Developmental Studies on the Seed and Seedling of Aconitum Kusnezoffii Reichb

The seeds of Aconitum kusnezoffii Reichb. take three months to germinate after shedding. This is due to the fact that the embryo of A. kusnezoffii is not fully developed at the time of shedding, remaining in the stage of heart-shaped or early torpedo-shaped embryo. The germination of seed is epigeal, but in the first year the shoot apex remains in the soil and the short subterraneous stem hibernates with the thickened root-hypocotyl. In the following spring, the stem sprouts out and the axillary bud of the first year's radical leaf develops into a monkshood-tuber. The individual monkshood-tuber is monocarpic, each sprouts out one flowering stem and, at the same time, gives rise to one or sometimes more monkshood-tubers from the underground basal buds, thus, A. kusnezoffii may actually be considered as a “replaced biannial plant”.     

怀地黄块根的形态发生和结构发育

观察了怀地黄(Rehmannia glutinosa cv．Hueichingensis Hsiao．)块根的形态发生和生长发育过程中的形态结构变化。采用怀地黄的传统栽培方法,即用上一年的块根作母根进行繁殖,分别从母根和不定芽的茎基部发生不定根。怀地黄不定根的初生结构和维管形成层的发生与一般双子叶植物相同,但其次生生长却有两种方式,即正常次生生长和异常次生生长。一类不定根的形成层产生的次生结构与一般双子叶植物相同,即次生木质部中主要是导管,而薄壁细胞较少。这类不定根其次生生长为正常次生生长(normal secondary growth),是担负吸收和固着作用的正常根。另一种类型的不定根,其形成层产生的次生木质部含有大量的薄壁细胞,少量的导管分散在薄壁细胞之间。这种次生生长为异常次生生长(anomalous secondary growth),从而使不定根膨大,形成块根。因此,怀地黄的药用部分在起源和结构上都属于根的性质,其药用部分应称为块根。     

菊芋试管苗的初代培养及愈伤组织不定芽诱导

菊芋（Helianthus tuberosus Linn.）为菊科（Asteraceae）向日葵属（Helianthus Linn.）多年生草本植物,耐寒、耐旱、耐贫瘠、耐盐碱[1];其地下块茎富含菊糖,还可通过发酵生产乙醇,在功能性食用多糖及生物能源方面的开发潜力巨大。菊芋主要通过块茎进行无性繁殖,其种子成活率和发芽率均很低[2],严重阻碍了菊芋的杂交育种。近年来以植物组织培养为基础的一系列现代育种技术为菊芋的种质改良提供了新途径,但由于菊芋的愈伤组织难以诱导不定芽或体胚发生,导致以农杆菌转化为主的转基因育种技术的应用受到限制。     

Effect of light quality (red: far-red ratio) and defoliation treatments applied at a single phytomer on axillary bud outgrowth in Trifolium repens L.

We studied the effects of light quality and defoliation on the rate of phytomer appearance and axillary bud outgrowth in white clover. The treatments were applied to one phytomer, a phytomer being defined as the structural unit comprising a node, internode, axillary bud, subtending leaf and two nodal root primordia. Light of a low red:far-red (R:FR) ratio (0.27) was applied to a target phytomer either (i) within the apical bud and then to the axillary bud after emergence of the phytomer from the apical bud, or (ii) to the axillary bud only after emergence. The light conditions were directed to these specific parts of the plant by collimating light from small FR light-emitting diodes; with this technique we were able to change the light quality without any change in the level of photosynthetically active radiation. The subtending leaf of the target phytomer was retained or defoliated when it had emerged from the apical bud. FR light applied from the time the phytomer was within the apical bud caused a delay in branch appearance at the target phytomer. In contrast, direct treatment of the axillary bud with FR light after it had emerged from the apical bud did not result in any delay in branch appearance. As the light treatment of the apical bud may have changed the light environment of any of the organs contained in the bud we were unable to ascribe the delay in branch appearance to light perception by any particular organ. However, indirect evidence leads to the conclusion that the likely site of light perception was the developing leaf subtending the axillary bud while it was the outermost phytomer within the apical bud. These results do not support the hypothesis that the R:FR ratio of light incident at an axillary bud site is the environmental factor that controls bud development. Defoliation of the unfolding leaf reduced the rate of phytomer appearance on the main stolon but had no immediate effect on branch appearance. As a consequence there was a reduction in the number of phytomers between the stolon apical meristem and the first phytomer with a branch. This is frequently taken to indicate a relaxation of apical dominance, but in this case was found not to involve a direct effect on bud activity. A current model of white clover growth suggests that there is integration of activity between apical meristems but independence of activity and response to the local micro-environment by axillary buds. In contrast, we found that (i) defoliation reduced phytomer appearance only at the main stolon apical meristem and not at all the meristems in the plant and (ii) that a change in the local light environment of an axillary bud had no discernible effect on bud activity once the bud had emerged from the apical bud but could delay branching if applied before emergence. These results are at variance with the predictions of the model.     

