Evidence that cytokinin controls bud size and branch form in Norway spruce

Shoot elongation in many coniferous species is predetermined during bud formation the year before the shoot extends. This implies that formation of the primordial shoot within the bud is the primary event in annual shoot growth. Hormonal factors regulating bud formation are consequently of utmost importance. We followed the levels of the endogenous cytokinins zeatin riboside (ZR) and isopentenyladenosine (iPA) in terminal buds, whorl buds and lower lateral buds of the uppermost current-year whorl shoots of 15- to 20-year-old trees of Norway spruce [ Picea abies (L.) Karst.] from June to September. Cytokinins were isolated with affinity chromatography columns, purified by high performance liquid chromatography, and quantified by ELISA. The level of ZR was low in June but increased gradually in all buds until September. Throughout the measurement period, the ZR level was highest in terminal buds and lowest in the scattered lateral, buds, with the whorl buds intermediate. The level of iPA peaked in July and decreased later without any consistent differences among the three classes of buds. The development of different kinds of buds was followed by scanning electron microscopy. We found that bud growth was greatest during August and September. The final size of primordial shoots within the buds varied considerably and the weight of the terminal bud was three times that of the whorl buds and more than five times that of the other lateral buds.
We conclude that the increase in ZR level during the period of active bud development is indicative of the importance of cytokinin for this process. Furthermore, the positive correlation between the level of ZR and bud growth during the period of predetermination of next year's branch growth suggests that this hormone indirectly controls the form of single branches in the spruce tree.     

Studies on the Active Changes of GA3 and Cytokinins During Development and Ripening in Seabuckthorn Fruits

The phenological stages in seabuckthorn (Hippophae rhamnoides L. Subsp. sinensis Rousi and H. thibetana Schlechted) distributed naturally over an area of Wushao ridge were observed. The changes in levels of endogenous phytohormones GA3, iPA, zeatin, IAA and ABA were investigated systematically during development and ripening periods in the two sorts of fruits. The results showed that two peak values of GA3 level in seeds were detected (in 105—109 days and 128--132 days after anthesis). The first peak value of isopentenyl adenine (IPA) in seeds was determined in 92--96 days when the fruit was starting to change its colour and just right now the zeatin first appeared. The iPA content reached the second peak value in 127-136 days after anthesis during fruit full ripening and beginning to deciduous leaf and the maximum of zeatin in seeds appeared near the same time (in 127 days after anthesis). It was remarkable that the zeatin content in fruit stalk and flesh still was kept on high level, in the meantime the zeatin level in seeds dropped down rapidly. Based on the facts that the time of the first peak value in GA3 and iPA level is close to the date when ABA is first detected, and the date of second peak value in GA3, iPA and IAA is coincident with the time of maximum in ABA and zeatin levels make it reasonable to consider that the balance of phytohormones may be more important than absolute amounts of any single hormone during the periods of fruit development and ripening, and meanwhile it also proved that GA3 and CTK play an important regulatory role in controlling fruit ripening and colour changing process of seabuckthorn fruit.     

烟草传粉前后生殖器官中细胞分裂素含量的变化

经免疫亲和层析系统纯化后,用间接竞争ＥＬＩＳＡ 法测定了烟草（Ｎｉｃｏｔｉａｎａ ｔａｂａｃｕｍ ）生殖器官在传粉前后细胞分裂素（ｔ－ＺＲ,ｉＰＡ）含量的变化． 开花前５ ｄ,花药和花丝中的细胞分裂素（ＣＴＫ）含量均达到最高值,以后随雄蕊发育逐渐下降． 授粉使花柱ＣＴＫ 含量急剧上升,授粉后１ ｄ 达到高峰,未经受粉的花柱ＣＴＫ 开花后下降．授粉后２ ｄ,子房中的ＣＴＫ 开始上升,在授粉后４ ｄ 达到最高值,而未受精的子房ＣＴＫ 含量开花后下降． 传粉后雌蕊中ＣＴＫ含量随花粉管生长而有规律地增加,ＣＴＫ 积极参与植物的传粉和受精过程     

Change in Cytokinin Levels in Reproductive Organs of Nicotiana tabacum Before and After Pollination

Immunoaffinity systems and indirect competitive ELISA were used to determine the changes of cytokinin (CTK) content in reproductive organs of Nicotiana tabacum before and after pollination. It was found that t-ZR and iPA existed in all reproductive organs tested, and their contents were higher in female than in male organs. On the 5th day before anthesis. CTK reached its peak value in anthers and filaments, then it declined. In styles, CTK content increased after pollination and reached its peak one day later. In ovaries, levels of CTK began to increase two days after pollination and reached its peak two days later, just at the time when fertilization took place. If unpollinated, CTK levels decreased both in styles and ovaries. Pollination and fertilization resulted in an increment of CTK in pistils, accompanied with the process of pollen germinfition and pollen tube growth. It could thus be inferred that t-ZR and iPA played some active role in pollination and fertilization.     

