烟草愈伤组织继代培养期间呼吸途径与活性氧水平动态变化

继代培养期间的烟草愈伤组织总呼吸速率分别在第11天和第19天出现两次跃升,同时抗氰呼吸的发生与运行逐渐加强,在两呼吸高峰之间达到极大值,随后则逐渐下降,但愈伤组织的电子传递仍以细胞色素途径为主．通过对愈伤组织衰老过程中活性氧代谢变化分析,发现抗氰呼吸发生与H     

烟草愈伤组织生长和衰老期间呼吸代谢的改变

前人(Ross和Thorpe 1973,Thorpe和Laishley 1973,Brown和Thorpe 1982)曾报道了烟草愈伤组织芽形成期间呼吸速率、线粒体活性、底物代谢途径和有关呼吸酶活性的变化。我们对烟草愈伤组织呼吸代谢的研究证明:组织分化和芽原基的形成与HMP途径运行升高相联系(毕玉蓉和梁厚果1987);愈伤组织的呼吸链存     

甘肃黄花烟草愈伤组织抗氰呼吸的研究

根据呼吸抑制剂试验和氧肟酸滴定法测定结果表明,甘肃黄花烟草愈伤组织呼吸中有明显的抗氰交替途径运行,平均占总呼吸的31%;但仍以细胞色素途径为主,平均占总呼吸的46%;还有23%不受 KCN 加 m-CLAM 抑制的未知剩余呼吸。改变培养基的激素成分和浓度,在不引起愈伤组织发生明显分化条件下,愈伤组织的生长和呼吸速率虽有不同,但抗氰交替途径和细胞色素途径对总呼吸的相对贡献程度和二者的变化趋势基本一致。     

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     

柳叶烟草愈伤组织分化期间抗氰呼吸的改变

继代培养的柳叶烟草愈伤组织有明显的抗氰呼吸。交替途径的相对贡献约占总呼吸的29—38%;但仍以细胞色素途径为主,约占总呼吸的44—51%。接种在分化培养基上的愈伤组织在发生组织分化和芽原基形成期间,交替途径运行量占总呼吸的41—47%,承担呼吸电子传递的主要部分;而细胞色素途径只占总呼吸的29—32%。交替途径运行程度的增高可能与烟草愈伤组织的分化有一定相关性。     

盐胁迫下烟草愈伤组织内源活性氧及乙烯的产生与交替途径发生,？…

This paper reported firstly the dynamic changes of the alternative pathway and the cytochrome pathway in tobacco callus under different concentration of salt. The production rate of endogenous ethylene, the contents of active oxygen species (O2-., .OH and H2O2) and the activities of related enzyme (SOD and CAT) were also investigated simultaneously. The results indicated that the actual operation of the alternative pathway (rho Valt) increased gradually and reached the maxima at 0.75% salt concentration, then declined, while the capacity of the alternative pathway (Valt) didn't exhibit the same change pattern with rho Valt and the cytochrome pathway (rho' Vcyt) changed contrary to rho Valt. At the same time, H2O2 and O2-. accumulated rapidly and reached their peak value at about 0.5% and 0.75% salt concentration respectively, while the content of .OH increased consistently. The production rate of endogenous ethylene increased rapidly and reached its maxima at about 0.5% salt concentration. These data demonstrated that changes of Valt in tobacco callus were associated with a parallel production of H2O2 and endogenous ethylene and a opposite production of .OH, while rho Valt changed parally with the production of O2-.. On the basis of above results, it was deduced that the changes of the development and operation of the alternative pathway in tobacco callus under salt stress might be correlated with the production of endogenous ethylene and the active oxygen species. The possible participation of the alternative pathway in response to salt stress was also discussed.     

烟草愈伤组织继代培养与分化期间核酸代谢的比较研究

Changes in the contents of DNA and RNA, RNA species, the synthesis rates of DNA and RNA, and the activity of DNase and RNase were investigated in the callus of tobacco (Nicotiana tabacum L. cv. Willow Leaf) during subculture and differentiation. The contents of DNA and RNA were higher in differentiating callus than that in subcultured callus. After day 12, the contents of DNA and RNA in differentiating callus rose continuously while the contents of DNA and RNA in subcultured callus remained constant. Changes in RNA species and its relationship to total RNA level were also analyzed. At the stage of shoot primordium formation in differentiating callus, the activity of RNase increased markedly and the synthesis rate of RNA increased continuously; while the RNase activity and the synthesis rate of RNA in subcultured callus were much lower during the same period. During the period of shoot growth, the synthesis rate of DNA in differentiating callus was elevated compared to that in subcultured callus. The results above suggested that the metabolism of nucleic acids in differentiating callus was more active than that in subcultured callus.     

