外源过氧化氢对蚕豆气孔运动的影响

运用外源过氧化氢(H2O2)处理、光镜观察的方法研究了H2O2对蚕豆气孔运动的影响．结果表明，H2O2诱导气孔关闭的最适浓度和最佳时间分别为100μmol／L和3h．H2O2促进气孔关闭的作用可被抗坏血酸和过氧化氢酶(CAT)逆转．还就内源H2O2在光、暗调控的气孔运动中的作用进行了讨论．     

NO,H2O2介导根系渗透胁迫和脱落酸诱导的气孔关闭

运用表皮实验和激光扫描共聚焦显微镜技术对NO和H2O2在根系渗透胁迫和外源脱落酸（ABA）处理诱导蚕豆气孔关闭中的作用及其相互关系进行了研究．结果表明，渗透胁迫及外源ABA处理既促进保卫细胞内源NO和H2O2形成，也诱导气孔关闭；外源H2O2和SNP可促进气孔关闭，也分别诱导保卫细胞NO和H2O2产生．还对根系渗透胁迫诱导蚕豆气孔关闭中ABA、NO和H2O2的关系进行了讨论，认为渗透胁迫可能通过ABA诱导NO和H2O2产生，促进气孔关闭且NO和H2O2之间存在相互作用．     

ABA和H2 O2在NaCl诱导的气孔关闭中的作用

以拟南芥野生型（wt）和ABA合成缺失突变体（aba3）为材料，采用表皮生物分析法研究了NaCl胁迫条件下，ABA和H2O2在气孔关闭中的作用。结果表明：100mmol/L的NaCl可有效诱导wt气孔关闭，而对aba3的气孔运动无明显影响；10^-2mmol/L的H2O2处理或100mmol/L的NaCl与10^-2mmol/L ABA共处理可有效诱导wt与aba3的气孔关闭，且幅度类似；H2O2的性清除剂CAT可部分逆转NaCl处理及NaCl与ABA共处理引起的气孔关闭，因此推测，NaCl胁迫条件下，植物保卫细胞内ABA浓度升高，诱导H2O2的产生，进而诱导了气孔关闭。     

茉莉酸甲酯诱导气孔关闭的信号转导机制初探

用不同浓度的茉莉酸甲酯处理拟南芥叶片的下表皮，发现10^-5mol/L的茉莉酸酯是诱导气孔关闭的最适浓度，而且还进一步证明了在茉莉酸甲酯诱导气孔关闭过程中，H2O2和Ca2 有可能是诱导气孔关闭转导链之中的中间环节。     

水杨酸在氯化镉胁迫诱导蚕豆气孔运动中的作用

本文采用药理学方法,研究了氯化镉(CdCl2)、水杨酸(salicylicacid,SA)以及两者共同处理对蚕豆幼苗气孔开度的效应,以探明SA在CdCl2胁迫诱导蚕豆气孔运动中的作用.结果表明,0.025mg/L~10mg/LCdCl2处理显著诱导气孔关闭,随着Cd2+浓度的增加,气孔开度逐渐减小,且随着处理时间的延长,其诱导气孔关闭的效应也显著增强.不同浓度SA(0.01mmol/L、0.1mmol/L、0.5mmol/L和1mmol/L)单独处理表皮条时能显著诱导气孔开度减小,且具有明显的时间效应;1mmol/LSA处理2h~3h后,气孔接近完全关闭.与CdCl2单独处理相比,0.01mmol/LSA与CdCl2复合处理能显著抑制气孔关闭,但随着SA浓度的增加,抑制效应逐渐减弱.总之,一定浓度SA具有缓解CdCl2胁迫诱导蚕豆幼苗气孔关闭的效应.     