Evidence that cytokinin controls bud size and branch form in Norway spruce

Shoot elongation in many coniferous species is predetermined during bud formation the year before the shoot extends. This implies that formation of the primordial shoot within the bud is the primary event in annual shoot growth. Hormonal factors regulating bud formation are consequently of utmost importance. We followed the levels of the endogenous cytokinins zeatin riboside (ZR) and isopentenyladenosine (iPA) in terminal buds, whorl buds and lower lateral buds of the uppermost current-year whorl shoots of 15- to 20-year-old trees of Norway spruce [ Picea abies (L.) Karst.] from June to September. Cytokinins were isolated with affinity chromatography columns, purified by high performance liquid chromatography, and quantified by ELISA. The level of ZR was low in June but increased gradually in all buds until September. Throughout the measurement period, the ZR level was highest in terminal buds and lowest in the scattered lateral, buds, with the whorl buds intermediate. The level of iPA peaked in July and decreased later without any consistent differences among the three classes of buds. The development of different kinds of buds was followed by scanning electron microscopy. We found that bud growth was greatest during August and September. The final size of primordial shoots within the buds varied considerably and the weight of the terminal bud was three times that of the whorl buds and more than five times that of the other lateral buds.
We conclude that the increase in ZR level during the period of active bud development is indicative of the importance of cytokinin for this process. Furthermore, the positive correlation between the level of ZR and bud growth during the period of predetermination of next year's branch growth suggests that this hormone indirectly controls the form of single branches in the spruce tree.     

多胺对菊花激素含量与花芽分化的影响

以切花菊（Dendranthema morifolium）品种‘神马’为试材,外源喷施0．1mmol·L-1的亚精胺（Spd）与多胺合成抑制剂D-精氨酸（D．Arg）,转入昼10h／夜14h的短日条件下进行开花诱导,测定不同花芽分化时期顶芽内源多胺[腐胺（Put）、亚精胺（Spd）、精胺（spm）]和几种激素[生长素（IAA）、玉米素核苷（ZR）、异戊烯基腺苷（iPA）、赤霉素（GA）]含量的动态变化,分析多胺对激素和花芽分化的作用关系。结果表明,外源多胺和多胺合成抑制剂能够显著影响顶芽内源多胺（Put、Spd、Spm）和激素（IAA、ZR、iPA、GA）的含量,顶芽内高水平多胺有利于菊花花芽分化的启动和保持;外源多胺及多胺合成抑制剂可能通过影响内源多胺含量从而影响内源激素或者直接影响内源激素和内源多胺,进而调控花芽分化：内源Put与IAA关系密切,高水平的内源Put不利于IAA的积累;ZR和iPA含量与内源多胺总量的变化趋势一致;外源多胺及多胺合成抑制剂对GA的影响主要在花序分化期和小花分化期,且高水平的内源Spd和Put不利于GA的积累。     

云南黑籽南瓜砧木对低温下嫁接黄瓜生理特性的影响

以‘津研4号’黄瓜(Cucumis sativus‘Jinyan No.4’)为接穗,云南黑籽南瓜(Cucurbita ficifoliaBouch啨)和黄瓜为砧木,研究了低温条件下黄瓜/云南黑籽南瓜嫁接株(黄瓜/南瓜)、黄瓜/黄瓜嫁接株和自根黄瓜株叶片的蔗糖(Suc)、葡萄糖(Glc)和可溶性蛋白质(Pr)含量的变化以及叶片羧化效率(CE)及不同叶位叶片、不同节位茎段中异戊烯基腺嘌呤核苷(iPA)含量的差异。结果表明,黄瓜/南瓜嫁接株叶片的Suc、Glc及Pr含量和CE值均显著高于自根黄瓜株和黄瓜/黄瓜嫁接株,自根黄瓜株与黄瓜/黄瓜嫁接株间差异不显著。iPA在嫁接植株和自根植株茎中均呈梯度分布,其含量在生长锥中最高,其次为上部茎段,下部茎段中的含量最低;自根黄瓜株和黄瓜/黄瓜嫁接株茎中的iPA含量显著低于黄瓜/南瓜嫁接株,而叶片中iPA含量显著高于黄瓜/南瓜嫁接株。研究结果表明,以黑籽南瓜为砧木可提高嫁接黄瓜对低温的耐受性。     

Unique presence of 2-methylthio-ribosylzeatin in the transfer ribonucleic acid of the bacterium Pseudomonas aeruginosa

Analysis of ³⁵S labled nucleosides prepared from tRNA of Pseudomonas aeruginosa by phosphocellulose column chromatography, thin layer chromatography and Sephadex LH-20 column chromatography revealed the presence of 2-methylthioribosylzeatin in it.     

Amperometric immunosensor based on polypyrrole/poly(m-pheylenediamine) multilayer on glassy carbon electrode for cytokinin N6-(Delta2-isopentenyl) adenosine assay

A novel immunosensor based on a multilayer-coated glassy carbon electrode was designed to determine isopentenyl adenosine (iPA) in plants. The multilayer consists of polypyrrole and poly(m-phenylenediamine) with K4Fe(CN)6 and horseradish peroxidase (HRP) entrapped during electropolymerization. The ferrocyanide doped in polypyrrole functions as the mediator. The glucose oxidase bound on the immunosensor by the competitive immunoreaction involving iPA catalyzed the oxidation of the added glucose with the formation of H2O2, which is in turn reduced in the presence of HRP entrapped in poly(m-phenylenediamine). The current of the oxidized production of ferrocyanide reduced at -50 mV is inversely proportional to the concentration of iPA in the competitive immunoreaction. This immunosensor is able to be used about 40 times; after that its surface can be regenerated for a new immunosensor assembly by washing with 0.1M citrate-phosphate buffer (pH 4.6). The percentage of current response reduction (CR%) (y) is linearly related to the logarithm of the concentration of iPA (x) in the 5-300 microg/ml range, with a regression equation of the form y = 42.13x - 27.79 and a correlation coefficient of 0.9861. Five hybrid rice grain samples were analyzed with results in satisfactory agreement to those obtained by high-performance liquid chromatography.