A bifurcating pathway directs abscisic acid effects on stomatal closure and opening in Arabidopsis

Terrestrial plants lose water primarily through stomata, pores on the leaves. The hormone abscisic acid (ABA) decreases water loss by regulating opening and closing of stomata. Here, we show that phospholipase Dalpha1 (PLDalpha1) mediates the ABA effects on stomata through interaction with a protein phosphatase 2C (PP2C) and a heterotrimeric GTP-binding protein (G protein) in Arabidopsis. PLDalpha1-produced phosphatidic acid (PA) binds to the ABI1 PP2C to signal ABA-promoted stomatal closure, whereas PLDalpha1 and PA interact with the Galpha subunit of heterotrimeric G protein to mediate ABA inhibition of stomatal opening. The results reveal a bifurcating signaling pathway that regulates plant water loss.     

Growth and Eco-Physiological Performance of Cotton Under Water Stress Conditions

A cotton cultivar Xinluzao 8 was grown under four levels of water stress treatments （normal irrigation, slight, mild and severe water stress） from the initial reproductive growth stage in Shihezi, Xinjiang, China, in 2002, to evaluate the growth and eco-physiological performances. Under water stress conditions, the transpiration ability decreased while the leaf temperature increased. Although the relative leaf water content decreased as water stress increased, the differences among the treatments were small, indicating that cotton has high ability in maintaining water in leaf. The stomatal density increased as water stress increased, while the maximum stomatal aperture reduced only in the severest stressed plants. The time of the maximum stomatal aperture was delayed in the mild and severe stressed plants. When severe stress occurred, the stomata were kept open until the transpiration decreased to nearly zero, suggesting that the stomata might not be the main factor in adjusting transpiration in cotton. Cotton plant has high adaptation ability to water stress conditions because of decrease in both stomatal conductance and hydraulic conductance from soil-to-leaf pathway. The actual quantum yield of photosystem Ⅱ （PS Ⅱ） decreased under water stress conditions, while the maximum quantum yield of PS Ⅱ did not vary among treatments, suggesting that PS II would not be damaged by water stress. The total dry weight reduced as water stress increased.     

水稻叶片气孔的研究 Ⅰ、气孔密度与长度

观察比较了威优64、7944、科辐红等9个水稻品种主茎叶片气孔密度和长度的相关变化动态。结果表明,随着叶位的上升,气孔密度逐渐增大,至剑叶最大;气孔长度则逐层减短,至剑叶最短;根椐气孔长度可把水稻主茎叶片分为4个叶层,体现了叶片气孔数量组成与功能的统一。比较了9个品种,发现剑叶气孔数量组成的合理程度有沿着水稻系统发育顺序,从野生稻到栽培稻逐步提高的趋势。     

人工光照对一年生三七形态和光合特性的影响*

 通过不同光照处理对一年生三七叶组织结构、相对含水量、蒸腾速率、光合指标及植株生长的影响,研究一年生三七的光合特性。结果表明：持续的强光照射会导致三七叶片失水皱缩和气孔关闭,叶片的相对含水量和蒸腾速率下降,气孔导度和净光合速率也呈下降趋势。由此可知,三七植株对光极为敏感,连续光照通过改变三七叶片的水分供需状况而影响叶组织的形态结构、蒸腾速率和相应的光合指标,进而影响植株的生长。因此,在生产实际中应进行适度的遮荫,才能保证三七植株的正常生长。研究为三七光合特性的系统研究和生产中三七的有效光照管理奠定了基础。     

植物表皮形态建成的分子调控机制

植物表皮细胞在组织器官的生长发育和形态建成中发挥非常重要的作用。植物的表皮是由原表皮发育来的,表皮包括表皮(扁平)细胞、气孔器和表皮毛等。双子叶植物的表皮由不规则的表皮细胞、气孔器和表皮毛组成;单子叶植物的表皮由长形的表皮细胞、短形的硅化和栓化表皮细胞、泡状细胞、气孔器和表皮毛等组成。近年来,随着生物技术的不断提高,人们对全球淡水资源紧缺的认识加强,对培育农业抗旱品种的渴求,因此,对植物表皮形态建成的研究已经成为一大热点。本文综述了目前有关双子叶模式植物拟南芥中气孔及扁平细胞的图式发育及参与调控的分子遗传调控网络,以及单子叶植物水稻、玉米中参与气孔及表皮细胞图式发育的功能基因。旨在阐明单双子叶模式植物表皮发育调控的分子机制。     

