Euphorbia escula L. Root and Root Bud Indole-3-Acetic Acid Levels at Three Phenologic Stages

Endogenous indoleacetic acid (IAA) levels of Euphorbia esula L. primary root and root buds were examined at three phenologic stages. High performance liquid chromatography coupled with fluorescence detection and gas chromatography-mass spectrometry, using ¹³C₆[benzene ring]-indole-3-acetic acid as internal standard, were used to measure root bud free and bound IAA levels in vegetative, full flower, and post-flower plants. Highest levels of free IAA (103 nanograms per gram fresh weight) were found in root buds during full flower. Esterified and amide IAA increased significantly in root buds of full flower and post-flower plants, but were not detectable in root buds of vegetative plants. Primary rootfree IAA was highest in vegetative and full flower plants (34.5 nanograms per gram fresh weight) and decreased by 50% in post-flower plants.     

Apical dominance and the levels of indole acetic acid in Phaseolus lateral buds

Combined gas chromatography-mass spectrometry procedures have been used to establish that the indole acetic acid levels of lateral buds from Phaseolus seedlings rise following removal of the shoot apex.Abbreviations GC gas chromatograph - GC-MS combined gas liquid chromatography mass spectrometry - bis-TMS bis-trimethylsilyl - IAA indole acetic acid - MPM multiple-peak monitoring - MS mass spectrometer - GLC gas liquid chromatography - TLC thin-layer chromatography     

Influence of water deficits on the abscisic Acid and indole-3-acetic Acid contents of cotton flower buds and flowers

A field experiment was conducted during the summer of 1988 to test the hypothesis that water deficit affects the abscisic acid (ABA) and indole acetic acid (IAA) concentrations in cotton (Gossypium hirsutum L.) flower buds in ways that predispose young fruits (bolls) that subsequently develop from them to increased abscission rates. Water deficit had little effect on the ABA content of flower buds but increased the ABA content of flowers as much as 66%. Water deficit decreased the concentrations of free and conjugated IAA in flower buds during the first irrigation cycle but increased them during the second cycle. Flowers contained much less IAA than buds. Water deficit slightly increased the conjugated IAA content of flowers but had no effect on the concentration of free IAA in flowers. Because water deficit slightly increased the ABA content but did not decrease the IAA content of flowers, any carry-over effect of water deficit on young boll shedding might have been caused by changes in ABA but not from changes in IAA.     

Auxin in scapes,flower buds,flowers, and fruits of daffodil (Narcissus pseudonarcissus L.)

Summary Diffusates from flower buds, flower fruits, and scape segments, and extracts of flower stalks of Narcissus pseudonarcissus contain an auxin active in the Avena geo-curvature test. The auxin behaved like indole-3-acetic acid (IAA) in thin-layer chromatography (TLC) with neutral and basic solvents on different adsorbents. After TLC, the auxin of the extracts showed chromogenic reactions identical with those of IAA; in gas-liquid chromatography on two different columns, the purified substance, after methylation, appeared at the retention time of IAA methyl ester. The auxin content of the extracts has been estimated to be equivalent to ca. 10 g IAA kg^–1 fresh weight. Diffusates, collected at the basal end of excised flowering apices and of scape segments at different developmental stages, showed highest auxin activity when collected from old buds and young flowers, and from the basal, rapidly elongating scape regions. The diffusible auxin obtained from scape segments was very likely produced by the segments themselves. Thus, the shoot of Narcissus appears to possess two different sites of auxin production, namely, the apical region represented by the flower bud, the flower or the fruit, and the scape.Abbreviations IAA indole-3-acetic acid - IAA-OMe indole-3-acetic-acid methyl ester - TLC thin-layer chromatography - GLC gas-liquid chromatography     

Androgenesis in Citrus aurantifolia (Christm.) swingle

By means of gas chromatography-selected ion monitoring-mass spectrometry using an isotope-dilution assay with 4,5,6,7-tetradeutero-indole-3-acetic acid as the internal standard, indole-3-acetic acid has been estimated to be present in aseptically cultured gametophytes of wild-type Physcomitrella patens (Hedw.) B.S.G. at a level of 0.075 g g^–1 dry weight or 2.1 ng g^–1 fresh weight.Abbreviations IAA indole-3-acetic acid - d₄IAA 4,5,6,7-tetra-deutero-indole-3-acetic acid - [¹⁴C]IAA indole-3-[2-¹⁴C]-acetic acid - GC-SIM-MS gas chromatography-selected ion monitoring-mass spectrometry     

