Flower Formation from Citrus unshiu Buds Cultured In Vitro

Flowers were formed in vitro when buds of Satsuma mandarin (Citrusunshiu Mare) from the summer flush of growth harvested duringthe winter rest period before the onset of flower initiation,were grown on a solid Murashige and Skoog medium supplementedwith sucrose and a cytokinin. Flower development was dependentupon illumination, and was enhanced when a piece of stem wasattached to the bud. The percentage of flowering explants wasalways lower than the percentage of naturally flowering budsin spring, but treatments such as ringing which increase floweringin vitro, increased the number of explants flowering int vitroas well. Citrus unshiu Marc, ‘Satsuma’ mandarin, in vitro flowering, ringing     

连翘花蕾与花的挥发性成分研究

本文采用顶空固相微萃取和气相色谱质谱联用(HS-SPME-GC-MS)技术比较分析了连翘花蕾和花的挥发性成分。从连翘花蕾和花中共鉴定了83个化合物,其中40个化合物是共有的。连翘花蕾的挥发性成分以烃类(41.04%)为主,而连翘花的挥发性成分以醇、醛和酮类化合物(26.46%)为主;酯类化合物在花蕾中的含量为8.11%,在花中下降到2.12%;而酸类化合物则从3.56%上升到5.18%。结果表明,随着花蕾的开放,酯类成分逐渐被水解为酸。     

连翘花的结构与繁育系统研究

通过定株观察、解剖和人工套袋交叉授粉试验对连翘花的生长发育和繁殖系统进行研究.结果表明:(1)连翘具有2种避免自交的方式,雌雄异位和雌雄异熟.其雌雄异位表现为长雄蕊短雌蕊花型和短雄蕊长雌蕊花型;雌雄异熟表现为长雄蕊短雌蕊花型为雄蕊先于雌蕊成熟,短雄蕊长雌蕊花型表现为雌蕊先于雄蕊成熟.(2)连翘花P/O值测定和户外套袋交叉授粉试验显示,P/O值为2 000±300;不同类型花的异花授粉结果率在50.64%~80.32%,其中短型花的花粉授到长型花柱头的结果率最高,达80.32%,而长型花和短型花的同型花授粉结果率分别为2.92%和34.15%,表明连翘的异花授粉结果率高于自花授粉,以异交为主,其繁育系统属兼性异交.研究结果认为,连翘雌雄异位和雌雄异熟是其自然结果率低下的主要原因,为进一步探讨连翘在木犀科中的系统进化提供了生殖生态学的依据.     

蝴蝶兰快速繁殖及花芽诱导(简报)

以Hyponex为基本培养基,蝴蝶兰杂交后代种子[Dtps.Taisuco Happy Smile‘Ta Bei chou’×(Dtps.Taisuco Firebird×P.New Cinderella)]在不加生长调节剂的条件下萌发率达80%,添加适宜浓度的NAA和BA均能诱导出芽并增殖生根。实生苗经预处理后,再转入附加BA和TDZ的VW培养基中培养可诱导出花芽,若辅以低温处理,花芽诱导率可提高至51.7%。     

Biosynthesis of Caffeine in Flower Buds of Camellia sinensis

The biosynthesis of purine alkaloids in flower buds of tea plantswas investigated. More than 25% of total radioactivity of [8-¹⁴C]adeninetaken up by stamens isolated from tea flower buds was foundto have been incorporated into purine alkaloids, namely, theobromineand caffeine, 24 h after administration of the labelled compound.Pulse-chase experiments indicated that [8-¹⁴C]adenine takenup by the stamens was converted to adenine nucleotides and subsequentlyincorporated into theobromine and caffeine. Since 5 µMcoformycin, an inhibitor of AMP deaminase, inhibited the incorporationof radioactivity into the purine alkaloids, synthesis of caffeinefrom adenine nucleotides seems to be initiated by the reactionof AMP deaminase. Although most of the radioactivity from [8-¹⁴C]inosinewas recovered as CO₂ and ureides, considerable amounts of radioactivitywere recovered as purine alkaloids. The incorporation of radioactivityfrom [8-¹⁴C]inosine into the purine alkaloids was not affectedby coformycin. The five enzymes involved in synthesis of 5-phosphoribosyl-1-pyrophosphatefrom glucose were present in the stamens and petals of tea flowerbuds. From present and previous results, the pathway for thebiosynthesis of caffeine from adenine nucleotides in flowerbuds of tea is discussed.Copyright 1993, 1999 Academic Press Camellia sinensis, tea, stamen, flower, biosynthesis, purine alkaloids, caffeine, theobromine, adenine nucleotides, nucleotide biosynthesis     