烟草愈伤组织中不被KCN加氧肟酸抑制的剩余呼吸研究

烟草愈伤组织中存在有大约占总呼吸20—30%的不被 KCN 加 m-CLAM 抑制的“剩余呼吸”,它的性质和在细胞中的定位都不清楚。本研究发现,乙醇酸和乙醛酸都明显促进不被KCN(或 NaN_3)加 m-CLAM 抑制的剩余呼吸;乙醇酸听引起的氧吸收和剩余呼吸可被α-羟基乙磺酸钠抑制;线粒体呼吸被 KCN 加 m-CLAM 完全抑制;除去线粒体的上清液中发现有乙醇酸和乙醛酸氧化活性的存在。初步确定,烟草愈伤组织中这部分剩余呼吸主要是由非线粒体乙醇酸氧化酶所催化的。     

Changes in the metabolism of nucleic acids during the growth and senescence of tobacco callus

Changes in DNA and RNA metabolism, DNA composition and RNA species in callus of tobacco ( Nicotiana rustica L. cv. Gansu Yellow Flower) were investigated during the growth and senescence. DNA and RNA contents remained almost unchanged during the callus growth period, but started to decrease synchronously at the time that callus senescence was initiated. Synthesis of DNA and RNA, as measured by incorporation of [³H]-labelled precursor, increased during the growth period and did not decrease until late in senescence. The activities of DNase and RNase (pH 4.5) increased during the early senescence period in accordance with the decrease in the levels of DNA and RNA, but appeared to decrease during late senescence. These results suggest that the decrease in the levels of DNA and RNA in senescing tobacco callus may stem from the increase in the hydrolytic activities of DNase and RNase (pH 4.5) in the early stage of senescence, and that the slowdown of synthesis in the late senescence period may also be a cause. DNA and RNA electrophoresis showed that a low-molecular-weight satellite DNA band disappeared after the onset of senescence and that the nuclear main band DNA gradually decreased, whereas the high-molecular-weight satellite DNA seemed to undergo no significant changes during the senescence period tested. Of the RNA species, 4–5S RNA was far more susceptible to damage during senescence than 25S and 18S rRNA. This suggests different susceptibilities of different DNA and RNA components to damage during the senescence of tobacco callus or alternatively a highly sequenced degradation of DNA and RNA molecules.     

Sucrose metabolism during tobacco callus growth

Activities of soluble and insoluble invertases and sucrose synthetase in tobacco callus increased significantly within the first 3 days of culture. After this period soluble invertase activity declined, while the activities of the insoluble invertase and the sucrose synthetase were relatively unchanged.     

Changes in isoperoxidases during shoot formation in tobacco callus

Summary Shoot formation in tobacco (Nicotiana tabacum L.) callus is accompanied by an increase in peroxidase activity which takes a form similar to a sigmoid curve. The “stationary” phase coincide with the period of organ formation. Characteristic changes in isoperoxidase pattern are found in the shoot-forming part of the callus. These changes are different from those in the nonshoot-forming part or in gibberellin-treated tissue, which does not form shoots.     

Carbohydrate oxidation during Nicotiana tabacum callus growth

Tobacco callus was cultured in light or dark, with or without giberellic acid, and with various carbon sources in the medium, and the growth rate and activities of some enzymes of the Embden-Meyerhof-Parnas and pentose phosphate pathway were determined. No changes in the specific activities of enzymes of either pathway could be correlated with growth but there was a light-dependent stimulation of the pentose phosphate pathway enzymes examined.     

