两个不同基因型小麦光抑制特性的比较

比较了两个不同基因型小麦(Triticum aestivum L.)"京411"和"小偃54"的原初光能转化效率、荧光猝灭参数和光合色素对强光胁迫的响应.在正常生长条件下"京411"的光合色素含量高于"小偃54";但在高光强下"京411"出现明显的光抑制,而"小偃54"对高光强的适应上优于"京411"."小偃54"适应高光强的原因是它在高光强下能大幅度地提高叶黄素循环的调控因子抗坏血酸的浓度及紫黄素脱环氧化酶(vDE)的活性,从而加速叶黄素循环对过多光能的耗散过程.     

玉米C4光合叶不同部位解剖结构和光抑制特性的比较

以玉米第54i全展叶（C4光合叶）为材料,分别测定基部、中部和顶部的光合速率后,将叶片置于强光（2000μmol·m^2·s^-1）下处理3h和暗中恢复3h,再测定这3个部位在处理期间的叶绿素荧光参数变化;然后分别从叶片的基部、中部和顶部取样观察显微结构和超微结构,测定叶绿素含量。结果表明,3个部位光合速率和叶绿素含量的大小依次为：中部〉顶部〉基部。基部的维管束鞘细胞叶绿体数量少,体积小,排列无规律,类囊体膜有部分垛叠;中部和顶部维管束鞘细胞叶绿体数量多,体积大,大部分围绕维管束呈离心排列,类囊体膜垛叠消失。在强光下,基部、中部和顶部均发生光抑制,但光抑制程度不同,根据严重度依次为：基部〉顶部〉中部,3个部位在暗中的光抑制恢复能力依次为：中部〉顶部〉基部。与叶基部相比,叶中部在强光下能维持较高的电子传递效率（φEo）和较低的热耗散比率（φDo）。这表明,C4光合循环是保持较高电子传递效率、减轻光抑制的重要因子。     

玉米C4光合叶不同部位解剖结构和光抑制特性的比较

以玉米第5位全展叶(C4光合叶)为材料,分别测定基部、中部和顶部的光合速率后,将叶片置于强光(2000μmol·m-2·s-1)下处理3h和暗中恢复3h,再测定这3个部位在处理期间的叶绿素荧光参数变化;然后分别从叶片的基部、中部和顶部取样观察显微结构和超微结构,测定叶绿素含量。结果表明,3个部位光合速率和叶绿素含量的大小依次为:中部>顶部>基部。基部的维管束鞘细胞叶绿体数量少,体积小,排列无规律,类囊体膜有部分垛叠;中部和顶部维管束鞘细胞叶绿体数量多,体积大,大部分围绕维管束呈离心排列,类囊体膜垛叠消失。在强光下,基部、中部和顶部均发生光抑制,但光抑制程度不同,根据严重度依次为:基部>顶部>中部,3个部位在暗中的光抑制恢复能力依次为:中部>顶部>基部。与叶基部相比,叶中部在强光下能维持较高的电子传递效率(φEo)和较低的热耗散比率(φDo)。这表明,C4光合循环是保持较高电子传递效率、减轻光抑制的重要因子。     

光胁迫下银杏光合作用的光抑制

自然条件下晴天银杏叶片光系统Ⅱ光化学效率表现明显日变化。上午Ｆｖ／Ｆｍ随光照的增强而降低,至１４：００左右达最低值。其后随着光强的减弱Ｆｖ／Ｆｍ缓慢恢复。一天中叶黄素循环关键组分玉米黄质（Ｚ）含量与Ｆｖ／Ｆｍ呈负相关,用二硫苏糖醇（ＤＴＴ）阻断Ｚ的形成后,光抑制程度大大加深。结果表明与叶黄素循环有关的非辐射能量耗散的增加是产生光抑制的原因之一。强光处理前饲喂Ｄ１蛋白合成抑制剂林可霉素（ＬＭ）,ＦＶ     

