Short-term Water Stress Research Articles

Nitrogen metabolism correlates with the acclimation of photosynthesis to short-term water stress in rice (Oryza sativa L.)

Nitrogen metabolism is as sensitive to water stress as photosynthesis, but its role in plant under soil drying is not well understood. We hypothesized that the alterations in N metabolism could be related to the acclimation of photosynthesis to water stress. The features of photosynthesis and N metabolism in a japonica rice ‘Jiayou 5’ and an indica rice ‘Zhongzheyou 1’ were investigated under mild and moderate soil drying with a pot experiment. Soil drying increased non-photochemical quenching (NPQ) and reduced photon quantum efficiency of PSII and CO2 fixation in ‘Zhongzheyou 1’, whereas the effect was much slighter in ‘Jiayou 5’. Nevertheless, the photosynthetic rate of the two cultivars showed no significant difference between control and water stress. Soil drying increased nitrate reducing in leaves of ‘Zhongzheyou 1’, characterized by enhanced nitrate reductase (NR) activity and lowered nitrate content; whereas glutamate dehydrogenase (GDH), glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) were relative slightly affected. ‘Jiayou 5’ plants increased the accumulation of nitrate under soil drying, although its NR activity was increased. In addition, the activities of GDH, GOT and GPT were typically increased under soil drying. Besides, amino acids and soluble sugar were significantly increased under mild and moderate soil drying, respectively. The accumulation of nitrate, amino acid and sugar could serve as osmotica in ‘Jiayou 5’. The results reveal that N metabolism plays diverse roles in the photosynthetic acclimation of rice plants to soil drying.

Differential physiological performance of two Eucalyptus species and one hybrid under different imposed water availability scenarios

Eucalyptus forest reproductive material responded differently to the imposed water scenarios through different water resistance mechanisms. Eucalyptus is amongst the most planted genera in the world. The focus of this study was to evaluate the ability of different forest reproductive material to withstand the occurrence of drought under different possible climate scenarios, both experienced by plants in the field: a long-term water deficit period (WS) and a short-term water deficit period followed by recovery, in comparison with a well-watered condition. The performance of two Eucalyptus species (Eucalyptus globulus and Eucalyptus nitens) and one hybrid (Eucalyptus globulus × Eucalyptus cypellocarpa), under such conditions, was assessed through several morphological and physiological traits. Under prolonged water stress, E. globulus, which experienced the lowest water potential values, suffered a decrease in CO2 assimilation rates as a result of stomatal limitations that, together with high oxidative damage, led to growth impairment. It also exhibited the slowest recovery from a short-term water stress period. The hybrid reacted to the prolonged water stress period through an active antioxidant system which allowed a higher photosynthetic assimilation rate and overall growth. Though it experienced a decrease in CO2 assimilation rate, due to non-stomatal limitations, E. nitens was able to maintain its growth under a prolonged water deficit period. Furthermore, under short-term drought stress followed by recovery, E. nitens was able to completely recover its gas-exchange parameters and increase overall growth production conferring a physiological advantage under the tested conditions. Our data demonstrate that, under the experimentally imposed water stress scenario, plants have different adaptive mechanisms to cope with continuous water deficit and recovery after a short-term stress situation.

Analysis of changes in anatomical characteristics and physiologic features of heteromorphic leaves in a desert tree, Populus euphratica

Populus euphratica Oliv. is well-adapted to extreme desert environments and possess the characteristic of heterophylly. On the same tree, the lanceolate, broad-ovate, and dentate broad-ovate leaves distribute in the different tiers of the canopy. The lanceolate leaves distribute on the lower canopy, broad-ovate leaves on the middle canopy, and dentate broad-ovate leaves on the upper canopy. The leaf structure was found to be xeromorphic. The stomatal densities of the three typical leaves were different and decreased in value from dentate broad-ovate, to broad-ovate, and to lanceolate leaves. The osmotic potentials at full and zero turgor were lowest in dentate broad-ovate leaves. In an appropriate growth environment, the chlorophyll fluorescence parameters of the three leaf types were almost the same and significantly changed upon exposure to short-term water stress. These results showed that dentate broad-ovate leaves can maintain their normal size and shape under arid and hot conditions because of their relatively thick cell wall and high mechanical strength. Moreover, dentate broad-ovate leaves had more developed vascular bundles in the main vein than the other types and thus more efficiently transported water and salts. These results suggested that dentate broad-ovate leaves can efficiently adapt to changing conditions, with more obvious xeromorphic characteristics and a relatively higher photosynthesis rate under drought conditions, compared with the others leaf types.

