盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

锰胁迫对垂序商陆叶片形态结构及叶绿体超微结构的影响

以超富集植物垂序商陆为实验材料,通过温室实验,研究不同锰处理条件下垂序商陆叶片受害症状、叶片形态结构和叶绿体超微结构的变化。当生长介质中锰供应水平为1 000 μmol?L-1时,垂序商陆生长良好,叶片未表现出受害症状,其形态结构和超微结构也没有明显的变化;当锰供应水平为5 000 μmol?L-1时,叶片开始出现褪绿现象,叶肉细胞排列疏松,栅栏组织细胞膨胀, 叶绿体数量减少,外膜部分解体,类囊体膨胀, 基质片层扭曲, 淀粉粒颗粒变小;当锰供应水平为12 000μmol?L-1时,叶片发生大量的褪绿现象,伤害率高达87.33%,并且伤害率随着锰胁迫时间的延长明显升高,叶肉细胞发生扭曲变形,叶绿体皱缩,外膜解体,类囊体空泡化加剧,基质片层严重扭曲,基粒排列紊乱甚至模糊成絮状,嗜锇颗粒增多。 尽管在高锰浓度胁迫条件下植物叶肉细胞及叶绿体超微结构出现一定程度的毒害特征,但垂序商陆仍能完成部分功能,维持其个体的生长,这进一步表明超富集植物垂序商陆具有极强的锰耐性。     

NaCl对小麦幼苗叶肉细胞超微结构的影响

在含NaCl的培养液中培养小麦幼苗,3天后取样观察叶肉细胞,其超微结构基本正常,细胞核和细胞壁没有明显变化。但线粒体结构普遍受到损害,表现在外膜、内膜和嵴膨胀,结构模糊。叶绿体被膜和片层结构仍保持完整,仅有部分叶绿体的片层排列方向发生改变,由原来平行排列扭转为近于垂直排列。     

NaCl胁迫对5个桂花品种叶片超微结构的影响

该研究以5个桂花品种为材料,以Hoagland培养液为对照,设计2个NaCl含量(70、100 mmol/L)处理10 d后利用透射电镜和扫描电镜观察各处理不同品种的叶片超微结构特征,以明确桂花品种对耐NaCl胁迫的解剖结构响应机制。结果显示：(1)透射电镜观察发现：随NaCl 胁迫程度的加强,5个桂花品种叶肉细胞中叶绿体结构受到不同程度地破坏;70 mmol/L NaCl处理后,5个品种的细胞核基本保持正常,而100 mmol/L NaCl处理后核内染色质发生降解;随着NaCl胁迫程度的加强,5个桂花品种的类囊体片层结构中嗜锇颗粒明显增多;在膜结构方面,大叶银桂的叶肉细胞被破坏程度最为严重,叶绿体膜被破坏,叶绿体形状基本不能辨认。(2)扫描电镜观察结果显示：随着NaCl浓度的增大,5个品种叶片表面的气孔密度不断增大,而张开气孔的密度却不断减小,且叶肉细胞体积均缩小;‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的栅栏组织占叶厚的比重随NaCl胁迫浓度的增大而升高,‘潢川金桂’和‘紫梗籽银桂’的栅栏组织占叶厚的比重则随NaCl胁迫浓度的增大而呈先升高后降低的趋势。研究表明,NaCl胁迫对桂花叶片细胞叶绿体、细胞核等的超微结构会造成损伤,且NaCl胁迫浓度越高损伤越明显。该试验可初步判断‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的耐盐性略高于‘潢川金桂’和‘紫梗籽银桂’。     

干旱胁迫对不同耐旱性大麦品种叶片超微结构的影响

选用耐旱性不同的3个大麦（Hordeum sativum）品种作为研究对象,分析干旱胁迫对其叶肉细胞叶绿体、线粒体和细胞核超微结构的影响。结果表明,3个大麦品种在非胁迫条件下其超微结构无明显差异。遭受干旱胁迫后,不耐旱大麦品种Moroc9-75叶片细胞核中染色质的凝聚程度高,叶绿体变形,外被膜出现较大程度的波浪状和膨胀,同时基粒出现弯曲、膨胀、排列混乱的现象;线粒体外形及膜受到破坏、内部嵴部分消失等。耐旱大麦品种HS41-1叶片细胞中染色质虽出现凝聚,但凝聚程度低;其叶绿体及线粒体与非胁迫条件下基本相似,多数未见明显损伤。耐旱中等的大麦品种Martin叶片超微结构的变化则介于二者之间。因此,干旱胁迫下叶绿体外形、基粒和基质类囊体膜结构的完整性与基粒的排列次序、染色质的凝聚度和线粒体膜及嵴的完整性与大麦的耐旱性相关,这些特性可作为评价大麦耐旱性强弱的形态结构指标。     

