NO与Ca2+对蚕豆保卫细胞气孔运动的互作调控

以蚕豆(Vicia faba L.)为材料研究NO和Ca²⁺对蚕豆气孔运动及质膜K⁺通道的影响。结果表明,10 mmol L^-1 Ca²⁺和100 µmol L^-1 NO供体SNP均有效抑制气孔开放,NO清除剂c-PTIO不能缓解Ca²⁺抑制气孔开放,相反胞外加入0.1 mmol L^-1 Ca²⁺可以明显加强NO对气孔开放的抑制程度,该现象可被La³⁺(Ca²⁺通道抑制剂)缓解。以膜片钳技术记录全细胞K⁺电流发现,胞外10 µmol L^-1或100 µmol L^-1 SNP均可选择性抑制蚕豆保卫细胞质膜内向K⁺通道,追加0.1 mmol L^-1 Ca²⁺可显著激活质膜外向K⁺通道,且可被La³⁺所缓解,然而0.1 mmol L^-1 Ca²⁺单独作用并不影响质膜外向K⁺通道活性。10 mmol L^-1 Ca²⁺单独处理可激活质膜外向K⁺通道,但不能被c-PTIO缓解。分别用Ca²⁺和NO专一的荧光探针Fluo-3-AM和DAF-2DA标记蚕豆保卫细胞原生质体,检测胞内Ca²⁺和NO的水平变化发现,100 µmol L^-1 SNP明显诱导胞内Ca²⁺积累,但10 mmol L^-1 Ca²⁺并不能诱导NO在细胞内积累。记录保卫细胞质膜Ca²⁺通道电流发现,NO可明显激活质膜Ca²⁺通道。表明NO有效抑制气孔开放,可能主要通过激活质膜Ca²⁺通道,提高胞内Ca²⁺,激活质膜外向K⁺通道促进K⁺外流,同时,可选择性抑制内向K⁺通道阻止K⁺内流,两种途径共同作用抑制气孔开放。然而,胞外10 mmol L^-1 Ca²⁺对气孔和质膜K⁺通道活性的调节并不依赖于NO。     

盐胁迫对花生幼苗离子动态及耐盐基因表达的影响

不同花生品种的耐盐能力各有差异,本研究以耐盐花生品种花育25 (Huayu 25,HY25)和盐敏感品种花育20(Huayu 20,HY20)为材料,利用非损伤微测技术,测定盐胁迫下花生幼苗根尖中Na⁺、K⁺、Ca²⁺、NH₄⁺、NO₃^–、Cl^–的流速;并同期检测了幼苗的生长性状、主要耐盐基因的表达及渗透调节物质(可溶性糖、脯氨酸)含量的变化,以明确花生的耐盐能力与离子吸收、转运及抗逆调控的关系。结果表明:(1)盐胁迫下Na⁺内流减弱,外排速率增加,K⁺内流提高,但是相对而言,HY25的Na⁺外排速率及K⁺内流速率均高于HY20,表明HY25通过排Na⁺保K⁺提高耐盐性;(2)盐胁迫促进Ca²⁺迅速内流,并且耐盐品种比盐敏感品种Ca²⁺内流...     

燕麦对碱胁迫的阳离子响应机制

以耐碱性燕麦品种Vao-9和碱敏感性品种白燕5号为试验材料,采用盆栽法,用25、50、75、100 mmol L^-1碱浓度(Na₂CO₃和NaHCO₃按摩尔比1∶1混合)进行短期(14 d)和长期(28 d)胁迫处理,观测两品种根、茎、叶中Na⁺、K⁺、Ca²⁺、Mg²⁺吸收及分配特点,并从离子平衡吸收与分配角度,探讨燕麦对碱胁迫的生理适应机制。胁迫处理14 d后,燕麦体内Na⁺增加,K⁺下降,Ca²⁺和Mg²⁺变化不大,且两品种间各器官中4种离子的分配比例差异不显著。胁迫处理28 d后,两品种各器官中Na⁺增幅较大,K⁺、Ca²⁺和Mg²⁺降幅较大。Vao-9植株体内Na⁺、Ca²⁺含量大于白燕5号,但K⁺、Mg²⁺含量与白燕5号无显著差异,但两品种间各器官中4种离子的分配特点不同;当胁迫浓度达到100 mmol L^-1时,与白燕5号相比,Vao-9叶片中少分配5.9个百分点Na⁺,多分配13.5个百分点K⁺、28.9Ca²⁺、10.9Mg²⁺,茎中多分配5.4个百分点Na⁺,少分配9.8个百分点K⁺,根中少分配28.9个百分点Ca²⁺、10.9Mg²⁺,因而Vao-9叶片中Na⁺ /K⁺、Na⁺ /Ca²⁺、Na⁺ /Mg²⁺值较白燕5号低。可见,燕麦通过提高阳离子选择吸收及器官分配能力以适应碱胁迫。     

干旱胁迫下一氧化氮对小麦离体根尖离子吸收的影响

为阐明干旱胁迫下一氧化氮(NO)对植物的保护机制,利用干旱敏感性不同的3个小麦(Triticum aestivum L.)品种的离体根尖,比较了NO对干旱胁迫的响应及其对离子吸收的影响。在干旱胁迫下, 耐旱品种陇春8139根尖中大量产生NO, K⁺和Ca²⁺被大量吸收, 而Cl^-1被排出体外, 质膜H⁺-ATPase活性升高; 而干旱敏感品种甘麦8和定西24的根尖中NO、离子含量和质膜H⁺-ATPase活性的变化呈相反趋势。NO供体硝普纳(SNP)处理使3个品种根尖中的K⁺和Ca²⁺含量增加,Cl^-1含量下降,并能提高质膜H⁺-ATPase活力;NOS抑制剂N^ω-nitro-L-arginine(LNNA)和NO清除剂2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl- 3-oxide(PTIO)能够逆转这一效果。Na⁺含量在所有处理下都没有明显变化。试验结果证明,NO能够通过调节质膜H⁺-ATPase活力影响植物对离子的选择吸收,从而提高耐旱性。     

基于主成分分析法的干旱区典型绿洲土壤盐分特征分析——以新疆第二师31团为例

为研究新疆典型绿洲土地盐分特征及分布特征,以新疆第二师31团为例,采用GPS对研究区域进行定点采样(N=66),采样深度为100 cm,采样层数为5层,对土壤盐分离子进行化验检测,运用SPSS软件对数据进行描述性、离子间相关性及离子主成分分析。结果表明:不同土壤层中各离子处于中等以上变异程度,各土壤层的pH=8.11,各土壤层中Cl^-、K⁺+Na⁺与SO₄^2-离子含量大于HCO₃^-、Ca²⁺与Mg²⁺离子;Cl^-、K⁺+Na⁺、SO₄^2-、Ca²⁺、Mg²⁺之间的相关系数较高,呈现极显著相关性。各土壤层的第一主成分主要包含Cl^-、SO₄^2-、Ca²⁺、Mg²⁺、K⁺+Na⁺离子信息,第二主成分与第三主成分主要包含HCO₃^-离子信息。以第一主成分、第二主成分及第三主成分所表征不同信息为基准,分析了研究区不同位置不同土壤层的盐渍化程度及碱度,该研究区域受盐碱影响较大。     

