Audiovocal interactions during development? Vocalisation in deafened young horseshoe bats vs. audition in vocalisation-impaired bats

Summary Horseshoe bats (Rhinolophus rouxi) were deafened in their 3rd–5th postnatal week. Subsequently their vocalisations were monitored to evaluate the impact of audition on the development of echolocation pulses. Hearing impairment affected the echolocation pulses as follows: the frequency of the constant frequency (CF) component was altered by between + 4 kHz and – 14 kHz, and the dominance of the second harmonic of the pulses was neutralised by a relative increase in intensity of the first and third harmonics.A second experiment focused on possible influences of acoustical self-stimulation with echolocation pulses on the establishment of auditory fovea representation in the inferior colliculus (IC). Frequency control of echolocation pulses was disrupted by larynx denervation. Thereafter, the bats produced multiharmonic echolocation signals (4–11 harmonics) varying in frequency. IC tonotopy, however, as monitored by stereotaxic electrophysiology, showed the same developmental dynamics as seen in control specimens (Fig. 10).Both experiments indicate that throughout postnatal development echolocation pulses are under auditory feedback control, whereas maturation of the auditory fovea and shifts in its frequency tuning represent an innate process. The significance of this postnatal development might be the adjustment of the vocal motor system of each bat to the frequency of its personal auditory fovea.Abbreviations CF constant frequency - CF1, CF2, CF3 harmonics of pure tone components of the echolocation pulses - FM frequency modulation - IC inferior colliculus of the midbrain     

Comparative collicular tonotopy in two bat species adapted to movement detection,Hipposideros speoris andMegaderma lyra

Summary The tonotopic organization of the inferior colliculus (IC) in two echolocating bats,Hipposideros speoris andMegaderma lyra, was studied by multiunit recordings.InHipposideros speoris frequencies below the range of the echolocation signals (i.e. below 120 kHz) are compressed into a dorsolateral cap about 400–600 m thick. Within this region, neuronal sheets of about 4–5 m thickness represent a 1 kHz-band.In contrast, the frequencies of the echolocation signals (120–140 kHz) are overrepresented and occupy the central and ventral parts of the IC (Fig. 3). In this region, neuronal sheets of about 80 m thickness represent a 1 kHz-band. The largest 1 kHz-slabs (400–600 m) represent frequencies of the pure tone components of the echolocation signals (130–140 kHz).The frequency of the pure tone echolocation component is specific for any given individual and always part of the overrepresented frequency range but did not necessarily coincide with the BF of the thickest isofrequency slab. Thus hipposiderid bats have an auditory fovea (Fig. 10).In the IC ofMegaderma lyra the complete range of audible frequencies, from a few kHz to 110 kHz, is represented in fairly equal proportions (Fig. 7). On the average, a neuronal sheet of 30 m thickness is dedicated to a 1 kHz-band, however, frequencies below 20 kHz, i.e. below the range of the echolocation signals, are overrepresented.Audiograms based on thresholds determined from multiunit recordings demonstrate the specific sensitivities of the two bat species. InHipposideros speoris the audiogram shows two sensitivity peaks, one in the nonecholocating frequency range (10–60 kHz) and one within the auditory fovea for echolocation (130–140 kHz).Megaderma lyra has extreme sensitivity between 15–20 kHz, with thresholds as low as –24 dB SPL, and a second sensitivity peak at 50 kHz (Fig. 8).InMegaderma lyra, as in common laboratory mammals, Q_10dB-values of single units do not exceed 30, whereas inHipposideros speoris units with BFs within the auditory fovea reach Q_10dB-values of up to 130.InMegaderma lyra, many single units and multiunit clusters with BFs below 30 kHz show upper thresholds of 40–50 dB SPL and respond most vigorously to sound intensities below 30 dB SPL (Fig. 9). Many of these units respond preferentially or exclusively to noise. These features are interpreted as adaptations to detection of prey-generated noises.The two different tonotopic arrangements (compare Figs. 3 and 7) in the ICs of the two species are correlated with their different foraging behaviours. It is suggested that pure tone echolocation and auditory foveae are primarily adaptations to echo clutter rejection for species foraging on the wing close to vegetation.Abbreviations BF Best frequency - CF constant frequency - FM frequency modulated - IC inferior colliculus - HS Hipposideros speoris     