干旱胁迫对不同耐旱性大麦品种叶片超微结构的影响

选用耐旱性不同的3个大麦(Hordeum sativum)品种作为研究对象, 分析干旱胁迫对其叶肉细胞叶绿体、线粒体和细胞核超微结构的影响。结果表明, 3个大麦品种在非胁迫条件下其超微结构无明显差异。遭受干旱胁迫后, 不耐旱大麦品种Moroc9-75叶片细胞核中染色质的凝聚程度高, 叶绿体变形, 外被膜出现较大程度的波浪状和膨胀, 同时基粒出现弯曲、膨胀、排列混乱的现象; 线粒体外形及膜受到破坏、内部嵴部分消失等。耐旱大麦品种HS41-1叶片细胞中染色质虽出现凝聚, 但凝聚程度低; 其叶绿体及线粒体与非胁迫条件下基本相似, 多数未见明显损伤。耐旱中等的大麦品种Martin叶片超微结构的变化则介于二者之间。因此, 干旱胁迫下叶绿体外形、基粒和基质类囊体膜结构的完整性与基粒的排列次序、染色质的凝聚度和线粒体膜及嵴的完整性与大麦的耐旱性相关, 这些特性可作为评价大麦耐旱性强弱的形态结构指标。     

Na2CO3胁迫对星星草叶肉细胞超微结构的影响

利用透射电镜技术对Na2CO3胁迫下星星草叶肉细胞超微结构进行了观察。结果表明：未胁迫的叶肉细胞排列疏松,各种细胞器结构完整,叶绿体含少量淀粉粒和脂质球。轻度盐胁迫（2g/L,4g／LNa2CO3）对叶肉细胞超微结构影响较小。中度盐胁迫（6g／L,8g／L Na2CO3）引起叶肉细胞超微结构的变化,叶绿体类囊体肿胀,基粒紊乱,不含淀粉粒,脂质球数量增加,叶绿体由原来的梭形或椭球形变成圆球状;部分线粒体嵴消失,出现晶体结构;中央大液泡破裂;核逐渐降解。高度盐胁迫（10g／L,12g／LNa2CO3）下,叶绿体片层结构消失,脂质球数量增加,体积变大,被大量的膜片层所包围,叶绿体内、外膜消失,叶肉细胞中看不到叶绿体的存在;膜片层包围线粒体;叶肉细胞中可见大量的泡状结构和膜片层,叶肉细胞死亡。上述结果表明,细胞器特别是叶绿体膜结构的破坏与盐胁迫叶肉细胞最终死亡密切相关。     

干旱胁迫对3种不同光合类型荒漠植物叶绿体和线粒体超微结构的影响

以荒漠木本C_3植物天山猪毛菜、C_3-C_4中间型植物松叶猪毛菜、C_4植物木本猪毛菜为研究对象,采用盆栽控水试验,设置正常供水和轻度、中度和重度干旱处理(土壤含水量分别为田间持水量的80%、60%、45%和35%),研究不同程度干旱胁迫对3种不同光合类型荒漠植物叶片超微结构的影响。结果表明:(1)正常水分条件下,叶肉细胞中各细胞器结构完整。(2)轻度干旱胁迫下,3种植物叶片超微结构未受损伤,无明显变化。(3)中度干旱胁迫下,天山猪毛菜和松叶猪毛菜叶肉细胞壁界限不清晰,类囊体片层扩张且排列不紧密,不同之处在于,天山猪毛菜线粒体最先出现降解,内含物流失,而松叶猪毛菜线粒体外膜轮廓变形,嵴减少;木本猪毛菜线粒体无明显变化,叶绿体轻微扩张。(4)重度干旱胁迫下,天山猪毛菜和松叶猪毛菜叶绿体受损且结构混乱,线粒体出现降解;木本猪毛菜叶绿体出现膨胀,线粒体外膜轮廓模糊,嵴减少且结构模糊不清楚。研究认为,不同程度干旱胁迫下木本猪毛菜叶绿体和线粒体的受损程度都最低;干旱胁迫下天山猪毛菜和松叶猪毛菜叶绿体的受损程度大致相似;松叶猪毛菜和木本猪毛菜线粒体对干旱胁迫的耐受力要比叶绿体强。     

