Showing papers on "Zeatin published in 1988"

Cytokinin gene fused with a strong promoter enhances shoot organogenesis and zeatin levels in transformed plant cells

Abstract: The isopentenyltransferase (ipt) gene associated with cytokinin biosynthesis in plants was cloned from a tumor-inducing plasmid carried by Agrobacterium tumefaciens and placed under the control of promoters of differing activities, the cauliflower mosaic virus 35S promoter and the nopaline synthase promoter. These promoter-gene constructs were introduced into wounded Nicotiana stems, leaf pieces, and cucumber seedlings by A. tumefaciens infection. Shoots were observed in the infection site on all responding genotypes of Nicotiana plants infected with the 35S promoter construct (35S—ipt), whereas only 41% responded similarly to infection with the unmodified gene. Furthermore, shoots were observed 19 days after infection with the 35S—ipt gene but not until 28 to 45 days with the unaltered ipt gene. Shoots were more numerous (>40) on galls incited by 35S—ipt and were up to 6 times taller than shoots induced by the native gene. On Cucumis (cucumber), shoots were observed only on galls incited by the 35S—ipt construct. These galls were on the average 7.5 times larger than those incited by the nopaline synthase promoter construct (NOS—ipt) or the unmodified ipt gene. Zeatin and zeatinriboside concentrations averaged 23 times greater in the 35S—ipt transformed shoots than in ones transformed with the native ipt gene. These results suggest that a more active promoter on the ipt gene can enhance or change the morphogenic potential of transformed plant cells by increasing their endogenous cytokinin levels.

Cell number, cell size and hormone levels in semi-isogenic mutants of Lycopersicon pimpinellifolium differing in fruit size

Abstract: Tomato fruit growth parameters, cell number and cell size, and hormone levels [IAA, abscisic acid (ABA), zeatin (Z)/zeatin riboside (ZR), isopentenyladenosine (i-Ado)/isopentenlyadenine (i-Ade)], in the wild-type (Lycopersicon pimpinellifolium Mill.) and a semi-isogenic mutant (mutant III) differing in fruit size were investigated during fruit development. An image-processing system was used for the determination of cell number and single cell size per fruit and hormone levels were measured by radioimmuno-assay (RIA). The bigger fruits of mutant III showed higher cell numbers throughout fruit development and cells enlarged faster than in wild-type fruits. During the first 10 days of fruit growth, the main cell division period after fertilization, high concentrations of cytokinins were found, these being correlated with high cell division activity. There were only slight differences in IAA and ABA levels in the different sized fruits. The results emphasized the importance of the cell number per fruit at anthesis as a determining factor of final fruit size in tomatoes. A possible relationship between cytokinins and subsequent fruit development is discussed.

Cytokinin Biochemistry in Relation to Leaf Senescence IV. Cytokinin Metabolism in Soybean Explants

Abstract: When [(3)H]dihydrozeatin riboside and [(3)H]zeatin riboside were supplied to soybean (Glycine max L.) explants (comprising one leaf, associated pods, and subtending stem) via the xylem at mid to late podfill, 0.1% of the supplied (3)H was extracted from the seeds. The distribution of (3)H in the explants was similar to that bound previously following uptake of [(3)H]zeatin riboside at earlier stages of pod development. Metabolites formed in the explants from (3)H-labeled zeatin, zeatin riboside, and dihydrozeatin riboside were identified and related to the endogenous cytokinins shown to be present. When zeatin riboside and zeatin were supplied for 1 hour, zeatin nucleotide was the principal metabolite formed and this appeared to be the precursor of the other metabolites detected subsequently. Explants supplied with zeatin riboside or dihydrozeatin riboside for 1 hour, and then transferred to water for 20 to 24 hours, yielded leaf blades in which the main metabolites were O-glucosyldihydrozeatin, adenosine, and adenine. The metabolism of zeatin riboside in blades of explants at pre-podfill, early podfill, and mid to late podfill did not differ appreciably. The results are discussed in relation to leaf senescence and seed development.

Inhibition of somatic embryogenesis in orchardgrass by endogenous cytokinins.

