植物ABA-H2O2介导的气孔关闭

本文综述了脱落酸作为根源信号物质经由木质部被传递到叶片,经重新分配再与脱落酸受体结合,然后刺激气孔开放因子,调节烟酰胺腺嘌呤二核苷酸磷酸氧化酶等关键酶活性产生过氧化氢,过氧化氢可使胞质碱化并刺激钙离子通道使钙离子内流,活化阴离子通道使阴离子外流,最终导致气孔关闭的一系列过程。该过程涉及到的因子包括：脱落酸受体、气孔开放因子、磷脂酰环己六醇、分裂原激活蛋白激酶、烟酰胺腺嘌呤二核苷酸磷酸氧化酶、Ca^（2＋）、pH、一氧化氮等。     

腐植酸钠调节气孔开启度与植物激素作用的比较观察

比较腐植酸钠(HA)、脱落酸(ABA)和激动素(KT)对蚕豆叶片气孔开启度的影响。5 ppm ABA显著抑制气孔开启,而5 ppm KT则明显促进气孔开张。不同来源的HA及黄腐酸(FA)类似ABA的作用,抑制气孔开启,但其作用浓度较ABA高,以100 ppm为宜。在一定浓度范围内KT可以抵消ABA与FA的作用。而FA与ABA的协同作用并不明显。这说明FA抑制气孔开启的作用机理与ABA不尽相同。对不同来源的HA及FA进行比较试验,发现它们抑制气孔开启的效果不同。进一步对大同HA的不同组份作对比试验,抑制效果虽有差别,但都有一定作用。对FA抑制气孔开启的原理还进行了初步探讨。     

脱落酸信号转导途径在植物应对非生物胁迫响应中的作用

脱落酸(abscisic acid, ABA)是植物用来抵抗外界威胁的一种重要激素,它通过影响其信号通路中下游调控因子的转录和转录后修饰,控制植物对生物和非生物环境胁迫作出响应,从而增强植物的抗性。其核心反应首先是脱落酸受体接受脱落酸分子信号后,变构抑制蛋白磷酸酶2C(protein phosphatase 2C, PP2C)的活性,从而减轻或消除PP2C对蔗糖非发酵相关蛋白激酶2(sucrose non-fermented related protein kinase 2, SnRK2)的抑制,增强SnRK2激酶对底物蛋白的磷酸化来调节植物脱落酸的总体反应。其次,当感知到外界威胁时植物通过激活编码脱落酸生物合成酶基因的表达,促进脱落酸的生物合成和积累,从而激活脱落酸信号通路中下游胚胎发育晚期丰富蛋白(late embryogenesis abundant proteins, LEA)的表达,增多的LEA蛋白可以保护细胞膜的稳定性从而增进植物的抗逆性。另外,脱落酸在触发保卫细胞气孔关闭方面也起关键作用,脱落酸可以调节细胞离子通量,介导气孔闭合,减少水分流失。     

Tween-80引起玉米气孔夜间开放的机制

在T-80的作用下,与夜间气孔开放、蒸腾提高的同时,玉米叶片含水率及水势明显下降,水分饱和亏缺程度增大,此时,虽然气孔在黑暗中开放,但K~ 并未在保卫细胞内累积,而且,脱落酸也不能阻止这种气孔的夜间开放及蒸腾的提高。在被水蒸汽饱和的环境中,T-80处理与对照一样,蒸腾停止进行,T-80亦不再能使玉米气孔在黑暗中开放,叶片水势下降及水分饱和亏缺度增大的现象均随之消失。 T-80引起玉米气孔在黑暗中开放这一现象,与一般情况下和K~ 主动转移相关联的气孔主动开放运动不同,很可能是T-80改变了角质层的状况,使角质蒸腾大幅度提高,由此引起叶片含水率及水势的下降,进而引起表皮细胞膨压的下降,最终导致气孔的被动开放。     

脱落酸调节植物抵御水分胁迫的机制研究

干旱、盐渍、低温等均可导致植物可利用水分的亏缺,表现为水分胁迫。植物感受到水分胁迫,诱导脱落酸（abscisic acid,ABA）生物合成。ABA可通过促使气孔关闭或抑制气孔开放,使作物尽可能地降低蒸腾失水,以抵御水分胁迫。该文就植物激素ABA及其下游信号过氧化氢（hydrogenperoxide,H2O2）、一氧化氮（nitric oxide,NO）以及Ca2＋等在植物气孔运动调节方面的研究进展进行概述,以构建水分胁迫下ABA调节植物气孔运动的可能模式。     

