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.     

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     

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.     

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.     

Flower Formation in Excised Tobacco Stem Segments: III. Deoxyribonucleic Acid Content in Stem Tissue of Vegetative and Flowering Tobacco Plants

A method has been developed that extracts DNA from stem tissue of flowering tobacco plants, Nicotiana tabacum cv. Wis. 38. The DNA content of stem tissue from a flowering tobacco plant is correlated with its capacity to flower in vitro. Stem segments known to form 100% floral buds contain 10 times more DNA per gram fresh weight than segments that form 5% floral buds and 95% vegetative buds, and in the uppermost 28 centimeters of flowering tobacco plant stems the DNA content decreases roughly in parallel with the floral gradient.     

Hormonal Profile in Vegetative and Floral Buds of Azalea: Levels of Polyamines, Gibberellins, and Cytokinins

The floral transition includes a complex system of factors that interact and involve various biochemical signals, including plant growth regulators. The physiological signals involved in the control of the floral transition have been sparsely studied and mainly in plant species whose genetics are poorly known. In this work, the role of polyamines, gibberellins, and cytokinins was investigated by analyzing their endogenous content in vegetative and floral buds of azalea. The results showed that there is a clear distinction between floral and vegetative buds with respect to the levels of these plant hormones, with floral buds containing higher amounts of conjugated polyamines, gibberellins (GAs) from the non-13-hydroxylation pathway (GA₉, GA₇, and GA₄), and cytokinins (particularly isopentenyl-type species), and vegetative buds containing higher amounts of free polyamines and gibberellins from the early 13-hydroxylation pathway and fewer cytokinins. In conclusion, there is a specific pattern of endogenous hormone profiles in both vegetative and floral bud development in azalea, which may be relevant for future research on the control of flowering by exogenous hormone applications.     

In vitro formation and development of floral buds on tobacco stem explants: effects of kinetin and other factors

Stem segments were excised from plants of Wisconsin 38 tobacco (Nicotiana tabacum L.) in three regions differing in their distance below the inflorescence. They were cultured in vitro in 8- or 16-hr days. After 8 weeks, floral and vegetative buds were counted, and extent of floral development was assessed. Kinetin at 10(-5)m inhibited formation and development of floral buds regardless of indoleacetic acid concentration. Supplied at this concentration with adequate auxin, kinetin stimulated vegetative bud formation and may have caused floral bud abortion. Indoleacetic acid (>/= 10(-6)m) inhibited vegetative and floral bud formation when supplied with low kinetin concentration (/= 10(-6)m), it inhibited floral bud formation and stimulated vegetative bud formation. More floral buds were formed in 16-hr days than in 8-hr days. Few formed on explants other than those derived from the region nearest the inflorescence regardless of other treatment.     

赤霉素对大岩桐花蕾离体培养直接再生花芽的影响（简报）

植物经过一定时期的营养生长(或感受外界信号)后,就能产生成花刺激物。成花刺激物被运输到茎尖,诱导发生一系列的反应。随后其分生组织在一定时期内处于一个相对稳定的状态,即成花决定态。植物成花决定态建立的过程称为成花决定。对成花决定的研究进行了许多年,但是其确切的机理仍不清楚.     

Floral bud reversion in Impatiens balsamina under non-inductive photoperiods

Summary All floral buds of Impatiens balsamina plants exposed to 4 short-day (SD) cycles and then returned to long days reverted to vegetative growth. The same happened with the upper buds of plants receiving a larger number of SDs, even as many as 90 cycles. The reversal proceeded in a basipetal order. The number of floral buds and flowers increased, and their reversion to vegetative growth was delayed with increasing numbers of SD cycles. Depending upon the stage attained by the floral bud before the transfer of the plant to noninductive photoperiods one or more inner whorls of the flower were replaced by a vegetative apex. The tip of the placenta was able to resume vegetative growth even after the formation of fertile anthers and an ovary with abortive ovules, showing that the potentiality for reversion is maintained till quite late stages in floral bud development. Continuous exposure to SD cycles is required not only for the continued production of floral buds, but also for their development to mature flowers, indicating that the floral stimulus in this plant is not self-perpetuating.     

枇杷成花过程叶片蛋白质变化动态

研究了温室内水分胁迫下盆栽枇杷和大田枇杷的成花和未成花枝梢叶片可溶性蛋白质含量在花芽分化过程中的变化动态,同时对成花和未成花枝梢顶芽进行特异蛋白双向凝胶电泳研究。结果表明,枇杷成花诱导需经历可溶性蛋白质含量一定程度的升高,然后急剧下降的过程,即可溶性蛋白质的升高对应成花诱导,而蛋白质的下降与形态分化紧密相关。成花植株枝梢顶芽与未成花植株枝梢顶芽的2-DE图谱总模式相同,但前者比后者多了两种蛋白质,其分子量和等电点一为MW 14110.5±110.8、pI 5.350±0.008,另一为MW 66446.3±260.9、pI 4.730±0.032,两种蛋白质均呈酸性,可能与枇杷成花密切相关。     

赤霉素对大岩桐花蕾离体培养直接再生花芽的影响(简报)

植物经过一定时期的营养生长(或感受外界信号)后,就能产生成花刺激物。成花刺激物被运输到茎尖,诱导发生一系列的反应。随后其分生组织在一定时期内处于一个相对稳定的状态,即成花决定态。植物成花决定态建立的过程称为成花决定。对     