Variations in abscisic acid, indole-3-acetic acid and zeatin riboside concentrations in two Mediterranean shrubs subjected to water stress

Water stress induced an increase in endogenous concentrations of ABA in Lavandula stoechas L. plants to 13100 pmol ABA g^–1 FW, which may contribute to the maintenance of water relations between the second and the third day of water stress treatment. After the third day, a sharp decrease in ABA levels was observed to 2630 pmol ABA g^–1 FW, together with a decrease in water content and water potential and a loss of plant response to water stress. Water deficit did not induce an increase in endogenous ABA concentration, which remained at 514 pmol ABA g^–1 FW in Rosmarinus officinalis L., which is more sclerophyllous than L. stoechas. Nevertheless, the relative water content of Rosmarinus officinalis L. after seven days of water stress decreased more than 40% and reached values of –3.2 MPa. R. officinalis showed lower levels of ABA, but significantly higher levels of IAA and ZR than L. stoechas (4 times and 6 times respectively in well watered-plants). The increase in ABA levels is not a common mechanism in these two Mediterranean shrubs which survive under water stress conditions.Abbreviations ABA abscisic acid - d days of water stress treatment - DW dry weight - FW fresh weight - IAA indole-3-acetic acid - RP Reversed Phase - RWC relative water content - TW turgid weight - WC water content - ZR zeatin riboside - water potential     

Measurement of Indole-3-Acetic Acid in Peach Fruits (Prunus persica L. Batsch cv Redhaven) during Development

The amount of indole-3-acetic acid (IAA) was measured in peach fruits by gas chromatography-mass spectrometry-selective ion monitoring using an isotope dilution assay with [¹³C₆]IAA as an internal standard throughout the growing season. Ethylene evolution of the fruit was also measured. IAA levels were 25 nanograms per gram fresh weight, 18 days after anthesis. Both IAA levels and rates of ethylene evolution declined to their lowest levels (7 nanograms IAA per gram fresh weight and 0.01 nanoliter ethylene per gram per hour) in the second stage of fruit growth. Endogenous levels of free-IAA and ethylene evolution increased in the last stage of peach fruit development to 32 nanograms per gram fresh weight and 0.27 nanoliter per gram per hour, respectively. IAA amounts peaked in the ovules 67 days after anthesis.     

Changes in Amide-Linked and Ester Indole-3-Acetic Acid in Cotton Fruiting Forms during Their Development

The concentration of free indoleacetic acid (IAA) is high in cotton (Gossypium hirsutum L.) fruiting forms before anthesis, but is low at and for a few days after anthesis. Amide-linked and ester IAA were measured in fruiting forms at 9, 6, and 3 days before anthesis; at anthesis; and at 2, 4, 7, and 9 days after anthesis to determine if free IAA decreased because it was converted to a conjugated form. That did not appear to be the case. While the major decrease in free IAA occurred during the 6 days before anthesis, ester IAA increased only a small amount and amide-linked IAA decreased even more than free IAA. During the 6 days before anthesis free IAA decreased from 0.62 to 0.12 micrograms per gram and amide-linked IAA decreased from 19.14 to 1.16 micrograms per gram dry weight. No evidence was found that a large amount of amide-linked IAA was converted to an insoluble form; flowers contained less than 1 microgram per gram of insoluble IAA. The free and amide-linked IAA must have been converted to other forms, perhaps by oxidation. Soluble amide-linked IAA remained low after anthesis. No ester IAA was detected 6 days before anthesis and only 0.08 microgram per gram dry weight was measured at anthesis. The concentration of ester IAA increased thereafter to 4.43 micrograms per gram at 9 days after anthesis. Therefore, amide-linked IAA was the major form of IAA in flower buds and ester IAA was the major form in young fruits (bolls). Minimum concentrations of free and total IAA occurred during the 4 days after anthesis, a stage when cotton fruiting forms are most likely to abscise. The large decreases in free and amide-linked IAA during the 6 days before anthesis may indicate a rapid turnover of IAA in flower buds. But, the decrease in free IAA was not accompanied by a comparable increase in ester or amide-linked IAA.     

