甘蔗喷施稀土增产增糖机理的研究：Ⅰ.叶片超微结构的研究

甘蔗喷施稀土后,叶片的超微结构发生了明显的变化,叶肉细胞及维管束鞘细胞的叶绿体数增多,叶肉细胞叶绿体的基粒数及基粒片层数也增多,光合膜面积增大,利于光能的吸收和光合作用的进行。     

NaCl 胁迫对烤烟叶肉细胞超微结构的影响

为了探明NaCl 胁迫条件下烤烟叶片细胞超微结构的变化规律,利用透射电子显微镜对NaCl 胁迫下烤烟叶肉细胞超微结构进行了观察,并分析了烤烟应对NaCl 胁迫时细胞结构的变化。结果发现,未胁迫处理的叶绿体结构完整,形态未随处理时间的增加而发生明显改变,线粒体内外膜完整,核液浓度较高,大液泡结构清晰,细胞质与细胞壁结合紧密;盐胁迫处理后,叶绿体基粒片层松散、变形,失去清晰结构,整体结构紊乱,与自然衰老的叶肉细胞相比,未见明显的被膜破裂,线粒体膜内陷、破裂,外膜部分受损,细胞核液浓度降低,出现明显的异染色质化,核膜部分破损、界限模糊,液泡所占细胞比例变小,发生质壁分离。     

烟草腺毛发育的形态学研究

采用显微技术,对不同发育时期烟草叶面腺毛的形态变化和超微结构进行了观察,将腺毛发育过程划分为生长期、成熟期和分泌期3个阶段.生长期腺毛进行旺盛的细胞牛长和分裂活动,细胞质浓厚,线粒体叶绿体丰富,基粒片层清晰;成熟期腺毛形态发育完成,细胞数目稳定,叶绿体内基粒片层消失,嗜锇颗粒逐渐增多、增大,表明细胞开始进行活跃的物质合成和转化;分泌期腺毛细胞黏性增大,叶绿体降解,嗜锇颗粒进入细胞质并转运至液泡中积累,细胞开始降解,细胞质稀薄,大最嗜锇物质聚集在质膜附近.     

盐分胁迫对烤烟叶片亚细胞结构及生理生化指标的影响

  目的  探究不同浓度NaCl和Na₂SO₄溶液对烤烟叶肉细胞超微结构以及对叶片抗氧化系统的影响。  方法  利用透射电镜对不同浓度的盐溶液处理下烤烟叶肉细胞进行观察,并检测其抗氧化酶活性。  结果  在低浓度盐溶液（100 mmol/L NaCl和50 mmol/L Na₂SO₄）处理条件下,烤烟叶肉细胞壁厚度有所减小,细胞内各细胞器无明显变化。中等浓度NaCl（200 mmol/L）处理条件下,烤烟叶肉细胞的叶绿体背膜边缘模糊,嗜锇颗粒增多,淀粉粒含量减少;线粒体内出现空泡,嵴减少,部分膜结构边缘模糊;细胞核核仁密度降低,核膜凹凸不平。中等浓度Na₂SO₄（100 mmol/L）处理条件下,叶绿体基粒片层间空隙增大;线粒体形态饱满,但内膜凹陷;细胞核染色质分布均匀,但核仁边缘模糊。高浓度NaCl（400 mmol/L）使烤烟叶肉细胞叶绿体基粒片层结构失去完整性;线粒体结构瓦解,几乎没有完整结构的嵴。高浓度Na₂SO₄（200 mmol/L）处理条件下,叶绿体肿胀,变为球形,内膜及部分基粒片层溶解,淀粉颗粒进一步减少;线粒体内膜溶解,基质密度降低;细胞核核仁解体,甚至溶解消失。随着NaCl和Na₂SO₄浓度的升高,过氧化氢酶活性逐渐增强;丙二醛含量和超氧化物歧化等酶活性先升高后降低;过氧化物酶活性先降后升之后再降低。  结论  烤烟对Na₂SO₄溶液的耐受能力强于NaCl溶液。      