Abstract: Endogenous indoleacetic acid (IAA) and cytokinin concentrations were measured by high performance liquid chromatography in leaf sections of an orchardgrass (Dactylis glomerata L.) genotype which exhibited a high capacity for somatic embryogenesis in vitro and in two genotypes that did not exhibit this capacity. The nonembryogenic genotypes contained 3- to 4-fold higher concentrations of zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, and total cytokinins than the embryogenic genotype. There were no significant differences in IAA concentrations between genotypes. Cytokinin concentrations between basal and distal sections of embryogenic genotype were not different, but the IAA concentration was significantly greater in basal sections. Somatic embryogenesis was inhibited in the embryogenic genotype by 0.001 micromolar exogenously added zeatin.

Cytokinins in the root pressure exudate of Citrus jambhiri Lush. colonized by vesicular-arbuscular mycorrhizae.

Abstract: Summary The influence of vesicular-arbuscular mycorrhizal (VAM) symbiosis on the transport of cytokinins from the root to the shoot of Citrus jumbhiri Lush. seedlings inoculated with cultures of Glomus etunicatum (Becker and Gerd.), G. fusciculatum (Thaxt.) Gerd. and Trappe, or G. mosseae (Nichol. and Gerd.) was investigated. Cytokinins collected from root exudates over a 90-day period were analyzed by high-performance liquid chromatography, mass spectrometry and a bioassay. The flux of cytokinins was independent of root exudate flux. Seedlings inoculated with G. fasciculatum or G. mosseae yielded a greater flux of zeatin, dihydrozeatin and zeatin riboside than non-inoculated seedlings. The flux of zeatin riboside was significantly greater than the flux of zeatin in seedlings inoculated with VAM symbionts. Vesicular-arbuscular mycorrhizal relationships apparently contributed to, or inguenced, the export of cytokinins from the root. The elevated cytokinin flux of inoculated seedlings was associated with improved tissue phosphorus nutrition and a significant increase in seedling biomass.

Genotypic and media effects on plant regeneration from cotyledon explant cultures of some Brassica species

Abstract: Conditions were established for efficient plant regeneration from cotyledon explant calli in different cultivars ofBrassica juncea, B. campestris andB. carinata on Murashige & Skoog's (MS) medium supplemented with various combinations of cytokinins and auxins. Regeneration frequency, however, varied with genotype and the different growth hormone combinations in media. Almost in all species, MS medium with zeatin (1.0 mg 1-1) and IAA (0.1 mg l-1) was found to be best for shoot organogenesis followed by the ones containing high kinetin (2.0 mg l-1) and low IAA (0.02 or 0.2 mg l-1) concentrations. On these media, the cotyledonary explants invariably underwent callusing followed by multiple shoot formation, which could be separated and subcultured for further propagation. Number of shoots per cotyledon explant cultured varied from 0 to as many as 50. InB. juncea andB. campestris, the regeneration frequency declined sharply in the absence of auxin in medium. BAP in combination with NAA yielded no or a reduced number of shoots. Shoot organogenesis also declined with the reduction in photoperiod from continuous light to 16 hours. Shoots were easily rooted during prolonged incubation on the same medium and whole plants were transferred to pots in the greenhouse and grown to maturity.

Plant regeneration from cell suspension cultures of Vigna aconitifolia.

Abstract: Plant regeneration has been achieved routinely from established cell suspension culture lines of Vigna aconitifolia (moth bean), a highly drought tolerant grain legume. The cultures originated from three-week-old leaf callus. Several media including MS, B5, AA, SL, PCM, SH and L-6 were tested for their effects on cell growth. Maximum growth was observed in L-6 medium containing 44.5 μM 2,4-D. After 6 to 8 weeks the suspensions were filtered through 500, 250, 125 and 60 μm sieves, respectively, for four to five subcultures. An embryogenic cell line (VA-686) was obtained from the cell fraction collected below 250 μm. The VA-686 cell line is being maintained on L-6 medium with 4.5 μM 2,4-D and 2.3 μM Zeatin. Somatic embryogenesis was induced by transferring the cells to L-6 medium with 4.6 μM zeatin in which green cell clusters were produced. The somatic embryos developed from most of the cell clusters when plated on L-6 agar medium with 2.3 μM BA. Plantlets were obtained from the embryos on L-6 medium with 10.0 μM IBA. The regenerated plants were grown to maturity in the greenhouse.

Inducible expression of cytokinin biosynthesis in Agrobacterium tumefaciens by plant phenolics.