Comparative Analysis of Phosphoproteome Remodeling After Short Term Water Stress and ABA Treatments versus Longer Term Water Stress Acclimation.

Several studies have used short term dehydration, osmotic stress or Abscisic Acid (ABA) treatments to identify the initial protein phosphorylation-dephosphorylation responses to drought and low water potential or ABA treatments. However, longer term drought acclimation leads to altered expression of many kinases and phosphatases suggesting that it may also produce unique changes in phosphoproteome composition. To get a better overview of the state of drought-related phosphoproteomics and investigate this question of short versus longer term phosphoproteome regulation, we compared three Arabidopsis thaliana studies analyzing short term phosphoproteome changes to recent data from our laboratory analyzing phosphoproteome changes after a longer drought acclimation treatment. There was very little overlap of phosphoproteins with putative stress-induced phosphorylation or dephosphorylation among these studies. While some of this is due to technical limitations and limited coverage of the phosphoproteome achieved by each study, biological differences and the type of stress treatment used also play a role. This comparative analysis emphasized how both short and long term analysis of physiologically relevant stress treatments, as well as validation of phosphoproteomic data, will be needed to move past just scratching the surface of the stress phosphoproteome. In drought acclimation experiments, distinguishing between changes in protein abundance versus phosphorylation stoichiometry is a key challenge. We discuss initial work in using Arabidopsis seedling transient expression combined with Phos-tag gel analysis as a way to validate drought-induced phosphorylation-dephosphorylation of candidate proteins.

Evaluation and strategies of tolerance to water stress in Paspalum germplasm

The evaluation of genetic resources in germplasm banks of Paspalum can contribute to their use in breeding programs and for advanced research in biotechnology. This study evaluated the tolerance of 11 Paspalum accessions to abiotic stress caused by soil water deficit in a greenhouse experiment at Embrapa Pecuaria Sudeste, Sao Carlos, state of Sao Paulo, Brazil. The variables analyzed were: dry biomass of green matter, dead matter and roots; leaf area; leaf water potential; number of days to lose leaf turgor (wilting); soil moisture at wilting; and number of tillers per pot. The results showed high genetic variability for all traits, not only among species but also within species, and also reflected the existence of different strategies of response and potential adaptation to water deficit events. For breeding programs, when the aim is to produce materials better adapted to the occurrence of prolonged drought, 5 accessions from this group seem to have good potential: P. malacophyllum BGP 289, P. quarinii BGP 229, P. regnellii BGP 112, P. conspersum BGP 402 and P. urvillei x P. dilatatum BGP 238. Conversely, when the goal is to select materials for short-term water stress conditions, 6 accessions stand out: P. atratum BGP 308, P. regnellii BGP 215, 248 and 397, P. dilatatum BGP 234 and P. malacophyllum BGP 293.

Drought effects on US maize and soybean production: spatiotemporal patterns and historical changes

Maximizing agricultural production on existing cropland is one pillar of meeting future global food security needs. To close crop yield gaps, it is critical to understand how climate extremes such as drought impact yield. Here, we use gridded, daily meteorological data and county-level annual yield data to quantify meteorological drought sensitivity of US maize and soybean production from 1958 to 2007. Meteorological drought negatively affects crop yield over most US crop-producing areas, and yield is most sensitive to short-term (1–3 month) droughts during critical development periods from July to August. While meteorological drought is associated with 13% of overall yield variability, substantial spatial variability in drought effects and sensitivity exists, with central and southeastern US becoming increasingly sensitive to drought over time. Our study illustrates fine-scale spatiotemporal patterns of drought effects, highlighting where variability in crop production is most strongly associated with drought, and suggests that management strategies that buffer against short-term water stress may be most effective at sustaining long-term crop productivity.