玉米与大豆间作对玉米叶片气孔及光合效率的影响

 气孔是植物进行气体、水分交换与代谢,响应环境条件,包括病菌侵染的重要通道,其大小、密度和分布既受到遗传的控制,也受到生长环境的影响。为了研究玉米与大豆间作对玉米叶片气孔的影响,笔者采用改良刮制法对玉米叶片下表皮的气孔器长度、宽度和密度进行了观测。结果表明,与净作玉米相比,间作玉米植株上部、中部和下部叶片的气孔密度较净作显著降低,而气孔器长度较净作显著增加;植株中、下部叶片的气孔器宽度也较净作显著增加,植株上、中、下部叶片的光合速率和蒸腾速率都较净作显著增大。这些结果表明,间作对玉米气孔的影响是系统性的,而且气孔这些特征的变化是有利于提高产量、减少叶斑病发生的。     

Stomatal patterning and differentiation by synergistic interactions of receptor kinases

Coordinated spacing and patterning of stomata allow efficient gas exchange between plants and the atmosphere. Here we report that three ERECTA (ER)-family leucine-rich repeat-receptor-like kinases (LRR-RLKs) together control stomatal patterning, with specific family members regulating the specification of stomatal stem cell fate and the differentiation of guard cells. Loss-of-function mutations in all three ER-family genes cause stomatal clustering. Genetic interactions with a known stomatal patterning mutant too many mouths (tmm) revealed stoichiometric epistasis and combination-specific neomorphism. Our findings suggest that the negative regulation of ER-family RLKs by TMM, which is an LRR receptor-like protein, is critical for proper stomatal differentiation.     

喷施化学调控剂缩节胺、乙烯利对棉花植株氨挥发的影响

【目的】研究喷施化学调控剂缩节胺、乙烯利对新疆棉花植株氨挥发影响,揭示其影响机理,丰富棉花氮素营养理论。【方法】喷施化学调控剂缩节胺和乙烯利后,应用密闭生长室抽气法定期监测棉花植株氨挥发变化,同时监测可溶性蛋白质、与氮代谢相关酶活性及气孔特性等指标。【结果】棉花花铃期,喷施1g·L-1和1.5g·L-1的缩节胺棉花植株氨挥发平均降低28.80%和35.15%,氨挥发量与叶片可溶性蛋白质、气孔面积显著正相关(P0.05),与硝酸还原酶活性和谷氨酰胺合成酶活性呈显著负相关(P0.05);喷施1.5mL·L-1和2.5mL·L-1的乙烯利叶片氨挥发平均增加47.30%和37.40%,氨挥发量与叶片可溶性蛋白质、硝酸还原酶活性和谷氨酰胺合成酶活性之间呈显著负相关(P0.05),与气孔面积呈显著正相关(P0.05)。【结论】喷施缩节胺促进了叶片同化物向生殖器官转移,降低叶片可溶性蛋白质含量,增强了叶片硝酸还原酶和谷氨酰胺合成酶活性,缩小了叶片气孔面积,抑制了棉花植株氨挥发;喷施乙烯利加速了植株的衰老和蛋白质的降解,抑制了叶片硝酸还原酶和谷氨酰胺合成酶活性,增大了叶片气孔面积,促进棉花植株氨挥发。     

Improvement of Drought Tolerance in Transgenic Tobacco Plants by a Dehydrin-Like Gene Transfer

A full-length cDNA of dehydrin BcDh2 from Boea crassifolia and its antisense nucleotide sequence have been transferred into tobacco (Nicotiana tabacum) NC89 under the control of a caulifower mosaic virus 35S promoter. Under a progressive water stress, photosynthetic rate, transpiration rate and stomatal conductance of the sense and antisense plants reduced, and those of the control reduced much more. Photosynthetic rate, transpiration rate and stomatal conductance of all plants tested increased significantly 24 hours later after recoveried water supply, and those of the sense and antisense plants were higher than control. These indicated that overexpression of a dehydrin gene in tobacco may improve tolerance to water stress for plants, however, antisense BcDh2 gene in transgenic plant did not influence physiological conditions. The results of germination experiment of the transgenic seeds showed that on MS medium with different concentration PEG (8000), sense seed could more endure drought than control, while antisense seed was sensitive to drought. The results suggested that the overexpression of a dehydrin gene in tobacco might improve the tolerance to water stress for plants.     