气孔运动调控中过氧化氢和一氧化氮信号途径的交叉作用

用NO荧光指示剂DAF-2DA测定了H 2 O 2 对蚕豆和鸭跖草气孔保卫细胞NO的影响;以蚕豆幼苗为材料研究了H 2 O 2 和NO在调控气孔运动中的相互关系.结果表明,H 2 O 2 能够诱导保卫细胞胞质NO的形成,其诱导作用可以被2-苯-4,4,5,5-四甲基咪唑-1-氧-3-氧化物(PTIO)所清除和N G -氮-L-精氨酸-甲酯(L-NAME)所阻断.推测保卫细胞中可能存在一氧化氮合酶(NOS)类似物.H 2 O 2 主要是通过NOS途径诱导产生NO.在10～100μmol/L范围内,NO的供体硝普钠(SNP)和H 2 O 2 都可诱导气孔关闭,并具明显的浓度效应.H 2 O 2 清除剂过氧化氢酶(CAT)能够完全抵消NO的诱导气孔关闭作用;H 2 O 2 合成抑制剂二苯基碘(DPI)可部分减弱NO诱导的气孔关闭.NO合酶抑制剂L-NAME和NO的清除剂与H 2 O 2 共处理时,H 2 O 2 诱导气孔关闭的作用被大大减弱.结果说明,在调控气孔运动中H 2 O 2 和NO具有相互依赖性,H 2 O 2 和NO信号分子具有信号自身放大功能,共同参与了对气孔运动的调控.     

油菜素内酯诱导蚕豆气孔关闭与过氧化氢和一氧化氮的关系

研究了油菜素内酯(BR)对蚕豆气孔运动的效应及其与过氧化氢和一氧化氮的关系。结果表明,BR能显著诱导气孔关闭,其最适处理浓度和时间分别为5μmol/L和3h。H2O2清除剂抗坏血酸和过氧化氢酶、NO清除剂c-PTIO和血红蛋白、过氧化氢产生酶NADPH氧化酶抑制剂二苯基碘和NO产生酶一氧化氮合酶(NOS)抑制剂L-NAME均显著抑制BR诱导的气孔关闭,显示NADPH氧化酶催化产生的H2O2和NOS催化产生的NO参与BR诱导气孔关闭。BR有显著抑制ABA诱导气孔关闭的效应。     

活性氧与NO在SO2诱导蚕豆气孔运动中的作用

以蚕豆叶表皮为材料,研究SO2胁迫时叶面气孔运动及其调节途径.研究发现,用浓度1～200μmol/L的SO2衍生物(亚硫酸钠与亚硫酸氢钠混合液)处理蚕豆叶下表皮后,气孔开度明显减小,气孔保卫细胞内活性氧(ROS)、一氧化氮(NO)和钙离子(Ca2+)水平显著升高.采用抗氧化剂抗坏血酸和过氧化氢酶,钙离子干扰剂EGTA和LaCl3,以及NO合成抑制剂NaN3与NO清除剂c-PTIO,分别与SO2衍生物同时作用时,SO2诱发的气孔关闭效应得到有效缓解,保卫细胞内ROS、NO和Ca2+水平随之改变.抗氧化剂和NO干扰剂能阻止SO2诱导的胞内ROS、NO和Ca2+水平升高;EGTA和LaCl3能降低SO2诱导的胞内NO和Ca2+升高,但不影响ROS水平.研究结果表明,较高浓度SO2能诱导气孔关闭,SO2胁迫诱导ROS和NO合成增加,ROS和NO通过钙信号系统调节气孔开度.     

壳梭孢素促进蚕豆气孔开放与保卫细胞H2O2的关系

研究了壳梭孢素(FC)诱导蚕豆气孔开放与保卫细胞过氧化氢(H2O2)水平的关系.结果证明,FC、H2O2清除剂抗坏血酸(ASA)和H2O2合成抑制剂二苯基碘(DPI)均能于暗中诱导气孔开放.另外,FC和ASA不仅阻止外源H2O2诱导气孔关闭,而且促进暗诱导已关闭气孔重新开放,但DPI无此效应.将上述结果联系起来考虑,表明FC通过清除降低保卫细胞内源H2O2水平进而促进气孔开放.     