草甘膦对大豆叶片超微结构及生化指标的影响

喷施草甘膦后研究大豆莽草酸、叶绿素以及叶片超微结构变化,揭示草甘膦对大豆伤害的机理。喷施草甘膦后,大豆品种东农42叶绿体内产生嗜锇颗粒,片层结构变得稀薄,淀粉粒减少;由于叶绿素含量降低,东农42莽草酸积累;随后叶绿体变形裂解,细胞膜从细胞壁上脱落,细胞瓦解。相比之下,GTS40-3-2叶肉细胞的液泡、叶绿体、叶绿体片层、淀粉粒等先出现一定程度的变化,后恢复;叶肉细胞出现嗜锇颗粒,表现为先增多,后减少,大约1周后消失;莽草酸含量几乎没有变化,叶绿素先下降后恢复,恢复过程需要2周左右。     

黄茶“中黄2号”的亚细胞结构透射电镜观察

利用透射电镜技术研究了黄化品种"中黄2号"与正常品种"龙井43"第2、6叶的亚细胞结构差异。结果发现中黄2号与龙井43在细胞核、胞质、线粒体、高尔基体等亚细胞结构和分布规律方面基本一致,而叶绿体结构则有较大差异。中黄2号第2叶叶绿体明显偏小,且基粒片层堆叠少于龙井43。其第6叶片层堆叠多于第二叶,但仍少于龙井43。叶绿体内片层堆叠情况与其含量测定结果一致。同时,遮荫处理后中黄2号叶色变绿,叶绿体片层堆叠也增多。研究发现,中黄2号的黄化可能与其叶绿体基粒片层合成受阻有关,该结果为深入解析中黄2号黄化的机理打下基础。     

海拔对烤烟叶片亚显微结构的影响

采用田间试验研究了不同海拔条件下烟草成熟期上、中、下3个叶位叶片的表皮结构特征和超微结构的变化,并探讨了海拔高度对烟草叶片生长发育及品质的影响。结果表明:随着海拔高度的增加,叶片叶绿体内淀粉粒积累和气孔密度有减少的趋势;表皮腺毛数量,细胞壁厚度,胞内嗜锇物质,囊泡的体积和数量呈现出增加的趋势;叶片内叶绿体完整程度和基粒片层数表现一致。     

矮化大豆的解剖学研究

通过对两种试材东农42及其矮化突变体HK808,不同生长期外部形态建成及内部解剖学结构分析表明,两种试材的株高差异是由第5 ～13节间差异决定的.根部解剖学分析表明,东农42的导管面积显著大于HK808,导管面积与导管数量的动态曲线存在着互补的关系;HK808的根皮率显著高于东农42.两种试材茎部的导管面积及数量、薄壁细胞面积及数量均呈显著差异,维管束数目较稳定无差异.两种试材叶柄部各项解剖学指标比较分析结果与茎部相似;叶部东农42的叶片厚度及导管面积显著大于矮化突变体,HK808叶片的栅栏组织与海绵组织比显著大于东农42.两种试材电镜观察表明叶肉细胞叶绿体大小、叶绿体基粒片层数及片层形态均存在显著差异.     

不同烟区及土壤改良措施下烟叶显微与超显微结构的动态观察

为了解烟叶显微与超显微结构变化的一般规律及其在不同烟区与不同土壤改良措施下的差异,为优质烟叶的栽培提供科学的依据,应用光学显微镜、透射电子显微镜对不同地域及不同土壤改良措施下烟叶显微与超显微结构进行动态观察,结果表明:烟叶显微结构与超显微结构变化一般规律:细胞从排列紧密到疏松,最终细胞收缩、解体.前期叶绿体内淀粉粒较多,中期减少,后期增多.叶绿体高基粒片层逐渐减小.嗜锇颗粒呈加速增多的趋势.不同烟区及不同土壤改良措施下的差异主要表现在后期,栅栏组织细胞出现收缩与海绵组织细胞间隙扩大及细胞的降解的程度不同;叶绿体高基粒片层、嗜锇颗粒、淀粉粒的数量差异大.施草炭的细胞大幅度收缩,细胞间隙扩大,各处理的比对照都有相对较多的孔隙;施用饼肥的嗜锇颗粒数量明显多于其他处理,纯施化肥的最少.施草炭、施饼肥比对照的叶绿体高基粒片层多.纯施化肥的叶绿体内淀粉粒后期迅速增大超过其他3处理.不同地域和不同土壤改良措施下烟叶从糖类物质合成向脂类物质合成转变的程度不同,烟区土壤改良措施能够进行有效调节.     

