distinguishing the subsections in sect. Meclatis (Spach) Tamura and in sect. Fruticella Tamura. The results also support that there are several separate evolutionary processes in the genus Clematis .展开更多
Photosynthetic rate ( P n ), transpiration rate ( E ), stomatal conductance ( g s ), water use efficiency ( WUE ), intercellular CO 2( C i ) and leaf water potential ( Ψ ) in varieties of soybean ( G...Photosynthetic rate ( P n ), transpiration rate ( E ), stomatal conductance ( g s ), water use efficiency ( WUE ), intercellular CO 2( C i ) and leaf water potential ( Ψ ) in varieties of soybean ( Glycine max (L.) Merr.) measured in the past three decades (1970s, 1980s and 1990s) and their inter_relationships were analyzed. These parameters of soybean changed with development stages. It is shown that there was a strongly positive relationship between the yield of soybean and its net photosynthetic rate. Soybean varieties with high yield potential had higher P n , g s and Ψ than those with low yield potential. Their values of C i were remarkably lower. Such relationship was especially remarkable at the critical stage of pod_bearing. P n of soybean of high yield was obviously higher than that of low yield. Of the different stages, the highest P n was found in the pod_bearing stage and other values were higher, too. P n and Ψ of modern soybean varieties were higher and such was continuing. Increased partitioning of carbon to seed and the size of sink may also be important for yield formation when P n values were remarkably higher in the pod_bearing stage.展开更多
基金supported jointly by the earmarked fund for CARS-10-GW2the key research and development program of Hainan Province(Grant No.ZDYF2020226)+1 种基金Collaborative innovation center of Nanfan and high-efficiency tropical agriculture,Hainan University(Grant No.XTCX2022NYC21)funding of Hainan University[Grant No.KYQD(ZR)22123]。
文摘Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes.Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions.This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants.Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,respectively.This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous exchange.However,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress.In particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,respectively.Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants.Overall,these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes.This stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.
基金supported by the Natural Science Basic Research Program of Shaanxi Province,China(2024JCYBQN-0491)Heng Wan would like to thank the Chinese Scholarship Council(CsC)(202206300064)。
文摘While biochar amendment enhances plant productivity and water-use efficiency(WUE),particularly under waterlimited conditions,the specific mechanisms driving these benefits remain unclear.Thus,the present study aims to elucidate the synergistic effects of biochar and reduced irrigation on maize(Zea mays L.)plants,focusing on xylem composition,root-to-shoot signaling,stomatal behavior,and WUE.Maize plants were cultivated in splitroot pots filled with clay loam soil,amended by either wheat-straw biochar(WSB)or softwood biochar(SWB)at 2%(w/w).Plants received full irrigation(FI),deficit irrigation(DI),or partial root-zone drying rrigation(PRD)from the 4-leaf to the grain-filling stage.Our results revealed that the WSB amendment significantly enhanced plant water status,biomass accumulation,and WUE under reduced irrigation,particularly when combined with PRD.Although reduced irrigation inhibited photosynthesis,it enhanced WUE by modulating stomatal morphology and conductance.Biochar amendment combined with reduced rrigation significantly increased xylem K^(+),Ca^(2+),Mg^(2+),NO_(3)^(-),Cl^(-),PO_(4)^(3-),and SO_(4)^(2-)-but decreased Na+,which in turn lowered xylem pH.Moreover,biochar amendment and especially WSB amendment further increased abscisic acid(ABA)contents in both leaf and xylem sap under reduced irrigation conditions due to changes in xylem ionic constituents and pH.The synergistic interactions between xylem components and ABA led to refined adjustments in stomatal size and density,thereby affecting stomatal conductance and ultimately improving the WUE of maize plants at different scales.The combined application of WSB and PRD can,therefore,emerge as a promising approach for improving the overall plant performance of maize plants with increased stomatal adaptations and WUE,especially under water-limited conditions.
基金SupportedbytheNationalNaturalScienceFoundationofChina(39970 6 2 2 )andtheTeachingandResearchAwardProgramforYongCadremanTeachersinHigherEducationInstitutionsofMOE P .R .China
文摘To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2000, with the LI 1600 Steady Porometer and the general weather information. The daily variation of transpiration in black locust forest ( Robinia pesudoacacia L.) is modeled by Penman Monteith equation. As a result of the model, a continuous daily transpiration in the growth season was calculated. The net radiation, intercepted by black locust forest canopy, was acquired from a semi empirical equation of measuring net radiation R n with the extinction coefficient k and leaf area index LAI . The canopy integral stomatic resistance is a mimesis with an empirical equation of measuring data. Compared with measuring data, the relative error of the modeled ones is less than 12% averagely. At last, the total transpiration of black locust forest during the period of 1998 and 2000 in the growth season of May to October, as an average transpiration of the different density stands, were 192 46, 187 07 and 195 59?mm respectively.
