Here the regulatory role of CO during stomatal movement in Vicia faba L. was surveyed. Results indicated that, like hydrogen peroxide （H2O2）, CO donor HemaUn induced stomatal closure in dose- and time-dependent mann...Here the regulatory role of CO during stomatal movement in Vicia faba L. was surveyed. Results indicated that, like hydrogen peroxide （H2O2）, CO donor HemaUn induced stomatal closure in dose- and time-dependent manners. These responses were also proven by the addition of gaseous CO aqueous solution with different concentrations, showing the first time that CO and H2O2 exhibit the similar regulation role in the stomatal movement. Moreover, our data showed that ascorbic acid （ASA, an important reducing substrate for H2O2 removal） and diphenylene iodonium （DPI, an inhibitor of the H2O2-generating enzyme NADPH oxidase） not only reversed stomatal closure by CO, but also suppressed the H2O2 fluorescence induced by CO, implying that CO induced-stomatal closure probably involves H2O2 signal. Additionally, the CO/NO scavenger hemoglobin （Hb） and CO specific synthetic inhibitor ZnPPIX, ASA and DPI reversed the darkness-induced stomatal closure and H2O2 fluorescence. These results show that, perhaps like H2O2, the levels of CO in guard cells of V. faba are higher in the dark than in light, HO-1 and NADPH oxidase are the enzyme systems responsible for generating endogenous CO and H2O2 in darkness respectively, and that CO is involved in darkness-induced H2O2 synthesis in V. faba guard cells.展开更多
Mitogen-activated protein (MAP) kinase is involved in ABA- or H2O2-signaling, and H2O2 acts as inter-mediate in the downstream of ABA signal transduction pathway, which has recently emerged as a secondary mes-senger o...Mitogen-activated protein (MAP) kinase is involved in ABA- or H2O2-signaling, and H2O2 acts as inter-mediate in the downstream of ABA signal transduction pathway, which has recently emerged as a secondary mes-senger of ABA signaling. Using an epidermal strip bioassay and laser scanning confocal microscope, we provided the first evidence that MAP kinase plays an important role in H2O2 signal initial, amplification and specific targeting in response to stimuli in guard cells. ABA- or H2O2-induced Vicia faba stomatal closure was inhibited or reversed by the specific inhibitor PD98059 of MEK1/2; the guard cells were pre-incubated or -microinjected by 10 mmol·L-1 PD98059, ABA could not enhance the fluorescence intensity of H2O2 probe dichlorofluorescein (DCF). Meanwhile, after ABA induced the H2O2 accumulation in guard cells, the exogenous or intracellular PD98059 could reduce the DCF fluorescence intensity. Most interestingly, on the contrary to ABA, the DCF fluorescence intensity of guard cells treated by 100 mmol·L-1 salicylic acid (SA) was not down-regulated by PD98059, yet PD98059 did not regulate the stomatal move-ment being induced by light, dark or salicylic acid. These results suggest that MEK1/2 could mediate stomatal closure by abolishing the ABA-induced H2O2 generation/accumula- tion in the specific manner.展开更多
Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cell...Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen per- oxide, or sodium hydrogen carbonate. Guard cells kept in the dark （closed stomata） showed increases in microtubule struc- tures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrange- ment must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin dis- rupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not dis- rupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.展开更多
蒙古沙冬青是一种豆科,常绿灌木,主要分布在我国西北地区。蒙古沙冬青作为沙生植物的一种,有很强抗旱能力。蒙古沙冬青具有很低的蒸腾强度,其蒸腾作用与气孔的活动密切相关。气孔开放过程,保卫细胞质膜上的内向钾离子通道介导钾离子进...蒙古沙冬青是一种豆科,常绿灌木,主要分布在我国西北地区。蒙古沙冬青作为沙生植物的一种,有很强抗旱能力。蒙古沙冬青具有很低的蒸腾强度,其蒸腾作用与气孔的活动密切相关。气孔开放过程,保卫细胞质膜上的内向钾离子通道介导钾离子进入保卫细胞。本研究通过观测蒙古沙冬青和拟南芥气孔及保卫细胞原生质体,结果显示,蒙古沙冬青气孔密度明显比拟南芥气孔密度要低;蒙古沙冬青气孔保卫细胞周长是拟南芥的1.7倍;而蒙古沙冬青保卫细胞的体积约是拟南芥的3倍。通过膜片钳技术,记录蒙古沙冬青和拟南芥保卫细胞原生质体内向钾离子通道电流,膜电位为-180 m V时,蒙古沙冬青电流密度明显小于拟南芥。蒙古沙冬青保卫细胞内向钾离子通道转运钾离子的能力比较弱,可推测蒙古沙冬青气孔不易开放。通过比较发现,旱生植物蒙古沙冬青低的气孔密度和保卫细胞弱的转运钾离子能力,是其具有低的蒸腾强度关键。展开更多
基金Supported by the Natural Science Research Plan of Shaanxi Provine of China(2005C112).