乙醇对鲜切西兰花抗氧化酶及叶绿体超微结构的影响

;乙醇(6ml/kg,5h)处理显著降低了4℃贮藏期间鲜切西兰花失重和叶绿素含量的下降,促进了抗氧化酶SOD、CAT的活性.对鲜切西兰花叶绿体超微结构的研究表明,乙醇对叶绿体外膜及内部基粒片层结构均起到保护作用,减小了贮藏期间叶绿体的破坏程度,显著延缓了叶绿体结构的解体.     

褪黑素对低温贮藏期间荠菜衰老和抗氧化能力的影响

以‘板叶’荠菜为实验材料,采用100 μmol/L褪黑素浸泡处理10 min,研究2 ℃贮藏期间褪黑素处理对荠菜品质和抗氧化能力的影响,并观察荠菜叶片细胞叶绿体超微结构的变化。结果表明：100 μmol/L褪黑素处理明显降低了贮藏期间荠菜的呼吸速率,抑制了荠菜叶绿素的降解,减少了活性氧自由基的积累,同时提高了超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）、过氧化物酶（peroxidase,POD）和抗坏血酸过氧化物酶（ascorbate peroxidase,APX）等抗氧化酶活力以及抗氧化物质含量;在贮藏第18天,褪黑素处理荠菜的呼吸速率较对照降低了17.3%,抗坏血酸（ascorbic acid,ASA）、还原型谷胱甘肽（glutathione,GSH）含量分别是对照的1.18 倍和2.23 倍,SOD、谷胱甘肽还原酶（glutathione reductase,GR）活力比对照明显提升;超微结构观察结果表明褪黑素处理组荠菜叶片的叶绿体形状和基粒片层结构维持较好。结论：褪黑素处理能够有效抑制贮藏期间荠菜黄化,维持荠菜品质以及叶绿体结构完整,提高荠菜的抗氧化能力。     

逆境下茶树叶绿体的理化特征研究进展

在逆境下,茶树叶绿体脂质过氧化程度加剧,会积累较多丙二醛,增强超氧化物歧化酶活性;活性氧代谢改变,致使抗氧化酶活性升高,一些毒害类物质(O_2~-、H_2O_2等)增多,一些非酶抗氧化性物质减少;并且叶绿体的类囊体和基粒片层等超微结构也发生变化。同时,通过施用抗坏血酸等外源物质能一定程度上减轻逆境对叶绿体造成的损伤。然而,有关茶鲜叶中的叶绿体在加工中的变化特征研究相对较少,不利于深度解析机械胁迫对乌龙茶品质的影响。本文通过对茶树叶绿体的生理生化响应特征的阶段性研究文献综述,阐明水分胁迫、光照胁迫、氟胁迫等非生物胁迫对茶树叶绿体的影响。本文进行乌龙茶加工中叶绿体的理化特征研究,期待从细胞器水平上研究乌龙茶加工原理。     

Chlorophyll fluorescence imaging of individual algal cells: effects of herbicide on Spirogyra distenta at different growth stages

Serious environmental degradation of aquatic ecosystems has been caused by eutrophication and by pollutants such as herbicides. Therefore, measurement of in situ algal photosynthetic activity is important for environmental monitoring. With ordinary nonimaging fluorometers, algal chlorophyll fluorescence can be measured easily, but heterogeneity within samples cannot be detected. Effects of a herbicide preparation containing 3-(3,4-dichlorophenyl)-1,1 -dimethylurea (DCMU) on photosynthetic activity at different growth stages of Spirogyra distenta were investigated by using a computer-aided microscopic imaging system for chlorophyll afluorescence. Photosystem II photochemical yield (phiPSII) images were used to diagnose photosynthetic activity of spiral filate chloroplasts in algal cells. The herbicide treatment caused a stronger decline in phiPSII values in younger than in mature algae cells. This result indicated that heterogeneity within algal samples should be considered when algae are used for environmental monitoring. Thus, measurement of chlorophyll fluorescence from young and mature chloroplasts with a microscopic imaging system makes it possible to improve the sensitivity for monitoring the environmental degradation of aquatic ecosystems.     