Abstract: Nopaline strains of Agrobacterium tumefaciens contain a gene, tzs, that encodes a cytokinin biosynthetic prenyl transferase. The gene is located adjacent to the Ti plasmid virulence region and is constitutively expressed at low levels. As a result, bacteria containing tzs secrete low levels of zeatin into the medium. We find zeatin secretion to be induced more than 100-fold by acetosyringone, one of a number of naturally occurring phenolics produced by plants in response to wounding. Induction was very sensitive to the pH of the medium (optimum pH 5.5) and was due to massive overexpression of tzs-encoded cytokinin prenyl transferase activity. The relative ability of members of a set of phenols to induce tzs expression was examined and found to be parallel to that reported for activation of other virulence genes. A series of molecular cloning experiments established that virA and virG, two genes known to be essential to the virulence induction process, were necessary and sufficient for phenolic-induced tzs expression. Sequences present in the promoter region of tzs were found to be similar to those present in genes regulated by bacterial two-component positive regulatory systems.

Plant regeneration from protoplasts of Capsicum annuum.

Abstract: Leaf protoplasts were isolated from axenic shoot cultures of four varieties of Capsicum annuum (Americano, Dulce Italiano Florida Gynat and Nigrum) and a wild species C. chinense. Protoplasts of both species, cultured in KM8P medium and using agarose bead culture, entered division with the exception of the variety Nigrum. Cell colonies formed callus in agar-solified MS medium supplemented with zeatin and for C. annuum v. Dulce Italiano shoots were regenerated when protoplast-derived calli were transferred to MS medium with 6-BAP. Excised shoots were rooted on MS medium which lacked phytohormones.

Regeneration from long-term cell suspension cultures of tepary bean (Phaseolus acutifolius).

Abstract: Plant regeneration has been achieved from long-term cell suspension cultures established from leaf derived callus of tepary bean (Phaseolus acutifolius). The proportion of densely cytoplasmic cells in suspension culture increased when cultured in the L-6 medium with 54 μM NAA and 2 μM KN. Filtration of the cells at each of five consecutive subcultures resulted in the isolation of a plant regenerating cell line (TB 686), which is being maintained in L-6 medium with 4.5 μM 2,4-D and 2.3 μM zeatin. Differentiated green cell aggregates were obtained when cells from maintenance medium were transferred to the same medium with 10 μM BA. Embryo-like structures developed from these aggregates on L-6 medium with 2.3 μM zeatin, 0.69 μM GA3 and 1.5 μM NAA. Plantlets regenerated from these structures when they were cultured on L-6 medium with 7.0 μM NAA and 1.0 μM KN. Plant regeneration from the cell line remained relatively constant for 270 days. Regenerated plants were grown to maturity in the greenhouse.

Cytokinins of dry Zea mays seed: Quantification by radioimmunoassay and gas chromatography-mass spectrometry

Abstract: The endogenous cytokinins present in dryZea mays seed were determined using both radioimmunoassay and gas chromatography—mass spectrometry. Similar values for bases and ribosides were obtained by the two methods. The cytokinins present in embryo and endosperm were estimated separately using radioimmunoassay; similar levels of cytokinins were found in these two tissues. The major cytokinins detected on a whole-seed basis were dihydrozeatin riboside, O-glucosyldihydrozeatin riboside, zeatin 9-glucoside, zeatin, and the nucleotides of zeatin, dihydrozeatin, and isopentenyladenine. Cytokinin levels in the mature dry seed were considerably lower than cytokinin levels published in the literature for immature seed. Unexpected activity in the radioimmunoassays was detected in the wash from the DEAE cellulose column chromatography step. The compound(s) responsible for this activity did not have the solvent partitioning characteristics of a cytokinin base or riboside. They eluted as a single fraction following high-performance liquid chromatography on a Zorbax C8 column; this fraction showed no activity in theAmaranthus bioassay for cytokinins, but inhibited the activity of authentic zeatin riboside present at an optimal concentration.

Regeneration of tepals, stamens and ovules in explants from perianth of Hyacinthus orientalis L. importance of explant age and exogenous hormones.