Hormonal Regulation of Pedicel Abscission in Begonia Flower Buds

In order to analyse the hormonal regulation of flower bud shedding in Begonia, levels of indoleacetic acid (IAA), abscisic acid (ABA) and ethylene were determined in buds and pedicels. The translocation and metabolism of ¹⁴C-labeled IAA in pedicel segments were also studied. In a monoecious Begonia fuchsioides hybrid, abscising male flower buds contain about 1% of the IAA present in non-abscising female flowers. In a male Begonia davisii hybrid, the seasonal variation in bud drop coincides with changes in the IAA content of the buds, while also the release of IAA from the bud to the pedicel is hampered. Abscission zones of these pedicels always contain abscission promoting ethylene concentrations. The tissue is prevented from responding with abscission by IAA from the flower buds. The buds also contain ABA but without influencing abscission considerably. Pretreatment with ethylene or ABA does not affect IAA transport in pedicel segments. The rate of this transport is 4–6 mm × h^–1:; the capacity increases with the transverse area. In young segments, IAA is decarboxylated and also otherwise metabolized.     

The Formation and Development of Adventitious Buds on Potato Sprouts

Potato tubers were pre-sprouted in trays at 10 C for 28 d.The scale leaves at the base of the sprouts were marked andtubers then planted in field soil. Twenty-eight days after plantingan average of three adventitious buds were present per sproutcompared with an average of six below-ground axillary buds.Ten per cent of adventitious buds formed stolons compared withalmost 100 per cent of axillary buds. Similar responses wereseen with tubers pre-sprouted either in the light or dark.     

Cell Wall Solubilization in Pedicel Abscission of Begonia Flower Buds

Effects of metabolic inhibitors and growth regulators on the course of abscission and on the activities of cell wall solubilizing enzymes were studied in pedicel explants of Begonia flower buds. Actinomycin D, chloramphenicol and 2,4-dinitrophenol slightly retarded abscission, whereas cycloheximide exerted a strong inhibition if applied until 10.5 h after explant excision. Indoleacetic acid retarded and ethylene promoted abscission and cell wall solubilization. However, the activities of cell wall solubilizing enzymes did not correspond with the course of abscission. No polygalacturonase and pectic acid and pectin transeliminases could be detected in the abscission zone during abscission, whereas a low pectin methylesterase activity did not change. Endo- and exocellulase activities did not increase until about 10 h after the onset of abscission, indicating that they are the result rather than the cause of abscission.     

The Exogenous Hormornal Control of the Development of Regenerated Flower Buds in Hyacinthus orientalis