Statistical analysis of short-term water stress conditions at Riggs Creek OzFlux tower site

A large range of indices and proxies are available to describe the water stress conditions of an area subject to different applications, which have varying capabilities and limitations depending on the prevailing local climatic conditions and land cover. The present study uses a range of spatio-temporally high-resolution (daily and within daily) data sources to evaluate a number of drought indices (DIs) for the Riggs Creek OzFlux tower site in southeastern Australia. Therefore, the main aim of this study is to evaluate the statistical characteristics of individual DIs subject to short-term water stress conditions. In order to derive a more general and therefore representative DI, a new criterion is required to specify the statistical similarity between each pair of indices to allow determining the dominant drought types along with their representative DIs. The results show that the monitoring of water stress at this case study area can be achieved by evaluating the individual behaviour of three clusters of (i) vegetation conditions, (ii) water availability and (iii) water consumptions. This indicates that it is not necessary to assess all individual DIs one by one to derive a comprehensive and informative data set about the water stress of an area; instead, this can be achieved by analysing one of the DIs from each cluster or deriving a new combinatory index for each cluster, based on established combination methods.

Seasonal Variation in the NDVI–Species Richness Relationship in a Prairie Grassland Experiment (Cedar Creek)

Species richness generally promotes ecosystem productivity, although the shape of the relationship varies and remains the subject of debate. One reason for this uncertainty lies in the multitude of methodological approaches to sampling biodiversity and productivity, some of which can be subjective. Remote sensing offers new, objective ways of assessing productivity and biodiversity. In this study, we tested the species richness–productivity relationship using a common remote sensing index, the Normalized Difference Vegetation Index (NDVI), as a measure of productivity in experimental prairie grassland plots (Cedar Creek). Our study spanned a growing season (May to October, 2014) to evaluate dynamic changes in the NDVI–species richness relationship through time and in relation to environmental variables and phenology. We show that NDVI, which is strongly associated with vegetation percent cover and biomass, is related to biodiversity for this prairie site, but it is also strongly influenced by other factors, including canopy growth stage, short-term water stress and shifting flowering patterns. Remarkably, the NDVI-biodiversity correlation peaked at mid-season, a period of warm, dry conditions and anthesis, when NDVI reached a local minimum. These findings confirm a positive, but dynamic, productivity–diversity relationship and highlight the benefit of optical remote sensing as an objective and non-invasive tool for assessing diversity–productivity relationships.

Charting trends in the evolution of the La Alhambra forest (Granada, Spain) through analysis of pollen-emission dynamics over time

Changing climate conditions are having an appreciable impact both on the adaptive response of the species growing in urban and peri-urban forests (UPF) and on their evolutionary dynamics. This study sought to chart the evolution and pollen dynamics of major species growing in the La Alhambra peri-urban forest (Granada, Spain) over the last 22 years, to examine correlations with weather-related parameters and to estimate potential trends in the event of future climate change. Findings showed that overall pollen levels have gradually increased over the study period, reflecting both plant species diversification and the ability of Mediterranean species—particularly Pinus and Quercus—to adapt to short-term water stress situations. Nevertheless, the climate conditions expected over the coming years in the Mediterranean region, with considerable increase in winter temperatures and a drop in precipitation by up to 24 % for summer rainfall, there is likely to be a reduction in the intensity of pollen emissions, at least from species with strict environmental requirements. The results confirm that pollen emission is a valuable biological indicator for estimating the adaptive response of various species and the resilience of the forest mass to climate-change events.