Phénolamides et induction florale de Cichorium intybus dans différentes conditions de culture en serre ou in vitro

Phenolamides and floral induction of Cichorium intybus in different conditions of culture in glass-room or in vitro. Three complexes between phenols and amines (phenolamides) have been found in Cichorium intybus L., a plant with an absolute requirement of vernalisation followed by long days for flowering. Upon hydrolysis, these complexes (A, B and C) liberate aromatic amines whose exact identification is in progress, but which are closely related to dopamine, tyramine and serotonin, respectively. In a first series of experiments, phenolamides were studied in the buds of plants grown in the greenhouse under varying conditions. Only buds from plants which flower in long days contained large amounts of these compounds. Much smaller amounts were found in buds at the end of vernalisation (at 2–4°C) before long-day treatment as well as in buds kept in the vegetative state after vernalisation by being grown in short days (8 h light) or in total darkness. In a second series of experiments, phenolamides were studied in bud-forming calli induced in vitro on explants of tuberised root. After sixteen days of culture in continuous light, large quantities of phenolamide were found in the buds and calli of the upper part of the explant, while the lower part which never produces buds contained much less. Buds formed under continuous light produce inflorescences in approximately one month. Various other culture conditions make it possible to maintain the explants in the vegetative state. This can be obtained by short-day conditions, or otherwise under continuous illumination by decreasing the sugar or increasing the NAA levels in the medium. After 13 days of culture, the phenolamide levels were much lower under all of these conditions, than under conditions favourable to floral induction. Compound C is absent or present in trace amounts in vegetative buds. The significance of the differences observed between floral and vegetative buds is supported by the sensitivity of the analytical techniques used. The accumulation of phenolamides in tissues of Cichorium intybus appears to be closely linked to floral induction. Under continuous light it begins very early in young buds and even in the calli that bear these buds.     

Further experiments on spermidine-mediated floral-bud formation in thin-layer explants of Wisconsin 38 tobacco

We studied the effects of various polyamines on bud regeneration in thin-layer tissue explants of vegetative and floweringNicotiana tabacum L. cv. Wisconsin 38, in which application of exogenous spermidine (Spd) to vegetative cultures causes the initiation and development of some flower buds (Kaur-Sawhney et al. 1988 Planta173, 282). We now show that this effect is dependent on the time and duration of application, Spd being required from the start of the cultures for about three weeks. Neither putrescine nor spermine is effective in the concentration range tested. Spermidine cannot replace kinetin (N⁶-furfurylaminopurine) in cultures at the time of floral bud formation, but once the buds are initiated in the presence of kinetin, addition of Spd to the medium greatly increases the number of floral buds that develop into normal flowers. Addition of Spd to similar cultures derived from young, non-flowering plants did not cause the appearance of floral buds but rather induced a profusion of vegetative buds. These results indicate a morphogenetic role of Spd in bud differentiation. Dedicated to Professor Hans Mohr on the occasion of his 60th birthday     

Photoperiodic studies on growth and development of Impatiens balsamina L.

Summary Seedlings of Impatiens balsamina raised under ND and LD conditions were divided into two sub-groups each when they had reached 5-leaf stage. While one sub-group was left under the same condition (NDND or LDLD), the other was transferred to the other photoperiod (NDLD or LDND). NDND plants were subdivided into 2 lots. One of these was transferred to SD in May. The dates of emergence of individual branches and floral buds were recorded and the vegetative period was calculated in each case.It was found that in NDND plants floral buds were produced from all the nodes except the lowermost which produced a single vegetative branch. In LDND plants the vegetative branches were produced from the lower 9 nodes but floral buds from those above these. Small leafy structures which ultimately dried up were produced from a few top nodes in both these cases. In contrast to this in LDLD plants only vegetative branches were produced from all the nodes. In NDLD plants floral buds were produced from the lower 3–5 nodes prior to transfer to LD condition, but vegetative branches were produced from the upper nodes after this transfer. Even some of the lower floral buds reverted to vegetative state under this condition.The production of floral buds or the vegetative branches as the case may be, occurred in acropetal succession under all the photoperiodic conditions and never in basipetal manner.LDLD and NDLD plants, which did not flower at all, continued to produce lateral branches without showing any sign of senescence, while LDND and NDND ones showed yellowing of the apical growing point which spread downwards and lead ultimately to the death of the plant. The senescence was hastened when these plants were transferred to SD condition towards the end of May. The senescence therefore, appears to be related with reproductive development. The results are discussed in the light of current literature.     

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.     

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。     

Influence des racines sur le développement végétatif ou floral des bourgeons cotylédonaires chez le Scrofularia arguta: role possible des cytokinines

Influence of roots on the vegetative or floral development of cotyledonary buds of Scrofularia arguta Sol.: A possible cytokinin role. This study shows that the presence of “nonabsorbing roots” insures a vegetative development of cotyledonary buds cultured in vitro whereas buds growing without roots produce flowers early. In the same way, roots suppress floral expression of axillary meristems of the same cotyledonary buds and induce these buds to vegetative functioning. Various trophic modifications in the culture medium are ineffective on non-rooted buds as also are gibberellin As and adenine. On the contrary, several cytokinins (kinetin, benzyladenine and zeatin) exert the same influence as roots. These results suggest that roots regulate meristematic functioning through cytokinins.     

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。