脱落酸对Bt基因抗虫棉产量和品质的影响(简报)

植物在长期进化中，对于干旱等胁迫从生理、生化和分子水平上产生了适应性变化，从而增加对逆境的适应能力。在这些响应过程中，脱落酸(ABA)起着极其重要的作用。在水分亏缺时，ABA重要的生理功能是促进离子流出保卫细胞和降低保卫细胞的膨压，诱导气孔关闭，从而降低水分消耗，增加植株在干旱条件下的保水能力引。通过ABA在Bt转基因抗虫棉上进行应用，     

脱落酸信号调控植物干旱胁迫响应的研究进展

对脱落酸代谢途径和信号途径在干旱胁迫响应中的调控作用进行了综述，揭示脱落酸介导的信号网络调控植物应答干旱的分子机制，同时对异三聚体G蛋白参与脱落酸信号调控干旱胁迫响应的最新研究进行介绍，最后对未来脱落酸调控干旱胁迫响应的研究方向提出了展望，以期为今后深入研究脱落酸信号调控干旱胁迫响应及培育抗旱能力强的植物提供理论参考.     

水分胁迫下植物体内的信号传递

本文综述了水分胁迫下植物体内的干旱信号传递，包括水分胁迫下信号的识别、信号通过第二信使、蛋白磷酸化/去磷酸化参与的胞内传递，水分胁迫下木质部汁液中蛋白质、pH值的变化及化学物质脱落酸(ABA)、茉莉酸(JA)等参与的化学信号传递等。     

蓝光调节气孔运动的信号途径及其与脱落酸相互关系研究

气孔运动与植物水分代谢密切相关.保卫细胞可有效感知和整合多种环境信号,通过控制离子进出调节其膨压,影响气孔开与闭.诸多研究表明,蓝光信号诱导气孔开放和逆境信号脱落酸(ABA)促进气孔关闭构成了气孔运动的两大研究领域.该文就保卫细胞中蓝光信号传递及与ABA信号交叉控制气孔开闭的研究进展进行综述,以了解气孔对蓝光和ABA反应的最新进展,为发展耐旱与提高作物水分利用效率生物技术的改进提供理论支持.     

木本植物响应干旱胁迫的研究现状

为深入了解木本植物响应干旱胁迫的分子机理，本文系统的从木本植物对干旱信号的感知、信号转导到转录调控、生理生化反应以及表型变化等方面总结了木本植物对干旱胁迫可能的响应过程.认为木本植物由于其固着根生的特点，不得不进化出相应的机制来应对不断变化的环境.当遭受干旱胁迫时，木本植物根系细胞膜上的感受器首先感知到土壤水分状态的变化，细胞内的蛋白质和激素调控系统触发相应的干旱适应反应.干旱信号通过细胞间的信号传导路径传递到植物体内的各个部位，主要的信号传导途径包括Ca²⁺信号、激素信号和转录因子调控等.一些关键基因和信号通路，如脱落酸(ABA)信号通路、DREB蛋白家族等也参与调控植物的干旱适应性.木本植物也会发生形态和解剖上的变化来减少水分蒸发和增强根系的吸水能力.本文可为抗旱型木本植物选育提供见解.     

脱落酸与植物抗旱性及其机理研究的进展

本文主要介绍脱落酸在水分胁迫时合成机理、调节气孔开闭机理研究的概况，及脱落酸在植物抗旱应用方面的趋势。同时，对某些争论的问题提出自己的拙见。     

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。     

干旱胁迫下蒙古沙冬青AmNAC1基因的表达差异及功能分析

测定蒙古沙冬青NAC家族成员的编码基因AmNAC1在干旱胁迫和外源ABA处理下的表达模式,通过转基因拟南芥在干旱胁迫下的表型分析,探究AmNAC1的功能和作用机理.结果显示:AmNAC1在蒙古沙冬青幼苗中受干旱以及外源ABA的诱导;超表达AmNAC1可以不同程度地提高转基因拟南芥对干旱胁迫的耐性,也可以提高转基因拟南芥离体叶片和幼苗在自然干燥期间的保水能力,但对其种子萌发期响应外源ABA的敏感性无明显影响.结果表明AmNAC1在植物响应和抵抗干旱胁迫中起重要调节作用.     

