烟草薄层培养器官发生的控制及细胞学观察

普通烟草(Nicotiana tabacum)花梗表皮薄层组织在不同生长素和细胞分裂素配比的MS培养基上及不同的培养条件下,可分别诱导,得到直接发生的营养芽和花芽,以及根和不发生器官分化的愈伤组织。组织间的相互联系,影响器官发育潜能的发挥。细胞学观察发现,直接发生的营养芽和花芽起源于薄层组织的亚表皮细胞层。     

花叶千年木单个生殖器官和营养器官的体外直接再生的控制——单个器官直接再生的规律性

花叶千年木(Dracaena fragrans cv.massangeana Hort．)的各种单个器官(花被片、花芽、花序分枝、花序、成年态营养芽和幼态营养芽)在离体培养中被愈伤组织直接再生了。在这些单个器官的再生期间,一些规律性现象被观察到了。首先,单个再生器官种类的范围与分离外植体的器官在植物个体发育中被分化的时期有密切关系。从植株个体发育某个时期(时期A)分化的地上部分器官上分离的外植体能够分别再生下面这些地上部分器官：稍晚于时期A分化的器官,与时期A同期分化的器官和早于时期A分化的所有器官。其次,在这个范围内,究竟再生哪一种器官被再生取决于培养基中外源生长素的浓度。随着2,4-D浓度从0．005mg／L逐渐升高到0．5mg／L,单个再生器官的种类将按如下的次序变化：营养芽,花序,花序分枝,花芽,花被片。这些规律性现象将被用于诱导一个给定的被子植物地上部分器官的直接再生。     

花叶千年木单个生殖器官和营养器官的体外直接再生的控制--单个器官直接再生的规律性

花叶千年木(Dracaena fragrans cv.massangeana Hort.)的各种单个器官(花被片、花芽、花序分枝、花序、成年态营养芽和幼态营养芽)在离体培养中被愈伤组织直接再生了.在这些单个器官的再生期间,一些规律性现象被观察到了.首先,单个再生器官种类的范围与分离外植体的器官在植物个体发育中被分化的时期有密切关系.从植株个体发育某个时期(时期A)分化的地上部分器官上分离的外植体能够分别再生下面这些地上部分器官:稍晚于时期A分化的器官,与时期A同期分化的器官和早于时期A分化的所有器官.其次,在这个范围内,究竟再生哪一种器官被再生取决于培养基中外源生长素的浓度.随着2,4-D浓度从0.005 mg/L逐渐升高到0.5 mg/L,单个再生器官的种类将按如下的次序变化:营养芽,花序,花序分枝,花芽,花被片.这些规律性现象将被用于诱导一个给定的被子植物地上部分器官的直接再生.     

从植物学角度说核桃

<正>核桃为胡桃科植物,是我国广泛栽培的一种落叶乔木果树。同其他木本植物一样,核桃树有生长器官和结果器官之分。生长器官芽芽是指着生在各种枝条上的芽体。根据芽的性质和特点,分为混合芽(混合花芽)、叶芽(营养芽)、雄花芽和休眠芽(潜伏芽)4种。     

烟草茎薄层培养直接形成花芽及其极性现象(简报)

烟草的表皮薄层组织离体培养在IAA和KT的适当浓度下能直接形成花芽原基或营养芽原基。形成花原基的潜在能力,在花梗区到茎基部有明显的生理梯度。花原基细胞核的DNA含量高于营养芽及愈伤细胞。培养基中IAA和KT浓度相等(10~(-6)mol/L)时,花芽原基发生在外植体的形态学下端,有极性表现。KT浓度提高(10~(-5)mol/L)则两端均发生营养芽原基;KT浓度降低(10~(-7)或5×10~(-7)mol/L)则两端发生愈伤组织,极性消失。     

黄瓜离体子叶节花芽和营养芽分化中CFL基因的表达

CFL基因是从黄瓜中克隆到的拟南芥LEAFY(LFY)同源基因.以离体黄瓜子叶培养物成花为实验体系,利用mRNA原位杂交技术对CFL基因在花芽和营养芽分化过程中的时空表达进行了分析.结果如下:在花芽分化过程中,CFL基因在花原基形成、花器官原基分化及各轮花器官形成之初强表达,在花器官形成以后表达减弱或不表达;在营养芽分化过程中,CFL基因在分生组织、叶原基和幼叶中有明显表达,在成熟组织中不表达.结果说明CFL基因的表达在黄瓜子叶节花芽和营养芽分化中原基的分化形成是必需的.结果提示CFL基因可能参与细胞分裂调控和启动、营养性分生组织向花分生组织转变等过程.     