The critical role of exogenous hormone on inducing the initiation of different floral organs in the regenerated flower bud and controlling their numbers was further evidenced. The initiation of the flower buds was first induced from the perianth explants of Hyacinthus orientalis L. cv. White pearl by a combination of 2 mg/L 6-BA and 0.1 mg/L 2,4-D, and then a continuous initiation of over 100 tepals (a flower bud of H. orientalis in situ has only 6 tepals) was successfully controlled by maintenance of such a hormone concentration. However, a change of hormonal concentration (2 mg/L 6-BA and 0-0.000 1 mg/L 2,4-D) caused cessation of continuous initiation of the tepals but gave rise to induction of stamen initiation. Keeping the changed hormone concentrations could successfully control the continuous initiation of over 20 stamens (a flower bud of H. orientalis in situ has only 6 stamens). The experiment showed that the number of identical floral organs in the regenerated flower buds can be controlled by certain defined concentrations of the exogenous hormones, and the amount of the induced identical floral organs has no effect on the differentiation sequence of the different floral organs in the regenerated flower bud. Based on a systematic research on controlling the differentiation of the floral organs from both the perianth explants and the regenerated flower buds by the exogenous hormones in H. orientalis over the past decade, the authors put forward here a new idea on the role of phytohormone in controlling the automatic and sequential differentiation of the different floral organs in flower development. The main points are as follows: 1. the development of flower bud in plant is a process in which all of the floral organs are automatically and sequentially differentiated from the flower meristem. 2. Experiments in vitro showed that the effect of exogenous hormones in controlling the initiation of different floral organs is strictly concentration dependent, i.e., one kind of the floral organ can continuously and repeatedly initiate from the flower meristem as long as it is maintained in that specific concentration of the exogenous hormone which is suitable for the initiation of that particular kind of floral organ. 3. It shows that the flower buds in situ must be automatically able to adjust the endogenous hormonal concentrations just after the completion of the differentiation of one whorl of floral organ to suit the differentiation of the next whorl. Thus, the phytohormone in different concentrations takes after many change-over switches of the organ differentiation and plays a connective and regulatory role between the differentiation of every two whorls of the floral organ. In other words, these change-over switches play the roles of inhibiting the expression of the genes which control the initiation of the floral organs in the first whorl, meanwhile, activating the expression of the genes which control the initiation of the floral organs in the second whorl during the successive initiation of the different floral organs from the flower bud. It results in the automatic and sequential initiation of the various floral organs from the floral meristem.      

外源激素对风信子再生花芽发育的控制

外源激素在诱导再生花芽花器官发生和控制它们的数目中的关键作用被进一步证实。首先通过２ｍｇ／Ｌ ６－ＢＡ和０．１ｍｇ／Ｌ ２,４－Ｄ的激素组合诱导风信子Ｈｙａｃｉｎｔｈｕｓ ｏｒｉｅｎｔａｌｉｓ Ｌ．ｃｖ．Ｗｈｉｔｅ ｐｅａｒｌ）花芽从花被外植体发生,然后保持这种激素浓度,成功地控制了１００多片花被片的连续发生（自然情况下一个风信子花芽仅有６片花被片）。改变激素浓度（２ｍｇ／Ｌ ６－ＢＡ和０～０．０     

Cold-pretreatment of Excised Flower Buds in Float Culture of Tobacco Anthers

Pretreatment of excised flower buds at 7–9 °C is shownto be more effective in float culture of Nicotiana tabacum anthersthan pretreatment at 5 °C. The small temperature differenceresults in greatly enhanced embryo yields when the treatmentis given just before (stage 3), during (4) or just after (5)the first pollen division. Anther productivity (total embryoyield per anther) increases with the time of pretreatment toa peak beyond which further pretreatment is deleterious. Thepeak is attained sooner at 9 than at 7 °C and sooner inanthers pretreated at stage 5 than at stage 3. Peak productivityappears always to be the same. Owing to batch variations, accuratepretreatment-times cannot be specified. Suggested mean timesfor buds of mixed stage are about 12–14 days at 7 °Cand about 7–9 days at 9 °C. Anthers dehisce in culture, the time to dehiscence decreasingwith increasing anther stage. Mid-stage-5 anthers open withinthe first few days, sooner with pretreatment at 9 than at 7°C, and high-yielding free pollen cultures can be obtainedwithout mechanical disruption of the anthers. Buds survive longest when harvested at the beginning of theearly flowering period and kept at 7 °C. It is proposedthat the pretreatment exerts its effect not by altering thecourse of the first pollen division, as suggested by others,but by delaying anther deterioration and thus assuring survivalof a greater proportion of the pollen grains switched into embryogenesis. Nicotiana tabacum L., tobacco, anther culture, embryogenesis     

The Photography of Ice Formation in Plant Tissue

A procedure is described which enables ice to be photographedas it forms at an exposed cut surface of plant tissue. Epi-illuminationwith u.v. light is used to excite the fluorescence of substancesapplied to the cut surface in aqueous solution. The fluoresceris chosen to have a high quantum yield when absorbed on plantcell walls and when trapped in ice crystals. Time lapse photographyusing this method shows that the first tissue to freeze in ahardy plant is the vascular system.     