Micropropagation of Mexican redbud,Cercis canadensis var. mexicana

Mexican redbud (Cercis canadensis var. mexicana) shoot cultures were initiated from explants taken from both mature and juvenile stock plants. Culture conditions affecting shoot growth and proliferation and rooting of three clones were investigated. Shoot growth was best on media supplemented with 0.25% activated charcoal and solidified with 0.2% Gelrite. Four commercially available salt formulations (Anderson's rhododendron medium, WPM, MS, DKW) were tested for growth of shoot cultures, and Anderson's rhododendron basal salt mixture was superior. Axillary shoots grew from explants cultured media supplemented with a wide range of concentrations of benzyladenine and thidiazuron. Benzyladenine at 5.6–22.2 M supported the best combination of shoot quality and number. Rooting of microshoots in vitro was best on half-strength WPM containing 6.71 M naphthaleneacetic acid and 0.1% activated charcoal.Abbreviations BA 6-benzyladenine - IBA indole-3-butyric acid - 2iP 6-(, -dimethylallylamino)purine - DKW Driver & Kuniyuki Walnut - kinetin 6-furfurlaminopurine - MS Murashige & Skoog - NAA -naphthaleneacetic acid - WPM Woody Plant Medium - TDZ thidiazuron - 1-phenyl-3 (1,2,3-thidiazol-5-yl)urea     

Ontogenesis of tonotopy in inferior colliculus of a hipposiderid bat reveals postnatal shift in frequency-place code

Summary The postnatal development of midbrain tonotopy was investigated in the inferior colliculus (IC) of the south Indian CF-FM batHipposideros speoris. The developmental progress of the three-dimensional frequency representation was determined by systematic stereotaxic recordings of multiunit clusters from the 1st up to the 7th postnatal week. Additional developmental measures included the tuning characteristics of single units (Figs. 3f; 4f; 5f), the analysis of the vocalised pulse repertoire (Figs. 3e, 4e, 5e), and morphometric reconstructions of the brains of all experimental animals (Fig. 1).The maturation of auditory processing could be divided into two distinct, possibly overlapping developmental periods: First, up to the 5th week, the orderly tonotopy in the IC developed, beginning with the low frequency representation and progressively adding the high frequency representation. With regard to the topology of isofrequency sheets within the IC, maturation progresses from dorsolateral to ventromedial (Figs. 3c, 4c). At the end of this phase the entire IC becomes specialised for narrowly tuned and sensitive frequency processing. This includes the establishment of the auditory fovea, i.e. the extensive spatial representation of a narrow band of behaviorally relevant frequencies in the ventromedial part of the IC. In the 5th postnatal week the auditory fovea is concerned with frequencies from 100–118 kHz (Fig. 4c, d). During subsequent development, the frequency tuning of the auditory fovea increases by 20–25 kHz and finally attains the adult range of ca. 125–140 kHz. During this process, neither the bandwidth of the auditory fovea (15–20 kHz) nor the absolute sensitivity of its units (ca. 50 dB SPL) were changed. Further maturation occurred at the single unit level : the sharpness of frequency tuning increased from the 5th to the 7th postnatal weeks (Q-₁₀-dB-values up to 30–60), and upper thresholds emerged (Figs. 4f, 5f).Although in the adult the frequency of the auditory fovea matches that of the vocalised pulses, none of the juvenile bats tested from the 5th to the 7th weeks showed such a frequency match between vocalisation and audition (Figs. 4e, 5e).The results show that postnatal maturation of audition in hipposiderid bats cannot be described by a model based on a single developmental parameter.Abbreviations BF best frequency - CF constant frequency - Cer cerebellum - CN cochlear nucleus - CO auditory cortex - CUF cuneiform nucleus - DAB days after birth - FAL forearm length - FM frequency modulation - IC inferior colliculus - NLL nucleus of the lateral lemniscus - PAG periaqueductal gray - SC superior colliculus     

Effect of genotype,explant and medium onin vitro regeneration of red pepper

In vitro plant regeneration was achieved inCapsicum praetermissum, C. baccatum andC. annuum cvs. G4, Bhiwapuri Sweet pepper, Cayenne pepper and Hybrid pepper. Shoots were induced from hypocotyl, cotyledon and leaf explants on Murashige and Skoog medium supplemented with 5.7 M indoleacetic acid (IAA)+13.3 M benzyladenine (BA); 22 M BA; and 44 M BA. Analysis of variance revealed that the most significant effect on shoot regeneration was due to the explant and it accounted for 56.3% of total variation observed. The genotype x explant effect on regeneration was minor relative to all other 2- and 3-way interactions because leaf explants consistently regenerated more shoots than hypocotyls or cotyledons in all the genotypes and thereby reduced the variation among the genotypes. Explant x medium interaction revealed that 22 M BA was the best growth regulator supplement in regeneration medium for optimal shoot regeneration from leaf explants. Rooting of regenerated shoots was achieved on 5.7 M IAA-containing medium, and the rooting response was better from shoots induced on medium fortified with 5.7 M IAA plus 13.3 M BA. Complete plantlets with diploid chromosome number (2n=2x=24) were transferred to soil and 60–70% of these plantlets survived and grew well.     