基金supported by the National Key R&D Program of China(2022YFE0127900,2021YFD2200401)the National Natural Science Foundation of China(31901278).
文摘Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree species in boreal Eurasia,calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology.Here,we conducted a short-term rainfall(−60% ambient rainfall;three-year)and snowfall(−73% ambient snowfall;two-year)exclusions experiment in Larix gmelinii forest in northeastern China,and aimed to explore the responses of hydraulic(leaf pressure-volume traits,leaf and branch hydraulic conductivity and embolism resistance),stomatal(stomatal closure point and stomatal safety margin),and economic(photosynthetic rate,nutrient and non-structural carbohydrates contents)traits to rainfall and snowfall reductions.Despite the weak alternation of leaf and branch hydraulic traits,both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins(the difference between stomatal closure point and xylem embolism threshold,describing drought resistance by merging both hydraulic and stomatal strategies).Reductions in rainfall and snowfall induced water or/and low-temperature stress,resulting in more conservative leaf economic traits,including a reduced photosynthetic rate,lower leaf nitrogen concentration,and higher leaf density.In addition,larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem,which helps repair embolism or lower the freezing point acting as osmolytes.Overall,our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing,at the cost of carbon assimilation.
基金support from the Study on Vegetable Science of Farmland System in Qinghai-Tibet Plateau(Grant No.2019QZKK0303)funded by the Sichuan International Science and Technology Innovation Cooperation/Hong Kong Macao Taiwan Science and Technology Innovation Cooperation Project(Grant No.2022YFH0071)。
文摘Secondary salinization is a major environmental factor that causes a stress response and growth inhibition in plants in protected agriculture.The positive effect of a low red to far-red light ratio(R:FR)in salt tolerance through antioxidant defense has been reported,while the underlying model remains obscure.In this study,we used physiological and genetic approaches to investigate the relationship between H_(2)O_(2) signaling and low R:FR-induced salt tolerance and antioxidant capacity in tomato seedlings.This study found that low R:FR treatment with calcium nitrate stress(SL treatment)enhanced the growth of plants and increased the net photosynthetic rate 5 days after stress compared with a higher R:FR ratio and calcium nitrate stress(S treatment).With transcriptomic analysis of tomato leaves at 5 d,compared with CK,most of glutaredoxin genes and antioxidant enzymes were upregulated by S treatment,which were upregulated further by SL treatment.Compared to the S treatment,within 5 days,the H_(2)O_(2) level was increased faster before 24 h and it was slowed down after 24 h by SL treatment,with less H_(2)O_(2) accumulation at 5 d than that of S treatment.The enhancement of gene expression of RBOH genes were also shown at 24 h under SL.It was found that stomatal conductance followed the dynamic change of H_(2)O_(2),with a rapid closure of stomata of a decrease at 3 h and an increase after 9 h in SL treatment compared to S treatment,respectively.There was same trend of stomata opening degrees of tomato leaves observed by optical microscope.However,the inhibitor of H_(2)O_(2) production(DPI pretreatment)weakened the positive effect of low R:FR on the regulation of stomatal movement.In addition,SL treatment increased the antioxidant enzyme activities and proline content and decreased the MDA content as compared to the S treatment,while the enhancement of ROS homeostasis was reduced by the DPI pretreatment.In conclusion,low R:FR improved redox homeostasis and stomatal status under calcium nitrate stress through H_(2)O_(2)signaling,improving the adaptation of tomato seedlings to soil salinization stress.