盐胁迫下芦苇叶肉细胞超微结构的研究

对青藏高原柴达木盆地柯柯盐湖边盐碱地上生长的芦苇叶肉细胞的超微结构进行了研究,并以西宁地区非盐碱地上生长的芦苇作对照。结果表明：西宁地区的芦苇叶肉细胞的叶绿体呈椭圆形,其膜系统完整,基粒片层和基质片层发育良好。在盐碱地上生长的芦苇叶肉细胞的叶绿体呈圆形,叶绿体内出现较大的淀粉粒,并发现有线粒体嵌入叶绿体的现象。叶绿体的类囊体膨大,线粒体的嵴也有膨大的现象。在盐湖水中生长的芦苇叶肉细胞,叶绿体的类囊体排列紊乱、扭曲、松散。类囊体膜局部被破坏,部分类囊体膜解体,空泡化,甚至消失,一些溶解了的类囊体流进细胞质中。综上所述,芦苇叶肉细胞超微结构的变化是该植物适应柯柯盐湖地区盐渍、低温、低气压、强辐射等环境因子的结果。     

NaCl对齿肋赤藓叶肉细胞超微结构的影响

齿肋赤藓(Syntrichia caninervis)是古尔班通古特沙漠苔藓结皮层中的优势物种,对荒漠生态系统的稳定性及功能多样性具有十分重要的意义。利用透射电镜技术对不同浓度Na Cl胁迫下齿肋赤藓叶肉细胞超微结构进行了观察。结果表明:齿肋赤藓叶肉细胞在未胁迫(0 mmol/L)处理下排列疏松,各种细胞结构完整,叶绿体基质排列均匀且叶绿体内含少量淀粉粒和脂质球。在轻度盐Na Cl胁迫(100 mmol/L)下,齿肋赤藓叶肉细胞结构依然保持完整,叶绿体基质均匀,叶肉细胞超微结构仅有较小变化。在中度盐Na Cl胁迫(200、300 mmol/L)下,齿肋赤藓叶肉细胞发生质壁分离,出现晶体结构,且中央大液泡发生破裂;叶绿体由梭形变成椭球形或圆球状,出现空泡化并伴随有轻微的解体;叶绿体类囊体肿胀,脂质球数量增加。在高度Na Cl胁迫(400、500 mmol/L)下,齿肋赤藓细胞的质壁分离加剧,叶肉细胞出现大量泡状结构和膜片层,叶肉细胞死亡;叶绿体片层结构消失,空泡化加重,脂质球数量增加且体积变大,叶绿体内外膜消失,叶绿体大部分解体,在叶肉细胞中几乎看不到叶绿体的存在。上述结果表明,叶绿体膜结构的损伤与盐胁迫下叶肉细胞死亡有密切关系。     

Salt impact on photosynthesis and leaf ultrastructure of <Emphasis Type="Italic">Aeluropus littoralis</Emphasis>

The effects of salinity (400 mM NaCl) on growth, biomass partitioning, photosynthesis, and leaf ultrastructure were studied in hydroponically grown plants of Aeluropus littoralis (Willd) Parl. NaCl produced a significant inhibition of the main growth parameters and a reduction in leaf gas exchange (e.g. decreased rates of photosynthesis and stomatal conductance). However, NaCl salinity affected neither the composition of photosynthesis pigments nor leaf water content. The reduction in leaf gas exchange seemed to correlate with a decrease in mesophyll thickness as well as a severe disorganisation of chloroplast structure, with misshapen chloroplasts and dilated thylakoid membranes. Conspicuously, mesophyll chloroplasts were more sensitive to salt treatment than those of bundle sheath cells. The effects of NaCl toxicity on leaf structure and ultrastructure and the associated physiological implications are discussed in relation to the degree of salt resistance of A. littoralis.     