红厚壳茎段丛生芽诱导与植株再生

红厚壳(Calophyllum inophyllum)为藤黄科红厚壳属多年生木本植物,有很高的药用价值。该研究以红厚壳带节茎段为外植体,探讨生长调节剂对腋芽萌发及丛生芽诱导、伸长和试管苗生根的影响。研究结果表明,外植体腋芽萌发和丛生芽诱导效果最好的培养基是MS+NAA1.0+TDZ0.5,在此条件下培养21天后,转入添加0.5 g·L–1活性炭且无生长调节剂的MS培养基,可有效促进不定芽的伸长。将带不定芽的外植体先在附加1.0 mg·L–1NAA的1/2MS培养基上进行生根诱导4周,之后转入附加1.0 g·L–1活性炭的无激素培养基进行根的伸长培养,这样的两步生根法能有效促进红厚壳生根。     

旋扭山绿豆（Desmodium intortum）营养器官的形态解剖特点与高固氮、耐阴和水土保持的关系

旋扭山绿豆（Ｄｅｓｍｏｄｉｕｍｉｎｔｏｒｔｕｍ）不仅是营养价值高的牧草,而且是耐阴、高固氮和适于水土保持的植物。本植物由主根、各级侧根和不定根组成庞大的根系．各种根都可长出根瘤。其根瘤形成时间较早．数量较多．８５％以上为有效根瘤．类菌体力棒形．茎半匍匐,分枝多,复盖面积大,节及节间都能产生不定根。其叶较薄．气孔较少．叶绿体较大．其内淀粉粒少．基粒片层较丰富,因而能耐阴、在２０％遮阴下生长最好。     

A new conception of the shoot of higher plants

According to the classical model, the “shoot” consists only of the categories “caulome” (“stem” sensu lato) and “phyllome” (“leaf” sensu lato), (and “root” in cases of “adventitious” root formation). If lateral shoots are present, their position is axillary. Consequently, caulome as well as phyllome are inserted on the caulome and only on the caulome. This classical model of the shoot has two disadvantages of great consequence: (1) Intermediate organs cannot be accepted as such, but have to be interpreted (i.e. categorized) as either caulome or phyllome (or root) by distortion of the actual similarity. (2) Certain positional changes of organs cannot be accepted as such, but have to be “explained” by congenital fusion. The new conception of the shoot will have the advantages of the classical model but not its disadvantages. Hence, the shoot may consist of the following parts: (main and lateral) shoot, caulome, phyllome, root, emergence, and structures intermediate between (i.e. partially homologous to) any of the preceding. Thus, the five categories of the classical model, namely “shoot”, “caulome”, “phyllome”, “root” and “emergence” are no longer mutually exclusive; they may merge into each other due to an actual or potential continuum. Intermediate organs are therefore accepted as such; for example, an organ may be characterized as an intermediate form between a caulome and a phyllome. Besides intermediate forms, all changes in position are accepted as such. Hence, the following positional relations are possible: caulome and phyllome may be inserted on the caulome, caulome and phyllome may be inserted on the phyllome; roots may be inserted on caulome or phyllome; intermediate forms may be inserted on the caulome, phyllome, or other intermediate forms. Consequences of the new conception for morphological research are pointed out, especially for homologization, evolutionary considerations, and the direction in which research progresses.     

Erratum

The number of nodes produced by a bud meristem before differentiation into a flower is defined as its developmental potential. Decapitation, rooting, and grafting experiments were used to measure the developmental potential of the vegetative axillary bud meristems on Nicotiana tabacum. Decapitation experiments measure the in situ developmental potential while rooting and grafting experiments measure developmental potential in isolation and at a new location on the organism, respectively. A rooted or grafted bud exhibits one of two patterns of development: (1) It develops like an in situ bud or (2) It develops according to its new environment. For example, second axillary buds below the inflorescence produced 18.8 ± 0.8 nodes in situ, 17.9 ± 0.9 or 39.8 ± 1.1 nodes when rooted, and 22.2 ± 0.6 or 34.2 ± 0.7 nodes when grafted to the base of the plant. These results suggest that the buds which develop like in situ buds are developmentally determined while buds that develop according to their new environment are undetermined. On an individual plant, determined and undetermined buds are separated by one internode and only first, second, and third buds below the inflorescence exhibit determination.     

