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1.
干旱胁迫是影响植物生长发育的主要限制因素之一。到目前为止,许多研究都仅关注于植物对干旱反应的信号转导网络,而对其中一些很重要的中间成分却知之甚少。保卫细胞定位于植物叶片的表皮中,控制二氧化碳的吸收以及水分的散失,已经成为一种高度特化的细胞体系,可用来研究植物早期干旱信号转导机制。控制气孔的开度在提高植物的抗旱性方面具有重要意义。通过使用远红外热成像仪检测植物叶片表面温度的微小差异,我们成功地筛选并获得了拟南芥(Arabidopsis thaliana)干旱敏感突变体doi1。在干旱胁迫条件下,该突变体表现为叶面温度低于野生型,且失水率比野生型高。利用TAIL-PCR技术成功克隆到该突变体基因NCED3,并利用RT-PCR方法验证了TAIL-PCR结果的可靠性。  相似文献   

2.
为探索DELLA蛋白缺失对拟南芥耐旱能力的影响,对拟南芥野生型Ler和DELLA蛋白缺失突变体della进行干旱处理,测定存活率、萌发率、离体叶片的失水率、脯氨酸、可溶性糖和丙二醛含量,并对发挥植物细胞脱水保护功能的胚胎晚期丰富蛋白编码基因LEA和ABA应答基因LOX3、COR15b、COR413的表达量进行了检测。结果表明:(1)干旱21d后复水,della突变体的存活率明显高于野生型Ler;(2)della突变体在含甘露醇的固体培养基上的萌发率显著高于Ler;(3)della突变体离体叶片的失水速率明显低于Ler;(4)干旱胁迫后,della突变体脯氨酸、可溶性糖和丙二醛含量的积累低于Ler;(5)干旱胁迫后,della突变体的LEA基因上调表达程度高于Ler,而ABA应答基因上调表达程度低于Ler。研究表明,DELLA蛋白的缺失有助于提高植物抗旱能力。  相似文献   

3.
以拟南芥(Arabidopsis thaliana)为研究材料,从T-DNA突变体库中筛选分离得到1株脱落酸(ABA)敏感突变体asm1(ABA sensitive mutant 1,asm1),在含有ABA的培养基中,与野生型相比,asm1突变体的根伸长明显受到抑制,且其种子萌发结果显示asm1对ABA同样表现出敏感特性。在生长发育方面,asm1突变体抽苔时间提前,植株矮化,并且荚果长度明显小于野生型。利用远红外成像系统分析发现,在干旱胁迫下asm1突变体叶面温度高于野生型;失水率分析显示突变体失水率降低以及水分散失减少。遗传学分析表明,asm1是单基因隐性突变且与一个T-DNA插入共分离;通过图位克隆成功获得候选基因ASM1。RT-PCR结果显示,在突变体中ASM1的表达受到抑制,并且能够调控多种ABA信号通路和胁迫应答基因的表达水平。研究结果表明,ASM1可能参与调控ABA信号转导并应答干旱胁迫。  相似文献   

4.
油菜素内酯(brassinosteroid,BRs)是一类重要的植物激素,在植物的生长发育过程中发挥重要的调节作用。BRs的信号转导研究在双子叶植物拟南芥中已取得重大进展,但在单子叶植物水稻中,BRs的信号转导途径尚不很清楚。本研究从水稻T-DNA插入突变体库中筛选出一个叶片直立突变体el(erect leave mutant)。该突变体与野生型植株相比,叶夹角减小。遗传分析显示,el的突变性状由一对显性基因控制。该基因经图位克隆定位于水稻第5染色体引物InDel3和InDel4之间,物理距离为700 kb。本研究明确了一个水稻BRs不敏感突变体的表型特征及遗传规律,为进一步研究水稻BRs信号转导调控机制奠定基础。  相似文献   