Effects of salt-tolerant rootstock grafting on ultrastructure,photosynthetic capacity,and H<Subscript>2</Subscript>O<Subscript>2</Subscript>-scavenging system in chloroplasts of cucumber seedlings under NaCl stress

Plant growth, photosynthetic parameters, chloroplast ultrastructure, and the ascorbate-glutathione cycle system in chloroplasts of self-grafted and rootstock-grafted cucumber leaves were investigated. Grafted plants were grown hydroponically and were exposed to 0, 50, and 100 mM NaCl concentrations for 10 days. Under NaCl stress, the hydrogen peroxide (H₂O₂) content in cucumber chloroplasts increased, the chloroplast ultrastructure was damaged, and the gas stomatal conductance, intercellular CO₂ concentration, as well as shoot dry weight, plant height, stem diameter, leaf area, and leaf relative water content were inhibited, whereas these changes were less severe in rootstock-grafted plants. The activities of ascorbate peroxidase (APX; EC 1.11.1.11), glutathione reductase (GR; EC 1.6.4.2), and dehydroascorbate reductase (DHAR EC 1.8.5.1) were higher in the chloroplasts of rootstock-grafted plants compared with those of self-grafted plants under 50 and 100 mM NaCl. Similar trends were shown in leaf net CO₂ assimilation rate and transpiration rate, as well as reduced glutathione content under 100 mM NaCl. Results suggest that rootstock grafting enhances the H₂O₂-scavenging capacity of the ascorbate–glutathione cycle in cucumber chloroplasts under NaCl stress, thereby protecting the chloroplast structure and improving the photosynthetic performance of cucumber leaves. As a result, cucumber growth is promoted.     

遮荫对南美蟛蜞菊、蟛蜞菊及其自然杂交种叶片显微结构及叶绿体超微结构的影响

利用JSM-6360LV型扫描电镜和JEM-1010型透射电镜,观察了南美蟛蜞菊、蟛蜞菊及其自然杂交种新近成熟和老熟叶片的解剖结构及叶绿体超微结构。结果表明:遮荫后该杂交种与其亲本新近成熟叶片均表现为上下表皮气孔密度、叶片总厚度及上下表皮厚度、栅栏组织、海绵组织厚度减小,叶绿体肿胀变形,基粒片层垛叠程度增加,淀粉粒增多变大;遮荫后杂交种老熟叶片总厚度及上表皮、栅栏组织、海绵组织厚度增加,入侵种的下表皮厚度及本地种的上表皮厚度增加,叶绿体超微结构在遮荫后均出现严重损伤,基粒片层类囊体结构边缘溶解等。说明三种蟛蜞菊属物种及各物种不同叶龄叶片对弱光条件的响应存在差异;杂交种叶片显微及超微结构在不同光照下的变化介于亲本之间,对遮荫环境能较好适应。     

New ultrastructural features of organelles in leaf cells of Deschampsia antarctica Desv

An electron microscope has been used to investigate the ultrastructure of leaf cells in Deschampsia antarctica Desv. (Poaceae). The leaf anatomy exhibits features typical of xerophytes. New ultrastructural features were found in mesophyll cells. Chloroplasts in mesophyll cells of D. antarctica leaves form small vesicles and pockets. The outer chloroplast membrane forms vesicles, and pockets are invaginations of both membranes. The invaginations contain small vesicles, mitochondria, or lipid droplets. The mitochondria or peroxisomes adhere very tightly to the chloroplasts.     

Structural and Functional State of Thylakoids in a Halophyte Suaeda altissima before and after Disturbance of Salt–Water Balance by Extremely High Concentrations of NaCl

Halophyte plants Suaeda altissima L. were grown in water culture at different concentrations of NaCl in the medium, and their leaves were sampled to examine the ultrastructure of chloroplasts. In parallel tests, the functional state of chloroplasts was assessed from parameters of chlorophyll fluorescence. In addition the effects of NaCl on plant growth and on the contents of Na⁺, K⁺, and water in organs of S. altissima were investigated. At a wide range of external salt concentrations (0–750 mM NaCl), S. altissima plants retained the chloroplast ultrastructure and photosynthetic function in an intact condition. The impairment of thylakoid ultrastructure and the accompanying increase in nonphotochemical quenching of excited states of chlorophyll was only observed at an extremely high concentration of NaCl in the medium (1 M) that led to disruption of ionic homeostasis and lowered water content in tissues.     