Suppression of a vegetative MADS box gene of potato activates axillary meristem development

Potato MADS box 1 (POTM1) is a member of the SQUAMOSA-like family of plant MADS box genes isolated from an early stage tuber cDNA library. The RNA of POTM1 is most abundant in vegetative meristems of potato (Solanum tuberosum), accumulating specifically in the tunica and corpus layers of the meristem, the procambium, the lamina of new leaves, and newly formed axillary meristems. Transgenic lines with reduced levels of POTM1 mRNA exhibited decreased apical dominance accompanied by a compact growth habit and a reduction in leaf size. Suppression lines produced truncated shoot clusters from stem buds and, in a model system, exhibited enhanced axillary bud growth instead of producing a tuber. This enhanced axillary bud growth was not the result of increased axillary bud formation. Tuber yields were reduced and rooting of cuttings was strongly inhibited in POTM1 suppression lines. Both starch accumulation and the activation of cell division occurred in specific regions of the vegetative meristems of the POTM1 transgenic lines. Cytokinin levels in axillary buds of a transgenic suppression line increased 2- to 3-fold. These results imply that POTM1 mediates the control of axillary bud development by regulating cell growth in vegetative meristems.     

Occurrence of spontaneous shoot regeneration on leaf stipules in relation to hyperflowering response in micropropagated strawberry plantlets

Summary Stipular bud (SB) formation occurred spontaneously on “Gorella” strawberry leaf stipules during proliferation phase on Boxus medium. These buds gave rise to normal shoots on the inner median zone between the stipule tips. Some stipular buds also have been observed on other parts of adaxial surface of the stipule. Stipular bud formation took place directly on the stipule without an intermediate callus. The first stage consisted of subspherical protrusions of small cells which progressively differentiated into shoots that were able to proliferate and to root. Scanning electron microscopy was used to examine the developmental stages of this adventitious organogenesis and to describe morphologic abnormalities, e.g., multiapex formation and fasciation. In vitro cloning of plantlets was made from axillary and SBs produced by the same tufts. The greater flowering abundance of stipular plants resulted in a drastic reduction of the commercial production and the fruit caliber when compared to axillary plants. However, the general phenotype of the mother cultivar (Gorella) was not affected in either case.     

Rapid in vitro propagation of Aloe barbadensis Mill

Axillary bud development and adventitious bud formation was obtained with decapitated shoot explants of Aloe barbadensis Mill. Maximal bud growth and rooting of shoots was obtained on a modified medium of Murashige and Skoog supplemented with 5 M IBA. More adventitious and axillary buds developed on nutrient media supplemented with IBA than with NAA. Axillary buds but not adventitious buds developed with IAA in the medium. Morphogenesis was inhibited by 2,4-D. Kinetin, benzyladenine and thidiazuron were toxic to the explants and did not stimulate the development of axillary of adventitious buds. The optimal temperature for bud growth and development was 25°C. Axillary bud growth and the formation of adventitious buds was slowed down at 10°C and totally inhibited by 30°C. The optimal sucrose concentration was 3% with the inhibition of bud growth and development by higher sucrose levels.     

Influence of Position and Number of Nodal Roots on Outgrowth of Axillary Buds and Development of Branches in Trifolium repens (L.)

The implications of the presence of a root, either at the parentnode or at neighbour nodes, on branch formation of Trifoliumrepens (white clover) was investigated. Plants were freely rootedor rooting was restricted to every sixth or every twelfth nodealong the parent axis. The absence of a root at the parent nodehad little influence on the probability of the subtending axillarybud forming a branch but, on average, delayed the outgrowthof the bud. The probability that an axillary bud, emerging froma non-rooted parent node, developed to a lateral branch (branchwith elongated internodes) decreased with decreasing proximityof the parent node to a rooted node. Lateral branches emergingfrom non-rooted parent nodes which were two nodes distal toa rooted node had a higher rate of node appearance, a greatermean internode length and area per leaf, and were more branchedthan lateral branches emerging from other non-rooted parentnodes. The dry mass of each single root and of branches grownat rooted parent nodes were significantly higher in plants withrestricted rooting than in freely rooted plants. Restrictionin the number of rooted nodes per plant increased the numberof inflorescences. It is concluded that the whole plant responseto restricted root formation was continuous growth of the parentaxis and compensatory growth of the branch at the rooted node.In general, growth was slow for axillary buds whose developmentwas dependent on the basipetal movement or cross-transport withinthe stolons of resources exported from roots. Trifolium repens (L.); white clover; axillary bud outgrowth; branch development; clonal growth; nodal root     