Responses of hawaiian plants to volcanic sulfur dioxide: stomatal behavior and foliar injury

Hawaiian plants exposed to volcanic sulfur dioxide showed interspecific differences in leaf injury that are related to sulfur dioxide-induced changes in stomatal condutance. Species with leaves that did not close stomata developed either chlorosis or necrosis, whereas leaves of Metrosideros collina closed stomata and showed no visual symptoms of sulfur dioxide stress.     

大别山5种黄精属植物叶表皮的初步比较研究

利用光镜初步比较研究了大别山区八居群5种黄精属(Polygonatum)植物的叶表皮特征.结果显示,表皮细胞形状、气孔器类型与分布等特征,在黄精属的各种植物之间、同种植物的不同种群、同一种群的不同生境以及同一株植物的不同着生部位的叶上,具有较高一致性.表皮细胞大小和垂周壁的式样、气孔大小、气孔密度、气孔指数等特征在各种间存在一定的差异,可以作为本属种间分类的参考依据.     

水分胁迫对辣椒光合作用及相关生理特性的影响

 【目的】研究水分胁迫对辣椒光合作用及相关生理特性的影响, 揭示水分胁迫与辣椒光合作用及生理指标之间的关系,为辣椒栽培管理,抗性筛选提供理论参考。【方法】采用盆栽的方式,分别在正常供水和水分胁迫条件下,研究辣椒生长形态及相关生理指标,光合参数,叶绿素荧光参数,叶片气孔特征及叶绿体超微结构的变化。【结果】水分胁迫显著抑制了辣椒的生长,植株总的干物质含量下降,并且干物质含量向根的分配比例增加,向茎叶的分配比例减少。叶片水势（Ψ）、叶片相对含水量（RWC）、叶绿素（Chl.）及类胡萝卜素（Car.）的含量显著下降,叶片中丙二醛（MDA）含量,游离脯氨酸（Pro）的含量,超氧化物歧化酶（SOD）,过氧化物酶（POD）的活性均有所提高。叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、PSⅡ光化学量子效率（ΦPSⅡ）、光化学猝灭系数（qP）及光合电子传递速率（ETR）均下降,非光化学猝灭系数（NPQ）和水分利用效率（WUE）提高。水分胁迫后叶片气孔密度、气孔长度、气孔宽度均有所下降,大部分气孔关闭深陷。叶绿体变圆,基粒片层和基质片层弯曲排列紊乱,淀粉粒减少或消失。【结论】水分胁迫下辣椒光合速率的下降主要是由气孔限制引起的。光合参数、叶绿素荧光参数、叶片气孔特征以及叶绿体超微结构的变化与品种的抗性密切相关。     

Regulation of abscisic acid-induced stomatal closure and anion channels by guard cell AAPK kinase

Abscisic acid (ABA) stimulates stomatal closure and thus supports water conservation by plants during drought. Mass spectrometry-generated peptide sequence information was used to clone a Vicia faba complementary DNA, AAPK, encoding a guard cell-specific ABA-activated serine-threonine protein kinase (AAPK). Expression in transformed guard cells of AAPK altered by one amino acid (lysine 43 to alanine 43) renders stomata insensitive to ABA-induced closure by eliminating ABA activation of plasma membrane anion channels. This information should allow cell-specific, targeted biotechnological manipulation of crop water status.     