铜胺氧化酶在乙烯诱导蚕豆气孔关闭中的作用

研究了铜胺氧化酶(CuAO)及其催化产物过氧化氢(H2O2)在乙烯利诱导蚕豆气孔关闭中的作用.乙烯释放化合物2-氯乙基磷酸(乙烯利)激活了非质体CuAO活性、提高了保卫细胞H2O2产生并诱导气孔关闭,乙烯利的上述效应被CuAO的两种不可逆抑制剂氨基胍(AG)和2-溴乙胺(BEA)抑制.在几种CuAO催化产物中,只有H2O2能阻止AG或BEA抑制乙烯利诱导气孔关闭.CuAO的主要底物腐胺(Put)也不抑制乙烯利诱导气孔关闭.研究结果表明,CuAO催化产生的H2O2参与了乙烯诱导的蚕豆气孔关闭.     

Protein tyrosine phosphatases involved in signaling of the ABA-induced H2O2 generation in guard cells of Vicia faba L.

Although protein tyrosine phosphatases (PTPases) play an important role in signal transduction in animal cells, little is known about the function of PTPases in higher plants. Hydrogen peroxide (H2O2) and mitogen-activated protein kinases (MAPKs) are the critical components of ABA signaling pathway in guard cells. PTPase is an important regulator of MAPK, which is believed to mediate ABA-induced H2O2 generation in guard cells of Vicia faba L. Here, we investigate the possible role of PTPases in stomatal movement process. Phenylarsine oxide (PAO), a specific inhibitor of PTPases, could prevent ABA or H2O2-induced stomatal closure of Vicia faba L; furthermore, it could promote opening of the stomata closed by ABA or H2O2. The activity of PTPases can be effectively inhibited by PAO and H2O2. DTT had no effect on the PAO-induced inhibition of PTPases activity, but it could relieve the inhibition of H2O2 on PTPases activity. PAO could also inhibit the ABA-induced H2O2 generation in guard cells of V‘wia faba L. These results suggested that PTPases is a critical signaling component in ABA-induced stomatal closure, and serve as targets for H2O2 lying on the signaling pathways downstream of ABA induced H2O2 generation.     

紫外分光光度技术测定植物细胞中H2O2的含量

利用H2O2在24Onm处有吸收光谱的特性，建立了快速测定植物活细胞产生H2O2的方法．同时利用该技术进一步定量检测了ABA诱导蚕豆气孔保卫细胞H2O2的产生．     

MAP kinase specifically mediates the ABA-induced H<Subscript>2</Subscript>O<Subscript>2</Subscript> generation in guard cells of<Emphasis Type="Italic">Vicia faba</Emphasis> L.

The plant hormone abscisic acid (ABA) is involved in regulating adverse physiological processes, including stomatal closure, seed development and germination, and mediating many environmental stress responses, such as drought, salinity and extreme temperatures[1,2]. In re-sponse to various stress stimuli, ABA synthesis is in-creased in plant cells, which triggers a series of physio-logical responses to adapt the stress conditions[1—3]. For example, under water deficit, ABA acts directly on…     

Ca^2＋ is involved in muscarine-acetylcholine-receptor-mediated acetylcholine signal transduction in guard cells of Vicia faba L.

Acetyicholine (ACh) is an important neuro-chemical transmitter in animals; it also exists in plants and plays a significant role in various kinds of physiological functions in plants. ACh has been known to induce the stomatal opening. By monitoring the changes of cytusolic Ca^2 with fluorescent probe Fiuo-3 AM under the confocal microscopy, we found that exogenous ACh increased cytosolic Ca^2 concentration of guard cells of Vicia faba L. Muscarlne, an agonist of muscarine acetyicholine receptor (mAChR), could do so as well. In contrast, atropine, the antagonist of mAChR abolished the ability of ACh to increase Ca^2 in guard cells. This mechanism is similar to mAChR in animals. When EGTA was used to chelate Ca^2 or ruthenium red to block Ca^2 released from vacuole respectively, the results showed that the increased cytosolic Ca^2 mainly come from intracellular Ca^2 store. The evidence supports that Ca^2 is involved in guard-cell response to ACh and that Ca^2 sigual is coupled to mAChRs in ACh signal transduction in guard cells.     