秋水仙素浓度和处理时间对茉莉腋芽生长发育的影响

为了解秋水仙素处理对茉莉﹝Jasminum sambac (Linn.) Aiton〕腋芽生长发育的影响,以长度为0(未萌发)、3~5和8~10 mm腋芽为实验材料,对500、1000和2000 mg·L-1秋水仙素溶液分别处理24和48 h后腋芽的生长状况以及萌发枝条和叶片的生长和发育状况进行分析,同时,对各处理组花粉母细胞的减数分裂行为进行观察;在此基础上,对秋水仙素处理后茉莉腋芽及萌发枝条的各生物学效应指标进行相关性分析。结果显示：经秋水仙素处理后,各处理组腋芽的生长率和处理指数,以及萌发枝条的长度、最大节间长、最大叶长、最大叶宽、现蕾数、现蕾率、最大蕾长、最大蕾宽和开花率总体上显著(P<0.05)低于对照组(用清水处理未萌发腋芽48 h),而腋芽的抑制率和死亡率显著高于对照组。总体上看,随秋水仙素质量浓度提高,腋芽的生长率和处理指数降低,而抑制率和死亡率升高,萌发枝条的长度和最大节间长缩短,开花率升高,其他指标呈波动变化;随处理时间延长,腋芽的生长率、死亡率和处理指数降低,但抑制率升高,萌发枝条仅现蕾数和开花率降低,其他指标均逐渐提高;随腋芽长度增加,腋芽的抑制率和处理指数降低,但死亡率升高,萌发枝条的现蕾率、现蕾数、最大蕾长和开花率均呈波动变化,其他指标均降低。经秋水仙素处理后,茉莉花粉母细胞在减数分裂过程中存在落后染色体、染色体桥和微核等异常现象,且随秋水仙素质量浓度和腋芽长度增加及处理时间延长,减数分裂后期的细胞异常率逐渐升高。相关性分析结果显示：细胞异常率与腋芽生长率呈显著负相关,与腋芽死亡率呈极显著正相关;腋芽生长率与腋芽抑制率和开花率分别呈显著和极显著(P<0.01)负相关;腋芽抑制率与现蕾率呈显著正相关;处理指数与细胞异常率呈极显著负相关。研究结果表明：秋水仙素浓度和处理时间对茉莉腋芽的生长发育有一定影响;综合考虑各生物学效应指标,茉莉腋芽适宜的诱导条件为用500 mg·L-1秋水仙素溶液处理3~5 mm腋芽24 h。此外,建议将处理指数作为秋水仙素对茉莉腋芽细胞减数分裂影响效应的评价指标之一。     

Hormonal Regulation of Lateral Bud (Tiller) Release in Oats (Avena sativa L.)

Stem segments containing a single node and quiescent lateral bud (tiller) were excised from the bases of oat shoots (cv. `Victory') and used to study the effects of plant hormones on release of lateral buds and development of adventitious root primordia. Kinetin (10⁻⁵ and 10⁻⁶ molar) stimulates development of tillers and inhibits development of root primordia, whereas indoleacetic acid (IAA) (10⁻⁵ and 10⁻⁶ molar) causes the reverse effects. Abscisic acid strongly inhibits kinetin-induced tiller bud release and elon-gation and IAA-induced adventitious root development. IAA, in combination with kinetin, also inhibits kinetin-induced bud prophyll (outermost leaf of the axillary bud) elongation. The IAA oxidase cofactor p-coumaric acid stimulates lateral bud release; the auxin transport inhibitor 2,3,5-triiodo-benzoic acid and the antiauxin α (p-chlorophenoxy)-isobutyric acid inhibit IAA-induced adventitious root formation. Gibberellic acid is synergistic with kinetin in the elongation of the bud prophyll. In intact oat plants, tiller release is induced by shoot decapitation, geostimulation, or the emergence of the inflorescence. Results shown support the apical dominance theory, namely, that the cytokinin to auxin ratio plays a decisive role in determining whether tillers are released or adventitious roots develop. They also indicate that abscisic acid and possibly gibberellin may act as modulator hormones in this system.     