Responses to simulated echoes by neurons in the barn owl's auditory space map

The natural acoustical environment contains many reflective surfaces that give rise to echoes, complicating the task of sound localization and identification. The barn owl (Tyto alba), as a nocturnal predator, relies heavily on its auditory system for tracking and capturing prey in this highly echoic environment. The external nucleus of the owl's inferior colliculus (ICx) contains a retina-like map of space composed of space-specific auditory neurons that have spatially limited receptive fields. We recorded extracellularly from individual space-specific neurons in an attempt to understand the pattern of activity across the ICx in response to a brief direct sound and a simulated echo. Space-specific neurons responded strongly to the direct sound, but their response to a simulated echo was suppressed, typically, if the echo arrived within 5 ms or less of the direct sound. Thus we expect there to be little or no representation within the ICx of echoes arriving within such short delays.Behavioral tests using the owl's natural tendency to turn their head toward a sound source suggested that owls, like their space-specific neurons, similarly localize only the first of two brief sounds. Naive, untrained owls were presented with a pair of sounds in rapid succession from two horizontally-separated speakers. With interstimulus delays of less than 10 ms, the owl consistently turned its head toward the leading speaker. Longer delays elicited head turns to either speaker with approximately equal frequency and in some cases to both speakers sequentially.Abbreviations IC inferior colliculus - ICx external nucleus of the inferior colliculus - ITD interaural time difference - ISI interstimulus interval - LS left speaker - RS right speaker - CS centering speaker - RF receptive field     

Adventitious shoot regeneration from cultured petal explants of carnation

Adventitious shoot regeneration was compared among leaf, stem and petal explants of carnation (Dianthus caryophyllus L.) cv. Scania on MS medium containing different concentrations of 6-benzyladenine (BA) and -naphthaleneacetic acid (NAA). High frequency regeneration was obtained only from petal explants on the media containing 5 to 10 M BA with or without 5 M NAA. Among the cytokinins tested, N-2-chloro-4-pyridyl-N-phenylurea and N-1,2,3-thiadiazol-5-yl-N-N-phenylurea were more effective than BA, kinetin, N⁶-2-isopentenyl adenine and zeatin on regeneration from petal explants. Although, high frequency shoot regeneration was obtained from all petal explants harvested from various developmental stages of buds, a significant decrease in regeneration capacity was observed in the explants obtained from fully-opened flowers. High frequency shoot regeneration was also obtained from the petal explants of cvs. Coral. Lena, Nora and White Sim, and an interspecific cultivar Eolo using the method developed in this study.Abbreviations NAA -naphthaleneacetic acid - BA 6-benzyladenine - GA₃ gibberellic acid - 2iP N⁶-2-isopentenyl adenine - KT-30 N-2-chloro-4-pyridyl-N-phenylurea (also called 4PU) - TDZ N-1,2,3-thiadiazol-5-yl-N-phenylurea (also called thidiazuron)     

Regeneration of plantlets through organogenesis in the Himalayan yellow poppy,Meconopsis paniculata

Plantlet formation through organogenesis in callus cultures of Himalayan yellow poppy,Meconopsis paniculata D.Don (Prain), a threatened taxon of ornamental value, is described. Hypocotyl segments from 3-month-old laboratory-raised seedlings produced callus on agar-solidified Murashige and Skoog medium (MS) containing 10 M -naphthaleneacetic acid and 1 M kinetin. Shoots differentiated best from callus on MS containing 10 M indolebutyric acid (IBA) and 1 M 6-benzyladenine. The regenerated shoots rooted best on MS medium containing 10 M IBA. From seed germination to differentiation of plantlets through the two-step organogenesis process required 28–29 weeks.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - FAA formalin-acetic acid-alcohol - BA 6-benzyladenine - IAA indole-acetic acid - IBA indolebutyric acid - GA₃ gibberellic acid - NAA -naphthaleneacetic acid - RH relative humidity     