Short-term water stress affecting NO3− absorption by almond plants

Identifying the rates of nitrate absorption by almond plants under water stress is important for improving nitrogen use efficiency in almond orchards. This study aimed to determine the rates of nitrate absorption by almond plants subjected to short-term water stress and no water stress, and the kinetic NO3− absorption parameters in well-watered three-year-old almond plants. Two assays were performed. In the first, fourteen plants arranged in completely randomized design received nutrient solutions with water potentials (Ψw) of 0.0, −0.2, −0.4 and −0.7MPa and containing 1.2mmoll−1 KNO3. We accessed the NO3− depletion in these solutions over an 8-h interval and estimated regression curves of the quantity of nitrate in the nutrient solution (Q) as a function of time (t). Subsequently nitrate uptake rates were calculated. Water loss; nitrate reductase activity; nitrate and total N of the sap; nitrate concentration of leaf dry matter; and nitrate and nitrite concentration of root dry matter were, either, evaluated. The second assay was performed the same way of the first one, with four well-watered plants submitted to 0.3mmoll−1 KNO3 as initial concentration, and allowed estimating NO3− absorption parameters Vmax, Km and Cmin. We observed a linear decrease in the nitrate content of the containers receiving 1.2mmoll−1 of NO3− over a period of 8h. In this concentration, the rates of NO3− uptake ranged from 1.11 to 3.43μmolg−1h−1 and decreased in low water potentials at the root medium. Root nitrate reductase activity followed the same trend of nitrate absorption. In the low NO3− concentration range, the absorption showed a Michaelis–Menten pattern, being the kinetic parameters of NO3− absorption 1.15±0.27μmolg−1h−1, 28.81±4.12μmoll−1 and 17.93±1.1μmoll−1 for Vmax, Km, and Cmin, respectively. We concluded that NO3− uptake of almonds is affected by short periods of water stress, with harmful effects occurring at Ψw below −0.18MPa.

Effects of water stress and rewatering on photosynthesis, root activity, and yield of cotton with drip irrigation under mulch

Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V1) and moderate water stress (V2) imposed at one of four cotton growth stages [i.e., S1 (from the full budding to early flowering stage), S2 (from early flowering to full flowering), S3 (from full flowering to full bolling), and S4 (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70-75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S2V2 treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S1V1, the root activity in the 20-100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S1V1 showed no significant effect on the yield but it increased total WUE and irrigation WUE. These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas.

Retrieval and assessment of CO2 uptake by mediterranean ecosystems using remote sensing and

Retrieval and assessment of CO2 uptake by mediterranean ecosystems using remote sensing and

Experimental investigation and numerical simulation of the electrolyte loss in a HT-PEM fuel cell

In this work, long and short term degradation experiments concerning the electrolyte loss in a HT-PEM fuel cell based on the membrane system PBI/phosphoric acid were conducted. Particular emphasis was placed on the ionic conductivity which was investigated in-situ at regular intervals during the degradation test by means of electrochemical impedance spectroscopy (EIS) measurements. The long term test was executed over 4600 h including constant load and start-stop cycling operation. During the start-stop cycling operation at 150 °C, the load was intermitted for 680 times, cooled down to 60 °C, purged with nitrogen and heated up to the operating temperature of 150 °C, and operated for one hour at 0.2 Acm−2, before the cycle started all over again. Additionally, a special short term water stress test was developed to provoke acid leaching and to exclude aging effects of the catalyst to determine the effects of the electrolyte loss. Within 90 h, 59 water stress periods were performed, yielding a similar performance degradation as the long term test with respect to the membrane conductivity. The second part of this work concerns itself with the numerical simulation of the electrolyte loss in HTPEM fuel cells. The experimental results of the first part of this work were the basis to relate the electrolyte/phosphoric acid content in the membrane with predictable operating characteristics of the investigated fuel cell. It was found that a reduction of the phosphoric acid content within the membrane can explain the effects observed in the water stress experiment without the need to adopt further simulation parameters.

Short-term water stress impacts on stomatal, mesophyll and biochemical limitations to photosynthesis differ consistently among tree species from contrasting climates.