基金supported by the Natural Science Foundation of China(Grant No.32172512)the Jiangsu Special Fund for Frontier Foundation Research of Carbon Peaking and Carbon Neutralization(Grant No.BK20220005)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘5-Aminolevulinic acid(ALA)is a novel plant growth regulator that has shown outstanding capability to promote stomatal opening.Starch degradation,catalyzed byβ-amylase(EC3.2.1.2,BAM),plays an important role in stomatal opening.However,whether the starch breakdown is involved in ALA-regulating stomatal movement is unclear.In the current study,we found that exogenous ALA effectively stimulated the starch breakdown in guard cells,increasedβ-amylase activity and promoted stomatal opening in leaves of apple(Malus×domestica).Based on genome-wide identification,we identified a total of 119 members of BAM gene family in ten commonly Rosaceae crops.Analyses of gene structure,motif identification,and gene pair collinearity revealed relative conservation among members within the same group or subgroup.Among these genes,MdBAM17 and other 12 genes were identified as the orthologous genes of AtBAM1,which is responsible for starch degradation to modulate the stomatal movement in Arabidopsis.qRT-PCR analysis revealed a positive correlation between the expressions of MdBAM17 and stomatal aperture,as well asβ-amylase activity,whereas a negative correlation was observed with the starch content.Subcellular localization analysis confirmed that MdBAM17 is a chloroplast protein,consistent with the AtBAM1.MdBAM17 was mainly expressed in guard cells and responsive to exogenous ALA.Overexpressing MdBAM17 increasedβ-amylase activity and promoted starch breakdown,leading to stomatal opening,which was further strengthened by ALA.RNA-interfering MdBAM17 decreasedβ-amylase activity,resulting in starch accumulation,and impairing the stomatal opening by ALA.However,modulation of MdBAM17 expression did not affect the levels of flavonols and H_(2)O_(2)in guard cells,suggesting that MdBAM17-promoted starch degradation may function at downstream of ROS signaling in the ALAregulated stomatal opening.Our findings provide new insights into the mechanisms of ALA-regulated stomatal movement.
文摘Recurrent aphthous stomatitis(RAS)is a very frequent condition in developed countries whose basic symptom is a lesion referred to as an aphthous ulcer.High levels of interleukin(IL)-1 and IL-6 and low salivary levels of IL-10 are the basis of RAS pathogenesis.Sublingual supplements based on IL-10 can be very useful in reducing the phenomenon of aphthous recurrence in patients with RAS.An observational clinical experience with a group of 5 patients with RAS receiving a commercially available IL-10-based supplement was reported by the authors.The findings revealed a subsequent reduction in the incidence of mouth ulcers.
基金supported by the National Key Research&Development Project of China(No.2022YFF1300403)the National Natural Science Foundation of China(Nos.U21A2011,41971129,and 32401663)the Open Fund of the State Key Laboratory of Loess Science(No.SKLLQG2423).
文摘Soil water content(SWC)and meteorological conditions,as key environmental variables influencing tree water use,vary highly within the growing season,hindering a better understanding of environmental control mechanisms on canopy transpiration(Ec).Disentangling the effects of these variables on Ec across growing-season stages is crucial for Ec estimation and forest management.In this study,43-year-old Pinus tabuliformis Carr.and 31-yearold Platycladus orientalis(L.)Franco plantations in the semiarid Chinese Loess Plateau were monitored for Ec during the growing season of 2015-2020.The contributions of environmental factors to Ec were assessed using the boosted regression tree(BRT)model.Results showed that the contributions of SWC to Ec were greater at the early(May-June)and late(September)stages,while the contributions of vapor pressure deficit(VPD)and total solar radiation(Rs)to Ec increased at the middle(July-August)stage due to high soil water availability.Overall,Ec in both plantations was dominated by SWC(20.4%≤contributions≤48.8%)and Rs(22.7%≤contributions≤35.8%).Both species exhibited strong stomatal regulation of Ec.Specifically,stomatal opening was significantly inhibited by VPD at the early stage and strongly affected by SWC at the late stage.This study highlights that soil water conditions in artificial forests should be adjusted according to changes in influencing factors on Ec.Particularly during the early and late stages,measures(e.g.,land preparation,thinning,and pruning)can be implemented to improve soil moisture in such dryland forests.