Identification and measurement of indoleacetic and abscisic acids in the cambial region of Picea sitchensis (Bong.) Carr. by combined gas chromatography-mass spectrometry

Indole-3-acetic acid (IAA) and abscisic acid (ABA) were identified by combined gas chromatography-mass spectrometry (GCMS) in fractions obtained by diffusion and extraction from bark peelings of Sitka spruce. A procedure is described for the quantitative analysis of IAA and ABA levels in the same extract using the GCMS technique of single-ion current monitoring. This procedure was used to measure the diffusible, free, and bound fractions of IAA and ABA in the cambial region of Sitka spruce throughout one year; the range in concentration for these fractions was 0.06–0.30, 0.46–3.85, and 0.04–0.20 g/g oven-dry weight, respectively, for IAA, and 0–0.08, 0.03–2.21, and 0.13–0.66 g/g oven-dry weight, respectively, for ABA. Movement in the cambial region was found to be polar for endogenous IAA and nonpolar for endogenous ABA. Recoveries of [¹⁴C]IAA internal standards showed that 73–99.5% of the IAA was lost during purification, and that there could be up to 5-fold differences in recovery between purifications, indicating that IAA loss shold be measured in quantitative analyses.Abbreviations ABA aoscisic acid - GCMS combined gas chromatography-mass spectrometry - IAA indole-3-acetic acid - PVP polyvinylpyrrolidone - SICM single ion current monitoring - TMS trimethylsilyl     

Changes in Free and Conjugated Indole 3-Acetic Acid and Abscisic Acid in Young Cotton Fruits and Their Abscission Zones in Relation to Fruit Retention during and after Moisture Stress

Experiments were conducted with field-grown cotton (Gossypium hirsutum L.) in 1985 and 1986 to determine effects of water deficit on levels of conjugated indole 3-acetic acid (IAA) and abscisic acid (ABA) in young fruits (bolls) and their abscission zones in relation to boll retention. Tissues were harvested three times during an irrigation cycle in 1985. They were harvested twice during an irrigation cycle and once after irrigation in 1986 to determine extent of recoveries of measured parameters. As reported earlier, the free IAA content of abscission zones decreased with moisture stress. Irrigation caused a partial recovery in free IAA content of abscission zones and caused a partial recovery in rate of boll retention. In contrast to free IAA, conjugated IAA increased with water deficit, both in 3-day-old bolls and in their abscission zones. Bolls contained much more ester IAA than their abscission zones. Some, but not all, of the increase in ester IAA in bolls during moisture stress could have come from a conversion of amide-linked IAA. Amide IAA decreased slightly during stress and increased after irrigation, but the concentration was low relative to ester IAA. Free and conjugated ABA both increased during stress and decreased after irrigation. However, the concentration of conjugated ABA remained relatively high in abscission zones. Ester IAA, being more resistant than free IAA to enzymic destruction during stress, may hasten recovery of fruit retention after relief of stress by providing a source of free IAA in abscission zones to inhibit continued abscission.     

Contribution of sepals and gibberellin treatments to growth and development of rose (Rosa hybrida) flowers

The fresh weight of sepals during the development of the rose flowerbuds from 4 mm to 22 mm in diameter increased fromabout 30 mg to ca. 350 mg. However, due to a morerapid gain in the total fresh weight of the flower, the sepal fresh weight as aproportion of the total weight of the buds decreased from about 55% to only 8%at the end of the measurement period. The net photosynthesis of sepals,measuredclose to the flower harvest, was approximately 60% of that in the youngest,uppermost leaves whereas no photosynthesis occured in the petals. Theconcentration of sucrose in petals of almost fully developed, desepalledflowerswas 15% lower in comparison with the control flowers with intact sepals. On theother hand, the concentration of sucrose in petals of control and desepalledflowers that were kept for 10 days in complete darkness was equal, reachingabout 50% of the concentration in petals of flowers grown in the light.Periodicmeasurements of reducing sugars in the petals did not show differences in theirconcentration between the control and desepalled flowers during the first 8daysafter sepal removal. After an additional four days the concentration ofreducingsugars in petals of the desepalled flowers was only 50% in comparison to thatinpetals of control flowers. Excising the sepals reduced fresh and dry weights,aswell as the length of buds and the peduncles, indicating that sepals may be asource of gibberellins during flower development. Treatment with50mg GA₃ in lanolin paste, completely restored thelength of the peduncles, but only partially restored the other measuredparameters of the flowers. Formation of 'star-shape' abnormality indesepalled flowers, which is a common phenomenon in rose flowers exposed toexternal ethylene was completelly prevented by applying GA₃ afterthesepals were excisied. This supported the previously suggested hypothesis aboutthe flinction of gibberellins in reducing the sensitivity of rose flower organsto ethylene.     