Calcium channels activated by hydrogen peroxide mediate abscisic acid signalling in guard cells

Drought is a major threat to agricultural production. Plants synthesize the hormone abscisic acid (ABA) in response to drought, triggering a signalling cascade in guard cells that results in stomatal closure, thus reducing water loss. ABA triggers an increase in cytosolic calcium in guard cells ([Ca2+]cyt) that has been proposed to include Ca2+ influx across the plasma membrane. However, direct recordings of Ca2+ currents have been limited and the upstream activation mechanisms of plasma membrane Ca2+ channels remain unknown. Here we report activation of Ca2+-permeable channels in the plasma membrane of Arabidopsis guard cells by hydrogen peroxide. The H2O2-activated Ca2+ channels mediate both influx of Ca2+ in protoplasts and increases in [Ca2+]cyt in intact guard cells. ABA induces the production of H2O2 in guard cells. If H2O2 production is blocked, ABA-induced closure of stomata is inhibited. Moreover, activation of Ca2+ channels by H2O2 and ABA- and H2O2-induced stomatal closing are disrupted in the recessive ABA-insensitive mutant gca2. These data indicate that ABA-induced H2O2 production and the H2O2-activated Ca2+ channels are important mechanisms for ABA-induced stomatal closing.     

Involvement of nitric oxide in the signal transduction of salicylic acid regulating stomatal movement

The effects and the relationship between sali-cylic acid(SA)and nitric oxide(NO) on Vicia faba L.stomatal movement were studied.The results here showed that exogenous SA and NO induced stomatal closure,100μmol/L SA induced a rapid and striking NO increase in the cytosol of guard cells.This phenomenon was largely prevented by 2000μmol/L 2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide(PTIO),a specific NO scavenger,and 25μmol/L N^G-nitro-L-Arg-methyl eater (L-NAME),an inhibitor of NO synthase(NOS) in mammalian cells that also inhibits plant NOS.In addition,SA-induced stomatal closure was largely prevented by PTIO and L-NAME.These results provide evidence that guard cells generate NO in response to SA via NOS-like activity,and that such NO production is required for full stomatal closure in response to SA.H-(1,2,4)-oxadiazole-[4,3-α]quinoxalin-l-one(ODQ),an inhibitor of guanylate cyclase,and nicotinamide,an antagonist of cADPR production,inhibited the effects of SA-and NO-induced stomatal closure.It suggests that both cGMP and cADPR might mediate the signal transduction of SA and NO-induced stomatal closure.     

Na2CO3胁迫对蚕豆幼苗几种生理生化指标的影响

用Na2CO3处理蚕豆幼苗,处理浓度为25,50,75,100mmol／L,胁迫6天后取样,测定植株鲜干重、肉质化程度、细胞膜透性、丙二醛含量、脯氨酸含量叶绿素含量等生理指标．结果表明,一定浓度的Na2CO3促进了蚕豆幼苗鲜干重、肉质化程度、叶绿素含量的增加,100mmol／LNa2CO3处理明显抑制了蚕豆幼苗的生长．Na2CO3浓度超过75mmol／L时,蚕豆幼苗MDA含量急剧上升,质膜透性也明显增加,脯氨酸含量增加明显．     

重金属铅和汞对蚕豆根尖细胞的微核效应

以蚕豆根尖为试材,不同浓度的醋酸铅和氯化汞为受检物,探讨重金属Pb2+和Hg2+对蚕豆根尖细胞的微核效应。结果表明:Pb2+和Hg2+均能诱发蚕豆较高的微核率,且微核率随溶液浓度升高而增加,但当高于一定浓度后,微核率反而有下降的趋势。因此,蚕豆可以作为快速检测环境中Pb2+和Hg2+遗传毒性的材料。