文摘Here the regulatory role of CO during stomatal movement in Vicia faba L. was surveyed. Results indicated that, like hydrogen peroxide （H2O2）, CO donor HemaUn induced stomatal closure in dose- and time-dependent manners. These responses were also proven by the addition of gaseous CO aqueous solution with different concentrations, showing the first time that CO and H2O2 exhibit the similar regulation role in the stomatal movement. Moreover, our data showed that ascorbic acid （ASA, an important reducing substrate for H2O2 removal） and diphenylene iodonium （DPI, an inhibitor of the H2O2-generating enzyme NADPH oxidase） not only reversed stomatal closure by CO, but also suppressed the H2O2 fluorescence induced by CO, implying that CO induced-stomatal closure probably involves H2O2 signal. Additionally, the CO/NO scavenger hemoglobin （Hb） and CO specific synthetic inhibitor ZnPPIX, ASA and DPI reversed the darkness-induced stomatal closure and H2O2 fluorescence. These results show that, perhaps like H2O2, the levels of CO in guard cells of V. faba are higher in the dark than in light, HO-1 and NADPH oxidase are the enzyme systems responsible for generating endogenous CO and H2O2 in darkness respectively, and that CO is involved in darkness-induced H2O2 synthesis in V. faba guard cells.
文摘Mitogen-activated protein (MAP) kinase is involved in ABA- or H2O2-signaling, and H2O2 acts as inter-mediate in the downstream of ABA signal transduction pathway, which has recently emerged as a secondary mes-senger of ABA signaling. Using an epidermal strip bioassay and laser scanning confocal microscope, we provided the first evidence that MAP kinase plays an important role in H2O2 signal initial, amplification and specific targeting in response to stimuli in guard cells. ABA- or H2O2-induced Vicia faba stomatal closure was inhibited or reversed by the specific inhibitor PD98059 of MEK1/2; the guard cells were pre-incubated or -microinjected by 10 mmol·L-1 PD98059, ABA could not enhance the fluorescence intensity of H2O2 probe dichlorofluorescein (DCF). Meanwhile, after ABA induced the H2O2 accumulation in guard cells, the exogenous or intracellular PD98059 could reduce the DCF fluorescence intensity. Most interestingly, on the contrary to ABA, the DCF fluorescence intensity of guard cells treated by 100 mmol·L-1 salicylic acid (SA) was not down-regulated by PD98059, yet PD98059 did not regulate the stomatal move-ment being induced by light, dark or salicylic acid. These results suggest that MEK1/2 could mediate stomatal closure by abolishing the ABA-induced H2O2 generation/accumula- tion in the specific manner.
文摘Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP- tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen per- oxide, or sodium hydrogen carbonate. Guard cells kept in the dark （closed stomata） showed increases in microtubule struc- tures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrange- ment must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin dis- rupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not dis- rupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.
文摘蒙古沙冬青是一种豆科,常绿灌木,主要分布在我国西北地区。蒙古沙冬青作为沙生植物的一种,有很强抗旱能力。蒙古沙冬青具有很低的蒸腾强度,其蒸腾作用与气孔的活动密切相关。气孔开放过程,保卫细胞质膜上的内向钾离子通道介导钾离子进入保卫细胞。本研究通过观测蒙古沙冬青和拟南芥气孔及保卫细胞原生质体,结果显示,蒙古沙冬青气孔密度明显比拟南芥气孔密度要低;蒙古沙冬青气孔保卫细胞周长是拟南芥的1.7倍;而蒙古沙冬青保卫细胞的体积约是拟南芥的3倍。通过膜片钳技术,记录蒙古沙冬青和拟南芥保卫细胞原生质体内向钾离子通道电流,膜电位为-180 m V时,蒙古沙冬青电流密度明显小于拟南芥。蒙古沙冬青保卫细胞内向钾离子通道转运钾离子的能力比较弱,可推测蒙古沙冬青气孔不易开放。通过比较发现,旱生植物蒙古沙冬青低的气孔密度和保卫细胞弱的转运钾离子能力,是其具有低的蒸腾强度关键。
