冷锻炼对低温胁迫下夏威夷椰子膜脂过氧化及保护酶活性的影响

在－5℃低温胁迫下,夏威夷椰子（Pritchardia gaudichaudii H.Wendl.)幼苗叶片的丙二醛（MDA）含量逐渐增加,表明膜脂过氧化作用逐渐增强;含水量不断下降;细胞保护酶中的超氧化物歧化酶（SOD）、过氧化物酶（POD) 过氧化氢酶（CAT）酶活性均先升高,然后下降。冷锻炼处理可以减缓夏威夷椰子膜脂过氧化作用的增强,促进SOD酶活性的提高,同时抑制POD和CAT酶活性的变化,因而使夏威夷椰子幼苗的抗寒性得以提高,在－5℃低温胁迫下的半致死时间从1.6d延长到2.2d。     

发菜膜脂及其脂肪酸组成

对野生发菜(Nostocflagelliforme Bom.et Flab)的膜脂(主要成分为类囊体膜脂)及其脂肪酸组成进行了测定分析.发菜的膜脂由单半乳糖甘油二酯(MGDG)、双半乳糖甘油二酯(DGDG)、磷酯酰甘油(PG)和硫代异鼠李糖甘油二酯(SQDG)组成,其酯酰基连接有棕榈酸(16:0)、十六碳烯酸(16:1)、硬脂酸(18:0)、油酸(18:1)、亚油酸(18:2)和亚麻酸(18:3)6种脂肪酸.发菜的不饱和脂肪酸含量可达总脂的73%,特别是16:1和18:3分别高达29%和34%,远远高于已报道的其他蓝藻,说明了发菜类囊体膜具有较强的抗逆性特点.同时还对复水30 min和复水后生长24 h的发菜膜脂及其脂肪酸组成进行了分析.结果表明,复水对野生发菜的膜脂及其脂肪酸组成没有显著影响,说明发菜的膜脂和脂肪酸组成在干燥-吸水过程中能保持很高的稳定性.     

光合膜膜脂的结构、特性与分子组装

本文就叶绿体光合膜中主要膜脂的分子结构及其特性和在膜中的分子组装进行了综述,并指出了目前膜脂研究的趋势和存在的问题。     

光合膜膜脂的结构、特性与分子组装

本文就叶绿体光合膜中主要膜脂的分子结构及其特性和在膜中的分子组装进行了综述,并指出了目前膜脂研究的趋势和存在的问题     

拟南芥角果衰老过程中膜脂的变化

角果发育对某些物种的生殖发育具有重要的作用。拟南芥种子附着在角果里,角果在早期发育时进行光合作用,角果成熟后开裂散落种子之前,其细胞会经历一个衰老的过程。一般植物细胞在衰老过程中要经历膜脂降解的过程,但是角果细胞衰老过程仍未知。通过比较角果衰老过程中拟南芥野生型(WS)及与膜脂代谢密切相关的磷脂酶Dδ缺失突变体(PLDδ KO)中膜脂分子的组成情况、膜脂含量、相对含量及双键指数值,结果发现,在拟南芥角果衰老过程中：(i)质体膜脂和质体外膜脂显著下降;(ii)不同膜脂降解速率不一样,质体膜脂的降解比质体外膜脂的降解快;(iii)总的双键指数DBI下降;(iv)磷脂酶Dδ缺失突变体(PLDδ KO)的角果膜脂组成的基本水平和变化样式与野生型(WS)非常相似。结果说明,角果在衰老过程中发生了膜脂的激烈降解。据此推测：(i) 膜脂水解产物可能转移到种子中用于储藏脂三酰甘油的合成;(ii) 质体膜脂相对含量下降和质体外膜脂相对含量上升导致了总的DBI下降;(iii) PLDδ参与了角果衰老中的膜脂代谢。     