Effect of Heat Stress on Assimilate Metabolism in Tomato Flower Buds

Assimilate import by flower buds in two cultivars of tomato(Lycopersicon esculentum Mill.) was inhibited by heat stress.With increasing temperature, levels of sucrose in the sourceorgan increased while levels of starch decreased. The transportof radioactive carbon was correlated with the starch contentof the flower buds. In Saladette, a heat-tolerant cultivar,conversion of the imported carbon to starch occurred to a greaterextent than in Roma VF, a heat-sensitive cultivar. Uptake ofsucrose from agar medium by detached flower buds was negativelycorrelated with their internal ratio of sucrose to hexoses.Glucose uptake from agar medium by detached flower buds decreasedwith increasing temperatures. Sucrose hydrolysis was negativelyaffected by high temperatures, and this was more pronouncedin the heat-sensitive than in the heat-tolerant cultivar. Theeffect of heat stress on assimilate translocation from the leavesto the sink organ is discussed. Lycopersicon esculentum Mill., starch, sucrose, heat stress     

The relationship between vascular differentiation and the distribution of ice within Forsythia flower buds

The relationship between vascular development and the distribution of ice within overwintering forsythia flower buds was examined. Previous experiments demonstrated that ice formed in dormant buds within the bud scales, sepals, and in the peduncle and lower portions of the developing flower. The current study demonstrated that these tissues contained columns of primary xylem forming a continuous network with the subtending stem tissues. The vascular traces within the developing petals, anther filaments and pistil were not fully differentiated. Xylem vessels were not present and only procambial cells were observed. Large ice crystals did not accumulate in these tissues. When vascular development resumed in the spring, coincident changes in the distribution of ice within buds were noted. Observations were consistent with the hypothesis that ice propagates into buds via the vascular system, and that the segregation of ice within bud tissues reflects the distribution of xylem.     

节瓜茎尖多胺含量和比值与花性别分化的关系

以4个不同基因型的节瓜为材料,通过两个发育时期（10、19片叶展平）茎尖取样,研究了多胺（PA）含量和比值与植株花性别分化的关系。结果表明,节瓜茎尖4种多胺含量差异显著,两个取样时期都是亚精胺（Spd）〉腐胺（Put）〉尸胺（Cad）〉精胺（Spm）。10片叶展平时期多胺含量与节瓜花性别分化之间没有明确的相关性;19片叶展平时期,节瓜茎尖Put、Spd和多胺总量与植株雌花分化比例呈极显著的正相关,而Cad则与雌花分化比例呈极显著的负相关。在两个取样时期,复合指标Spd/PA都与植株雌花分化比例呈显著的正相关,而（Put＋Cad）/（Spd＋Spm）均与之呈显著的负相关,可以较好地预测节瓜的花性别分化状况。     

Freezing Tolerance of Shoot and Flower Primordia of Coniferous Buds by Extraorgan Freezing