Immunoaffinity purification using monoclonal antibodies for the isolation of indole auxins from elongation zones of epicotyls of red-light-grown Alaska peas

The endogenous indole auxins of red-light grown pea (Pisum sativum L.) epicotyls were investigated. Immunoaffinity purification of indole-3-acetic acid (IAA) and its methylester was achieved using two monoclonal antibodies. Antibodies against free IAA were raised against IAA-C5-BSA, a hapten-carrier-conjugate giving rise to highly specific antibodies for indole auxins with a free acetic-acid group at position 3. Immunoaffinity adsorbents prepared with these antibodies were used for single-step purification of extracts of Alaska pea epicotylar tissue prior to quantification by high-performance liquid chromatography (HPLC) with on-line fluorescence detection. Monoclonal antibodies against a hapten-carrier-conjugate with IAA linked to bovine serum albumin through the carboxyl group (IAA-C1-BSA) were used for the isolation of IAA esters. Indol-3-acetic acid was identified in the elongation zone of the third internode of red-light-grown Alaska pea. 4-Chloro-indole-3-acetic acid, a constituent of immature pea seeds which is considered to be a very active auxin, was absent from the elongation zone. Several compounds were retained by the column based on antibodies against IAA-C1-BSA. Of these the methylester of IAA was identified by HPLC with on-line fluorescence detection, by co-migration in thin-layer chromatography and by gas chromatography-mass spectrometry. The methyl ester of IAA was very active in promoting elongation of pea third-internode segments. When fed to the epicotylar segments the IAA methylester was rapidly metabolized with IAA being the major metabolite. The methylester of IAA should therefore be classified as a labile auxin conjugate.Abbreviations 4Cl-IAA 4-chloro-indole-3-acetic acid - GC-MS gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - IAA Indole-3-acetic acid - IAA-C5-BSA, IAA-C1-BSA, IAA-NI-BSA hapten-carrier-conjugates with IAA linked to bovine serum albumin through the C5-position, the carboxyl group, and the indole nitrogen, respectively - IAA-Me the methylester of IAA This study was supported by the Danish Research Council (SJVF 13-4148 and 13-4547 to P.U.) and by The Research Center for Plant Biotechnology.     

罗汉果花芽分化过程中形态及其激素水平变化特征

采用石蜡切片和酶联免疫法(ELISA)对罗汉果雄性、雌性、两性花芽分化过程的形态和激素水平变化进行观测,为罗汉果开花调控和品种选育提供科学依据。结果表明:(1)罗汉果雄性、雌性、两性花的花芽分化过程均可分为花芽未分化期、花芽分化初期、花序分化期、萼片原基分化期、花瓣原基分化期、雄蕊原基分化期和雌蕊原基分化期7个阶段。雄蕊原基分化期前,3种花芽分化过程无明显差异,各时期形态特征均依次为:茎端呈圆锥状(花芽未分化期)→茎端经半球形变成扁平状(花芽分化初期)→距茎端5~7节位处分化出穗状花序(花序分化期)→小花原基周围形成5个萼片原基(萼片原基分化期)→萼片原基内侧形成5个花瓣原基(花瓣原基分化期)。雄蕊和雌蕊原基分化期,3种花芽分化过程存在明显差异,雄蕊原基内侧出现雌蕊原基后,雄花芽雄蕊原基继续发育成雄蕊,雌蕊原基停滞生长,退为一个小突起;雌花芽雌蕊原基继续发育成雌蕊,雄蕊原基生长缓慢,退化为小花丝;两性花芽雌蕊和雄蕊原基均继续发育,形成外观正常的雌蕊和雄蕊。(2)内源激素脱落酸(ABA)、赤霉素(GAs)和玉米素核苷(ZR)含量在3种花芽分化过程中变化规律相似,即ABA含量在花芽生理分化期降低,花芽形态分化期升高,而GAs和ZR含量则基本保持不变;吲哚乙酸(IAA)含量在3种花芽分化过程中变化存在明显差异,雌花芽IAA含量在花芽生理分化期升高,花芽形态分化期逐渐降低,而雄性和两性花芽的IAA含量则基本保持不变。ABA/GAs、ABA/IAA、ZR/IAA和ZR/GAs激素含量比值在3种花芽分化过程中变化规律相似,ABA/GAs在花芽生理分化期降低,花芽形态分化期升高,而BA/IAA、ZR/IAA和ZR/GAs则基本保持不变。研究认为,罗汉果花芽分化过程经历一个"两性期",高ABA含量和ABA/GAs比值有利于罗汉果花芽分化,IAA可能对罗汉果花性分化具有重要作用。     