5.
干旱胁迫是影响农作物产量最重要的环境因素之一。硫化氢(H_2S)作为第三种气体信号分子在植物体内具有多样且积极的生理功能。目前已了解,H_2S在响应植物干旱胁迫应答以及增强植物光合作用的过程中发挥重要作用,但关于内源性H_2S对干旱胁迫下植物光合作用的调节机制未见报道。该研究以拟南芥哥伦比亚野生型(wild type Col-0,WT)、H_2S产生酶编码基因DES缺失突变体des以及H_2S产生酶编码基因DES过表达突变体OE-DES为实验材料,研究内源性H_2S对干旱胁迫下拟南芥光合作用的调节机制。研究结果显示,植株在正常生长条件下,内源性H_2S促使叶片净光合速率、蒸腾速率、叶绿素含量显著升高;植株遭受干旱胁迫时,内源性H_2S可以显著上调Rubisco和Rubisco活化酶(Rubisco activase,RCA)的表达水平,保护叶绿体结构的完整性,促使叶片净光合速率显著上升,维持叶片相应的蒸腾速率,并且引起叶片气孔关闭和胞间CO_2浓度显著升高。  相似文献   

6.
玉米干旱胁迫相关突变体在发掘玉米耐旱关键基因研究中具有重要利用价值。在玉米自交系综31的田间扩繁过程中,发现一个玉米干旱胁迫敏感的自然突变体,该突变体在轻度干旱条件下叶片发生卷曲,严重干旱时叶尖变黄,衰老坏死。遗传分析表明突变性状受1对主效单基因控制,表现为隐性遗传,将突变基因命名为DS。利用B73与突变体ds组配F2分离群体,以干旱条件下叶片是否卷曲为指标,将DS基因初定位在第3号染色体SSR标记umc1772和umc2158之间,物理距离为5 Mb。以上研究结果为该基因的克隆及功能分析奠定了基础。  相似文献   

7.
ATHKl基因调节拟南芥渗透胁迫信号转导过程   总被引:3,自引:0,他引:3  
以拟南芥ATHKl基因T-DNA插入所产生的缺失突变体和野生型ws(wassilewskija)生态型为材料,分析了它们在生理和基因表达方面的差异.结果表明突变体的离体叶片失水率明显大于野生型;在30%PEG-6000胁迫后,野生型和ATHKJ突变体的细胞膜离子外渗率比胁迫前分别增加了50%和80%.PEG胁迫48 h时突变体的萎蔫程度明显大于野生型ws.以上结果说明ATHKl突变体的抗渗透胁迫能力低于野生型,即ATHKl基因参与了拟南芥适应逆境的调节反应.利用DDRT-PCR技术研究二者在PEG胁迫36h后的基因表达差异,分离到9个在野生型中被PEG诱导表达而在突变体中未被诱导的参与逆境应答的基因片段,其中包括MAPKKKl8和丝氨酸/苏氨酸蛋白激酶基因,即ATHKJ基因失活引起下游基因响应渗透胁迫的能力减弱,进一步说明ATHKJ基因参与拟南芥适应逆境的调节反应,并且ATHKl可能在逆境信号转导组分MAPK的上游起作用,很可能是植物体中的渗透感受器.  相似文献   

8.
叶片是植物进行光合作用的重要器官。叶片适度卷曲能够提高水稻(Oryza sativa)生长中后期群体基部的光能利用率,因而有利于水稻产量的提高。该研究首先在水稻T-DNA插入突变体库中发现一份叶片反卷的突变体。遗传分析表明,该性状受到1对隐性核基因控制。扫描电镜观察结果显示,突变体成熟叶片上下表皮的气孔发生了畸变;且叶片上表皮气孔数目增多,而下表皮气孔数目与野生型基本相同。叶片横切面电镜观察结果表明,与野生型相比,突变体叶片的泡状细胞数目和面积在早期(二叶期)就开始增加,在成熟期更加明显,这可能是导致叶片反卷的主要原因。  相似文献   