Predicting the large-scale consequences of drought in contrasting environments requires that we understand how drought effects differ among species originating from those environments. A previous meta-analysis of published experiments suggested that the effects of drought on both stomatal and non-stomatal limitations to photosynthesis may vary consistently among species from different hydroclimates. Here, we explicitly tested this hypothesis with two short-term water stress experiments on congeneric mesic and xeric species. One experiment was run in Australia using Eucalyptus species and the second was run in Spain using Quercus species as well as two more mesic species. In each experiment, plants were grown under moist conditions in a glasshouse, then deprived of water, and gas exchange was monitored. The stomatal response was analysed with a recently developed stomatal model, whose single parameter g1 represents the slope of the relationship between stomatal conductance and photosynthesis. The non-stomatal response was partitioned into effects on mesophyll conductance (gm), the maximum Rubisco activity (Vcmax) and the maximum electron transport rate (Jmax). We found consistency among the drought responses of g1, gm, Vcmax and Jmax, suggesting that drought imposes limitations on Rubisco activity and RuBP regeneration capacity concurrently with declines in stomatal and mesophyll conductance. Within each experiment, the more xeric species showed relatively high g1 under moist conditions, low drought sensitivity of g1, gm, Vcmax and Jmax, and more negative values of the critical pre-dawn water potential at which Vcmax declines most steeply, compared with the more mesic species. These results indicate adaptive interspecific differences in drought responses that allow xeric tree species to continue transpiration and photosynthesis for longer during periods without rain.

Regulation of photosynthesis and stomatal and mesophyll conductance under water stress and recovery in olive trees: correlation with gene expression of carbonic anhydrase and aquaporins.

The hypothesis that aquaporins and carbonic anhydrase (CA) are involved in the regulation of stomatal (g s) and mesophyll (g m) conductance to CO2 was tested in a short-term water-stress and recovery experiment in 5-year-old olive plants (Olea europaea) growing outdoors. The evolution of leaf gas exchange, chlorophyll fluorescence, and plant water status, and a quantitative analysis of photosynthesis limitations, were followed during water stress and recovery. These variables were correlated with gene expression of the aquaporins OePIP1.1 and OePIP2.1, and stromal CA. At mild stress and at the beginning of the recovery period, stomatal limitations prevailed, while the decline in g m accounted for up to 60% of photosynthesis limitations under severe water stress. However, g m was restored to control values shortly after rewatering, facilitating the recovery of the photosynthetic rate. CA was downregulated during water stress and upregulated after recovery. The use of structural equation modelling allowed us to conclude that both OePIP1.1 and OePIP2.1 expression could explain most of the variations observed for g s and g m. CA expression also had a small but significant effect on g m in olive under water-stress conditions.