花生(Aracbis bypogaea L.)胚芽的离体培养

花生的胚芽外植体在附加KT、BA或ZT(2—5毫克/升)的MS培养基上培养时,可从基部切口处分化出具有数量众多的营养芽和花芽的芽簇。将芽簇切开后转移到同样的培养基上继续培养,两种芽都能不断分化。营养芽能够迅速生长成为完整的再生植株。花芽可进一步形成花蕾,并在既无根又无叶片的情况下开花。每天24小时光照,培养基中附加BA,有利于营养芽的分化和生长;而每天12或16小时光照,培养基中附加KT,有利于花芽的分化和开花。花生胚芽的离体培养不仅可为器官分化和开花生理的研究提供一种实验系统,而且可作为快速无性繁殖和种质保存的方法。     

应用整形素处理菠萝花芽诱导营养芽

为了提高菠萝无性繁殖的效率,通称为类植物调节化学药剂的整形素(Morphac-tins),已应用于菠萝花芽上。使用整形素之前先用乙烯利预处理菠萝试验材料的顶端,促使复合花芽同时诱发。由此诱导的花芽用不同浓度的整形素,于不同的发育阶段,用不同的方法再次进行处理。经整形素处理后的菠萝植株由合心皮果的小果上长出许多营养芽。这种现象在天然的菠萝植株里尚未见到自合心皮果发育成营养芽,也未见报道过应用整形素处理其他植物可产生营养芽的情况。本文把这些营养芽暂时命名为"果实芽"。如果乙烯利预处理后6-12天的菠萝再次用80ppm和100ppm浓度的整形素进行处理,那么有80%以上的植株产生"果实芽",从单株(也即单个合心皮果)获得的"果实芽"其平均数在8.8-15.7个之间.获得"果实芽"的最高数量是32个。已经发现花芽发育的某一阶段为整形素激活作用的临界点。这个阶段是合心皮果分化成花原基之前。另外,整形素也会引起诸如裔芽和吸芽自发性营养芽数目的增多,延缓复合花芽的出现,并使处理植株的顶生叶产生卷曲的现象,这就是整形素特有的功能。     

薄层细胞培养在细胞分化研究中的应用

在薄层培养中,不同的器官(如花芽、营养芽、根以及单细胞毛)可以从外植体上直接(不经过愈伤组织)分化出来。在烟草的薄层培养中,所有器官都起源于亚表皮细胞。器官的分化受控于植物激素、糖、多胺、寡聚糖等化学物质以及母体植株的生理状态。环境因素(如光)和生化因素(如核酸、酶)对器官分化影响的研究,都还处于探索性研究阶段。     

大蒜花序轴离体培养器官发生途径的解剖学研究

以大蒜品种‘三月黄’(Allium sativum L.cv. Sanyuehuang)花序轴为外植体进行离体培养,对其器官发生过程进行了形态学和解剖学观察。结果显示:大蒜花序轴离体培养不经过愈伤组织,通过器官直接发生途径形成不定芽,其不定芽起源于大蒜花序轴维管组织韧皮部一侧周围的皮层薄壁细胞,属于外起源;皮层薄壁细胞经脱分化后,由最先形成的拟分生组织发育为茎尖分生组织,然后环绕其形成叶原基,茎尖和叶共同构成一个完整的不定芽;大蒜花序轴离体培养发生的不定芽与花苞中自然形成的营养芽发生部位一致。不定芽通过壮苗、生根培养可正常生根形成植株,如果继代培养周期超过21 d,鳞茎形成率可达90.56%。     

Free and conjugated polyamines during de novo floral and vegetative bud formation in thin cell layers of tobacco