9.
盐胁迫下突变体和野生型叶片中的脯氨酸累积量均有显著的增加,野生型的增加幅度不及突变体。至96 h ,两者含量均下降,但突变体的脯氨酸含量仍高于野生型。100m mol/L的NaCl 胁迫72 h ,突变体叶片中可溶性糖的含量有显著的增加,增加量随盐浓度增加而降低。至96 h,各个盐浓度处理的突变体可溶性糖的含量基本恢复到其对照的水平;除100 mmol/L 盐胁迫处理组外,野生型叶片中可溶性糖含量均大幅度下降。盐胁迫下突变体和野生型叶片细胞可溶性蛋白组分有明显的差异。mRNA 差异显示结果表明,突变体有6 个差异性的cDNA 片段  相似文献   

10.
为了研究强抗逆植物沙冬青Am NAC3转录因子基因在抗旱性和抗寒性中的功能,首先利用半定量RT-PCR方法对该基因进行了表达分析。结果表明,在室内培养的沙冬青幼苗中,Am NAC3有一定量的基础表达,在干旱胁迫下其转录水平明显上调,而在低温胁迫下其表达上调较弱。然后利用5'RACE技术获得该基因的5'端序列及全长cDNA序列,并利用RT-PCR方法克隆到其全长编码区(846bp)。将编码区片段构建到植物表达载体上,利用农杆菌介导法获得转基因拟南芥。进一步分析表明,转基因拟南芥对于干旱和低温胁迫的抗性表型与野生型无明显差异,但其离体叶片的失水率和气孔开度均大于野生型。此外,转基因幼苗中气孔开闭相关基因ABI1和ABI2的表达量降低。这些结果表明,Am NAC3可能主要在响应干旱胁迫和调节气孔开闭及叶片保水性中发挥功能,而在抵抗低温胁迫中无明显作用。  相似文献   

11.
12.
Production of phytohormones is one of the main mechanisms to explain the beneficial effects of plant growth‐promoting rhizobacteria (PGPR) such as Azospirillum sp. The PGPRs induce plant growth and development, and reduce stress susceptibility. However, little is known regarding the stress‐related phytohormone abscisic acid (ABA) produced by bacteria. We investigated the effects of Azospirillum brasilense Sp 245 strain on Arabidopsis thaliana Col‐0 and aba2‐1 mutant plants, evaluating the morphophysiological and biochemical responses when watered and in drought. We used an in vitro‐grown system to study changes in the root volume and architecture after inoculation with Azospirillum in Arabidopsis wild‐type Col‐0 and on the mutant aba2‐1, during early growth. To examine Arabidopsis development and reproductive success as affected by the bacteria, ABA and drought, a pot experiment using Arabidopsis Col‐0 plants was also carried out. Azospirillum brasilense augmented plant biomass, altered root architecture by increasing lateral roots number, stimulated photosynthetic and photoprotective pigments and retarded water loss in correlation with incremented ABA levels. As well, inoculation improved plants seed yield, plants survival, proline levels and relative leaf water content; it also decreased stomatal conductance, malondialdehyde and relative soil water content in plants submitted to drought. Arabidopsis inoculation with A. brasilense improved plants performance, especially in drought.  相似文献   

13.
 在全球变化条件下,温度的升高和降水格局的变化,导致淡水资源更加匮乏。环境因子胁迫,如干旱和高温等,它们单独或联合的作用将导致 作物大幅度减产,引发自然生态系统退化。植物的碳氮代谢及其分配相互联系、不可分割,其生物过程及外界环境调节共同决定着植物的净生 产力和营养水平。该文试图从分子、组织、器官、个体和生态系统等层面上,就植物的碳氮关系及其环境调节(温度、水分和CO2浓度等)进行 综述,并提出了进一步展开相关研究应重点关注的几个方面。  相似文献   

14.
Salicylic acid (SA) is one of the important signal molecules modulating plant responses to environmental stress. In this study, the effects of exogenous SA on leaf rolling, one of drought avoidance mechanisms, and antioxidant system were investigated in Ctenanthe setosa during long term drought stress. The plants were subjected to 38-day drought period and they were treated with or without SA (10−6 M) on the 25th, 27th and 29th days of the period. Leaf samples were harvested on the 30th, 34th and 38th days. Some antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase), reactive oxygen species (hydrogen peroxide and superoxide) and lipid peroxidation were determined during the drought period. Treatment with SA prevented water loss and delayed leaf rolling in comparison with control leaves. Exogenous SA induced all antioxidant enzyme activities more than control leaves during the drought. Ascorbate and glutathione, α-tocopherol, carotenoid and endogenous SA level were induced by the SA treatment. Levels of reactive oxygen species were higher in SA treated plants than control ones on the 34th day. Their levels on the 38th day, however, fastly decreased in SA treated plants. SA treatment prevented lipid peroxidation while the peroxidation increased in control plants. The results showed that exogenous SA can alleviate the damaging effect of long term drought stress by decreasing water loss and inducing the antioxidant system in the plant having leaf rolling, alternative protection mechanism to drought.  相似文献   

15.
Transpiration, water uptake by the roots and CO2 exchange oftwo leaf succulents, Senecio medleywoodii (Asteraceae) and Aloejucunda (Asphodeliaceae), were monitored simultaneously andcontinuously with a gas exchange cuvette combined with an apparatusto quantify water uptake (= waterbudget- meter). Measurements,which are primarily valid for plants with a sufficient watersupply, were made with the same plant for up to 29 consecutivedays. Ambient air temperature varied between 17 and 35 C witha constant dewpoint temperature of 13C of the ambient air anda 12 h photoperiod at 400–500mol m–2s–1 photonirradiance. The net water flux (Jw(net)=water uptake–transpiration)and the water balance (Jw(net) integrated for a timespan) werecalculated. Various tests were made to determine the accuracyof the measurements made with this rather complex equipment.In most cases the errors for transpiration and uptake rateswere much lower than 8% determined under the conditions of drastically(about 10 K per 30 min) increased or decreased ambient air temperatures.The experimental set-up proved to be a most valuable tool todetermine and analyse interactions between transpiration andwater uptake, changes in plant water status and the bufferingof negative Jwnet). Increasing the temperature of ambient air resulted, for bothspecies investigated, in a quick and considerably enhanced transpiration,but there was only a minor impact on water uptake. Water lossexceeding uptake was buffered by internal water reserves whichwere refilled within about 1 d after the plant was relievedof heat and drought stress caused by a period of high ambientair temperatures and high water vapour saturation deficits ofthe air. Repeated simulation of such stress periods showed thatthe absolute values of transpiration and the water uptake for24 h can vary, but the diurnal course of the values showed thesame pattern if the environmental conditions were identical.Such standardized diurnal transpiration and water uptake curvescould be very useful for the validation of mathematical modelsused to describe plant water relations. Key words: Plant water relations, water budget, drought stress, transpiration, water uptake  相似文献   

16.
Abscisic acid (ABA) is an important signaling molecule for plants under drought tolerance. However, ABA itself has many limitations to be used in agriculture practically. Recently, AM1 (ABA-mimicking ligand) has been found to replace ABA. In this study, we have investigated AM1’s potential role for drought tolerance by growing two contrasting rapeseed (Brassica napus L.) genotypes: Qinyou 8 (drought sensitive) and Q2 (drought resistant) with exogenous ABA or AM1 application under well-watered and drought-stressed conditions. Results demonstrate that drought stress has hampered plant growth (relative height growth rate, plant biomass, leaf area), plant water status (leaf relative water content, root moisture content, leaf water potential), photosynthetic gas exchange attributes like net photosynthesis rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (E); chlorophyll fluorescence parameters like photosynthetic efficiency (Fv/Fm), effective quantum yield of PSII (Φ PSII ), photochemical quenching coefficient (qL), electron transport rate (ETR) and chlorophyll content, especially for Qinyou 8 significantly compared to well-watered plants. Whereas increased root/shoot ratio (R/S), water use efficiency (WUE) and non-photochemical quenching (NPQ) was recorded in both genotypes under drought stress. On the other hand, exogenous ABA or AM1 treatment has regulated all the above parameters in a rational way to avoid drought stress. Chloroplast transmission electron microscope images, especially for Qinyou8, have revealed that oxidative stress induced by drought has blurred the grana thylakoids, increased the size or number of plastoglobules due to lipid peroxidation, and the presence of starch granules depict weak capacity to convert them into simple sugars for osmotic adjustment. However, intact grana thylakoid, few plastoglobules with no or very few starch granules were observed in the chloroplast from ABA- or AM1-treated plants under drought. More importantly, AM1-treated plants under drought stress have responded in an extremely similar way like ABA-treated ones. Finally, it is suggested that AM1 is a potential ABA substitute for plant drought tolerance.  相似文献   

17.
Nitrogen fixation activity in common bean is generally thoughtto be low and sensitive to soil drying and, consequently, droughtcan have important negative effects on N accumulation and yieldpotential. The objectives of this research were to examine theresponse of N2fixation to drought stress in common bean, andto test the hypothesis that drought sensitivity of N2fixationin common bean is linked to ureide levels in the plants. Twoglasshouse experiments were conducted to compare the responsesof leaf transpiration and acetylene reduction activity (ARA)to soil water contents. ARA decrease during soil dehydrationwas found to lag behind the decline in transpiration. This indicatesthat ARA is relatively less sensitive to soil dehydration comparedto leaf gas exchange. Further, in comparing two cultivars therewas no consistent difference in the relative response of ARAand transpiration to soil drying. The ureide concentrationsmeasured in common bean plants were low, ranging from 0.1 to1.0 mmol l-1in xylem sap exudates. Ureide concentrations inthe sap exudate varied significantly among the two genotypeseven though there was no difference in ARA response to drought.It was concluded that in common bean, the lower sensitivityof N2fixation to drought compared to leaf gas exchange couldbe related to low ureide concentrations in petioles and xylemsap.Copyright 1998 Annals of Botany Company Phaseolus vulgaris,nitrogen fixation, drought stress, nodules, ureides.  相似文献   

18.
ABI3是ABA信号通路中关键的转录调控因子, 参与种子休眠、质体发育及苔藓耐干等重要生理过程, 在植物抗逆中发挥关键作用。以荒漠耐干苔藓——齿肋赤藓(Syntrichia caninervis)为材料, 克隆了抗逆基因ScABI3并获得3个独立的pCAMBIA1301-ScABI3转基因拟南芥(Arabidopsis thaliana)纯合株系。结果表明, 转基因拟南芥叶片气孔孔径增大, 单位面积气孔数量减少, 植株水分利用效率提高; 在干旱处理14天后转基因拟南芥植株存活率显著高于野生型, 离体叶片失水率显著低于野生型。进一步研究发现, ScABI3转基因拟南芥通过提高自身活性氧(ROS)清除能力增强植株抗旱性。研究结果可为开发利用荒漠植物基因资源培育抗逆作物品种奠定基础。  相似文献   

19.
The conservation of water in agriculture requires an understanding of the mechanisms of plant–water relations. This study aimed to reveal hydraulic regulation strategies of maize (Zea mays L.) for maintaining the plant water balance during drought. The water relations of two maize inbred lines (Tian4 and 478) that differ in their resistance to drought in the field were investigated under well-watered conditions and osmotic stress induced with 10 % PEG 6000. The leaf transpiration rate and leaf water potential of 478 varied diurnally, but remained constant in Tian4, which is more drought resistant. Tian4 plants showed morphological, anatomical and physiological advantages that protected them from foliar water loss. The strategies of leaf hydraulics to regulate leaf water balance during the day and during short-term osmotic stress also differed between Tian4 and 478. The leaf hydraulic conductivity of Tian4 and 478 increased temporarily, but their root hydraulic conductivities were reduced under osmotic stress. However, the root hydraulic conductivity of Tian4 subsequently recovered. Lower and rapidly reduced leaf transpiration and the ability of root hydraulics to recover from short-term osmotic stress can help explain the strategies for plant water balance of drought-tolerant maize.  相似文献   

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