磷脂酶Dδ缺失加剧UV-B诱导的膜伤害

检测了拟南芥野生型（WS）及磷脂酶D8缺失突变体在uV-B辐射下的膜脂分子变化,并比较了二者在紫外辐射下的膜脂含量、双键指数及碳链长度的差异。结果发现,紫外辐射导致植株膜脂发生了降解,其中叶绿体膜脂MGDG和DGDG是膜伤害的主要作用靶点,而且突变体中的膜脂降解比野生型剧烈。上述结果说明磷脂酶D8的缺失会加剧紫外辐射诱导的膜伤害,导致植株对紫外辐射更加敏感。     

植物冷驯化的分子机理研究进展

植物冷驯化是一个非常复杂的过程,包括植物将感受到的低温信号转变成生化信号,以激活冷诱导基因的启动子,刺激特定的mRNA的转录,并在特定的组织中合成冷驯化蛋白.冷驯化蛋白通过增强膜脂流动性和阻止胞间冰晶形成等方式,以保护细胞免受低温伤害.冷驯化基因的表达以转录后调控为主,也有转录调控.某些冷诱导基因也可受ABA或其他环境胁迫(如高温、干旱、高盐、脱水等)诱导表达.     

磷脂酶Dδ缺失加剧UV-B诱导的膜伤害

检测了拟南芥野生型（WS）及磷脂酶Dδ缺失突变体在UV-B辐射下的膜脂分子变化,并比较了二者在紫外辐射下的膜脂含量、双键指数及碳链长度的差异。结果发现,紫外辐射导致植株膜脂发生了降解,其中叶绿体膜脂MGDG和DGDG是膜伤害的主要作用靶点,而且突变体中的膜脂降解比野生型剧烈。上述结果说明磷脂酶Dδ的缺失会加剧紫外辐射诱导的膜伤害,导致植株对紫外辐射更加敏感。     

水稻离体叶片衰老过程中膜脂组分的变化

水稻离体叶片衰老过程中,膜脂磷脂含量随着叶片离体时间的增加而下降,而质膜透性则随时间的增加而上升。BA,Ni~(2 )能延缓叶片磷脂的丧失,ABA,ACC则加速其含量下降,但它们对磷脂酶D活性影响不大。膜脂脂肪酸组分在叶片衰老过程中也发生着变化,其中亚麻酸(18:3)含量下降,不饱和度降低。ABA,ACC促进亚麻酸含量和不饱和度的下降,BA,Ni~(2 )则有延缓作用。     

棉花叶片衰老过程中激素和膜脂过氧化的关系

以陆地棉品种辽棉9号的去根幼苗为材料,对其进行暗诱导衰老培养.在培养液中分别加入6-BA、ABA、GSH、H2O2、CaCl2、A23187 和A23187 CaCl2,测定在不同培养条件下棉花去根幼苗叶片内源激素、SOD酶活性和MDA含量的变化.结果表明:棉花叶片衰老表现为细胞分裂素含量的下降和ABA含量的上升.6-BA、GSH和钙离子均延缓叶片的衰老,ABA和H2O2促进叶片的衰老.     

油菜烯醇酶基因的克隆与分析(英文)

烯醇酶(enolase)是糖酵解途径中的一个重要酶类,它能够催化磷酸甘油酸酯(2-PGA)生成磷酸烯醇丙酮酸酯(PEP)。我们通过RACE-PCR方法从油菜(Brassica napus L. )中克隆到了编码烯醇酶的全长基因。序列分析表明该基因全长cDNA为1624bp,拥有一个由444个氨基酸组成的开放读码框,所编码的蛋白质分子量为47.38kD,等电点为5.78。比较发现,油菜烯醇酶与已分离出的其他烯醇酶氨基酸序列有较高的同源性。Southern杂交结果显示烯醇酶以低拷贝形式在油菜基因组中存在。RT-PCR和Northern分析表明烯醇酶基因在100mmol/L盐浓度胁迫条件下表达量上升,而在低温诱导时表达量下降。该研究表明所克隆基因是植物烯醇酶基因家族的新成员。     