NaCl胁迫下交替呼吸途径对烟草悬浮细胞死亡调节作用的研究

盐分胁迫是植物在自然环境中经常遭遇的环境胁迫因素之一,会引起植物代谢紊乱乃至细胞死亡,这严重限制了植物的生长、繁育和生存。交替呼吸途径是植物较之动物独特的线粒体呼吸途径。该研究在烟草悬浮细胞中调查了交替呼吸途径对Na Cl胁迫引起的植物细胞死亡过程的调节作用及相应的内在机制,以及在200 mmol·L~(-1)Na Cl处理的烟草悬浮细胞中研究了交替呼吸途径和细胞死亡发生及H_2O_2之间的关系。结果表明:(1)随着Na Cl处理浓度的增加,烟草悬浮细胞死亡水平逐渐增加,而交替呼吸途径的容量也逐渐上升。(2)与Na Cl处理相似,外源H_2O_2的处理也能导致烟草悬浮细胞死亡水平的增加。200 mmol·L~(-1)Na Cl的胁迫导致明显的细胞死亡发生和H_2O_2产量的显著性增加;而较之200 mmol·L~(-1)Na Cl胁迫下的细胞,用水杨基氧肟酸(交替呼吸途径的抑制剂)预处理后的细胞再置于200 mmol·L~(-1)Na Cl的胁迫下导致更高水平的细胞死亡和H_2O_2的产生。综上表明,高盐胁迫诱导了烟草悬浮细胞的交替呼吸途径的增加,而交替呼吸途径则可能通过抑制活性氧的产生而起到缓解细胞死亡发生的作用。     

Shoot histogenesis in tobacco callus cultures

Summary The earliest histological event observed in light-grown shoot-forming tobacco (Nicotiana tabacum L. cv. Wisconsin 38) callus was the deposition of safranin-stainable substances (probably suberin) on cut, exposed cell surfaces. This was followed by the initiation of cell files and the appearance of starch granules. Nodules with lignified tracheary elements also were observed in the upper part of the callus. Pronounced starch accumulation occurred in the lower part of the callus in which protrusions of tissue into the medium occurred. Meristemoids were found in these protrusions as well as elsewhere. In between meristemoids, parenchyma cells with starch granules of varying sizes were observed. Cell strands that connected with the meristemoids also were observed. These strands often terminated at the surface of the protrusion at which point shoot apices originated. The earliest shoots were formed in these protrusions. With time, additiional shoots were formed in other parts of the bottom of the callus and finally in the top part of the callus on prolonged culture. The determination of the loci at which shoot primordia were formed sequentially, was interpreted in relation to the physiological gradient concept. This work was carried out while E. M. was a Visiting Scientist at the University of Calgary under the Scientific Exchange Program between the National Research Council of Canada and the Japan Society for the Promotion of Science. Support for this study was provided by N.R.C. (Canada) Grant A-6467 to T. A. T.     

Mitochondrial activity during shoot formation and growth in tobacco callus

Mitochondria isolated from tobacco ( Nicotiana tabacum L. cv. Wisconsin 38) callus growing on either shoot-forming or non-shoot forming medium show an increase in state 3 and state 4 respiration and a drop in respiratory control and ADP/O ratios after subculture. the protein content of the mitochondria fraction and the activity of succinate dehydrogenase, malate dehydrogenase, cytochrome c oxidase and catalase also increase after subculture but there is no apparent difference between shoot-forming and non-shoot-forming tissue. For mitochondria assayed at their native osmolarities, a trend of higher respiration rates and respiratory control as well as lower levels of cyanide-resistant respiration was observed for shoot-forming tissue. Generally, differences were greatest after day 9 in culture, the time during which primordia formation occurred in the shoot-forming callus. These patterns are in concert with the view that the shoot-forming process has a high energy requirement which must be realized during the time of primordia formation.     

Coniferyl alcohol, sinapyl alcohol and scopoletin in tobacco callus tissue during growth of a subculture

Coniferyl and sinapyl alcohols were isolated, identified and quantitatively determined as unbound (or weakly bound) phenylpropanoids in neutral hot-water extracts of Nicotiana tabacum L. callus tissue. This is the first identification of these alcohols in cultured tobacco callus. Scopoletin was also detected in these extracts, and it was the most abundant of these three phenylpropanoids with concentrations that ranged from 50–119 μg/g dry wt. Coniferyl alcohol (17–34 μg/g dry wt.) and sinapyl alcohol (23–35 μg/g dry wt.) were present in nearly equimolar concentration ratios and at levels which were about half those determined for unbound (or weakly bound) scopoletin. The amount of scopoletin extracted increased about 10 times when 1 M HCl-50% methanol - 0.3% ascorbic acid was used as the extractant. This indicated that most scopoletin moieties were strongly bound, perhaps by acid-hydrolyzable linkage. Coniferyl alcohol and sinapyl alcohol were not found in the acid extracts, presumably because they were acid-labile. In general, the concentration of each endogenous unbound (or weakly bound) phenylpropanoid appeared to remain relatively constant throughout the growth phase of the subculture. The only exceptions to this were the relatively higher concentrations of scopoletin and coniferyl alcohol present during the initial 0–2 weeks of subculture.