Effects of 1-MCP on chlorophyll degradation pathway-associated genes expression and chloroplast ultrastructure during the peel yellowing of Chinese pear fruits in storage

The peel yellowing is an important pigment physiological process of green fruit ripening, which mainly results from chlorophyll degradation in the fruit peel. In this work, two typical cultivars with different ripening speed, a slow ripening pear 'Emerald' (Pyrus bretschneideri Rehd. cv. Emerald) and a fast ripening 'Jingbai' (Pyrus ussuriensis Maxim. cv. Jingbai) were used to investigate the molecular mechanism of chlorophyll degradation in pear yellowing/ripening during postharvest storage. The fruits after harvest were treated with 1-methylcyclopropene (1-MCP), an ethylene action inhibitor at 1.0 μLl(-1) to determine its effect on chloroplast ultrastructure and the expression of chlorophyll degradation associated genes in peel tissues. Our results show that the pears treated with 1-MCP had a lower ethylene production rate and higher chlorophyll content compared to those of untreated fruit. The more intact chloroplasts with well-organised grana thylakoids and small plastoglobuli were maintained in the peel of 1-MCP treated fruit for up to 30 and 15 d in 'Emerald' and 'Jingbai', respectively. The expression of chlorophyll degradation associated genes: pheophorbide a oxygenase (PAO), non-yellow colouring (NYC), NYC1-like (NOL), stay-green 1(SGR1), was suppressed, while no significant change was found in chlorophyllase 1 (CHL1) and red chlorophyll catabolite reductase (RCCR) in both cultivar fruits treated with 1-MCP. These results suggest that 1-MCP can delay chlorophyll degradation by inhibiting ethylene production and suppressing the gene expression of PAO, NYC, NOL and SGR1, which are closely associated with chlorophyll catabolic pathway.     

Relationship between structural development of cell walls and degradation of tissues in maize stems

Sections of internodes of growing maize stems were used to study the behaviour of cell walls of different tissues during in-vitro degradation with rumen fluid. Tissues with primary cell walls-middle lamellae, at early stages of development, were degraded completely. In specific tissues, newly synthesised secondary walls were highly digestible whereas the primary walls-middle lamellae of these tissues were indigestible. These primary walls-middle lamellae stained positively with acid phloroglucinol but showed no fluorescence. At pollination, when secondary walls were of considerable thickness, these walls were still completely digestible even though they stained intensely with acid phloroglucinol and showed reduced fluorescence. However, at some distance from the cut end of sections, the secondary walls of the elongated tube-like cells of sclerenchyma tissue showed considerable reduction in digestibility. Cross-sectional area and dry weight measurements of different stem tissues revealed the importance of secondary wall digestion of sclerenchyma compared with the thin-walled parenchyma. Chemical treatment with KmnO₄ or NaOH resulted in colourless secondary walls after staining whereas primary walls still reacted positively. It was concluded that very small amounts of phenolic compounds (lignin) located in the primary wall-middle lamella that are not removed by KmnO₄ and NaOH treatment are responsible for the decrease in digestibility of tissues during plant development. Histochemical ‘lignin’ reactions and fluorescence just detect phenolic compounds and cannot be correlated with degradation.     

抗病毒病K326新品系Y48抗TMV的细胞学机制研究

Y48是对主栽烤烟品种K326的病毒病抗性进行定向改良培育出的新品系,在保持原K326其他性状不变的前提下,对TMV和CMV抗性显著提高。为揭示其在细胞学方面的抗病机制,本研究利用透射电子显微镜（TEM）对TMV接种0~72 h后的K326和Y48叶片进行超微结构观察。结果显示,K326接种24 h时,叶绿体类囊体片层减少,线粒体膨大,胞内出现自噬结构,接种72 h时,叶绿体、线粒体被病毒完全破坏,叶肉细胞病理性坏死;而Y48,在接种48 h时才发生叶绿体内部沉积少量颗粒,线粒体嵴消失,胞内出现降解的囊泡,接种72 h叶绿体,线粒体全部降解,细胞质凝集,叶肉细胞程序化死亡。结果表明,相对于K326,Y48可以延迟TMV病毒的侵染,并启动超敏反应,发生HR-PCD,并且Y48接种8 h后出现过氧化物酶体,可能影响细胞内ROS代谢水平,二者或许是Y48对TMV表现抗病的细胞学证据,研究结果为进一步解析Y48的抗病分子机理奠定了基础。