干旱胁迫下甘蓝型油菜相关抗旱基因的表达分析

以抗旱性较强的甘蓝型油菜Holiday为材料,在开花初期对油菜进行干旱胁迫处理,采用RT-qPCR技术分析ABA2、BnSOS2、BnCS、CAM、CBF4、PIP1这6个油菜抗旱相关基因在干旱胁迫第1天、3天、5天、7天在根、茎、叶、花和青荚中的表达量.结果表明,干旱胁迫下,6个抗旱相关基因在油菜的不同器官中均出现了上调表达;在不同干旱胁迫下,各基因表达量呈现不同的变化趋势;在相同的器官中,各基因的表达量存在明显的不同,累积表达量表现为根中ABA2最大、CBF4最小,茎中CAM最大、CBF4最小,叶中PIP1最大、ABA2最小,花中CBF4最大、BnSOS2最小,青荚中BnCS最大,CBF4最小.说明植物在受到干旱胁迫时,不同的抗旱途径对干旱胁迫的响应程度是不同的;不同器官中各抗旱相关基因与胁迫时间的相关性分析表明,CAM基因在茎中的表达量、CBF4基因在花中的表达量与胁迫时间呈显著正相关.     

Guard cell abscisic acid signalling and engineering drought hardiness in plants

Guard cells are located in the epidermis of plant leaves, and in pairs surround stomatal pores. These control both the influx of CO2 as a raw material for photosynthesis and water loss from plants through transpiration to the atmosphere. Guard cells have become a highly developed system for dissecting early signal transduction mechanisms in plants. In response to drought, plants synthesize the hormone abscisic acid, which triggers closing of stomata, thus reducing water loss. Recently, central regulators of guard cell abscisic acid signalling have been discovered. The molecular understanding of the guard cell signal transduction network opens possibilities for engineering stomatal responses to control CO2 intake and plant water loss.     

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.     

SLAC1 is required for plant guard cell S-type anion channel function in stomatal signalling

Stomatal pores, formed by two surrounding guard cells in the epidermis of plant leaves, allow influx of atmospheric carbon dioxide in exchange for transpirational water loss. Stomata also restrict the entry of ozone--an important air pollutant that has an increasingly negative impact on crop yields, and thus global carbon fixation and climate change. The aperture of stomatal pores is regulated by the transport of osmotically active ions and metabolites across guard cell membranes. Despite the vital role of guard cells in controlling plant water loss, ozone sensitivity and CO2 supply, the genes encoding some of the main regulators of stomatal movements remain unknown. It has been proposed that guard cell anion channels function as important regulators of stomatal closure and are essential in mediating stomatal responses to physiological and stress stimuli. However, the genes encoding membrane proteins that mediate guard cell anion efflux have not yet been identified. Here we report the mapping and characterization of an ozone-sensitive Arabidopsis thaliana mutant, slac1. We show that SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1) is preferentially expressed in guard cells and encodes a distant homologue of fungal and bacterial dicarboxylate/malic acid transport proteins. The plasma membrane protein SLAC1 is essential for stomatal closure in response to CO2, abscisic acid, ozone, light/dark transitions, humidity change, calcium ions, hydrogen peroxide and nitric oxide. Mutations in SLAC1 impair slow (S-type) anion channel currents that are activated by cytosolic Ca2+ and abscisic acid, but do not affect rapid (R-type) anion channel currents or Ca2+ channel function. A low homology of SLAC1 to bacterial and fungal organic acid transport proteins, and the permeability of S-type anion channels to malate suggest a vital role for SLAC1 in the function of S-type anion channels.     

水分胁迫对梭梭叶片气体交换特征的影响

对梭梭叶片在自然水分胁迫下的气体交换特征进行了研究。结果表明,梭梭在旱季与雨季时的光合作用日变化曲线均呈双峰型,具有光合午休现象。在旱季,植物气孔开度减小,从而减少了水分的散失,而严重的水分胁迫引起叶肉细胞光合活性的降低。根据Farquhar和Sharkey提出的关于区分光合作用的气孔限制与非气孔限制的两个标准,在水分亏缺较严重的旱季,光合午休主要是由非气孔因素引起的;而在雨季,光合午休主要是由气孔因素导致的。通过光合午休、梭梭叶片1天中的气体交换主要发生在上、下午光合较高而蒸腾较低的那部分时间里,从而使水分利用效率比较高,这是梭梭对干旱生境的一种适应方式。     

Increased sensitivity to drought stress in <Emphasis Type="Italic">atlon4 Arabidopsis</Emphasis> mutant

The ATP-dependent serine protease Lon belongs to the AAA+ superfamily, which is widely distributed in bacteria, archaea, and eukaryotic cells. Lon participates in the regulation of numerous physiological processes and gene expression via degrading various unstable and non-native regulators. In this study, we showed that the Arabidopsis atlon4 mutant is more sensitive to drought stress than wild-type plants. Compared with wild-type plants, atlon4 mutant plants showed increased water loss, decreased water use efficiency, and impaired stomatal closure in drought stress conditions.     

枣树抗旱性研究初报

以盆栽2年生的蒙山脆枣和沾化冬枣为试材，对不同干旱胁迫程度下的叶片相对含水量、叶绿素含量、气孔导度、蒸腾速率、净光合速率、叶片光合水分利用效率等生理指标进行了研究，并对2个枣品种的抗旱性进行了评价，结果表明：尽管品种间的变化存在着差异，但随着干旱胁迫程度的加重；其叶片相对含水量、叶绿素含量、气孔导度、蒸腾速率及净光合速率均呈下降趋势，而单叶水分利用效率呈上升趋势；其永久萎蔫系数均低于3％。表明这二种枣树的抗旱能力较强。     

干旱胁迫对红皮柳光合特性日变化及生长的影响

红皮柳(Salix purpurea)是我国西北地区重要的乡土树种,生长快、适应性强,在水土保持、防护林和生物质能源等方面发挥重要作用。以红皮柳扦插苗为研究材料,通过盆栽试验,在4种不同程度干旱胁迫处理(对照、轻度干旱、中度干旱和重度干旱胁迫)下,测定叶片的光合作用参数及生长量,分析探讨干旱胁迫对红皮柳光合特性及生长的影响。结果表明:在轻度、中度和重度干旱胁迫下,红皮柳叶片净光合速率(P_n)日均值分别比对照下降10.4%(P＞0.05)、17.9%(P＜0.05)和58.2%(P＜0.05),中度和重度干旱胁迫下P_n下降量达到显著水平; 随着干旱胁迫程度的加剧,P_n的下降伴随着蒸腾速率(T_r)和气孔导度(G_s)的显著下降,水分利用效率(E_WUE)逐渐升高,胞间CO₂浓度(C_i)先下降后上升; 轻度干旱胁迫和中度干旱胁迫下P_n的降低是由于气孔限制引起,而重度干旱胁迫下受到气孔因素与非气孔因素的共同作用。而且,红皮柳生长受到干旱胁迫的显著影响,随着干旱胁迫程度的加重,株高和基径的相对增长率下降程度增大。     

水分胁迫对夏蜡梅气孔行为的影响

了解干旱对夏蜡梅光合作用的影响状况,为夏蜡梅的保护和培育提供理论依据,以盆栽2年生夏蜡梅幼苗为材料,分对照、轻度、中度、重度4组,研究了土壤水分胁迫下气孔导度的变化.结果表明:随着水分胁迫的加重,净光合速率、蒸腾速率和气孔导度降低;夏蜡梅气孔导度日变化曲线由双峰型逐渐转变为峰值很小的单峰型,与净光合速率有较好的相关性.重度水分胁迫下气孔限制和非气孔限制(为主)引起夏蜡梅净光合速率成倍降低,严重影响其生长.     

The HIC signalling pathway links CO2 perception to stomatal development

Stomatal pores on the leaf surface control both the uptake of CO2 for photosynthesis and the loss of water during transpiration. Since the industrial revolution, decreases in stomatal numbers in parallel with increases in atmospheric CO2 concentration have provided evidence of plant responses to changes in CO2 levels caused by human activity. This inverse correlation between stomatal density and CO2 concentration also holds for fossil material from the past 400 million years and has provided clues to the causes of global extinction events. Here we report the identification of the Arabidopsis gene HIC (for high carbon dioxide), which encodes a negative regulator of stomatal development that responds to CO2 concentration. This gene encodes a putative 3-keto acyl coenzyme A synthase--an enzyme involved in the synthesis of very-long-chain fatty acids. Mutant hic plants exhibit up to a 42% increase in stomatal density in response to a doubling of CO2. Our results identify a gene involved in the signal transduction pathway responsible for controlling stomatal numbers at elevated CO2.