基金financially supported by the National Natural Science Foundation of China (32071943, 31872853, 31871557)Jiangsu Provincial Department of Education and Yangzhou University (JS-2020-217)+3 种基金Zhejiang A&F University Research Development Fund (2023LFR003)in receipt of a Newton Advanced Fellowship (NA160430)the European Union SHui Project (773903)the GCRF RECIRCULATE (ES/P010857/1) Project
文摘Rhizosheath development benefits drought resistance in many upland crops.Although water-saving irrigation techniques induce rice rhizosheath formation,how and whether root hairs and different root types influence rice rhizosheath development and shoot water relations at seedling stage in drying soil are unclear.Wild-type(WT)seedlings with root hairs and its root hairless mutant rth2 were watered every 2 or 4 d,with root hair,whole root and shoot traits determined.Less frequent irrigation significantly increased rhizosheath of both genotypes by 14%during the seedling stage.Although root exudates from rth2 adhered 54%more soil than WT,facilitating rhizosheath development,root hairs and 25%greater lateral root proliferation of WT seedlings allowed 48%more rhizosheath especially in older seedlings.Greater root hair length,root hair length density and root hair number/root surface area on lateral than axial roots especially enhanced WT rhizosheath development.Soil water deficit increased root and leaf ABA concentrations especially in WT seedlings,causing stomatal closure that contributed to increased leaf water potential.In 36-d-old seedlings,10%greater shoot biomass of WT plants than rth2 accompanied 15%higher root and 36%higher foliar ABA concentrations and ultimately lower stomatal conductance.Higher ABA concentrations of WT plants at the same soil moisture suggested root hairs may be important in mediating shoot water status of rice seedlings.
基金funding from the Ongoing Research Funding program,ORF-2025-298,King Saud University,Riyadh,Saudi Arabia.
文摘The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.
基金supported by the Italian Integrated Environmental Research Infrastructures Systems(ITINERIS)(Nos.IR0000032 and CUP B53C22002150006).
文摘Cupressus sempervirens is a relevant species in the Mediterranean for its cultural,economic and landscape value.This species is threatened by Seiridium cardinale,the causal agent of the cypress canker disease(CCD).The effects of biotic stressors on O_(3)risk assessment are unknown and a comprehensive O_(3)risk assessment in C.sempervirens is missing.To fill these gaps,two clones of C.sempervirens,one resistant(Clone R)and one susceptible to CCD(Clone S),were subjected to three levels of O_(3)(Ambient Air-AA;1.5×AA;2.0×AA)for two consecutive years in an O_(3)-free-air controlled exposure facility and artificially inoculated with S.cardinale.Both the exposure-(AOT40)and flux-based(PODy)indices were tested.We found that PODy performed better than AOT40 to assess O_(3)effects on biomass and the critical level for a 4%biomass loss was 2.51 mmol/m^(2)POD2.However,significant O_(3)dose-response relationships were not found for the inoculated cypresses because the combination of middle level O_(3)(1.5×AA)and inoculation stimulated a biomass growth in Clone S as hormetic response.Moreover,we found a different inter-clonal response to both stressors with a statistically significant reduction of total and belowground biomass following O_(3),and lower root biomass in Clone S than in Clone R following pathogen infection.In summary,Clone R was more resistant to O_(3),and inoculation altered O_(3)risk via an hormetic effect on biomass.These results warrant further studies on how biotic stressors affect O_(3)responses and risk assessment.
基金funded by the National Natural Science Foundation of China(No.32171770)Natural Science Foundation Program of Jilin Provincial Department of Education(No.JJKH20230074KJ).
文摘Rhododendron micranthum Turcz.is a shrub esteemed for its ornamental and medicinal attributes within the Changbai Mountain range of China.We selected 3-year saplings and subjected them to four distinct light condi-tions:full light(CK),70%light(L1),50%light(L2),and 30%light(L3)to investigate variations in morphology,photosynthetic responses,stomatal ultrastructure as well as the mechanisms through which these saplings adapt to differing lighting environments.The results indicate that L2 leaves exhibit significantly greater length,width,and petiole development compared to other treatments across varying intensities.Over time,chlorophyll content and PSII levels in L2-treated saplings surpass those observed in other treatments;Proline(PRO),malondialdehyde(MDA),and soluble protein(SP)contents are markedly lower under L2 treatment.Catalase(CAT)and superoxide dismutase(SOD)demonstrate significant correlations across various light con-ditions but respond differently among treatments,indicat-ing distinct species sensitivities to light intensity while both contribute to environmental stress resistance mechanisms.Findings reveal that R.micranthum saplings at 50%light intensity benefit from enhanced protection via antioxidant enzymes,and shading reduces osmotic adjustment sub-stances yet increases chlorophyll content.Stomatal length/width along with conductance rates and net photosynthesis rates for L2 exceed those of CK,suggesting an improved photosynthetic structure conducive to efficient photosynthe-sis under this condition.Thus,moderate shading represents optimal growth at 50%illumination,a critical factor promot-ing sapling development.This research elucidates the ideal environment for R.micranthum adaptation to varying light conditions supporting future conservation initiatives.