Brassinosteroid-induced rice lamina joint inclination and its relation to indole-3-acetic acid and ethylene

Brassinosteroid (BR)-induced rice (Oriza sativa L.) lamina joint (RLJ) inclination and its relationship to indole-3-acetic acid (IAA) and ethylene were investigated using BR isolated from beeswax. The effect of BR on RLJ inclination was time- and concentration-dependent. Etiolated lamina were more sensitive to BR than green lamina. The BR-induced inclination was accompanied by increased lamina fresh weight, total water content, free-water content, proton extrusion and ethylene production, and decreased bound-water content. Lamina dry weight was not changed. The inclination was due to greater expansion of the adaxial cells relative to the dorsal cells in the lamina joint. This response was caused by BR and/or BR-induced signal(s) that were transported from the leaf sheath to the leaf blade. Both BR-induced RLJ inclination and ethylene production were inhibited by cobalt chloride (CoCl₂), an inhibitor of ACC oxidase. BR-induced inclination was much higher than that of IAA, and was inhibited by high concentration of 2,3,5-triiodobenzoic acid (TIBA), an inhibitor of IAA transport. A synergistic effect was observed between BR and IAA. These results suggest that the effects of BR on RLJ inclination and pulvinus cell expansion may be resulted from BR-increased water potential and proton extrusion in the lamina. The BR-induced RLJ inclination may involve the action of ethylene but may be independent of IAA.Abbreviations BR brassinolide or brassinosteroid(s) - IAA indole-3-acetic acid - TIBA 2,3,5-triiodobenzoic acid - RLJ rice lamina joint     

In vitro haploid plantlet induction in Physalis ixocarpa brot. through microspore embryogenesis

Anthers of Physalis ixocarpa Brot. exised from 2–3 mm long flower buds were treated for 2 d at 3°C, and were cultured on the basal medium of NN (1969), supplemented with plant hormones. They formed embryoids from microspores within 6 weeks. Upon transfer to a regeneration medium, embryoids grew into functional plants with the haploid number of chromosomes (n=12).Abbreviations CM Coconut-milk - IAA indole acetic acid - Kn Kinetin - MS Murashige and Skoog - NN Nitsch and Nitsch - ZEA Zeatin     

Effect of 2-chloroethyltrimethyl ammonium chloride on tuberization and endogenous GA3 in roots of potato cuttings

Cuttings of potato shoots treated with the plant growth retardant 2-chloroethyltrimethyl ammonium chloride (CCC) form tubers earlier and have less biologically-active gibberellin (GA)-like substances in the roots than control cuttings. The major GA-like substance in roots of potato cuttings was identified as GA₃ by gas-chromatography-mass spectrometry (GC-MS). The content of GA₃ in roots of control cuttings, estimated by GC-MS-selected ion monitoring (SIM) using [17, 17-²H]GA₃ as a quantitative internal standard, was 38.8 ng per g fresh weight (fw), and in roots of CCC-treated cuttings, in which tuberization was promoted, was 0.6 ng per g fw. Gibberellin A₁, GA₈ and GA₂₀ were also indicated as minor components of roots from both control and CCC-treated cuttings. The comparatively high GA₃ content in roots of control cuttings might be the root factor responsible for delaying tuberization in potato.Abbreviations CCC 2-chloroethyltrimethyl ammonium chloride - dw dry weight - EtOAc ethyl acetate - GA gibberellin - GC-MS-SIM gas chromatography-mass spectrometry-selected ion monitoring - HPLC high performance liquid chromatography - IAA indole-3-acetic acid - KRI Kovats' retention index - MeOH methanol - MeTMSi methyl ester trimethylsilyl ether - NAA naphthalene acetic acid - SD short day(s) - 2,4-D 2,4-dichlorophenoxy acetic acid     

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.     