Sugar compartmentation in frost-hardy and partially dehardened cabbage leaf cells

In frost-hardy and partially dehardened leaves of Brassica oleracea L. var. sabellica L. the distribution of cryoprotective sugars and of chloride between chloroplasts and the nonchloroplast part of leaf cells was investigated using the nonaqueous isolation technique as a means of cell fractionation. In chloroplasts of frost-hardy leaves high concentrations of sucrose and raffinose and comparatively low concentrations of chloride have been found. The ratios between sugars and chloride were so as to ascertain complete protection of the frost-sensitive thylakoid membranes during freezing. During dehardening, sugars decreased especially in the chloroplasts. There was a conversion of sucrose and raffinose into monosaccharides. This led to a large increase in the concentration of glucose and fructose in the nonchloroplast parts of the cells. There is evidence that the sugar concentration in the vacuole increased at the expense of sugars located in chloroplasts and cytoplasm. The quantity of sugars that remained in the chloroplasts did not appear to be sufficient for complete membrane protection at very low freezing temperatures.     

日光温室光温因子对黄瓜叶绿体超微结构及其功能的影响

在日光温室内,研究了光温因子对黄瓜叶绿体超微结构及其功能的影响．结果表明,因季节之间光、温条件不同,日光温室黄瓜叶片显微结构和叶绿体超微结构有一定差异,1月份光照弱叶肉细胞较大,而5月份光照强叶绿体数较多．在该试验条件下,未发现叶片光合速率与叶绿体超微结构之间有直接或密切的相关性．在各生长季节其光合速率均为第4叶>初展叶>基部叶,与叶龄及各叶位的受光量有关．如果将不同叶位叶放在相同的光照下,则差异明显减少．黄瓜叶片的叶肉细胞、叶绿体和淀粉粒的大小以及叶绿体数、基粒数、基粒厚度、基粒片层数都随叶位的下降而呈增加趋势。不同品种、同品种不同生长时期的叶片显微结构和叶绿体超微结构及其功能也有一定的差异．限制日光温室冬季黄瓜光合作用的主要因素是光照弱、有效光照时数少,而在晴天温度的限制作用相对较小。阴天因光照弱而导致的室内低温则是限制黄瓜生长的关键因素．     

油茶叶肿病变态叶片的形态特征和超微结构观察

利用扫描电镜(SEM)对油茶叶肿病变态叶叶片表面和横切面进行观察,利用透射电镜(TEM)对其细胞超微结构进行观察,以期探明油茶叶肿病变态叶的形态特征和细胞学特征。结果表明:(1)变态叶是受感染油茶幼叶组织增生形成的,肿大的叶片厚度比正常叶片厚度增加3~5倍,细胞体积增大3~8倍,细胞数增加1~2倍,叶片细胞形态和结构发生了变化。(2)叶片受细丽外担菌侵染后,菌丝存在于下表皮向内的4~7层细胞间隙中,感染后期叶片下表面脱落露出子实层。(3)变态叶细胞出现叶绿体膜破裂、类囊体片层膜数目减少及细胞器成分被破坏等异常现象。     

Effect of Pb on leaf antioxidant enzyme activities and ultrastructure of the two ecotypes of <Emphasis Type="Italic">Sedum alfredii</Emphasis> Hance

Hydroponic experiments were conducted to study the effect of Pb on growth, leaf antioxidant enzyme activities, and ultrastructure of the accumulating ecotype (AE) and non-accumulating ecotype (NAE) of Sedum alfredii Hance. AE was found to be more tolerant to excessive Pb levels in growth medium. Concentrations of Pb in the shoots of the AE were 1.98 times higher than those in the NAE when 0.2 mM Pb was supplied. Both chlorophyll a and b did not decrease significantly in AE plants after Pb treatment, while a significant decrease was noted in chlorophyll a and b of NAE plants treated with Pb concentrations greater than 0.05 mM. The results showed that activities of superoxide dismutase (SOD) and catalase (CAT) were elevated in the leaves of AE under Pb stress. However in NAE, Pb-caused enhancement was noticed only in the activity of SOD while activity of CAT was declined as compared to the control plants. With increased Pb level, malondialdehyde (MDA) content increased significantly in both ecotypes of S. alfredii, indicating that Pb toxicity led to lipid peroxidation and membrane damage, but MDA content in the leaves of NAE was always higher than in AE plants. The ultrastructural analysis of the spongy mesophyll cells revealed that excessive Pb concentrations obviously damaged the cell membrane, chloroplasts, and mitochondria of both the ecotypes but damage was more severe in NAE. Although growth, leaf physiology, and ultrastructure of both the ecotypes were affected by Pb treatment, deleterious effects were more pronounced in NAE. This text was submitted by the authors in English.