<Emphasis Type="Italic">In vitro</Emphasis> propagation of the genus <Emphasis Type="Italic">Clivia</Emphasis>

We have developed a protocol for the in vitro propagation of the genus Clivia. Shoots were regenerated when fragments of the peduncle-pedicel junction (PP junction) from young inflorescences were used as explants. The optimal media for PP junction were Murashige and Skoog (MS)-based medium containing 10 M of 6-benzyladenine (BA) and 10 M of 2,4-dichlorophenoxyacetic acid (2,4-D) or MS supplemented with 5 M BA, 10 M -naphthaleneacetic acid (NAA), 250 mg l^-1 glutamine and 500 mg l^–1 casein hydrolysate and their usage depended on the breeding lines. Multiplication from initiations and in vitro seedlings was the best when the explants were cut longitudinally through the meristem and placed on MS plus 44 M BA. Plantlets were transferred on to hormone -free MS medium with charcoal for rooting.     

In vitro propagation of Rauwolfia micrantha, a rare medicinal plant

Shoot tip and single node explants from young shoots of 1-year old flowering plants of Rauwolfia micrantha Hook. f. were cultured on Murashige & Skoog (MS) medium variously supplemented with 6-benzyladenine (BA) and -naphthaleneacetic acid (NAA). A combination of 13.2 M BA and 2.68 M NAA induced high frequency (77%) formation of up to 3 shoots from each node in 8 weeks. The regeneration of shoot tips from the field-grown plants and in vitro shoots placed horizontally differed. Repeated subculturing of the shoot tips and single nodes at 6-week intervals for over a year in combination of 4.4 M BA and 0.27 M NAA enabled mass multiplication of shoots without any evidence of decline. Rooting of the excised shoots on medium containing 2.6 M NAA was preceded by callus formation. The rooted plants were removed off the callus, hardened off and 80% established in pots. Micropropagated plants displayed uniform morphological, growth, flowering, fruiting and seed germination characteristics.Abbreviations BA 6-benzyladenie - IAA indole-3-acetic acid - IBA indole-3-butyrie acid - 2-ip 2-isopentenyladenine - MS Murashige & Skoog (1962) - NAA -naphthaleneacetic acid     

Artemisia annua L.: dedifferentiated and differentiated cultures

Dedifferentiated and differentiated tissue cultures ofArtemisia annua L. for artemisinin production were carried out. The calluses were initiated on MS medium supplemented with sucrose (30 g l^-1), myoinositol (100 mg l^-1) and RT vitamins. The auxins used were naphtaleneacetic acid (NAA), indoleacetic acid (IAA), indolebutyric acid (IBA) and 2,4-dichlorophenoxyacetic acid (2,4-d). These were added to the basal medium either singly or in combination. The best results were obtained with 2.4-d (4.5 M : 0.02 d^-1) and NAA (5.4 M : 0.06 d^-1). Cell suspensions were established on the same media without agar. Suspension cultures showed different morphological characteristics according to the plant growth regulator supplied. Organized cultures were initiated from callus obtained on 2,4-d (4.5 M) and from bud cultures. Medium containing 6-benzylaminepurine (BA) (8.9 M)+NAA (0.54 M); Zeatin (45.62 M)+NAA (5.37 M) or BA (8.9 M) stimulated both organogenesis in callus (frequency of induction =50%) and semi-organized tissue in shoot buds. BA (13.32 M)+NAA (1.08 M) or BA (13.32 M) only stimulated multiple shoot cultures (frequency of induction =80%). Regarding artemisinin content, while the values obtained were 1.13 and 0.78 mg gDW^-1 in primary callus, artemisinin was not detected in cell suspension and only traces of it were found in multiple shoot cultures.     

Purine glucosylating activity in cell suspension cultures ofSolanum tuberosum L.

Cell suspension cultures ofSolanum tuberosum L. cv. Adretta were established from leaf-derived calluses. In the search for purine glucosylating activity, the metabolism of 6-benzylaminopurine was studied. The main metabolite of BA was isolated and identified as 6-benzylaminopurine 7--d-glucopyranoside indicating the occurrence of purine glucosylating activity.Abbreviations BA 6-Benzylaminopurine - [3G]BA BA 3--d-glucopyranoside - [7G]BA BA 7--d-glucopyranoside - [9G]BA BA 9--d-glucopyranoside - RA Radioactivity - R _T Retention Time     

Spatial tuning of neurons in the inferior colliculus of the big brown bat: effects of sound level, stimulus type and multiple sound sources

We examined factors that affect spatial receptive fields of single units in the central nucleus of the inferior colliculus of Eptesicus fuscus. Pure tones, frequency- or amplitude-modulated sounds, or noise bursts were presented in the free-field, and responses were recorded extracellularly. For 58 neurons that were tested over a 30 dB range of sound levels, 7 (12%) exhibited a change of less than 10° in the center point and medial border of their receptive field. For 28 neurons that were tested with more than one stimulus type, 5 (18%) exhibited a change of less than 10° in the center point and medial border of their receptive field.The azimuthal response ranges of 19 neurons were measured in the presence of a continuous broadband noise presented from a second loudspeaker set at different fixed azimuthal positions. For 3 neurons driven by a contralateral stimulus only, the effect of the noise was simple masking. For 11 neurons driven by sound at either side, 8 were unaffected by the noise and 1 showed a simple masking effect. For the remaining 2, as well as for 5 neurons that were excited by contralateral sound and inhibited by ipsilateral sound, the peak of the azimuthal response range shifted toward the direction of the noise.Abbreviations E/E excitation at either ear - I/E inhibition at the ipsilateral ear, excitation at the contralateral ear - O/E no effect from the ipsilateral ear, excitation at the contralateral ear - FM downward frequency modulation - FM upward frequency modulation - IC inferior colliculus - ICC central nucleus of the inferior colliculus - ILD interaural level difference - ITD interaural time difference - PT pure tone - SAM sinusoidally amplitude modulated sounds - SFM sinusoidally frequency modulated sounds     

Plant regeneration from nucllar tissues of Aegle marmelos through organogenesis

A protocol for organogenesis from nucellar explants excised from fertilized ovules of immature fruits of Aegle marmelos Corr. was developed. Adventitious buds were initiated on Murashige and Skoog's (MS) medium containing various combinations of 6-benzyladenine (BA), -naphthalene-acetic acid (NAA), 3-indoleacetic acid and gibberellic acid. Medium containing 4.4 m BA and 2.7 M NAA produced the maximum number of adventitious buds per explant. Shoots were elongated by transferring explants with shoot buds to medium with a low concentration of BA (0.44 M). Rooting of in vitro-regenerated shoots was obtained in half-strength MS medium with 4.9 M indole-3-butyric acid. This is the first report of plant regeneration from nucellar explants of A. marmelos.Abbreviations BA benzyladenine - IAA indoleacetic acid - IBA indolebutyric acid - NAA naphthaleneacetic acid - GA₃ gibberellic acid     

Somatic embryogenesis and plant regeneration from cell suspensions of Exacum affine

Somatic embryos were produced in seven cultivars of Exacum affine Balf. using flower buds and peduncles as explants. Flowering plants were produced from five of the cultivars, and no visible mutations were detected. The best medium for callus induction and growth was MS supplemented with 9.0 M 2,4-dichlorophenoxyacetic acid and either zero or 0.089 M BA. Callus suspensions were made by passing the callus through a 100 m sieve. The best embryo regeneration was achieved on growth regulator-free medium. Callus and embryos could be grown in liquid medium.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - BA 6-benzyladenine - SD standard deviation     

Imazalil enhances the shoot-inducing effect of benzyladenine in Spathiphyllum floribundum Schott

In Spathiphyllum floribundum Petite Schott shoot induction by benzyladenine (BA) was enhanced dramatically by adding the imidazole fungicide imazalil to the medium. As the concentration of imazalil increased, the number of shoots increased, and finally their size was reduced to a small meristematic dome. An average of 127 shoots/ expiant developed when 2.5 mg/L BA was combined with 16 mg/L imazalil. Doubling the BA concentration had no significant effect on shoot induction. Imazalil did not affect the root-inhibiting effect of BA. When imazalil was applied without BA, the number of roots and total root length/plant were reduced, but no new shoots developed.Abbreviations GA gibberellic acid - BA benzyladenine - [9G]BA 9--d-glucopyranosylbenzyladenine - [9R]BA 9--d-ribofuranosylbenzyladenine.     

Factors that effect leaf regeneration efficiency in apple,and effect of antibiotics in morphogenesis

Several factors that affect the frequency of organogenesis in apple leaf explants were examined for the scion cultivars Empire, Freedom, Golden Delicious, Liberty, McIntosh, and Mutsu and for the rootstocks Malling 7A and Malling 26. The main factors affecting morphogenesis were BA concentration, basal medium, leaf explant origin and maturity, explant orientation, and photosynthetic photon flux. Depending on the genotype, optimal regeneration was obtained using either 22.2 or 31.1 M BA and the N6 basal medium, with the exception of Golden Delicious which regenerated better on MS medium. After 6 weeks, the average number of shoots per segment varied from 5 to 16, and the percentage of regeneration between 70 and 100%, depending on the genotype tested and the maturity of the explant. Regeneration capacity increased dramatically from the tip towards the base of the leaf, and was higher from the middle to the proximal end.Cefotaxime and carbenicillin, two antibiotics commonly used during transformation studies to eliminate Agrobacterium tumefaciens from plant tissue, were tested to determine their effect on morphogenesis. Cefotaxime at a dose of 250 mg 1^-1 enhanced regeneration and shoot development, whereas carbenicillin at a dose of 500 mg l^-1 induced abundant callus formation and inhibited regeneration. Kanamycin, a widely used selection agent for plant transformation, strongly inhibited regeneration even at very low doses. Schemes for selection and recovery of transgenic apple plants when kanamycin is used as the selection agent are discussed.Abbreviations BA benzyladenine - Cef cefotaxime - Crb carbenicillin - IBA indolebutyric acid - Kan kanamycin - LS Linsmaier and Skoog (1965) medium - M Malling - MS Murashige and Skoog (1962) medium - NAA naphthaleneacetic acid - N6 medium (Chu et al. 1975) as modified by Welander (1988) - PPF photosynthetic photon flux     

Uptake and metabolism of 6-benzyladenine in shoot cultures of Musa and Rhododendron

Shoots of Musa and Rhododendron were cultured in vitro on a medium containing 0.5 mg l^-1 BA. Shoots growing in the presence of [¹⁴C]BA were harvested at intervals during the culture period. Uptake of BA was linear throughout this culture period in Musa but slowed considerably in Rhododendron shoots after day 10. Rhododendron shoots absorbed 40% of the BA present in the medium and Musa shoots absorbed 52%. In each species the principal metabolite formed was [9G]BA. Benzyladenine was present in significant levels only in the pseudostem of Musa.Abbreviations BA 6-benzyladenine - [3G]BA 3--glueopyranosyl-BA - [7G]BA 7--D-glucopyranosyl-BA - [9G]BA 9--D-glucopyranosyl-BA - [9R-G]BA 9-(ribosylglucoside)-BA - [9R]BA 9--D-ribofuranosyl-BA - HPLC high performance liquid chromatography - PAR photosynthetically active radiation - TEAB triethylammonium bicarbonate     

In vitro plant regeneration via somatic embryogenesis from root culture of some rhizomatous irises

A method for plant regeneration of Iris via somatic embryogenesis is described. Root and leaf pieces from in vitro-grown plants of several genotypes of rhizomatous Iris sp. were cultured in vitro. Callus induction occurred only on root cultures incubated under low light intensity (35 mol m^-2 s^-1) on two induction media containing 2,4-D (4.5 or 22.5 M), NAA (5.4 M) and kinetin (0.5 M). Somatic embryos developed after transfer of callus onto four regeneration media containing 9 or 22 M BA, or 5 M kinetin and 2 M TIBA or 9 M BA and 4 M TIBA. Plantlets could be obtained from these somatic embryos. Genotypic differences were found both in callus induction and somatic embryo formation, with I. pseudacorus responding better than I. versicolor or I. setosa. Cytological analysis performed on root tips of 80 regenerated plants revealed that two of the I. pseudacorus regenerants were tetraploid.Abbreviations 2,4-D dichlorophenoxy acetic acid - NAA naphthaleneacetic acid - BA 6-benzyladenine - TIBA 2,3,5-triiodobenzoic acid - IBA indolebutyric acid     

In vitro micropropagation from nodal segments of Cleistanthus collinus

Cleistanthus collinus Benth. was micropropagated using nodal explants on MS medium supplemented with 2.2 M benzyladenine (BA). April to June was the best time for initiating shoot cultures. Shoot proliferation was enhanced when the BA concentration was lowered to 1.1 M. Rooting was achieved on half-strenth MS medium with 22.8 M indole-3-acetic acid for 7 days and continuous darkness for the first 72 h of the 7 days.Abbreviations MS Murashige & Skoog's medium - WPM Woody Plant Medium - BA 6-benzyladenine - IAA indole-3-acetic acid - IBA indole-3-butyric acid - NAA 1-naphthalenacetic acid