低温强光下籼粳稻紫黄质脱环氧化酶活性和类囊体膜脂不饱和度的变化

为了阐明籼稻(oryza sativa L.spp.indica)、粳稻(O.sativa L.spp.japonica)对低温强光敏感性的差异,着重研究了低温强光下水稻类囊体膜脂不饱和度与叶黄素循环的变化.随着低温强光处理时间的延长,类囊体膜脂不饱和脂肪酸含量降低,饱和脂肪酸含量增加,因而膜脂不饱和指数(IUFA)下降.同时,叶黄素循环的关键酶--紫黄质脱环氧化酶(VDE)活性降低,叶黄素循环组分中紫黄质(V)含量增加,而单环氧玉米黄质(A)和下米黄质(Z)的含量减少,表现为(A+Z)/(A+Z+V)比值下降.Arrhenius分析证明,VDE对低温和膜脂不饱和度都敏感.相关分析表明,类囊体IUFA分别与VDE活性、(A+Z)/(A +Z+V)和D1蛋白量呈显著的正相关.与粳稻9516相比,籼稻油优63类囊体膜的IUFA较低,低温下类囊体膜脂流动性和稳定性较差,VDE活性和(A+Z)/(A+Z+V)比值较低.     

天线蛋白和类囊体膜脂对光合系统紫黄质循环的调节作用研究进展

紫黄质循环是紫黄质(V)经过中间物单环氧玉米黄质(A)形成玉米黄质(Z)的可逆转换,是光合系统聚光复合体在低光下的聚光状态与高光下的能量耗散状态之间的转换开关.叶黄素中的玉米黄质可钝化(去激发)激发三线态叶绿素(3Chl*)和激发单线态氧(1O2*),紫黄质循环可直接或间接地通过非光化学淬灭(NPQ)耗散PSⅡ天线蛋白中的过量光能.天线蛋白被认为是依赖玉米黄质(Z)耗散过量光能的部位,天线蛋白通过结合紫黄质循环组分(V,A和Z)来调节紫黄质循环.类囊体膜脂的性质和结构影响紫黄质循环组分(V,A和Z)间的转换,V的脱环氧化速率依赖于V在类囊体膜脂上侧向扩散的速率,紫黄质脱环氧化作用第一步(由V到A的转换)的速度常数是第二步(由A到Z的转换)速度常数的4～6倍.现有的结果表明,天线蛋白和类囊体膜脂是紫黄质循环最基本的调节器.该文对近年来国内外关于紫黄质循环的基本反应及其功能、紫黄质循环酶结构性质和辅因子以及天线蛋白和类囊体膜脂对紫黄质循环的调节作用及其机理等方面的研究进展进行了综述.     

低温强光胁迫下籼粳稻的PSⅡ光化学效率和膜脂过氧化表现

研究了温光胁迫下籼 (OryzasativaL .spp .indica)粳稻 (O .sativaL .spp .japonica)生育后期叶片荧光参数和膜脂过氧化的关系。结果表明 ,低温强光下水稻光合机构中PSⅡ的D1蛋白量下降 ,叶黄素循环组分中环氧玉米黄质 (A)和玉米黄质 (Z)的形成受抑 ,PSⅡ光化学效率 (Fv/Fm)和非光化学猝灭 (qN)明显下降。加之内源活性氧清除剂超氧物歧化酶 (SOD)活性降低 ,超氧阴离子自由基 (O-·2 )和膜脂过氧化产物丙二醛 (MDA)积累增加 ,导致光氧化发生。上述过程在籼粳稻间有明显差异 ,低温强光结合抑制剂处理证明 ,籼稻较粳稻对低温强光敏感和光氧化严重。相关分析表明 ,D1蛋白量分别与Fv/Fm 和 (A Z) / (A Z V)呈极显著的正相关关系 ,Fv/Fm 与MDA呈极显著的负相关关系。据此认为 ,逆境下Fv/Fm是预测光氧化的关键指标 ,D1蛋白合成能力和叶黄素循环的保护作用是其生理基础     

小麦紫黄质脱环氧化酶（VDF）cDNA的克隆及表达

应用RT-PCR方法从小麦(Triticum aestivum L．cv．Xiaoyan 54)中克隆了紫黄质脱环氧化酶(violaxanthin de-epoxidase,VDE)cDNA,预测的蛋白质序列与拟南芥(Arabidopsis thaliana)、水稻(Oryza sativa)有很高的同源性。Southern杂交结果表明,在小麦中可能存在3个拷贝的紫黄质脱环氧化酶基因。Northern杂交结果表明它在绿色叶片中特异表达,在黄化小麦幼苗变绿过程中其mRNA水平受光诱导,并且强光增加了其mRNA在成熟叶片中的表达。     

小麦紫黄质脱环氧化酶(VDE) cDNA的克隆及表达

应用RT-PCR方法从小麦(Triticum aestivum L. cv.Xiaoyan 54)中克隆了紫黄质脱环氧化酶(violaxanthinde-epoxidase,VDE) cDNA,预测的蛋白质序列与拟南芥(Arabidopsis thaliana)、水稻(Oryza sati va)有很高的同源性.Southern杂交结果表明,在小麦中可能存在3个拷贝的紫黄质脱环氧化酶基因.Northern杂交结果表明它在绿色叶片中特异表达,在黄化小麦幼苗变绿过程中其mRNA水平受光诱导,并且强光增加了其mRNA在成熟叶片中的表达.     

低温强光胁迫下籼粳稻的PSⅡ光化学效率和膜脂过氧化表现

研究了温光胁迫下籼(Oryza sativa L. spp. indica)粳稻(O. sativa L. spp. japonica)生育后期叶片荧光参数和膜脂过氧化的关系.结果表明,低温强光下水稻光合机构中PSⅡ的D1蛋白量下降,叶黄素循环组分中环氧玉米黄质(A)和玉米黄质(Z)的形成受抑,PSⅡ光化学效率(Fv/Fm)和非光化学猝灭(qN)明显下降.加之内源活性氧清除剂超氧物歧化酶(SOD)活性降低,超氧阴离子自由基(O(-)/(*)2)和膜脂过氧化产物丙二醛(MDA)积累增加,导致光氧化发生.上述过程在籼粳稻间有明显差异,低温强光结合抑制剂处理证明,籼稻较粳稻对低温强光敏感和光氧化严重.相关分析表明,D1蛋白量分别与Fv/Fm和(A+Z)/(A+Z+V)呈极显著的正相关关系,Fv/Fm与MDA呈极显著的负相关关系.据此认为,逆境下Fv/Fm 是预测光氧化的     

小麦紫黄质脱环氧化酶(VDE)cDNA的克隆及表达(英文)

应用RT-PCR方法从小麦(Triticum aestivum L.cv.Xiaoyan 54)中克隆了紫黄质脱环氧化酶(violaxanthinde-epoxidase,VDE)cDNA,预测的蛋白质序列与拟南芥(Arabidopsis thaliana)、水稻(Oryza sativa)有很高的同源性。Southern杂交结果表明,在小麦中可能存在3个拷贝的紫黄质脱环氧化酶基因。Northern杂交结果表明它在绿色叶片中特异表达,在黄化小麦幼苗变绿过程中其mRNA水平受光诱导,并且强光增加了其mRNA在成熟叶片中的表达。     

Changes in Violaxanthin Deepoxidase Activity and Unsaturation of Thylakoid Membrane Lipids in Indica and Japonica RiceUnder Chill and Strong Light

To explore the differences of sesitivities to chill and strong light in indica and japonica rice (Oryza sativa), the changes in unsaturation of thylakoid membrane lipids and xanthophyll cycle were studied under Chill condition and strong light. The contents of unsaturated fatty acids of thylakoid membrane lipids decreased and that of the saturated ones increased with the time of Chill- and strong lighttreatment, resulting in the reduction of the index of unsaturation of fatty acids (IUFA). The activities of violaxanthin deepoxidase (VDE), a key enzyme of xanthophyll cycle, also reduced. The content of violaxanthin (V) increased, and the contents of antheraxanthin (A) and zeaxanthin (Z) decreased, the ratio of (A+Z)/(A+Z+V) decreased correspondingly. Arrhenius analysis showed that VDE was sensitive to both chill and unsaturation level of thylakoid membrane lipids. Correlation analysis showed that there was distinctly positive relationships between IUFA of thylakoid membrane lipids and the activity of VDE, Fv/Fm, and D1 protein content. Lower IUFA values, less fluidity and stability of thylakoid membrane lipids, lower VDE activity and (A+Z)/(A+Z+V) ratio were found in indica rice cv. Shanyou 63 than in japonica rice cv. 9516 under chill and strong light.     

Changes in Unsaturated Levels of Fatty Acids in Thylakoid PSII Membrane Lipids During Chilling-induced Resistance in Rice

Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non‐freezing temperature, as an inducer of “chilling resistance”, was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j‐9516), the two parental lines of superhigh‐yield hybrid rice between subspecies, Peiai/E32 (ji‐PE), and the traditional indica hybrid rice Shanyou 63 (i‐SY63). Leaves of chill‐treated rice showed chilling‐induced resistance, as an increase of their low‐temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem II (PSII) efficiency. After 5 d of exposure to 11°C under low light (100 μmol m^‐2 s^‐1), levels of unsaturated fatty acids in PSII thylakoid membrane lipids decreased during the initial 1‐2 d, then increased slowly and reached 99.2%, 95.3% and 90.1% of the initial value (0 d) in j‐9516, ji‐PE and i‐SY63, respectively, on the fifth day. However, under medium light (600 μmol m^‐2 s^‐1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1%, 53.8% and 44.5% of the initial values (0 d) in j‐9516, ji‐PE and I‐SY63 on the fifth day. Under either chilling‐induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents, electron transport activities of PSII (ETA), F_v/F_m, xanthophyl cycle activities expressed by DES (deepoxide state) were consistent with that of levels of unsaturated fatty acids in PSII thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling‐induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold‐harden can be enhanced by genetic engineering.     

大豆种子吸胀冷害抗性与其质体膜脂不饱和度正相关

吸胀冷害是干种子在吸胀阶段遭受低温造成不萌发的现象,结果可能造成农作物损失严重。虽然吸胀过程中细胞膜的修复是关键事件,而且细胞膜在响应水分和温度胁迫中扮演重要角色,但是种子吸胀过程中膜变化的过程,特别是膜流动性变化过程研究较少。本文比较了吸胀冷害耐受型（LX）和敏感型（R5）两个大豆品种在吸胀冷害过程中膜脂不饱和度（double bond index, DBI）的变化,结果发现,LX和R5在常温（25℃）吸胀时变化趋势一致,质体膜脂DBI升高,质体外膜脂中磷脂酰甘油(phosphatidylglycerol, PG)分子DBI下降。LX和R5在低温（4℃）吸胀时DBI变化有很大差异,低温吸胀仅仅延缓了耐受型LX中质体膜脂DBI的升高,但是敏感性R5质体膜脂DBI不仅没有升高反而下降。用浓度33%的聚乙二醇 (polyethylene glycol, PEG)引发没有直接引起DBI变化,但是所引起的细微而显著的变化可能为萌发做好准备。PEG引发处理后的R5在吸胀冷害后第二和第三阶段质体膜脂DBI迅速增加,这个增加模式与LX的DBI增加相似。结果表明,吸胀冷害延缓或者阻滞了质体膜脂不饱和度的升高,大豆种子的吸胀冷害抗性与质体膜脂不饱和度正相关,提高质体膜质DBI可以提高吸胀冷害抗性。     

盐胁迫对大麦叶片类囊体膜组成和功能的影响

盐胁迫下大麦叶片类囊体膜蛋白和叶绿素含量以及对绿素a／叶绿素b、磷脂／膜蛋白和膜脂结合半乳糖／膜蛋白的比值下降,膜脂中亚麻酸（18：3）摩尔百分数上升,不饱和指数上升,类囊体膜H －ATPase活性先升后降,希尔反应一直呈较高活性。类囊体膜组分和功能的变化可能与植物盐适应有关。     

Changes in the quantities of violaxanthin de-epoxidase,xanthophylls and ascorbate in spinach upon shift from low to high light

Zeaxanthin, a carotenoid in the xanthophyll cycle, has been suggested to play a role in the protection against photodestruction. We have studied the importance of the parameters involved in zeaxanthin formation by comparing spinach plants grown in low light (100 to 250 mol m^-2 s^-1) to plants transferred to high light (950 mol m^-2 s^-1). Different parameters were followed for a total of 11 days. Our experiments show that violaxanthin de-epoxidase decreased between 15 and 30%, the quantity of xanthophyll cycle pigments doubled to 100 mmol (mol Chl)^-1, corresponding to 27 mol m^-2, and the rate of violaxanthin to zeaxanthin conversion was doubled. Lutein and neoxanthin increased from 50 to 71 mol m^-2 and from 16 to 23 mol m^-2, respectively. On a leaf area basis, chlorophyll and -carotene levels first decreased and then after 4 days increased. The chlorophyll a/b ratio was unchanged. The quantity of ascorbate was doubled to 2 mmol m^-2, corresponding to an estimated increase in the chloroplasts from 25 to 50 mM. In view of our data, we propose that the increase in xanthophyll cycle pigments and ascorbate only partly explain the increased rate of conversion of violaxanthin to zeaxanthin, but the most probable explanation of the faster conversion is an increased accessibility of violaxanthin in the membrane.     

Carotenoids and Environmental Stress in Plants: Significance of Carotenoid-Mediated Modulation of Membrane Physical Properties

Carotenoids, apart of their antenna function in photosynthesis, play an important role in the mechanisms protecting the photosynthetic apparatus against various harmful environmental factors. They protect plants against overexcitation in strong light and dissipate the excess of absorbed energy, they scavenge reactive oxygen species formed during photooxidative stress and moderate the effect of extreme temperatures. One of the important factors involved in the protective action of carotenoids is their influence on the molecular dynamics of membranes. To obtain complex information about interactions between carotenoids and lipids in a membrane, different techniques were used. In this review, the data resulting from EPR–spin label spectrometry, ³¹P- and ¹³C-NMR, differential scanning calorimetry, and computer simulation of the membrane molecular dynamics are presented. The effects of selected, structurally different carotenoid species on various physical parameters of model and natural membranes are described and their relevance to protection against some environmental stresses are discussed.     

光照条件下低温对水稻籼粳亚种幼苗抗氧化物质含量的影响

与对低温不敏感的粳稻台北309和武育粳相比,对低温敏感的籼稻IR64、CA212和Pusa经光照条件下8℃处理后最大光合速率(Pmax)和原初光化学效率(Fv/Fm)下降较多,出现了O2-·、过氧化氢、氧化型谷胱甘肽(GSSG)和氧化型抗坏血酸(DHA)的大量累积,其GSSG和DHA的含量分别与叶绿素含量的下降呈极显著负相关,表明光照条件下低温胁迫下,还原态的谷胱甘肽(GSH)和抗坏血酸的再生受阻,不能有效地清除活性氧,导致其叶绿素含量降低和光合能力受抑,而汕优63的变化位于上述两种类型之间。其中AsA/DHA和GSH/GSSG的变化与叶绿素含量的变化呈极显著正相关。     

发菜类囊体膜色素蛋白复合物分离及其谱性质的研究

Nostoc flagelliforme Born. et Flah is highly adapted to drought stress, cold and light stresses, and suitable for growing in the unfavorable areas. This paper presents the results of the analysis of the membrane (mainly thylakoid membrane) lipids from N. flagelliforme in order to investigate the relationship between membrane lipid composition and stress resistance to this cyanobacteria. The membrane lipids are composed of monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), sulfoquinovosyl diacylglycerol (SQDG) and phosphatidylglycerol (PG). The major fatty acids in these lipids are palmitic (16∶0), palmitoleic (16∶1), stearic (18∶0), oleic (18∶1), linoleic (18∶2) and linolenic (18∶3) acids. In N. flagelliforme, polyunsaturated fatty acids account for 73% of the total fatty acids, much higher than that of the other cyanobacteria reported so far. Among which 16∶1 and 18∶3 are as high as 28.9% and 34.3% respectively. The high resistance of N. flagelliforme to abnormal conditions may be associated with the extent of unsaturation of fatty acids. In addition, the wild N. flagelliforme treated with water for 30 min and cultured for 24 h and the lipid and fatty acid composition were found to be not affected by water-absorption.