盐胁迫下水稻叶绿素荧光特性与离子积累的相关性分析

以4个北方常规粳稻品种为材料,于孕穗期施加80 mmol/L的NaCl胁迫测定了水稻叶片叶绿素荧光参数及体内离子含量的变化,以揭示盐胁迫下水稻离子积累与叶绿素荧光特性的相关性。结果表明盐胁迫下水稻叶片最大荧光(Fm)、最大光化学量子效率(Fv/Fm)、光系统Ⅱ的实际光合效率(PhiPSⅡ)、表观光合量子传递效率(ETR)和光化学猝灭(qP)均呈下降趋势最小初始荧光(Fo)和非光化学猝灭(qN)呈升高趋势。盐胁迫导致水稻体内Na⁺、Cl^-积累显著增加,K+积累显著下降,SO₄^2-、PO₄^3-和NO3-含量较对照差异不显著。盐胁迫下水稻叶绿素荧光参数与Na⁺、Cl^-和SO₄^2-含量呈显著负相关,与K+和PO₄^3-含量呈显著正相关,与NO3-含量相关性不显著。以上结果表明水稻体内有害离子在盐胁迫下会过量积累这是导致水稻叶片光合结构破坏和光合作用效率下降的重要原因。     

盐胁迫对台湾海桐幼苗光合生理及离子吸收的影响

为了解台湾海桐在盐胁迫下生长减弱的光合机理,通过温室盆栽的方法,设置0、6、9、12、15 g/kg 5个盐浓度,处理1年生台湾海桐实生苗,胁迫2个月后,对其主要光合参数、含水率变化及离子吸收与运输等指标进行测定。结果表明：随着盐浓度的升高,台湾海桐叶净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均显著下降,胞间CO₂浓度则缓慢升高,气孔限制值(Ls)和水分利用效率(WUE)均缓慢降低;随着盐浓度的升高,台湾海桐根部含水率降低,地上部分含水率升高;盐胁迫下,台湾海桐受Na⁺和Cl^-毒害严重,对K⁺和Ca²⁺的吸收受到抑制,其根部选择性吸收限制有害离子进入体内的能力有限。综合以上分析,盐胁迫下导致台湾海桐Pn下降的主要因素是非气孔限制因素,即叶肉细胞光合能力下降,这也许与其受到严重的离子毒害有关。     

氯离子和盐基阳离子对蔬菜种子萌发及其幼苗生长的影响

为研究蔬菜种子对不同盐基离子胁迫的响应问题,以空心菜、辣椒和菜心种子为实验材料,NaCl、KCl、CaCl₂和MgCl₂4种盐分作为胁迫因子,探究Cl^-及盐基阳离子对蔬菜种子萌发及其幼苗生长的影响。结果表明:(1)在设置的Cl^-浓度范围内,低浓度Cl^-促进空心菜和辣椒种子萌发及其幼苗生长;而高浓度Cl^-却显著抑制空心菜和辣椒种子萌发及其幼苗的生长。菜心种子的萌发及其幼苗生长受盐胁迫的影响表现为,随Cl^-浓度升高抑制作用逐渐增强。说明空心菜和辣椒具有一定的适应盐渍土壤环境的能力,而菜心不适应盐渍土壤环境。(2)相同Cl^-浓度下,不同盐基阳离子对空心菜和辣椒种子萌发的影响差异不显著;对菜心种子萌发的抑制作用表现为K⁺最强,Na⁺最弱。不同盐基阳离子对空心菜幼苗胚根和株高的抑制作用均表现为K+最强,Ca²⁺最弱;对菜心幼苗胚根和株高的抑制作用表现为Mg<...     

盐胁迫下玉米离子变化及转录组分析

为了研究玉米在盐胁迫下体内离子变化以及功能基因的响应,为今后培育耐盐玉米品种奠定基础。本研究以4份玉米自交系为研究对象,在200 mmol/L的NaCl溶液胁迫14天后,对玉米地下、地上部分中的Na⁺、K⁺、Ca²⁺含量进行测定并分析;同时,进行了转录组分析,研究玉米在盐胁迫下功能基因的表达情况。结果显示,4个自交系中叶片和根中Na⁺含量和Na⁺累积量最低的是S388,同时发现S388的Ca²⁺:Na⁺比在4个材料中表现出最高;转录组分析显示,S388参与了离子转运途径、逆境信号以及离子跨膜运输等代谢途径。研究表明,4份玉米自交系中S388对盐的耐受性最高,表型出叶片和根中积累了较少的Na⁺含量,这为今后耐盐品种培育提供了材料基础。     

盐渍土壤生境中大果沙枣成年树离子吸收、运输和分配特征研究

为揭示盐渍土壤中大果沙枣(Elaeagnus angustifolia Linn.)树体矿质离子分布规律,保障大果沙枣高效种植和丰产栽培,以不同盐度土壤中生长的成年大果沙枣树为材料,测定并分析了其根、枝、叶中Na⁺、K⁺、Mg²⁺和Ca²⁺的吸收、运输和分配特征。结果表明：盐土土壤环境中,大果沙枣叶片对Ca²⁺和Mg²⁺具有较强的选择吸收能力,低盐（I~II级）土壤环境中,叶内Na⁺含量明显上升,而至高盐（III~IV级）中,根部对Na⁺的吸收量明显高于枝和叶。随着林地土壤盐度的升高,K⁺、Ca²⁺、Mg²⁺在枝部和叶部的积累量明显增大,矿质离子由根部向枝、叶部运输的能力在I~III级盐度土壤环境中逐渐增大,并在IV级盐度土壤环境中受抑。同时,根和枝中K⁺/Na⁺和Mg²⁺/Na⁺值均是先增大后减小,叶中K⁺/Na⁺、Mg²⁺/Na⁺变幅较小,根和叶中Ca²⁺/Na⁺变幅较大。大果沙枣成年树的盐适应机制主要是通过根对Na⁺的聚积作用,叶对K⁺、Mg²⁺和Ca²⁺的选择性吸收能力增强来实现的,同时也与枝中相对稳定的K⁺、Na⁺、Mg²⁺和Ca²⁺的选择性运输能力有关。     

拟南芥H~+_-焦磷酸化酶AVP1互作小GTP结合蛋白AtRAB的特性鉴定与功能分析

以拟南芥AVP1为诱饵,采用膜蛋白酵母双杂交系统筛选拟南芥cDNA文库,获得一个与AVP1互作的小GTP结合蛋白AtRAB。酵母互作试验表明,AVP1和AtRAB存在互作;双分子荧光互补实验(BiFC)证明,AVP1和AtRAB能在质膜和细胞核上发生相互作用。野生型拟南芥(WT)、AtRAB和AVP1的拟南芥突变体rab和avp1在高盐胁迫条件下,随着NaCl浓度的加大,突变体rab和avp1的表型变化相似,相对于WT都表现为根长缩短,侧根数减少;在低磷处理条件下,随着磷浓度的逐渐降低,2个突变体的表型相似,相对于WT同样表现为根长缩短,总根面积减少,侧根数减少;在相同磷浓度条件下,突变体rab对胁迫的反应比avp1强;在低钾处理条件下,随着钾浓度的降低,2个突变体的表型与在低磷胁迫处理条件下的表型相似。结果说明,AVP1和AtRAB可以在细胞膜和细胞核上相互作用,AtRAB能够影响植物对离子的吸收,AVP1和AtRAB的突变体在高盐、低磷和低钾等胁迫条件下表型变化相似,证明了2个基因都正向调控植物对高盐、低磷和低钾胁迫的反应,它们属于同一信号途径。     

铝胁迫对花生根尖线粒体膜生理特性的影响

线粒体在植物生命活动中发挥重要作用,以花生为材料,研究了在铝胁迫条件下,花生根尖细胞线粒体膜生理变化。结果表明,通过根长试验、苏木精染色和根尖铝离子含量测定,筛选到耐铝品种LH11,铝敏感品种R1549。铝胁迫后,两个品种根尖线粒体MDA含量增加,R1549的MDA含量均高于LH11,在处理浓度是20 μmol L^-1和100 μmol L^-1时,两品种的MDA含量差异显著,但在400 μmol L^-1时,差异不显著;两品种根尖线粒体Ca²⁺-ATP酶活性和Ca²⁺含量呈下降趋势,且随铝溶液浓度增加而加快,R1549的线粒体Ca²⁺含量下降较LH11快;随处理铝溶液浓度增加,线粒体光密度持续下降,MPT不断增大,ΔΨ_m明显降低,线粒体中Cyt c/a减少,R1549较LH11下降更明显。试验结果说明在较高铝浓度胁迫下,两品种线粒体透性转换孔开放,膜透性增加,跨线粒体膜Ca²⁺转运系统活性降低,使胞质Ca²⁺超载,细胞色素C释放到细胞质中,诱导根尖细胞发生程序性死亡,从而抑制根生长;在低铝浓度下,与铝敏感品种相比,耐铝品种吸收铝少,脂质过氧化水平低,线粒体膜Ca²⁺-ATPase活性、MPTP和ΔΨ_m调控能力强,不易发生PCD,从而表现出较强的耐铝能力。     

盐胁迫条件下外源Ca2+对蚕豆气孔运动及质膜K+通道的调控

研究了Ca²⁺ 对NaCl胁迫下蚕豆气孔运动及质膜K+通道的影响。结果表明,100 mmol L^-1 NaCl可明显诱导气孔开放,该现象可被10 mmol L^-1 CaCl₂ 显著抑制。为探讨盐胁迫下Ca²⁺对K⁺和Na⁺跨膜运输的调控机制,我们利用膜片钳技术记录全细胞K⁺ 电流发现,在100 mmol L^-1 NaCl胁迫下,加入10 mmol L^-1 CaCl₂胞外处理,显著抑制质膜K+内向及外向通道电流,这种抑制可被1 mmol L^-1 La³⁺ (Ca²⁺通道抑制剂)缓解。非盐胁迫下,10 mmol L^-1 CaCl₂ 胞外处理也能显著抑制质膜内向K⁺通道,但明显激活其外向通道,加入1 mmol L^-1 La³⁺并不能被缓解。用H₂O₂专一的荧光探针二氯荧光素二乙酸酯(H2DCF-DA)单细胞分析保卫细胞内H₂O₂含量变化显示,在100 mmol L^-1 NaCl盐胁迫下,10 mmol L^-1 CaCl₂ 处理明显诱导H₂O₂在保卫细胞中积累;100 mmol L^-1 NaCl和10 mmol L^-1 CaCl₂单独处理并不能诱导H₂O₂积累。推测Ca²⁺在盐胁迫下可能先诱导H₂O₂在胞内积累,进而激活质膜Ca²⁺通道,迅速提高胞内Ca²⁺浓度以抑制Na⁺通过质膜K⁺通道跨膜内流,同时调节Na⁺外流,两种效应共同作用促使气孔关闭,减少盐胁迫下水分的过度散失。上述结果将为Ca²⁺调控作物抗盐机制研究提供新的思路。     

Understanding physiological and morphological traits contributing to drought tolerance in barley

Drought stress is a major limiting factor for crop production in the arid and semi‐arid regions. Here, we screened eighty barley (Hordeum vulgare L.) genotypes collected from different geographical locations contrasting in drought stress tolerance and quantified a range of physiological and agronomical indices in glasshouse trails. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at three‐leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, root length of the same genotypes was measured from stress‐affected plants growing hydroponically. Drought tolerance was scored 30 days after the drought stress commenced based on the degree of the leaf wilting, fresh and dry biomass and relative water content. These characteristics were related to stomatal conductance, stomatal density, residual transpiration and leaf sap Na, K, Cl contents measured in control (irrigated) plants. Responses to drought stress differed significantly among the genotypes. The overall drought tolerance was significantly correlated with relative water content, stomatal conductance and leaf Na⁺ and K⁺ contents. No significant correlations between drought tolerance and root length of 6‐day‐old seedling, stomatal density, residual transpiration and leaf sap Cl^? content were found. Taking together, these results suggest that drought‐tolerant genotypes have lower stomatal conductance, and lower water content, Na⁺, K⁺ and Cl^? contents in their tissue under control conditions than the drought‐sensitive ones. These traits make them more resilient to the forthcoming drought stress.     

转EdHP1(氢离子焦磷酸化酶)基因烟草促进钾离子吸收的生理机制

钾是植物生长必须的重要矿质元素,提高作物对钾的吸收是提高作物产量的重要途径。本研究以前期遗传转化披碱草EdHP1(H+-pyrophosphatase)基因的烟草为材料,在低钾处理条件下比较了转基因烟草和野生型烟草的生理特性。结果显示,在低钾条件下,野生型烟草体内K+积累量只相当于转基因烟草的62.9%。野生型烟草的总根长、总根表面积、总根体积明显低于转基因烟草(P0.05),分别为转基因烟草的72.9%、68.1%和60.6%。在不同直径根系(0.5～2.0、2.5～4.5、4.5mm分别为细根、中等根和粗根)中,细根发育差异最大,野生型烟草为转基因烟草的72.9%。低钾条件下,转基因烟草根系活力是野生型烟草的1.2倍,野生型烟草根系焦磷酸化酶活力相当于转基因烟草的46.4%,根部游离IAA含量相当于转基因烟草的66.2%。通过非损伤方法测定根部K+和H+流速结果显示,在根系表面积相似情况下,低钾条件下野生型烟草外排钾速率显著高于转基因烟草,而氢离子外排速率显著低于转基因烟草。综上所述,发达的根系和较高的K+转运体活性综合作用显著提高了转基因烟草根部对K+的吸收。     

DROUGHT STRESS: Comparative Time Course Action of the Foliar Applied Glycinebetaine,Salicylic Acid,Nitrous Oxide,Brassinosteroids and Spermine in Improving Drought Resistance of Rice

Worldwide rice productivity is being threatened by increased endeavours of drought stress. Among the visible symptoms of drought stress, hampered water relations and disrupted cellular membrane functions are the most important. Exogenous use of polyamines (PAs), salicylic acid (SA), brassinosteroids (BRs), glycinebetaine (GB) and nitrous oxide (NO) can induce abiotic stresses tolerance in many crops. In this time course study, we appraised the comparative role of all these substances to improve the drought tolerance in rice (Oryza sativa L.) cultivar Super‐Basmati. Plants were subjected to drought stress at four leaf stage (4 weeks after emergence) by maintaining soil moisture at 50 % of field capacity. Pre‐optimized concentrations of GB (150 mg l^?1), SA (100 mg l^?1), NO (100 μmol l^?1 sodium nitroprusside as NO donor), BR (0.01 μm 24‐epibrassinolide) and spermine (Spm; 10 μm ) were foliar sprayed at five‐leaf stage (5 weeks after emergence). There were two controls both receiving no foliar spray, viz. well watered (CK1) and drought stressed (CK2). There was substantial reduction in allometric response of rice, gas exchange and water relation attributes by drought stress. While drought stress enhanced the H₂O₂, malondialdehyde (MDA) and relative membrane permeability, foliar spray of all the chemicals improved growth possibly because of the improved carbon assimilation, enhanced synthesis of metabolites and maintenance of tissue water status. Simultaneous reduction in H₂O₂ and MDA production was also noted in the plants treated with these substances. Drought tolerance was sturdily associated with the greater tissue water potential, increased synthesis of metabolites and enhanced capacity of antioxidant system. Of all the chemicals, foliar spray with Spm was the most effective followed by BR.     

Physiological Responses of Krishum (Iris lactea Pall. var. chinensis Koidz) to Neutral and Alkaline Salts

The aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na⁺, K⁺, Ca²⁺, Mg²⁺), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na₂CO₃ and the mixture of the two salts in the same volume. All three treatments caused increases in Na⁺ concentration, proline content and REL and decreases in root Mg²⁺ and K⁺ content. Increased Ca²⁺ and antioxidase activities were observed at lower external Na⁺ concentrations. However, at higher external Na⁺ levels, decreased Ca²⁺ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na⁺ and low K⁺ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca²⁺ content in the plant under alkaline salt stress.