水稻叶片气孔分布与气孔密度的研究

用改良刮制法研究了水稻叶片的气孔分布与气孔密度。结果表明稻叶下表面气孔的分布不是随机的,表现出一定的规 律性。气孔在脉间区纵向排列成行;叶缘和主脉附近气孔分布较均匀;其他脉间区气孔行可分为两组,组内气孔行数因品种、 叶位和叶片上的具体部位而有差异。同一叶片气孔行数的顺序是基部>中部>尖部。稻叶气孔密度是籼稻普遍大于粳稻,且 籼稻、偏籼稻、粳稻和偏粳稻4种类型气孔密度的大小顺序为籼稻>偏籼稻>偏粳稻>粳稻,表现出明显的类型间差异。     

叶片δ13 C与长期水分利用效率的关系

该文测定并研究了不同水分处理下,不同黑杨无性系的长期水分利用效率（WUEL）、叶片δ13C、光合作用、气孔及其相互关系.结果显示:无性系间WUEL、δ13C、光合作用、气孔都存在差异. 4个水分处理下J2、J6、J7、J8、J9都是WUEL较优的无性系,同时它们的δ13C高、净光合速率Pn和瞬时水分利用效率WUEi较高、气孔频度和气孔大小适中、上/下表皮气孔数目比大.气孔的差异是导致无性系间Pn和WUEi差异,并最终导致WUEL、δ13C差异的关键因子.δ13C和WUEL呈正相关,充分供水条件下相关性最好.      

Mechanisms of Physiological Regulation for Improving Dryland Crop Water Use

This paper briefly reviews the physiological mechanisms for improving crop water use and water use efficiency in dryland farming regions of Loess Plateau on the basis of its environmental conditions and progress in crop water relations and the biological basis of water-saving agriculture, especially in non-uniform stomatal closure, ABA effects, communication between root and shoot, and water use efficiency. Root chemical signals about water shortage are feedforward effect which contributes to balanced water relations within the plant compartment of the soil-plant-atmosphere continuum. ABA production is increased in tissues during these stresses, and this causes a variety of physiological effects, including stomata closure in leaves. It is concluded that the root chemical signal ABA is very important to improve the crop water use efficiency in semi-arid area of Loess Plateau.     

极度濒危植物五针白皮松解剖生态学研究

与云南松和华山松比较,五针白皮松叶的生态解剖特点更接近云南松,具有更多的阳性叶特征,如表皮细胞大小、表皮和下皮的厚度等;叶肉组织致密度介于云南松和华山松之间;五针白皮松的气孔器大小是3 种松树中最大者,可能意味着五针白皮松适应更加湿润(降水量更大)凉爽的气候.五针白皮松对光、温度和水分的要求表明它可能更加适应高海拔生态条件,目前生境可能不是它最适宜的生活环境.     

CaCl2对干旱胁迫下甘蓝型油菜抗旱性相关的生理生化指标变化影响

分析了干旱诱导下抽薹期甘蓝型油菜的生化指标和蒸腾作用变化及Ca2 处理对其影响。结果表明,在干旱胁迫下,甘蓝型油菜叶片中的脯氨酸、可溶性糖以及丙二醛含量明显增加,经Ca2 预处理其脯氨酸和可溶性糖含量明显高于仅用双蒸水处理的材料,而丙二醛含量则是蒸馏水处理的材料高于Ca2 预处理的材料;气孔导度日变化分析以及气孔观察显示,Ca2 预处理可以明显促使干旱过程中叶片表皮气孔关闭,进而使叶片蒸腾速率和气孔导度降低,从而减少了干旱条件下水分的蒸发。     

棉属中染色体倍性与叶片气孔性状的关系

观察了棉属(Gossypium)不同染色体组、不同染色体倍性的种间杂种及其加倍后代的28个材料的叶片气孔,测定了气孔密度、气孔保卫细胞的大小及其中叶绿粒数目.结果表明,不同染色体组间、不同棉种间和不同染色体倍性间在这些性状上均存在明显的差异.这些差异的总趋势是染色体倍性间>染色体组间>种间>种内.染色体倍性提高,气孔保卫细胞的大小及其中叶绿粒数目增加,而气孔器密度减小.认为叶片气孔保卫细胞中的叶绿粒计数配合保卫细胞大小和气孔器密度的测量,可以用于不同染色体倍性棉花植株的鉴定.