温州蜜柑叶片光合作用光抑制的保护机理

晴天条件下,使用便携式调制荧光仪和分光光度计观察了温州蜜柑叶片光合作用光抑制发生过程中几个主要荧光参数（初始荧光F0、最大荧光Fm、PSⅡ的光化学效率Fv/Fm、非光化学猝灭qN及其快相qNf和慢相qNs）、电子传递速率（ETR）和玉米黄素相对含量的日变化,结果表明,随着光强的增强,ETR、qN及其qNr与qNs以及玉米黄素相对含量升高,Fv/Fm、Fm和F0下降。用DTT处理后,qNs较对照明显下降,F0较对照明显上升,可以认为,柑橘在光合作用日变化中存在依赖于叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散方式,而且它们在防御光破坏方面起着重要作用。     

遮荫棉花转入强光后光合作用的光抑制及其恢复

研究了遮荫棉花（Gossypium hirsutum L.）突然由遮荫条件暴露在自然强光下时,叶绿素荧光发射、叶绿体色素组成、净光合速率（Pn）等在光照转移当天以及随后的适应过程中（光照转换后15d内）的变化。遮荫棉花突然转到强光下,叶片发生了严重的光合作用光抑制,叶绿素荧光参数Fv/Fm和φPSⅡ急剧降低,且明显低于自然光照下生长的叶片,而F。值却明显升高。这些参数即使在光照转换的次日清晨也不能完全恢复。Fv/Fm和Pn在光照转换以后的4d内持续降低,在第6天以后开始逐渐升高,在10-12d达到稳定值,表现出遮荫棉花叶片对光强变化的一定适应性,但Fv/Fm和Pn均未达到自然光照条件下生长的棉花叶片的相应值。最后的Pn值较遮荫下叶片增加60%,但同自然光照下生长的叶片相比只有后的40%。试验结果还表明,光照转换以后叶片内叶黄素循环库逐渐增大,在较短的时间内（3d）即可达到较高的水平。遮荫棉花突然转么自然强光下,叶片Fv/Fm及Pn的降低与PSⅡ反应中心的破坏有关,在对强光的适应过程中依赖叶黄素循环的热耗散等保护机制增强。光保护机制的逐渐完善有助于减轻叶片由遮荫转到强光下遭受的光破坏。     

光合作用光抑制的研究进展

概述了植物光合作用光抑制的研究进展,包括造成光抑制和光氧化的活性氧的产生和作用机理,光抑制的作用部位,以及光保护机制等,着重从三个方面讨论了植物抗光抑制的保护机理：与光系统Ⅱ天线以及叶黄素循环相关的热耗散途径,包括光呼吸、H2O-H2O循环和环式电子传递在内的电子传递途径,以及活性氧清除机制等。     

田间小麦叶片光合作用的光抑制

通过人为改变小麦旗叶与茎秆的夹角,比较了晴天田间小麦直立叶（１０°）与平展叶（９０°）光合作用光抑制程度的差别。在叶温高达３７．６℃、最高光强为１６００μｍｏｌ．ｍ＾－２．ｓ＾－１的晴天,田间小麦经午间强光照射４ｈ后,ＰＳⅡ光化学效率明显下降。     

细胞色素 b559与PSⅡ光抑制的光保护机制

Cyt b559是由两条多肽,即α_、β_两个亚基组成的一种血红蛋白,是光系统Ⅱ（PSⅡ）蛋白复合体必不可少的组分。简要介绍了Cyt b559的分子组成及其氧化还原特性。重点阐述了在光抑制条件下Cyt b559对PSⅡ反应中心的可能保护机制和由Cyt b559参与的围绕PSⅡ的循环电子传递。     

细胞色素 b559与PSⅡ光抑制的光保护机制

Cyt b559是由两条多肽,即α、β-两个亚基组成的一种血红蛋白,是光系统Ⅱ(PSⅡ)蛋白复合体必不可少的组分。简要介绍了Cyt b559的分子组成及其氧化还原特性。重点阐述了在光抑制条件下cyt b559对PSⅡ反应中心的可能保护机制和由Cyt b559参与的围绕PSⅡ的循环电子传递。     

两种基因型小麦光合作用对NaHSO3响应的差别

两种不同基因型小麦京411(J411,北京地区高产小麦品种)和小偃54(X54,一种远源杂交品种)的光合作用对低浓度NaHS03处理的响应不同。NaHS031mmol／L处理能够提高京411在CO2浓度为350和900μL／L的空气中的净光合速率;而对小偃54,在这两种情况下的净光合速率均无明显影响。以往的研究表明NaHS03促进光合作用的原因类似于PMS(Phenazine methosulfate),都是增加了ATP的合成。此文再次证明并发现经过NaHS031mmol／L处理后,京411叶片作用光关闭后叶绿素荧光瞬时上升的幅度提高,远红光后P700^ (reaction center cholorophyll of PSI)再还原的半时间缩短,表明NaHS03可以促进小麦京411中围绕PSI循环电子传递及其耦联的磷酸化。然而,NaHS03对小偃54的作用光关闭后叶绿素荧光瞬时上升的幅度及远红光后P700^ 再还原的半时间均无明显影响。与小麦京411相比较,小偃54的作用光停止后叶绿素荧光瞬时上升的幅度增大,而且其在远红光后P700^ 再还原的半时间更短,表明小偃54的循环电子传递的能力远高于京411的。两种不同基因型小麦对NaHS03的响应不同很可能是由于二者在循环电子传递能力上有很大的差别。     

Photosynthetic Characteristics in Two Wheat Genotypes as Affected by Nitrogen Nutrition

Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photoinhibition in Chilling Stressed Wheat and Maize

At chilling stress, the contents of photosynthetic pigments decreased significantly in maize, but in wheat the contents of chlorophyll (Chl) remained unchanged whereas the contents of total carotenoids (Car) increased. In both species the contents of + carotene and lutein + lutein-5,6-epoxide remained unaffected, but the de-epoxidation state involving the components of the xanthophyll cycle increased. Under chilling stress the photosynthetic electron transport also displayed a general failure in maize but in wheat only photosystem (PS) 2 coupled to the water oxidation complex was inhibited. Moreover, in stressed maize the quinone pool decreased, while the low and high potential forms of cytochrome b ₅₅₉ increased. In wheat only the contents of cytochrome b _559LP decreased. Peroxidation of acyl lipids in the chloroplast lamellae became more distinct in chilling stressed maize but could also be detected in wheat. Thus in chilling stressed maize prevails an impairment of the acceptor site of PS2 while in wheat photodamage is restricted to the electron donation pathway from water to P680 or to the oxygen evolving complex.     

Comparative Metabolic Profiling of Two Contrasting Date Palm Genotypes Under Salinity

Since specific metabolites may be associated with salinity tolerance, this study aimed to decipher the salinity tolerance mechanism in date palm based on the information encoded by the metabolomic profiles of the salt-tolerant “Umsila” and salt-susceptible “Zabad” cultivars when grown under salinity conditions. Changes in the metabolomic profiles of the leaf and root tissues were determined using hydrophilic interaction liquid chromatography (HILIC) and reverse-phase liquid chromatography (RPLC) mass spectrometry. The global untargeted metabolomic analysis showed the presence of 4878 metabolites accumulated in leaf and root tissues of the date palm seedlings. Principal component analysis (PCA) revealed the presence of unique groups of metabolites for each treatment and tissue type. Pathway analysis showed the involvement of some of these metabolites in the biosynthesis of several types of membranous lipids and glycolipids molecules such as 18:0-lyso-phosphatidylethanolamine (lysoPE), and also the synthesis of cell-wall components such as 16-hydroxy hexadecanoic acid, which is an intermediate metabolite in cutin, suberin, and wax biosynthesis. Moreover, antioxidant flavonoids such as (+)-catechin and epicatechin, vitamins such as B₉, phytohormone-associated compounds such as dihydrozeatin-9-N-glucoside-O-glucoside, and osmolytes such as the sulfonic amino acid taurine were all significantly (p?≤?0.05, FWER?≤?0.05) altered in response to salinity in both cultivars. These results indicate that salinity tolerance in date palm involved a multi-dimensional mechanism, which includes the modification of the cell-wall and cellular membranes, the production of oxygen species scavengers, the adjustment of cellular osmotic pressure, and probably the alteration of the hormonal balance. The intracultivar metabolomic profile comparison strategy performed in this study represents an approach that may pave the road toward the identification of salinity tolerance mechanisms in date palm based on the final protein products.

     

不同光合特性大豆叶的比例解剖研究

本研究选取不同光合速率的品种‘黑农26'(高产低光效)、‘黑农40'、‘黑农41'(高产高光效)为材料,于大豆开花后的不同生育时期,对大豆的功能叶片、叶柄解剖学进行了研究.结果表明(1)不同类型大豆的叶肉结构有明显区别.叶片厚度依次为‘黑农40'>‘黑农41'>‘黑农26'.各期的基本趋势是一致的.栅栏组织的厚度和层数与叶片的厚度趋势一致.(2)各品种栅栏组织中的叶绿体数目均多于海绵组织,且高光效类型多于低光效类型.局部观察不同品种间,叶绿体内的基粒和间质片层结构高光效的也明显优于低光效的品种.(3)气孔包含数量和大小两个因素,气孔大小基本一致,下表皮数量>上表皮,高光效类型>低光效类型.(4)各品种主脉维管束中木质部的导管数目依次为‘黑农41'>‘黑农40'>‘黑农26'.     

不同光合特性大豆叶的比较解剖研究

本研究选取不同光合速率的品种‘黑农 2 6’(高产低光效 )、‘黑农 40’、‘黑农 41’(高产高光效 )为材料 ,于大豆开花后的不同生育时期 ,对大豆的功能叶片、叶柄解剖学进行了研究。结果表明 :(1 )不同类型大豆的叶肉结构有明显区别。叶片厚度依次为‘黑农 40’ >‘黑农 41’ >‘黑农 2 6’。各期的基本趋势是一致的。栅栏组织的厚度和层数与叶片的厚度趋势一致。 (2 )各品种栅栏组织中的叶绿体数目均多于海绵组织 ,且高光效类型多于低光效类型。局部观察不同品种间 ,叶绿体内的基粒和间质片层结构高光效的也明显优于低光效的品种。 (3 )气孔包含数量和大小两个因素 ,气孔大小基本一致 ,下表皮数量 >上表皮 ,高光效类型 >低光效类型。 (4)各品种主脉维管束中木质部的导管数目依次为‘黑农 41’ >‘黑农 40’ >‘黑农 2 6’。     

Root Respiration and Carbohydrate Status of Two Wheat Genotypes in Response to Hypoxia

To investigate root respiration and carbohydrate status in relationto waterlogging or hypoxia tolerance, root respiration rateand concentrations of soluble sugars in leaves and roots weredetermined for two wheat (Triticum aestivum L.) genotypes differingin waterlogging-tolerance under hypoxia (5% O₂) and subsequentresumption of full aeration. Root and shoot growth were reducedby hypoxia to a larger extent for waterlogging-sensitive Coker9835. Root respiration or oxygen consumption rate declined withhypoxia, but recovered after 7 d of resumption of aeration.Respiration rate was greater for sensitive Coker 9835 than fortolerant Jackson within 8 d after hypoxia. The concentrationsof sucrose, glucose and fructose decreased in leaves for bothgenotypes under hypoxia. The concentration of these sugars inroots, however, increased under hypoxia, to a greater degreefor Jackson. An increase in the ratio of root sugar concentrationto shoot sugar concentration was found for Jackson under hypoxicconditions, suggesting that a large amount of carbohydrate waspartitioned to roots under hypoxia. The results indicated thatroot carbohydrate supply was not a limiting factor for rootgrowth and respiration under hypoxia. Plant tolerance to waterloggingof hypoxia appeared to be associated with low root respirationor oxygen consumption rate and high sugar accumulation underhypoxic conditions.Copyright 1995, 1999 Academic Press Oxygen consumption rate, sugar accumulation, Triticum aestivum L., waterlogging tolerance     

基因型对春麦花粉植株诱导率影响的研究

花药培养中,不同基因型供体对于花粉植株的影响很大.几年来的研究结果表明,用花培品系做亲本配置杂交组合;不同世代的基因型,尤其是F_1代花药供体植株;亲本基因型在提高花粉愈伤组织出愈率、花粉绿苗分化及花粉绿苗率方面均有明显的效果.