ESI-MS/MS方法检测拟南芥膜脂分子对机械伤害的响应

利用一种灵敏的、基于ESI-MS／MS（electrospray ionization tandem mass spectrometry）的脂类组学方法,测定了机械伤害诱导的拟南芥6种磷脂（phosphohpids）、2种糖脂（glycolipids）、3种溶血磷脂（lysophospholipids）和约120种脂类分子的变化,探索了膜脂响应机械伤害的基本趋势。结果表明,机械伤害后磷脂酸（phosphatidic acid,PA）和3种溶血磷脂显著升高,而叶绿体膜上的糖脂减少;在测量的1小时范围内,不同脂类水解产生的磷脂酸分子的增加速度和强度不同,反映出它们经历了不同的生化过程。具体表现为：（1）叶绿体膜脂磷脂酰甘油（phosphatidylglycero,PG）分子34：4 PG水解的产物磷脂酸分子34：4 PA的积累速度明显慢于其它磷脂酸分子;（2）磷脂酸分子34：6 PA仅有少量的积累,其可能是由叶绿体膜脂单半乳糖二酰甘油（monogalactosyldiacylglycerol,MGDG）。分子34：6 MGDG和双半乳糖二酰甘油（digalactosyldiacylglycerol,DGDG）分子34：6 DGDG水解产生,然而这两种糖脂含量明显下降,说明它们有可能还参与了其它的反应。脂类的摩尔百分组成没有剧烈的变化。     

不同硼效率甘蓝型油菜品种细胞壁中硼的分配

应用不同硼效率甘蓝型油菜品种 ,研究硼在细胞壁中的分配。硼主要结合在细胞壁中 ,缺硼显著提高硼在细胞壁中的分配比例。根系细胞壁硼含量显著低于叶片 ,但根系细胞壁硼占根系总硼量之比例显著高于叶片。同一品种根系及其细胞壁、老叶细胞壁硼含量受生育期影响较小 ,新叶及其细胞壁、老叶硼含量受生育期影响较大。在正常供硼条件下 ,硼高效品种根系细胞壁和叶片细胞壁硼含量均低于低效品种 ;正常和缺硼条件下 ,硼高效品种细胞壁硼占器官总硼量之比例均低于低效品种。说明硼低效品种需较多的硼构建细胞壁。     

Effect of 17-DMC on Phytohormone Level and Growth of Rapeseed Plants (Brassica napus)

The effect of 17-dimethylmorpholinium chloride (17-DMC), a quaternary ammonium salt, on stem growth and productivity of spring rape (Brassica napus L., cv. Star), and on phytohormone content in stem tissues was studied. We found that the effects of 17-DMC on stem growth (inhibition of linear growth, development of anatomical structure and mechanical properties) were manifested as the changes in stem hormonal balance, particularly, in a decrease in the contents of GA, zeatin, and IAA and an increase in the ABA content. Seed weight increased due to the retarding effect of 17-DMC on stem growth and the promotion of silique and seed development.     

Evaluation of Genetic and Epigenetic Modification in Rapeseed （Brassica napus） Induced by Salt Stress

Salinity is an important limiting environmental factor for rapeseed production worldwide. In this study, we assessed the extent and pattern of DNA damages caused by salt stress in rapeseed plants. Amplified fragment length polymorphism （AFLP） analysis revealed dose-related increases in sequence alterations in plantlets exposed to 10-1000 mmol/L sodium chloride. In addition, individual plantlets exposed to the same salt concentration showed different AFLP and selected region amplified polymorphism banding patterns. These observations suggested that DNA mutation in response to salt stress was random in the genome and the effect was dose-dependant. DNA methylation changes in response to salt stress were also evaluated by methylation sensitive amplified polymorphism （MSAP）. Three types of MSAP bands were recovered. Type Ⅰ bands were observed with both isoschizomers Hpa Ⅱ and Msp Ⅰ, while type Ⅱ and type Ⅲ bands were observed only with Hpa Ⅱ and Msp Ⅰ, respectively. Extensive changes in types of MSAP bands after NaCI treatments were observed, including appearance and disappearance of type Ⅰ, Ⅱ and Ⅲ bands, as well as exchanges between either type Ⅰand type Ⅱ or type Ⅰ and type Ⅲ bands. An increase of 0.2-17.6% cytosine methylated CCGG sites were detected in plantlets exposed to 10- 200 mmol/L salt compared to the control, and these changes included both de novo methylation and demethylation events. Nine methylation related fragments were also recovered and sequenced, and one sharing a high sequence homology with the ethylene responsive element binding factor was identified. These results demonstrated clear DNA genetic and epigenetic alterations in planUets as a response to salt stress, and these changes may suggest a mechanism for plants adaptation under salt stress.     