弱光下水分胁迫对不同产地披针叶茴香幼苗生理特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 弱光下水分胁迫对不同产地披针叶茴香幼苗生理特性的影响 DOI: 10.5846/stxb201209241351 作者: 作者单位: 中国林业科学研究院亚热带林业研究所,中国林业科学研究院亚热带林业研究所,中国林业科学研究院亚热带林业研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省科技计划资助项目（2009C32097） Effects of water stress on physiological characteristics of different Illicium lanceolatum ecotypes under low light intensity Author: Affiliation: Research Institute of Subtropical of Forestry,Chinese Academy of Forestry,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选用4个不同产地披针叶茴香（Illicium lanceolatum）（浙江临安（LA）、浙江开化（KH）、江西武宁（WN）和福建南平（NP））1年生盆栽幼苗为试验材料，设置3个光照处理（Ⅰ：25 μmol·m-2·s-1；Ⅱ：50 μmol·m-2·s-1；Ⅲ：75 μmol·m-2·s-1）和2个水分处理（正常供水（CK）和自然干旱2d），探讨弱光环境下短期干旱对披针叶茴香幼苗生理特性及适应性的影响。结果表明：两种水分处理下，披针叶茴香幼苗抗氧化酶活性和渗透调节物质含量对弱光的敏感性存在明显差异。在光处理Ⅱ和Ⅲ条件下，WN产地幼苗经2d水分胁迫后，过氧化氢酶（CAT）活性比正常水分条件明显增加，过氧化物酶（POD）活性在光处理Ⅲ下比正常水分条件的显著增加，各光处理下超氧化物歧化酶（SOD）活性比正常水分的显著下降，丙二醛（MDA）含量相反。水分胁迫后，各光处理下LA产地幼苗的SOD和POD酶活性低于正常水分条件的，可溶性蛋白和MDA含量均较正常水分处理的增加。与正常水分条件相比，水分胁迫后的KH产地幼苗SOD、POD和CAT酶活性在光处理Ⅰ下均显著增加，可溶性蛋白和MDA含量有所下降。NP产地幼苗各光处理的酶活性均表现出水分胁迫后的比正常水分下的有所提高。可知，短期水分胁迫对提高KH、WN和NP产地幼苗对弱光环境的适应性具有显著促进作用。研究揭示短期水分胁迫可通过增加抗氧化酶活性和渗透调节物质含量来提高幼苗对弱光的适应性。 Abstract:Low availability of soil moisture is considered a major limiting factor for plant growth and crop yield worldwide, and it turns to be a more serious problem under the context of global change. A weak light stress, resulting from significantly lower light intensity than light saturation point of plant in long time, will affect the morphogenesis and physiological and biochemical processes of plant. The Chinese anise (Illicium lanceolatum), a traditional medicinal plant in China, has high content of shikimic acids which have effects of antiphlogosis and analgesis, and can reduce platelet aggregation and suppress vascular and cerebral thrombosis. Shikimic acid can also be an intermediate for antivirus and anticancer drugs. Scattering in its natural habitats, I.lanceolatum resources have experienced a rapid decline due to overexploitation. Therefore, it is necessary to study the protection and development strategies of I.lanceolatum resources. Soil moisture and light intensity are important restrictive impact factors for growth and biomass accumulation of I.lanceolatum seedlings. Until now, there is no reports about the mechanism of this species' response to water and light conditions. In order to explore the effect of short-term drought on the plant physiological characteristics and its adaptive capacity under low light intensity, a pot experiment was conducted with one year old I.lanceolatum seedlings for four ecotypes, respectively ecotypes from Linan Zhejiang (LA), Kaihua Zhejiang (KH), Wuning Jiangxi (WN) and Nanping Fujian (NP), treated under three low light intensity (Ⅰ:25μmol·m-2·s-1;Ⅱ:50 μmol·m-2·s-1;Ⅲ:75 μmol·m-2·s-1) and two water supply levels (normal water supply and watering after 2 days drought). The results showed that the sensitivity of antioxidant enzymes activity and osmotic substances contents of I.lanceolatum seedlings to low light intensity was significantly different between two water supply conditions. After 2 days' dought, catalase (CAT) activity of WN ecotype seedlings in the light treatments of Ⅱ and Ⅲ significantly increased compared with that under normal water condition, the peroxidase (POD) activity in the light treatments of Ⅲ also significantly increased, and the malondialdehyde (MDA) contents in all three light treatments increased while the superoxide dismutase (SOD) activity decreased. Under the water stress, the SOD and POD activity of LA ecotype seedlings in all light conditions were lower than those under normal water supply, and the soluble protein and MDA contents were higher. Compared with normal water supply, the SOD, POD and CAT activity of KH ecotype seedlings in the light treatment of Ⅰ increased significantly under water stress, while soluble protein and MDA content decreased. The enzymes activity of NP ecotype seedlings in all light treatments increased after short-term water stress. We concluded that the water stress can significantly promote the adaptability to weak light for KH, WN and NP ecotypes seedlings by increasing antioxidant enzymes activity and osmotic substances contents. This result will provide the theoretical foundation for ex-situ conservation, efficient cultivation, soil moisture and light condition management of I.lanceolatum. 参考文献 相似文献 引证文献

Enhanced tolerance of transgenic potato plants expressing choline oxidase in chloroplasts against water stress.