文摘Thalidomide,an immunomodulatory drug,is widely recommended for the treatment of recurrent aphthous stomatitis(RAS).This review aimed to assess the reliability of thalidomide for managing RAS,oro-genital ulcers associated with Behçet’s disease(BD),and RAS in individuals with HIV infection.A systematic review was conducted following PICOS(Patient,Intervention,Control,Outcome,Study design)principles.Given the heterogeneity across studies,a qualitative analysis was performed in place of a meta-analysis.Eight randomized controlled trials(RCTs)were deemed eligible for inclusion.In three RCTs focused on RAS,a dosage of thalidomide at 100 mg/d demonstrated efficacy,while a lower dose of 25 mg/d helped prolong the recurrence interval of RAS.For oro-genital ulcers of BD,two RCTs indicated that both 300 mg/d for 24 weeks and 200 mg/d for 28 d,preceded by an initial dose of 400 mg/d for 5 d,were effective.In three RCTs investigating RAS in HIV-infected patients,thalidomide at 200 mg/d for either 4 or 7 weeks,with an initial dose of 400 mg/d for the first week,proved effective.However,a regimen of 100 mg three times per week failed to prevent the recurrence of oral ulcers.Adverse reactions to thalidomide were generally tolerable within the dosage ranges used in these studies.Overall,thalidomide showed promising efficacy for treating RAS,oro-genital ulcers in BD,and RAS in HIV-infected individuals.However,the variability in trial designs,dosages,and treatment durations makes it challenging to recommend an optimal dose and course of therapy.Further high-quality RCTs are necessary to establish more definitive guidelines.
文摘【Objective】Jatropha curcas is a potential source of biodiesel plant grown on waste and unattended lands,and parts of the areas are often suffered from flooding.The present study was conducted to develop a model to calculate the net CO_(2)assimilation rate,transpiration rate and stomatal conductance with respect to leaf position,which affect the J.curcas productivity under soil flooding.【Method】The process of developing mathematical models for physiological responses associated with parameterization,optimization and validation.The concept was applied for the calculation of net CO 2 assimilation rate from transpiration rate and stomatal conductance,transpiration rate from net CO_(2)assimilation rate and stomatal conductance,and stomatal conductance from net CO_(2)assimilation rate and transpiration rate in different leaf positions of J.curcas.The models were tested under soil flooding and normal conditions to suffice its wider applicability.A model was proposed to calculate net CO 2 assimilation rate,transpiration rate and stomatal conductance responses from a known set of response function data by calculating a transformation characteristic constant between any two possible paired response functions.【Result】The mean deviations and root mean square errors(RMSE)of calculated physiological responses were low,which validated the proposed hypothesis and statistical models.The approach was applied for modeling physiological responses successfully in J.curcas.RMSE ranged from1.69%to 11.17%when transpiration rate and stomatal conductance were transformed to net CO_(2)assimilation rate,and from 1.70%to 11.61%in case net CO_(2)assimilation rate and stomatal conductance were transformed to transpiration rate,and from 3.87%to 13.21%if net CO_(2)assimilation rate and transpiration rate were transformed to stomatal conductance,respectively.【Conclusion】The model can be useful for calculating cumulative responses under different conditions from a basic known set of data.The key to successful physiological models is finding the better options that are realistic,easy to understand,interpretative and practical between adherence to reality,comprehensibility,interpretative value,and practical usefulness on sustainable agriculture in years to come.
文摘Seasonal changes in the photosynthetic characteristics of Ammopiptantus mongolicus (Maxim. )Chen f. were studied. When the net photosynthetic rate decreased with the elevation of air temperature, thestomatal conductance and stomatal limitation value tended to decline simultaneously, while the interoellularCO2 concentration was increased. According to the two criteria discriminating the stomatal limitation of Photosynthesis suggeSted by Fmrquhar and Sharkey, the seasonal changes in these parameters indicated that the decrease in Pn may not be due to stomatal factor. These studies proved that the relative contents of the large subunit of Rubisco and the photochemical activities correlated with the seasonal changes in the net photosyntheticrate, whieh may show that these two factors contribute primarily to the seasonal changeS in CO2 assimilation.