Cells within the nodal region of carnation shoots exhibit a high potential for adventitious shoot formation

Adventitious shoot formation was studied with leaf, stem and axillary bud explants of carnation (Dianthus caryophyllus L.). The shoot regeneration procedures were applicable for a wide range of cultivars and shoot regeneration percentages were high for all explant types. Using axillary bud explants, shoot regeneration efficiency was independent of the size of the bud and of its original position in the plant. In contrast, shoot regeneration from stem and leaf explants was strongly dependent on their original position on the plant. The most distal explants (just below the apex) showed the highest level of shoot regeneration. The adventitious shoot primordia developed at the periphery of the stem segment and at the base of leaf explants. In axillary bud, stem and leaf explants, shoot regeneration originated from node cells, located at the transition area between leaf and stem tissue. Moreover, a gradient in shoot regeneration response was observed, increasing towards the apical meristem.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid     

Axillary bud growth in relation to adventitious root formation in cuttings

Single-node leaf-bud cuttings of Schefflera arboricola Hayata and Stephanotis floribunda Brongn. were set and root formation, onset of axillary bud growth and plant height were measured. An increase in the number of roots in Schefflera, which was achieved with increasing cutting position on the stock plant (measured from top to base) or with increasing stem length below the node, accelerated the onset of axillary bud growth and resulted in an increase in plant height. Increasing the number of roots per cutting in Stephanotis through an increase in basal temperature also accelerated bud and shoot growth. Positional effects on root formation in Stephanotis showed no relationship with axillary bud growth and plant height. A positive relationship between number of roots per cutting and axillary bud growth was found among clones of Stephanotis . In general the results suggest that, with some exceptions, the onset of axillary bud growth is accelerated in cuttings as a result of accelerated root formation and a higher number of roots per cutting.     

NODE COUNTING IN AXILLARY BUDS OF NICOTIANA TABACUM CV. WISCONSIN 38, A DAY-NEUTRAL PLANT

A mature, quiescent, primary axillary bud on the main axis of a flowering Nicotiana tabacum cv. Wisconsin 38 plant, when released from apical dominance and before forming its terminal flower, produced a number of nodes which was dependent upon its position on the main axis. Each bud produced about one more node than the next bud above it. The total number of nodes produced by an axillary bud was about 6 to 8 greater than the number of nodes present above this bud on the main axis. At anthesis of the terminal flower on the main axis, mature, quiescent, primary axillary buds had initiated 7 to 9 leaf primordia while secondary axillary buds, sometimes present in addition to the primary ones, had initiated 4 to 5 leaf primordia. When permitted to grow out independently, primary and secondary axillary buds located at the same node on the main axis produced the same number of nodes before forming their terminal flowers. In contrast, immature primary axillary buds which had produced only 5 leaf primordia and which were released from apical dominance prior to the formation of flowers on the main axis produced only as many nodes as would be produced above them on the main axis by the terminal meristem, i.e., “extra” nodes were not produced. Therefore, it is the physiological status of the plant and not the number of nodes on the bud at the time of release from apical dominance that influenced the node-counting process of a bud. When two axillary buds were permitted to develop on the same main axis, each produced the same number of nodes as single axillary buds developing at these nodes. Thus, the counting process in an axillary bud of tobacco is independent of other buds. Axillary buds on main axes of plants that had been placed horizontally produced the same number of nodes as identically-positioned axillary buds on vertical plants, indicating that gravity does not play a major role in the counting, by an axillary bud, of the nodes on the main axis.     

茎杆的第一节间离体再生空心菜

以空心菜（Ipomoea aquatica Forsk.）品种‘白骨柳叶’为材料,通过筛选植物外植体和调整培养基激素配比等方法,首次建立了茎秆第一节间为外植体的空心菜离体再生体系。结果表明,在MS基本培养上添加0.05% 的植物组织培养抗菌剂PPM可获得大量空心菜无菌苗;植株子叶和下胚轴的切段均未诱导出不定芽,而茎秆第一节间为外植体能成功诱导出不定芽,诱导成功率为20%,最佳培养基配方为MS+1.0 mg/L 6-BA+0.1 mg/L IAA;不定芽诱导生根的最佳培养基配方为1/2 MS+0.1 mg/L NAA,生根率为100%。诱导成功后,将完整的再生苗移栽至基质土中,成活率可达100%。     

圆叶蔓绿绒快速繁殖条件的优化

以带侧芽茎段为外植体,对圆叶蔓绿绒组织培养及快速繁殖的研究表明,不同生长调节剂组合对圆叶蔓绿绒的离体形态发育及增殖均有重要影响。其中适合侧芽生长和不定芽分化的组合为BA 3.0mg/L+ IAA 0.5mg/L。采用BA 0.8mg/L+ KT 0.8mg/L+IAA 0.05mg/L的组合可在4周内可获得7.0的增殖系数。培养基中添加适量活性炭对生根有促进作用。适宜量为1.0g/L。