植物细胞钙依赖型蛋白激酶参与ABA信号转导过程的实验证据

利用膜片钳技术探讨了植物细胞钙依赖型蛋白激酶（ＣＤＰＫ）是否参与了植物激素脱落酸（ＡＢＡ）调控气孔运动的信号转导过程。胞外加入１μｍｏｌ／ＬＡＢＡ完全抑制光照条件下蚕豆叶片气孔的开放,同时加入ＣＤＰＫ抑制剂三氟拉嗪则显著降低ＡＢＡ对气孔开放的抑制作用。在胞内加入１μｍｏｌ／ＬＡＢＡ抑制全细胞内向钾电流约６０％,同时加入ＣＤＰＫ的底物组蛋白ⅢＳ则可完全逆转ＡＢＡ对内向钾电流的抑制作用。研究结果证明,ＣＤＰＫ可能通过对保卫细胞内向钾离子通道的调节介导了ＡＢＡ调控气孔运动的信号转导过程。     

干旱胁迫下氮素营养与根信号在气孔运动调控中的协同作用

干旱胁迫下根系与地上部分之间的信息传递可使植物叶片及时感知土壤水势变化, 从而使植物在没有真正受到干旱伤害时即可做出主动、快速的抗旱应答反应, 而在这一过程中, 脱落酸(abscisic acid, ABA)和pH起着关键的作用。本研究表明, 干旱胁迫下鸭趾草(Commelina communis L.)、番茄(Lycopersicon esculentum Mill.)和向日葵(Helianthus annuus L.)木质部汁液中pH的变化很不相同, 且该pH变化和木质部汁液中硝态氮离子浓度的变化没有直接的关系; 然而, 饲喂实验表明, 无论对于何种植物, 蒸腾流中硝态氮离子浓度的增加都可有效地增加气孔对ABA的敏感度; 分根实验进一步表明, 土壤中硝态氮营养的增加可明显提高气孔对根信号的敏感度。以上结果说明, 氮素营养可以和根信号相互作用共同操纵气孔运动。     

一氧化氮与植物激素的相互作用及其关系

NO在植物的生长发育、生理及信号传递过程中有着重要的调节作用。本文通过从植物根系的生长、种子萌发、程序性细胞死亡、光形态的建成、气孔的关闭及抑制其开放、成熟和衰老等方面对一氧化氮(NO)作为植物激素下游的信号分子发挥的生理功能进行了综述,进而对NO与植物激素生长素、赤霉素、细胞分裂素、脱落酸以及乙烯的相互作用加以讨论,来阐明NO与植物激素之间的关系,并对未来的研究方向作出展望,为NO与植物激素关系的研究提供理论参考。     

脱落酸和激动素对女贞叶气孔开闭的调节

叶气孔的开闭关系到植物同外界气体的交换,它对光合作用、呼吸作用和蒸腾作用均有很大影响。引起气孔运动的机理很复杂。前人的工作表明,激素亦参与气孔开闭的调节。如脱落酸(ABA)促进气孔的关闭,而激动素(KT)则促进气孔的开启。但这方面的研究多数是以草本植物进行的,木本植物的资料则少见。而这对控制干旱地区树木的     

保卫细胞的ABA信号转导

植物激素脱落酸(ABA)调节植物体多种生理过程,尤其在一些逆境条件下,植物体中ABA大量合成,诱导气孔关闭,从而有效地调控植物体内的水分平衡.尽管人们对ABA诱导气孔关闭作用已得到共识,但有关信号转导的细节还很不清楚.该文简要介绍了研究气孔保卫细胞信号转导途径的相关技术以及与ABA信号转导直接相关的ABA受体、第二信使、蛋白质磷酸化和离子通道调节等方面的最新妍究进展.并在前人研究工作的基础上,勾画出气孔保卫细胞ABA、H2O2的信号转导模式图.     

盐胁迫对露花叶片的脱落酸含量及磷酸烯醇式丙酮酸羧化酶昼夜调节特性的影响

兼性CAM植物在转为CAM型后,CAM代谢的关键酶磷酸烯醇式丙酮酸（PEP）核化酶会出现昼夜调节特性的变化（Osmond1978）。关于PEP梭化酶昼夜调节特性的机理存在两种观点：1．PEPK化酶昼夜聚合度发生了变化,白天为二聚体PEPK化酶,对苹果酸抑制敏感;而夜间为四聚体,对苹果酸抑制不敏感（U和Wedding1985）。2·nsv＄化酶昼夜磷酸化状态发生变化,夜间PEPW化酶磷酸化,对苹果酸抑制不敏感;而白天PEP＄化酶脱磷酸化,对苹果酸抑制敏感（Nimmo等1986）。植物生长调节物质如ABA和细胞分裂素对兼性CAM植物PEP＆化酶的表达有诱…     