The concentrations of three classes of polyamines, trichloroacetic acid-soluble (free), TCA-soluble conjugated (to small molecules) and TCA-insoluble conjugated (to macromolecules), was examined during de novo floral and vegetative bud formation in thin cell layers of Nicotiana tabacum L. cv. Samsun. Explants (consisting of 5–6 layers of epidermal, subepidermal and parenchyma cells) were excised either from floral pedicels or from stem internodes at the unripe fruit stage and cultured on the same medium. In the former, the first de novo formed flower buds appeared on day 8 of culture, while in the latter the first vegetative domes appeared on day 10. In both cases the number of floral and vegetative buds increased up to day 12 and 15, respectively. Changes in dry weight were determined throughout the culture period. Free and conjugated putrescine titer increased 5–60 times in both types of culture and in the three classes of polyamines examined; spermidine content also increased, while spermine, when present, did not show significant changes. TCA-soluble conjugated polyamines were most abundant, being about 2-fold the TCA-insoluble conjugated ones and 10-fold the free ones. The major increment in putrescine and spermidine content occurred in stem internode explants developing vegetative buds. In pedicel explants the maximum putrescine level was reached before or on day 8 in culture (emergence of the first flower buds with calyx initials), while in stem internode explants the maximum level was reached on day 12, at the emergence of the first vegetative buds with leaf primordia. While spermidine prevailed on day 0, putrescine was the most abundant polyamine during both differentiation processes. The putrescine content rapidly increased immediately after the onset of culture. Thus conjugated polyamines, especially putrescine, and not only the free ones, seem to be involved in both the reproductive and vegetative phases of tobacco growth and development.     

烟草茎薄层芽分化过程内源玉米赤霉烯酮含量的变化(简报)

自李季伦等首次发现越冬的冬小麦茎尖中存在玉米赤霉烯酮(zearalenone,以下简称ZEN)的类似物以后,大量的工作证实了高等植物可内源产生ZEN,并发现ZEN与植物的春化作用,光周期(短日)诱导以及花器官的分化、成熟乃至开花都密切相关。薄细胞层(Thin cell layers,以下简称TCL)具有外植体小和组成均匀,易于进行组织培养、对环     

Changes of Endogenous Hormone Contents During Floral Bud and Vegetative Bud Differentiation in Thin Cell Layer Culture of Cichorium intybus L. Explant

The sectioned thin cell layers (TCL) of flower stalk of Cichorium intybus L. were cultured in MS medium supplemented with NAA and BA or IAA and BA where floral and vegetative buds were developed from the explant. Endogenous IAA, DHZ+DHZR, iPA increased significantly during the floral bud formation, while Z+ZR remained changed. The levels of cytokinins, DHZ +DHZR, iPA, and Z-f-ZR all increased significantly during the vegetative bud formation, however IAA level was reduced during the first 7 days of culture and increased to two-thirds of initial values on the day when the bud primordia were formed. The results suggested that the initiation of floral buds was associated with a high IAA/CTK ratio, whereas the induction of vegetative bud differentiation was related to a low IAA/CTK ratio.     

菊苣薄层培养花芽,营养芽分化中内源激素的动态变化

菊苣（Ｃｉｃｈｏｒｉｕｍ ｉｎｔｙｂｕｓＬ．）花梗薄层细胞培养于ＭＳ附加ＮＡＡ 和ＢＡ 或ＩＡＡ 和ＢＡ 的ＭＳ培养基上有花芽或营养芽分化． 花芽分化中内源ＩＡＡ、ＤＨＺ＋ ＤＨＺＲ、ｉＰＡ 含量明显增加,而Ｚ＋ ＺＲ变化不明显．营养芽分化中内源细胞分裂素含量增加明显,而ＩＡＡ 在培养前７ ｄ 含量下降,随后有所增加,在原基形成时含量达原初水平的２／３． 可见,花芽分化比营养芽分化所需内源ＩＡＡ／ＣＴＫ 比值要高     

Shoot morphogenesis associated with flowering in Populus deltoides (Salicaceae)