Indole acetic acid (IAA) induced changes in growth, relative water contents and gas exchange attributes of barley (Hordeum vulgare L.) grown under water stress conditions

Effect of different concentrations of indole acetic acid (IAA) under varying soil water deficit conditions on two barley cultivars viz. B-99094 and Jau-87 was investigated in soil filled earthen pots. There were six treatments including control each with four replicates. Three concentrations of IAA (0, 15 and 30 mg l⁻¹) were applied as foliar spray 30 days after germination. After hormone application, half of the pots were subjected to one cycle of water stress (withholding of water till incipient wilting), followed by regular watering. Plant height, photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency relative water content, dry biomass, and grain yield/plant were significantly reduced by water stress. However, IAA treatments alleviated the adverse effect of water stress and successful in enhancing the plant growth and yield of barley cultivars. Barley cultivar Jau-87 performed better than B-99094. IAA application␣was effective in enhancing growth and photosynthetic efficiency of barley both under normal and water stress conditions.     

A specific radioimmunoassay for nanogram quantities of the auxin,indole-3-acetic acid

We have developed a specific radioimmunoassay [RIA] for indole-3-acetic acid (IAA) in the 0.2 ng to 12 ng range which, in principle, can be extended to other indole auxins as well. Methods are presented for obtaining suitable antibody, for the RIA procedure, and for measuring IAA in methanolic extracts of plant tissues. Antibody specific for IAA was obtained from rabbits immunized with IAA bound to bovine serum albumin by formaldehyde treatment. In assays with this antibody, 2,4-dichlorophenoxyacetic acid and indoles structurally related to IAA reacted from 300- to 3000-fold less than did IAA itself. However, -and -naphthaleneacetic acid reacted significantly and hence interfered with the assay. Extracts of tobacco (Nicotiana tabacum L.) tissue were immunoassayed after partial purification by buffer-ether partition. Crown-gall tumor tissue, which is auxin-autotrophic, and pith tissue depleted of auxin by the diffusion method contained, respectively, 26.7 ng and <0.5 ng extractable IAA per gram fresh weight.Abbreviations BSA bovine serum albumin - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - -NAA -naphthalenacetic acid - PBS phosphate-buffered saline - RIA radioimmunoassay     

Induction of callus from axillary buds of taro (Colocasia esculenta var. esculenta,Araceae) and subsequent plantlet regeneration

Summary Axillary buds of taro (Colocasia esculenta var. esculenta, Araceae) cultured on half strength Murashige-Skoog medium (HMS) containing taro extract (HMSTE) and 2, 4, 5-trichlorophenoxyacetic acid produce a compact, hard, slow growing callus which is not very active morphogenetically and produces only a few plantlets. When cultured on HMSTE plus 5 mg 1^–1 each of naphthaleneacetic acid and benzyl adenine (HMSNB) the buds produce a fast growing, friable and morphogenetically active callus. Meristematic regions form on the friable callus after 30 days on HMSNB. If transferred to HMSTE at this point the callus gives rise to plantlets. Addition of taro extract to the media is required for the culture of buds, induction of callus and plantlet regeneration.Abbreviations BA benzyl adenine - BNA b-naphthoxyacetic acid - CW coconut water (liquid endosperm) - DW dry weight - FW fresh weight - HMS half strength Murashige-Skoog medium - HMSCW HMSTE plus 100 ml CW 1^–1 - HMSNB HMSTE plus 5 mg 1^–1 each NAA and BA - HMSTE HMS plus 25 ml taro extract 1^–1 - HMSTR HMSTE plus 2 mg 2,4,5-T 1^–1 - MNA methyl-1-naphthaleneacetate - NAA naphthaleneacetic acid - OCPAA ortho-chlorophenoxyacetic acid - TE taro extract - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid