低温胁迫下甘肃黄花烟草愈伤组织的抗氰呼吸

继代培养的ｉｃｏｔｉｏｎｏ ｒｕｓｉｔｏａ Ｌ．ｃｖ．Ｇａｎｓｕ Ｙｅｌｌｏｗ Ｆｌｏｗｅｒ）愈伤组织经低温（４℃）处理后,交替途径容量９Ｖａｌｔ）和实际运行量（ρＶａｈ）均被显著地诱导,同时其电子传递途径也在发生交替变化。低温胁迫开始时以细胞色素途径为主,至第２天时则以交替途径为主,并一直持续到第５天,以后则又转为经细胞色素途径为主,而对照却始终以细胞色素途径为主。经放红菌酮或氯霉素处理后,受低     

Studies on the CN-resistant Respiration in Callus of Nicotiana rustica,Gansu Yellow Flower

In attempting to examine whether CN-resistant respiratory pathway is present in callus culture, we used tobacco callus cultures grown on different media. The M-1 medium contained tbe mineral and organic elements of MS medium and was supple,nented with 6-BA (0.5 mg/l) and 2,4-D (2 mg/l), and M-2 medium with 6-BA (2mg/l) and IAi (1 mg/l). No differentiation was observed in both of them. The respiration of M-1 callus was partly resistant to CN, and was markedly inhlbited by m-CLAM in the presence or absence of CN. Experiments of m-CLAM titration showed that the averages of relative contribution of alternative and cytochrome pathway in M-1 callus were 31% awl 46%of the total respiration respectively during the euliure period of 25 days. A same experiment was made on the M-2 callus. It was found that the pereeutages of relative contributions of the two electron transport pathways to the total respiration were approximately the same as those of the M-1 callus, although the respiratory rate was higher in M-2 callus. The above results showed that the bulk of respiratory electron flux was mediated by the eytoehrome pathway, although the alternative pathway was operative in callus of tobacco. The change of exogenous hormones added in the medium could not produee significant effects on the degree of relative contribution of two electron transport pathways under non-differentiation conditions.     

烟草愈伤组织在热胁迫过程中活性氧与抗氰呼吸变化的关系

烟草愈伤组织在 0～ 14h高温 (4 0℃ )胁迫期间 ,其体内的O- ·2 和H2 O2 迅速积累 ,分别在 2和 6h左右达到极大值。同时清除它们的酶SOD和CAT活性迅速上升 ,极大值的分布位置分别为 2和 10h左右 ,而胁迫期间的抗氰呼吸比未胁迫 (0h)时显著地下降 ,但在胁迫期间抗氰呼吸于 6h左右出现一峰值 ;用外源H2 O2 和O- ·2 及清除它们的酶的抑制剂AT和DCC分别处理愈伤组织 ,发现抗氰呼吸明显地加强。推测交替氧化酶可能同抗氧化酶如SOD和CAT一样参与了活性氧的清除 ,提出活性氧含量的变化可能是导致热胁迫过程中抗氰呼吸变化的主要原因之一。     

Changes of the CN-resistant Respiration in Callus Cultures of Nicotiana tabacurn during the Period of Differentiation

The callus cultures obtained from unpollinated young ovaries of willow leaf tobacco were transplanted separately on subculture medium (M-l) and differentiation medium (M-2). They were called M-1 callus and M-2 callus respectively. Only meristematic cells and parenchymas could be observed in M-1 callus. The M-2 callus, however, was able to differentiation into vascular systems, embryoids and bud primordia. The respiration of M-1 callus exhibited CN-insensitive. The relative contributions of alternative pathway and eytochrome pathway to the total respiration were 29–38% and 44–51% respectively during the culture period of 25 days. It was obvious that the bulk of the respiratory electron flux was mediated by the eytochrome pathway. The greater part of the respiration in M-2 callus was insensitive to cyanide. The relative contributions of alternative pathway and cytochrome pathway to the total respiration were 41–47% and 29–32% respectively. These results suggested that the increase in the participation of the alternative pathway in total respiration was probablely related to the differentiation of the callus culture.     

The Relationship Between the Activity of Cyanide-resistant Respiration and the Expression of Alternative Oxidase in Different Organs of Mung Bean Seedlings

Twelve peptides, including eight conservative amino acid residues in the amino acid sequence of hydrophilic S helix of the alternative oxidase (AOX), were synthesized by solid-phase method. The polypeptide was coupled to αchymotrypsinogen, and the antibodies against this complex were obtained in rabbit. By using these antibodies, which were raised to immunoreact with total proteins of purified mitochondria from different organs of mung bean (Phaseolous radiatus L.) seedlings, it was found that there were two hybridizable AOX fractions in the mitochondria of mung bean seedlings. Their molecular weight was about 35 kD and 38 kD, respectively. Moreover, among the respiratory parameters obtained in hypocotyl, true leaf and cotyledon of mung bean seedlings true leaf had the highest total respiration (Vt), alternative pathway (AP) capacity(Valt) and the activity of AP (ρValt). Hypocotyl Vt and ρValt were the lowest, but its Vt was higher than that of the cotyledon. The activities of total and cyanide-resistant respiration were consistant with the analysis of Western blotting of AOX expression. The highest Vt and ρValt in true leaf were accompanied by two hybridizable polypeptides of AOX protein. The next was cotyledon Vt and ρValt with only one 38 kD hybridizable polypeptide of AOX protein. Hypocotyl Vt and ρValt were the lowest and its immunobloting band was similar to that of the cotyledon, but the expression amount of 38 kD protein was less than that of the cotyledon. The 35 kD AOX may make the main contribution to the true leaf ρValt.     

不同低温胁迫对烟草愈伤组织抗氰交替途径诱导和交替氧化酶表达影响的比较

比较了不同低温(14℃和4℃)胁迫对烟草(Nicotiana rusticaL．)愈伤组织抗氰交替途径诱导和交替氧化酶表达的影响。结果显示,不同低温胁迫处理能显著诱导烟草愈伤组织交替途径容量和实际运行的增加,且都呈现出基本相同的变化模式：在胁迫的初期(1—3d)持续增加,在3d时达到最高,而后下降到一个相对恒定的水平。但交替途径容量增加的幅度与温度下降的程度密切相关,而交替途径实际运行量的诱导程度在不同低温胁迫下的差异却很小。表明交替途径容量和实际运行对低温胁迫的响应是不同的。免疫印迹分析结果表明：低温胁迫明显诱导了交替氧化酶总蛋白的增加,且其随低温胁迫进程的变化与交替途径容量的变化基本一致;而对交替氧化酶单体与二聚体在低温胁迫下的含量变化检测结果则显示,烟草愈伤组织中交替氧化酶主要以二聚体形式存在,且这一存在形式并不随低温胁迫程度的加深而发生改变。两种形式的交替氧化酶蛋白含量都能被低温胁迫诱导增加,但其单体水平在两种不同的低温胁迫下并无明显差别,而4℃低温胁迫诱导的二聚体交替氧化酶蛋白含量明显高于14℃。表明不同程度低温对抗氰交替途径发生的不同影响主要是由于对交替氧化酶蛋白二聚体形式的不同诱导程度所致;而高活性的交替氧化酶单体形式则不因低温胁迫程度的加重而被明显诱导升高,使得抗氰交替途径的运行程度在两种不同的低温胁迫处理条件下无显著差异。     

The overexpression of an alternative oxidase gene triggers ozone sensitivity in tobacco plants

The alternative oxidase (AOX) of plant mitochondria transfers electrons from the ubiquinione pool to oxygen without energy conservation and prevents the formation of reactive oxygen species (ROS) when the ubiquinone pool is over-reduced. Thus, AOX may be involved in plant acclimation to a number of oxidative stresses. To test this hypothesis, we exposed wild-type (WT) Xanthi tobacco plants as well as Xanthi plants transformed with the Bright Yellow tobacco AOX1a cDNA with enhanced (SN21 and SN29), and decreased (SN10) AOX capacity to an acute ozone (O3) fumigation. As a result of 5 h of O3 exposition (250 nL L(-1)), SN21 and SN29 plants surprisingly showed localized leaf damage, whereas SN10, similarly to WT plants, was undamaged. In keeping with this observation, WT and SN21 plants differed in their response to O3)for the expression profiles of catalase 1 (CAT1), catalase 2 (CAT2), glutathione peroxidase (GPX) and ascorbate peroxidase (APX) genes, and for the activity of these antioxidant enzymes, which were induced in WT. Concomitantly, although ozone induced H2O2 accumulation in WT and in all transgenic lines, only in transgenics with high AOX capacity the H2O2 level in the post-fumigation period was high. The alternative pathway of WT plants was strongly stimulated by O3, whereas in SN21 plants, the respiratory capacity was always high across the treatment. The present results show that, far from exerting a protective role, the overexpression of AOX triggers an increased O3 sensitivity in tobacco plants. We hypothesize that the AOX overexpression results in a decrease of mitochondrial ROS level that in turn alters the defensive mitochondrial to nucleus signalling pathway that activates ROS scavenging systems.     

Possible Participation of Active Oxygen Species in the Induction of Cyanide-Resistant Pathway at the Initial Senescence of Tobacco Callus

Changes in active oxygen species (AOS) and respiration, with special reference to the alternative pathway of respiration, were followed in callus of tobacco (Nicotiana rusticaL.) during its growth and senescence. Two peaks of the total respiration rate were observed: the first one appeared on day 11, and the second one on day 19 (in senescing callus). H₂O₂and O^– ₂contents increased gradually and reached the greatest values when callus senescence initiated (by day 11 and day 15, respectively), and then declined. The peaks of H₂O₂and O^– ₂before the onset of senescence coincided with the peaks of capacity V _altand activity V _altof alternative pathway, respectively. After the onset of senescence, ·OH accumulated abundantly and maintained at a relatively high level from then on, accompanied by the decrease in both V _altand V _alt. The conclusion is that these three active oxygen species operated coordinately to regulate the alternative pathway during growth and senescence of tobacco callus, as confirmed by the callus treatments with AOS scavengers, exogenous ·OH, and inhibitors of antioxidant enzymes. The possibility of AOS-induced alternative pathway respiration at the initial senescence of tobacco callus is discussed.     

桃芽自然休眠与两条主要电子传递途径变化的关系

花芽和叶芽总呼吸速率最低点均与自然休眠进程有关,第一个与自然休眠的起始时间相对应,最后一个则与自然休眠解除期相对应;细胞色素途径抑制剂氰化钾（KCN）对休眠芽的呼吸起部分抑制作用;抗氰呼吸抑制剂水杨基氧肟酸（salicylhydroxamic acid,SHAM）对总呼吸速率的效应随休眠进程而变化,休眠前期起促进作用,随休眠进程其促进作用逐渐减弱,从可调控休眠期（对外源措施敏感期）起转入抑制效应;KCN＋SHAM混合剂对总呼吸速率的效应与SHAM单独使用的效果相似,但其时总呼吸速率促进作用的起始点和结束点均较SHAM单独使用旱7d左右。     

转柽柳晚期胚胎富集蛋白基因烟草的耐低温性分析

目的:验证转柽柳晚期胚胎富集蛋白(LEA蛋白)基因烟草对低温的忍耐程度。方法:采用低温方式,对转LEA蛋白基因烟草的11个株系及非转基因对照烟草组培苗和大棚盆栽苗进行胁迫处理,测定其相对电导率和丙二醛含量。结果:烟草组培苗在非胁迫条件下,转基因和非转基因对照烟草的相对电导率、丙二醛含量无显著差异;在0℃胁迫条件下,非转基因对照烟草的相对电导率和丙二醛含量均明显高于转基因烟草。大棚盆栽烟草在-4℃条件下,各转基因烟草的相对电导率、丙二醛含量与0℃胁迫时均变化不大;但非转基因对照烟草相对电导率高于0℃胁迫的25.2%,丙二醛含量高于0℃胁迫的59.29%。结论:柽柳LEA蛋白基因的导入提高了烟草的耐低温能力。     

Differentiation in callus cultures of a tobacco (Nicotiana tabacum cv. White Burley) variant: some biochemical aspects

A slow-growing variant plant with distinct foliar and floral morphology was obtained in tissue cultures ofNicotiana tabacum cv. White Burley. The root and shoot differentiation in the callus derived from normal plants occurred on the 8th and 12th day, respectively, but took 10 and 14 days, respectively, in the variant callus. Amylase and acid phosphatase activities, starch and soluble carbohydrate contents were studied in non-differentiating callus (NDC), root differentiating callus (RDC) and shoot differentiating callus (SDC). The activities of amylase and acid phosphatase were low in the variant as compared to normal. Maximum amylase and acid phosphatase activities coincided with the appearance of roots or shoots. There was more starch accumulation in normal callus on differentiating media, but the variant showed a less pronounced change. The normal callus under differentiating conditions also showed more increase in soluble carbohydrates as compared to the variant. The increase in soluble carbohydrate was maintained till roots and shoot appeared. The increase the variant in differentiating was reflected in slow development of enzyme activities and low starch and sugar concentrations.     

低温下水稻幼苗形态生理应变研究

低温下水稻幼苗形态生理应变研究李太贵王磊（中国水稻研究所，杭州３１０００６）ＳｔｕｄｙｏｆＭｏｒｐｈｏＰｈｙｓｉｏｌｏｇｉｃａｌＳｔｒａｉｎｏｆＲｉｃｅＳｅｅｄｌｉｎｇＵｎｄｅｒＬｏｗＴｅｍｐｅｒａｔｕｒｅ．ＬｉＴａｉｇｕｉ，ＷａｎｇＬｅｉ（Ｃｈｉ...     

低温秸秆降解微生物菌剂的研究进展

秸秆的成分主要有纤维素、半纤维素和木质素等,降解秸秆的微生物包括细菌、放线菌和真菌。低温秸秆降解微生物的选育方法有直接从自然界中筛选、诱变育种、原生质体融合育种、基因工程育种等。目前,筛选获得的低温秸秆降解菌株的数量有限,降解秸秆的能力不高,低温条件下菌株的降解机理都需要进一步的研究。综述了低温条件下秸秆降解微生物菌剂的研究进展。     

低温胁迫下不同光照条件对锦熟黄杨抗氧化酶活性的影响

研究了锦熟黄杨（Buxus sempervirens L.）在低温胁迫下不同光照条件（12 h光照/12 h黑暗、24 h全光、24 h全黑）对其抗氧化酶活性的影响,结果表明：低温不同光照条件下细胞膜透性和丙二醛含量均高于对照（20℃ 12 h光照/12 h黑暗）,细胞膜透性和丙二醛含量在5℃ 24 h光照条件下最大;低温胁迫下SOD活性高于对照,并在5℃ 24 h光照条件下达到最高值;CAT的活性仍维持较高水平,5℃ 12 h光照/12 h黑暗显著高于对照及其它处理;在低温有光照条件下,POD活性升高,黑暗条件下POD活性低于对照。低温胁迫下POD、SOD和CAT的活性均呈上升趋势,可能是植株具有较强抗性的原因。     

甘蓝型油菜花粉超低温保存及其花粉活力的研究

研究超低温方法保存油菜花粉过程中的预冻和解冻处理方式对油菜花粉的形态、大小及其活力的影响。结果表明:采用0℃(12h)→-4℃(12h)→-20℃(12h)→-80℃(12h)变温预冻处理和用-80℃(1h)→-20℃(1h)→4℃(1h)逐步解冻后对油菜花粉形态大小和活力影响最小。而经过25℃室温解冻法和42℃快速解冻法处理后油菜花粉出现破裂,破裂率分别达到7.6%和9.1%。同时液氮保存油菜花粉的时间长短对花粉的大小及活力影响不大。     

Visualization of actin cytoskeletal dynamics during the cell cycle in tobacco (Nicotiana tabacum L. cv Bright Yellow) cells

BACKGROUND INFORMATION: The actin cytoskeleton forms distinct actin arrays which fulfil their functions during cell cycle progression. Reorganization of the actin cytoskeleton occurs during transition from one actin array to another. Although actin arrays have been well described during cell cycle progression, the dynamic organization of the actin cytoskeleton during actin array transition remains to be dissected. RESULTS: In the present study, a GFP (green fluorescent protein)-mTalin (mouse talin) fusion gene was introduced into suspension-cultured tobacco BY-2 (Nicotiana tabacum L. cv Bright Yellow) cells by a calli-cocultivation transformation method to visualize the reorganization of the actin cytoskeleton in vivo during the progression of the cell cycle. Typical actin structures were indicated by GFP-mTalin, such as the pre-prophase actin band, mitotic spindle actin filament cage and phragmoplast actin arrays. In addition, dynamic organization of actin filaments was observed during the progression of the cell from metaphase to anaphase. In late metaphase, spindle actin filaments gradually shrank to the equatorial plane along both the long and short axes. Soon after the separation of sister chromosomes, actin filaments aligned in parallel at the cell division plane, forming a cylinder-like structure. During the formation of the cell plate, one cylinder-like structure changed into two cylinder-like structures: the typical actin arrays of the phragmoplast. However, the two actin arrays remained overlapping at the margin of the centrally growing cell plate, forming an actin wreath. When the cell plate matured further, an actin filament network attached to the cell plate was formed. CONCLUSIONS: Our results clearly describe the dynamic organization of the actin cytoskeleton during mitosis and cytokinesis of a plant cell. This demonstrates that GFP-mTalin-transformed tobacco BY-2 cells are a valuable tool to study actin cytoskeleton functions in the plant cell cycle.     

低温下壳聚糖处理对黄瓜幼苗生理生化特性的影响

50 mg/L的壳聚糖处理减轻了低温对黄瓜幼苗膜的伤害,低温(6℃)处理4 d后,幼苗膜透性和MDA含量明显低于对照,并且显著减缓了低温导致的光合速率、实际光化学效率(ФPS Ⅱ)、光化学猝灭系数(qP)和1光系数(F’v /Em’)的下降;同时,处理使抗氧化酶SOD、POD、CAT和APX活性提高,可溶性蛋白和脯胺酸含量增加.因此,壳聚糖处理增强了黄瓜幼苗的抗冷性,保护了膜系统,提高了活性氧清除能力,减轻了低温对光合机构的破坏.     

低温胁迫对建兰叶片内源多胺含量的影响

以素心建兰为材料,研究低温胁迫(5℃)对建兰内源多胺含量的影响。结果表明,在低温胁迫下建兰生长期的叶片多胺(PAs)总量和亚精胺(Spd)、腐胺(Put)含量都表现为先升后降的变化,精胺(Spm)含量则是下降然后上升最后稳定在比原来含量更高的水平上,说明有可能在低温胁迫下建兰通过调节内源多胺的总量和不同多胺种类的比例来抵御低温对生理的破坏作用;开花期的建兰叶片因受低温胁迫的影响未能合成足够的亚精胺(Spd),从而抑制了建兰的开花。     

低温下的绿豆下胚轴细胞超微结构变化

采用透射电子显微镜观察经10℃低温处理2d的绿豆下胚轴细胞超微结构变化的结果表明,细胞受到不同程度的伤害,其中大部分细胞的损伤是可逆的而非致死性的,如内质网膜模糊和呈颗粒状;线粒体呈现不同程度的膨胀,其数量增加,且聚集分布在内质网和高尔基体附近,核糖体聚集成为多聚核糖体等。也有小部分细胞受到的伤害是致死性的,如细胞质电子密度显著升高,质体中淀粉粒过度积累,内质网和高尔基体膨胀和解体,小液泡频繁吞噬细胞质和细胞器,细胞自溶死亡等。