Temporal and spatial formation and differentiation of axillary buds in developing shoots of mature eastern cottonwood (Populus deltoides) were investigated. Shoots sequentially initiate early vegetative, floral, and late vegetative buds. Associated with these buds is the formation of three distinct leaf types. In May of the first growing season, the first type begins forming in terminal buds and overwinters as relatively developed foliar structures. These leaves bear early vegetative buds in their axils. The second type forms late in the first growing season in terminal buds. These leaves form floral buds in their axils the second growing season. The floral bud meristems initiate scale leaves in April and begin forming floral meristems in the axils of the bracts in May. The floral meristems subsequently form floral organs by the end of the second growing season. The floral buds overwinter with floral organs, and anthesis occurs in the third growing season. The third type of leaf forms and develops entirely outside the terminal buds in the second growing season. These leaves bear the late vegetative buds in their axils. On the basis of these and other supporting data, we hypothesize a 3-yr flowering cycle as opposed to the traditional 2-yr cycle in eastern cottonwood.     

The accumulation and metabolism of plant growth regulators during organogenesis in cultures of thin cell layers of Nicotiana tabacum

The accumulation and metabolism of exogenously applied and endogenously produced auxins and cytokinins were studied in relation to organogenesis in thin cell layers of Nicotiana tabacum L. It was shown that, in order to obtain maximal flower bud formation, both exogenous auxin and cytokinin needed to be present during the first 4 days of culture (to the formation of a subepidermal meristematic zone) whereas cytokinins needed to be present for at least 4 days more (until formation of organogenic centres). Explants taken from floral branches have higher endogenous indole-3-acetic acid (IAA) levels compared with explants from the basal part of the stem which form only vegetative buds. This might be related to a different IAA metabolism in these two types of explants as was shown by the different accumulation of exogenously applied IAA. Both 'floral' and 'vegetative' cells layers contained comparable amounts of zeatin riboside (ZR) as their major cytokinin. Free bases, zeatin (Z) and dihydrozeatin [(diH)Z], given exogenously, were largely metabolised to their respective ribosides. The observation that Z was less effective than (diH)Z in the induction of flower buds could be related to (diH)ZR apparently not being a substrate for cytokinin oxidase.     

Spermidine and flower-bud differentiation in thin-layer explants of tobacco

Three lines of evidence indicate a connection between high spermidine levels and floral initiation in thin-layer tissue cultures of Wisconsin-38 tobacco (Nicotiana tabacum L.). (1) Spermidine levels are much higher in floral buds than in vegetative buds. (2) Inhibition of spermidine synthesis by cyclohexylamine prevents the rise in spermidine titer, inhibits floral initiation and promotes the formation of vegetative buds instead. (3) Application of exogenous spermidine causes floral initiation in cultures which would otherwise form vegetative buds.     

烟草花柄愈伤组织花芽分化的能力(简报)

来源于开花植株的外植体(如花柄、花序轴等)具有在离体培养条件下直接分化花芽的能力,这一现象已在数十种植物的组织培养中得到证实。但是,这种成花能力能否保留在由这些外植体形成的愈伤组织之中?已有报道在风信子、布罗瓦利亚花、石龙芮、大蒜、矮通泉草等值物的愈伤组织中得到无     

Floral activity in solutions of deoxyribonucleic Acid extracted from tobacco stems

For Nicotiana tabacum cv. Wis. 38 plants, the capabilities of solutions containing DNA, extracted from either homogenates of stems in a floral state or nuclei of stems in a vegetative state, to effect flowering of vegetative plants have been studied. Previous work indicates that the DNA from homogenates of stems in a floral state is mainly nuclear. If DNA solutions are supplied to axillary buds of vegetative plants and if the axillary buds are defoliated every 4th day for 12 days, the buds supplied a solution of DNA from stems in a floral state initiate flowers under noninductive conditions, and the buds supplied a solution of DNA from stems in a vegetative state remain vegetative. Heating and rapidly cooling a solution of DNA from stems in a floral state enhances its floral activity. Heating and cooling a DNA solution also results in novel flowers showing up in many treated plants. Novel flowers are more striking in the offspring than in the parents. The capabilities of heated-cooled DNA solution to initiate flowers in noninductive conditions and to cause novel flowers are eliminated completely by treating (before heating and cooling) the DNA solution with deoxyribonuclease. Heated-cooled solutions of DNA extracted from nuclei of either vegetative stems or vegetative leaves contain no floral activity.