水分胁迫下ABA由蚕豆根向地上部的运输及其在叶片组织中的分布

蚕豆根装载的３Ｈ－ＡＢＡ可经５．６ｃｍ／ｍｉｎ以上的速率向冠部运输。短时间内（５ｍｉｎ）根运来的ＡＢＡ主要分布在有大量气孔密布的下表皮,但长时间内（３ｈ）则主要分布在对内组织中。抑制蒸腾可降低ＡＢＡ向叶片中的运输积累。光镜放射自显影术显示,根运来的ＡＢＡ可有效地在表皮细胞及保卫细胞的质外体积累。３Ｈ－ＡＢＡ由根向地上部快速运输及其在作用部位的有效积累,说明水分胁迫下蚕豆根部可以通过ＡＢＡ信号的传递控制气孔的行为。     

Control of Stomatal Behaviour by Abscisic Acid which Apparently Originates in the Roots

Two experiments indicate that abscisic acid (ABA) may influencestomatal behaviour of Commelina communis L. Stomatal conductancecould not be correlated with bulk leaf ABA content but whenthe abaxial epidermis was assayed for ABA, small increases inABA content correlated well with limitations of leaf conductance.Restricted conductance of the abaxial surface of leaves wasassociated with an increase of approximately 40 amole ABA perstomatal complex. This agrees with previously published figures. When roots of individual plants were split between two containers,drying the soil around one part of the root system restrictedleaf conductance, even though leaf water relations were notaffected. Increased ABA content of the epidermis coincided withincreased ABA content of the roots in drying soil. Other rootsof the same plant in moist soil did not show increased ABA content.These results suggest that in drying soil, ABA can move fromthe roots to the epidermis and restrict stomatal aperture evenwhen leaf water potentials and turgors remain constant. Theimportance of this mechanism in providing a sensitive foliarresponse to decreasing soil moisture is discussed. Key words: Soil drying, ABA, roots, stomata, water relations     

水分胁迫下丛枝菌根真菌对枳实生苗生长和渗透调节物质含量的影响

采用盆栽试验研究了水分胁迫下接种丛枝菌根真菌摩西球囊霉(Glomaus mosseae)对枳[Poncirustrifoliat(L.)Raf.]实生苗的生长和渗透调节物质含量的影响.结果表明,在土壤含水量为20%、16%和12%条件下,接种G.mosseae能够增加植株的生长(株高、茎粗、叶面积、地上部干重、地下部干重和植株干重),促进植株根系活跃吸收面积和根际土壤有效磷的吸收,提高叶片和根系可溶性糖含量的积累,降低叶片脯氨酸含量,增强植株的水分利用效率(达20%～40%),使枳实生苗的抗旱能力得到增强.土壤含水量为20%和16%条件下接种G.mosseae对植株的效果较土壤含水量为12%条件下更显著.12%的土壤含水量严重抑制Gmosseae的侵染,说明丛枝菌根侵染程度轻,其对植物的效果也差.     

JA、ABA在海棠幼苗和枝条中的传输分布以及与水分的关系

采用示踪技术探索了JA和ABA在海棠幼苗和技条中的传输分布以及与水分的关系,发现从的行径主要由韧皮部自上而下运输,ABA主要通过木质部由下向上运输。两者均对土壤水分变化敏感,水分亏缺会加速JA向下运输,促进ABA向上运输,推测JA下运除影响根系生长外,可能与根系对根际环境变化的感应以及根源ABA的合成有关。     

Leaf Abscission Induced by Ethylene in Water-Stressed Intact Seedlings of Cleopatra Mandarin Requires Previous Abscisic Acid Accumulation in Roots

The involvement of abscisic acid (ABA) in the process of leaf abscission induced by 1-aminocyclopropane-1-carboxylic acid (ACC) transported from roots to shoots in Cleopatra mandarin (Citrus reshni Hort. ex Tan.) seedlings grown under water stress was studied using norflurazon (NF). Water stress induced both ABA (24-fold) and ACC (16-fold) accumulation in roots and arrested xylem flow. Leaf bulk ABA also increased (8-fold), although leaf abscission did not occur. Shortly after rehydration, root ABA and ACC returned to their prestress levels, whereas sharp and transitory increases of ACC (17-fold) and ethylene (10-fold) in leaves and high percentages of abscission (up to 47%) were observed. NF suppressed the ABA and ACC accumulation induced by water stress in roots and the sharp increases of ACC and ethylene observed after rewatering in leaves. NF also reduced leaf abscission (7-10%). These results indicate that water stress induces root ABA accumulation and that this is required for the process of leaf abscission to occur. It was also shown that exogenous ABA increases ACC levels in roots but not in leaves. Collectively, the data suggest that ABA, the primary sensitive signal to water stress, modulates the levels of ethylene, which is the hormonal activator of leaf abscission. This assumption implies that root ACC levels are correlated with root ABA amounts in a dependent way, which eventually links water status to an adequate, protective response such as leaf abscission.     