BackgroundGlycinebetaine, whose biosynthesis could be catalyzed by choline oxidase (COD), is an extremely efficient compatible solute for scavenging oxidative stress-inducing molecules and protecting the photosynthetic system in plants. To study the effects of the codA transgene for choline oxidase on the drought resistance and recovery, a transgenic potato cultivar (SC) bearing codA gene and a non-transgenic (NT) control cultivar were raised in pots under moderate and severe drought stress. The experiment was constituted by a two-day-pretreatment with 20% PEG and a four-day-water stress combined with two-day-recovery treatment.ResultsUnder the four-day-water stress, plants were provided with normal water condition, 10% or 20% polyethylene glycol. The results of pretreatment showed an expression of codA gene in transgenic potato and an accumulation of glycine betaine (GB); leaf water potential was higher in SC than in NT. In the stress-recovery-treatment, SC showed stronger antioxidant ability, more efficient photosynthetic system, higher chlorophyll content, lower malondialdehyde content and better recovery from water deficit stress than NT.ConclusionAlthough this work concentrated on the short-term water stress and recover treatments on transgenic potato plants with the over-expression of CodA gene and its control line. The datas shows that the exogenous codA gene provided potato a stronger drought resistance and recovery ability.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-30) contains supplementary material, which is available to authorized users.

Gas exchange of root hemi-parasite Striga hermonthica and its host Sorghum bicolor under short-term soil water stress

The gas exchange of the upper fully expanded leaf of the root parasite Striga hermonthica and of its host Sorghum bicolor was measured under wet and dry conditions to identify the mechanisms of the devastating effects of the parasite on its hosts under drought. The short-term water stress severely reduced photosynthetic rate in infected sorghum, but less in S. hermonthica. Soil water stress did not affect leaf respiration rate in either S. hermonthica or infected sorghum. This suggests that under dry conditions both infected sorghum and S. hermonthica decreased autotrophic carbon gain. The transpiration rate of S. hermonthica, a major driving force for assimilate uptake from the host, was higher and less affected by water stress than that of infected sorghum. Stomatal density on the abaxial surfaces of the leaves was higher in S. hermonthica than in sorghum. Both S. hermonthica infection and water stress decreased stomatal conductance of the sorghum leaves. S. hermonthica, irrespective of soil water status, had greater stomatal aperture on the adaxial and abaxial surfaces of its leaves than infected sorghum. These results indicate that the higher transpiration rate of S. hermonthica even under water stress, achieved through higher stomatal density on the abaxial surfaces of the leaves and greater stomatal aperture on both surfaces of the leaves, may induce the maintenance of water and solute transfers from the host to the parasite leading to severe damage to the host under drought.

Patterns of protein expression in water-stressed wheat chloroplasts

The performance of control and water-stressed 10-d-old wheat seedlings was compared. During short-term water stress (irrigation was withheld for 9 d), rates of photosynthesis and transpiration, stomatal conductance, and relative water content decreased whereas the proline content increased. Chloroplast proteins were extracted from the leaves, separated by iso-electric focusing through two-dimensional electrophoresis, and stained with CBB R-250. Differentially expressed proteins were detected and analyzed with MALDI-TOF/TOF mass spectrometry. Under water stress, 9 proteins were up-regulated whereas 11 proteins were not affected. The ribulose-1,5-bisphospate carboxylase/oxygenase (Rubisco) small and large subunits, chloride carrier/channel family, and H+-ATPase were up-regulated by water stress whereas membrane-bound ATP synthase subunit b and cytochrome b6-f complex were down-regulated.

Metabolite Adjustments in Drought Tolerant and Sensitive Soybean Genotypes in Response to Water Stress

Soybean (Glycine max L.) is an important source of protein for human and animal nutrition, as well as a major source of vegetable oil. The soybean crop requires adequate water all through its growth period to attain its yield potential, and the lack of soil moisture at critical stages of growth profoundly impacts the productivity. In this study, utilizing 1H NMR-based metabolite analysis combined with the physiological studies we assessed the effects of short-term water stress on overall growth, nitrogen fixation, ureide and proline dynamics, as well as metabolic changes in drought tolerant (NA5009RG) and sensitive (DM50048) genotypes of soybean in order to elucidate metabolite adjustments in relation to the physiological responses in the nitrogen-fixing plants towards water limitation. The results of our analysis demonstrated critical differences in physiological responses between these two genotypes, and identified the metabolic pathways that are affected by short-term water limitation in soybean plants. Metabolic changes in response to drought conditions highlighted pools of metabolites that play a role in the adjustment of metabolism and physiology of the soybean varieties to meet drought effects.