Shoot and flower primordia of vegetative and flower buds ofextremely or very hardy conifers belonging to the subfamilyAbietoideae of the Pinaceae, survived between –40 and–70?C by extraorgan freezing, which differed greatly dependingupon species. The water in these organs gradually froze outwith decreasing temperatures when cooled very slowly, whichenabled these organs to survive %40?C or below. The same icesegregation in shoot and flower primordia by extraorgan freezingwas observed in most of the temperate conifers belonging toTaxaceae, Cephalotaxaceae, Taxodiaceae and Cuppressaceae, makingthem resistant to temperatures between –15 and –25?C.In these conifers, scales acted as an ice sink, unlike the conifersof Abietoideae. The rates of cooling and exosmosis of waterin the shoot or flower primordia, their size, and their abilityto tolerate freeze-dehydration or its related stress play animportant role in determining whether death is caused by freeze-dehydrationor intraorgan freezing. Even in very hardy conifers, low temperature exotherms fromfreezing within the shoot primordia appeared between –30and –35?C on the DTA profiles when cooled continuouslyunder laboratory conditions from 5?C to –50?C at 2 to5?C/h. Appearance of low temperature exotherms always resultedin death. However, in the coldest area of Hokkaido, where theair temperature cools down to –40?C or below nearly everyyear, such an intraorgan freezing seems seldom to occur, especiallyin natural stands. On the other hand, low temperatures below–25?C seldom occur in warm-temperate climates. Thus, itmay be considered that in both boreal and temperate coniferstheir shoot and flower primordia seem to tolerate freeze dehydrationby extraorgan freezing under natural conditions. ¹ Contribution No. 2431 from the rnstitute of Low TemperatureScience. (Received March 27, 1982; Accepted August 12, 1982)     

Levels and Aggregation of Ribosomes during Dormancy and Dormancy Break of Peach Flower Buds

The level of ribosomes and their aggregation state (monosomes-polysomes) have been investigated in relation to dormancy in peach flower buds (Prunus persica). The ribosomes were analysed by a linear sucrose gradient. The ribosomal content hardly changes in the bud before dormancy and until dormancy breaks; on the other hand after this period there is a remarkable increase in the ribosomal level strictly related to the increase in bud weight. The ribosomal content reaches the highest value at flowering. During dormancy break the largest portion of ribosomes is localized in flower primordia, not in scales. Polysomes, which are always present in buds, remain constant during dormancy (35%), increase at dormancy breaking, reaching the highest level at flowering.     

Synchronization of Cell Division During Flower Initiation in Third-Order Buds of Silene

Plants of Silene coeli-rosa were induced to flower with sevenlong days and then returned to non-inductive short days. Third-orderbuds were formed more than three weeks after the beginning ofinduction and third-order flowers were initiated about one weeklater. Comparison of the mitotic index with the ratio of cellsin the G2 and G1 phases of the cell cycle for each third-orderapex provided evidence for synchronization of cell divisionjust before flower initiation. It is suggested that this resultsfrom changes of competence of the apical cells to react to theirinternal environment rather than because of the arrival of afloral stimulus at the shoot apex. Silene, cell division synchrony, flowering, evocation, mitotic index, cell cycle, competence     

Shoot Regeneration from Fragmented Flower Buds of Carnation (Dianthus caryophyllus)

Adventitious shoots were regenerated from fragmented flowerbuds, individual petals and receptacles in a number of differentcarnation cultivars. The major site of shoot formation was thesubepidermal cells at the proximal end of the petals. The yieldof shoots from a single flower bud was high, ranging between70 and 275, for the 11 cultivars tested. The regeneration mediumcontained Murashige and Skoog basal medium supplemented with4–8 µm -naphthaleneacetic acid and 4–8 µmbenzyladenine. The preferred regeneration protocol appears highlysuited to the development of gene transfer systems. Adventitious shoots, Dianthus caryophyllus L., tissue culture, explant, auxin, cytokinin, cut flowers, floriculture, organogenesis     

Detection of Avocado Sunblotch Viroid in Flower Buds by Polyacrylamide Gel Electrophoresis

A Rapid PAGE index method for avocado sunblotch disease for field trees which takes only 6 h, compared with 2—5 days for other previously described tediniques, has been developed and tested. Flower bud? are used instead of leaves as source material. All 52 flower Duu Siimplcs irom known bunblotcn-infcctcd trees tested positive whilst only 37 out of 72 in-fccted leaf samples gave positive results.