拟南芥角果发育和开裂的调控机制及在油菜育种中的应用

十字花科芸苔属甘蓝型油菜(Brassica napus)在角果发育成熟过程中,因角果开裂种子散落引起产量损失最低达20%左右,最高可达50%左右。模式植物拟南芥在角果形态和开裂机制方面与甘蓝型油菜具有相似性,角果开裂主要与果瓣、胎座框和果瓣边缘层的细胞发育有关。通过对拟南芥角果发育期间基因对果瓣、胎座框和果瓣边缘层的识别和发育进行综述,明确了拟南芥角果发育和开裂的基因调控机制,提出了从模式植物到大田作物甘蓝型油菜抗裂角育种的新策略。     

Chlorophyllase and peroxidase activity during degreening of maturing canola (Brassica napus) and mustard (Brassica juncea) seed

Chlorophyllase and peroxidase activities were measured in relation to seed maturation and degreening in canola ( Brassica napus cvs Westar and Alto) and mustard ( Brassica juncea cvs Cutlass and Lethbridge 22A). Samples of seed collected at the same moisture content were pooled, then divided and used for each assay. During maturation the green pigment (chlorophyll and related pigments) content of canola seed decreased linearly and was lower than that measured in mustard at all moisture contents studied, except for the highest and lowest moisture contents. Chlorophyllides and pheophorbides were detected in canola and were essentially absent in mustard. This difference in accumulation of dephytylated pigments infers differences in the pigment degradation pathways in Brassica species. Interspecific differences in the enzymology of degreening were found. Green pigment degradation was associated with increased chlorophyllase activity and low peroxidase activity in canola and low Chlorophyllase and high perosidase activity in mustard. The possible role of ethylene in seed degreening is discussed.     

Changes in protein and carbohydrate content during development of seeds and siliquas of rapeseed (Brassica napus L.)

Abstract

A study was made on the changes observed in the protein, starch and soluble sugar content during development of siliquas and seeds of rapeseed grown in central Italy.

Concentration of starch and soluble sugars in the seed increases to 75 per cent dry matter during the first few weeks of pod development and then drops to minimum values. The protein increases steadily until maturity, when a level of 0.85 mg per seed is reached, equivalent to 18 per cent dry matter. The protein and starch in the hull? decrease continuously during development, while in the initial stages the soluble sugars are accumulated until they account for 33 per cent dry matter, after which they decline towards maturity.     

Fitness of hybrids between rapeseed (Brassica napus) and wild Brassica rapa in natural habitats

Fitness of hybrids between genetically modified (GM) crops and wild relatives influences the likelihood of ecological harm. We measured fitness components in spontaneous (non-GM) rapeseed x Brassica rapa hybrids in natural populations. The F1 hybrids yielded 46.9% seed output of B. rapa, were 16.9% as effective as males on B. rapa and exhibited increased self-pollination. Assuming 100% GM rapeseed cultivation, we conservatively predict < 7000 second-generation transgenic hybrids annually in the United Kingdom (i.e. approximately 20% of F1 hybrids). Conversely, whilst reduced hybrid fitness improves feasibility of bio-containment, stage projection matrices suggests broad scope for some transgenes to offset this effect by enhancing fitness.