文摘Stomatal conductance was found to change from steady-state to a slate of oscillations during daytime when vapour pressure deficit (VPD) increased to a value of 1 kPa in Glycyrrhiza inflata Batalin grown under the conditions of arid desert in north-west China. The injected metabolic inhibitors (NaN3 or carbonyl cyanide-m-chlorophenyl-hydrazone (CCCP)) slightly reduced the stomatal conductance but did not significantly decrease the intensity of stomatal oscillations (amplitude/average). The oscillation intensity was found to he significantly correlated with VPD and root resistance, but not with the respiration rate. There might exist a minimum threshold of VPD (0.8 kPa) and root resistance (1/4 relative value) that induced stomatal oscillations. These results suggested that stomatal oscillations induced by atmospheric drought stress and root resistance were mainly a type of hydropassive movement.
文摘Water channels or aquaporins are the main pathways of water transport. Both the existence and function of aquaporins in die guard cells of Vicia faba L. were investigated both by using RD28 cDNA and RD28 antibody as probes, and by controlling stomatal movement as a parameter combined with antibody and inhibitor of aquaporins respectively. The results revealed that RD28 mRNA, encoding a plasma membrane aquaporin, expressed in ale mesophyll cells and vascular tissues of V. faba, especially in guard cells. And the location of RD28-like proteins was mainly on plasma membrane of guard cells. The addition of 25 mumol/L HgCl2, an aquaporin blocker, and antibody of RD28 as well, greatly suppressed the stomatal opening or guardcell protoplast swelling induced by fusicoccin and light, and closing induced by abscisic acid. However, 5 mmol/L, beta-mercaptoethanol, a reverse reagent of aquaporin blocker, reversed the inhibitory effect of HgCl2 Pretreatment oil stomatal opening ( i.e., HgCl2 was removed after HgCl2 pretreatment for 10 min). The results suggest that the aquaporins in V. faba are associated with stomatal movement.
文摘Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer conductance. Leuning in his revised Ball's model replaced relative humidity with VPD s (the vapor pressure deficit from stomatal pore to leaf surface) and thereby made the relation with transpiration more straightforward, and made it possible for the regulation of transpiration and the influence of boundary layer conductance to be integrated into the combined model. If the differences in water vapor and CO 2 concentration between leaf and ambient air are considered, VPD s , the evaporative demand, is influenced by stomatal and boundary layer conductance. The physiological responses of photosynthesis, transpiration, and stomatal function, and the changes of intercellular CO 2 and water use efficiency to environmental factors, such as wind speed, photon flux density, leaf temperature and ambient CO 2, are analyzed. It is shown that if the boundary layer conductance drops to a level comparable with stomatal conductance, the results of simulation by the model presented here differ significantly from those by the previous model, and, in some cases, are more realistic than the latter.
文摘For finding valuable systematic characters, leaf epidermis of 77 taxa, representing 12 sections of the genus Clematis and three related genera in the Ranunculaceae, were examined mainly by means of light microscopy (LM), and partially by scanning electron microscopy (SEM). It was shown that the leaf epidermal cells were usually irregular or polygonal in shape. The patterns of anticlinal walls were straight, arched or undulate. The stomatal apparatus is anomocytic and exists in abaxial epidermis of all species, and in the adaxial epidermis of some species. Under SEM observation, the leaf epidermis was often striated, seldom nearly smooth, and often with flakes attached. Evidence from leaf epidermis serves as a criterion for distinguishing the subsections in sect. Meclatis (Spach) Tamura and in sect. Fruticella Tamura. The results also support that there are several separate evolutionary processes in the genus Clematis .
文摘Photosynthetic rate ( P n ), transpiration rate ( E ), stomatal conductance ( g s ), water use efficiency ( WUE ), intercellular CO 2( C i ) and leaf water potential ( Ψ ) in varieties of soybean ( Glycine max (L.) Merr.) measured in the past three decades (1970s, 1980s and 1990s) and their inter_relationships were analyzed. These parameters of soybean changed with development stages. It is shown that there was a strongly positive relationship between the yield of soybean and its net photosynthetic rate. Soybean varieties with high yield potential had higher P n , g s and Ψ than those with low yield potential. Their values of C i were remarkably lower. Such relationship was especially remarkable at the critical stage of pod_bearing. P n of soybean of high yield was obviously higher than that of low yield. Of the different stages, the highest P n was found in the pod_bearing stage and other values were higher, too. P n and Ψ of modern soybean varieties were higher and such was continuing. Increased partitioning of carbon to seed and the size of sink may also be important for yield formation when P n values were remarkably higher in the pod_bearing stage.