The relations of stomatal closure and reopening to xylem ABA concentration and leaf water potential during soil drying and rewatering

Two tropical tree species, Acacia confusa and Leucaena leucocephala, were used to study the relationships among stomatal conductance, xylem ABA concentration and leaf water potential during a soil drying and rewatering cycle. Stomatal conductance of both A. confusa and L. leucocephala steadily decreased with the decreases in soil water content and pre-dawn leaf water potential. Upon rewatering, soil water content and pre-dawn leaf water potential rapidly returned to the control levels, whereas the reopening of stomata showed an obvious lag time. The length of this lag time was highly dependent not only upon the degree of water stress but also on plant species. The more severe the water stress, the longer the lag time. When A. confusa and L. leucocephala plants were exposed to the same degree of water stress (around –2.0 MPa in pre-dawn leaf water potential), the stomata of A. confusa reopened to the control level 6 days after rewatering. However, it took L. leucocephala about 14 days to reopen fully. A very similar response of leaf photosynthesis to soil water deficit was also observed for both species. Soil drying resulted in a significant increase in leaf and xylem ABA concentrations in both species. The more severe the water stress, the higher the leaf and xylem ABA concentrations. Both leaf ABA and xylem ABA returned to the control level following relief from water deficit and preceded the full recovery of stomata, suggesting that the lag phase of stomatal reopening was not controlled by leaf and/or xylem ABA. In contrast to drying the whole root system, drying half of the root system did not change the leaf water relations, but caused a significant increase in xylem ABA concentration, which could fully explain the decrease of stomatal conductance. After rewatering, the stomatal conductance of plants in which half of the roots were dried recovered more rapidly than those of whole-root dried plants, indicating that the leaf water deficit that occurred during the drying period was related to the post-stress stomatal inhibition. These results indicated that the decrease in stomatal conductance caused by water deficit was closely related to the increase in xylem ABA, but xylem ABA could not fully explain the reopening of stomata after relief of water stress, neither did the leaf ABA. Some unknown physiological and/or morphological processes in the guard cells may be related to the recovery process.     

Field Studies of the Wheat Stomata Resistance Influenced by Soil Water Content

Concurrent observations of soil water potential and leaf stomata diffusion resistance were made on two, plots of wheat grown at Datun Agro-ecological Experimental Station in Beijing under two different soil water conditions. These data were further complemented by weather and physiological observation. In this paper, we mainly analysed the influence of soil water potential on the status of wheat leaf stomatal resistance. The results indicate that: (1) there is a obvious influence of soil water potential on the status of wheat leaf stomata under normal conditions and (2) there is a different upper and lower epidermis stomata of wheat leaf respond to the soil water potential. The lower epidermis stomata are more sensitive to soil water potential than upper epidermis one. (3) There is a linear relationship between the ratio of lower and upper epidermis stomata resistance and soil water potential in root layer, according to this we can diagnose the degree of wheat water deficit.     

土壤干旱条件下氮素营养对玉米内源激素含量影响

在田间持水量分别保持于35％、55％和75％±5％的土壤水分条件下,利用盆栽实验研究了土壤干旱和氮素营养对玉米内源激素和气孔导度的影响．结果表明,土壤干旱下氮素营养明显降低了玉米根系木质部汁液ABA浓度,而正常供水下施氮处理间则无显著差异(施氮处理仍较低),同时测定的叶片ABA浓度则呈相反的变化趋势,表现为干旱下施氮处理要高于不施氮处理;施氮处理木质部汁液中ZRs浓度应低于相应的不施氮处理,在调控气孔行为方面并未表现拮抗ABA作用;3种土壤水分条件下,施氮玉米叶片的气孔导度均高于不施氮处理,与木质部汁液ABA浓度呈负相关,说明施氮处理较低的根源ABA浓度是导致其气孔导度较大的主要原因．     

茉莉酸甲酯对花生幼苗生长和抗旱性的影响

经过茉莉酸甲酯处理的花生幼苗,在形态、解剖和生理上都发生变化,其中以１２５ｍｇ／Ｌ处理最显著。处理后的植株幼苗矮化,叶小而厚,叶片贮水细胞大、蒸腾减弱、内源脱落酸和脯氨酸含量增多、过氧化物酶活性加大。由于水分的丧失减少,叶片水分的贮存增加,从而提高幼苗的抗旱性。