Abstract: Regeneration of tepals, stamens and ovules from perianth explants of Hyacinthus orientalis L. in different developmental stages could be controlled by means of exogenous hormones. Perianth explants in a relatively early stage of development were competent for differentiation of tepals on Murashige and Skoog (MS) medium supplemented with 2 mg·1(-1) N(6)-benzylaminopurine (BAP) or zeatin and 0.1 mg·1(-1) 2,4-dichlorophenoxyacetic acid (2,4-D). Perianth explants in a later stage of development regenerated stamens and ovules, and marked difference was observed in the activity of BAP and zeatin in this regard. Zeatin stimulated more strongly stamen formation, while BAP enhanced ovule formation. Thus, stamens were formed when the explants were cultured for four months on medium with 2 mg·1(-1) BAP and 0.1 mg·1(-1) 2,4-D and then transferred to medium with 0.2 mg·1(-1) zeatin and 0.005 mg·1(-1) 1-naphthaleneacetic acid. On the other hand, differentiation of ovules occured in explants cultured for two weeks on the former medium and then transferred to medium with 0.1 mg·1(-1) BAP and 0.01 mg·1(-1) 2,4-D. Although ovule formation could also be obtained with 2 mg·1(-1) BAP alone, it was substantially enhanced by the presence of 0.1 mg·1(-1) 2,4-D in the medium in the early stages of culture. The results demonstrate the importance of both the developmental stage of the source organ from which explants are excised and of the hormone composition of the medium for the regeneration of different floral organs by perianth explants of Hyacinthus.

Seasonal changes in levels of cytokinin-like compounds from Douglas-fir xylem extrudate

Abstract: Summary High-performance liquid chromatography, immunochromatography, and radioimmunoassay were used to identify cytokinin-like bases and glycosrdes in xylem sap of Douglas-fir (Pseudotsuga menziesii (Mirb.) France). Isopentenyladenosine-type (isopentenyladenine and isopentenyladenosine) and zeatin-riboside type (zeatin, zeatin riboside, and dihydrozeatin riboside) cytokinins were detected during springtime. A glucosyl conjugate of zeatin riboside was also present in small amounts. Levels of cytokinin-like compounds varied throughout the spring but were generally highest in late April to early May.

Receptor-like cytokinin-binding protein(s) from barley leaves

Abstract: Purified fractions of soluble proteins from barley leaves have been shown to contain specific binding sites fortrans-zeatin, a natural cytokinin. Such binding is very strong in vitro in concentrated solutions of some salts (ammonium sulfate or potassium phosphate) with optimum at pH 7–8 and temperature within the range 0–20°C. The cytokinin-binding sites have high affinity for zeatin (Kd∼1.5·10−8 M) and low capacity corresponding to 1–1.5 pmol zeatin per milligram of initial soluble protein. Cytokinin binding is reversible; it is due to protein (or proteins) with molecular weight 40–45 kDa. This protein(s) does not bind3H-adenine and3H-abscisic acid. The ability of various compounds to displace3H-zeatin from its high-affinity binding sites is in strict accordance with their biological cytokinin activities. Other phytohormones as well as fusicoccin do not displace3H-zeatin from its binding sites. Specific zeatin binding is sensitive to heat, alkali, and pronase, but not to RNase treatment. The 150- to 200-fold purification of cytokinin-binding proteins was achieved by a combination of ammonium sulfate precipitation and Ultrogel AcA-54- and DEAE-cellulose chromatography. The zeatin-binding protein(s) from barley leaves is suggested to take part in cytokinin action in vivo.

Phytohormone Levels in the Florets of a Single Wheat Spikelet during Pre-Anthesis Development and Relationships to Grain Set

Abstract: Lee, B. T., Martin, P. and Bangerth, F. 1988. Phytohormone levels in the florets of a single wheat spikelet during pre-anthesis development and relationships to grain set.—J. exp. Bot. 39: 927-933. The gradient in grain number found within a single spikelet of wheat (higher grain numbers in proximal positions than in distal positions) was investigated with respect to endogenous levels of hormones in anthers and carpels. Auxins, abscisic acid and cytokinins were measured using radioimmunoassay. Measurements were made on both whole ears and floral organs (anthers and carpels) of a single spikelet during pre-anthesis development. Similar hormonal trends in whole ears compared to those of anthers and carpels were only found for anther abscisic acid and indole acetic acid levels and carpel zeatin/zeatin riboside levels. In the distal floret positions of the spikelet where fewer or no grains were set, anther abscisic acid levels were higher than in those of the proximal positions.

Mass-spectrometric quantitation of cytokinins in tobacco crown-gall tumours induced by mutated octopine Ti plasmids of Agrobacterium tumefaciens.

Abstract: The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5′-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with 15N- and 2H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N6-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.

Quantification by ELISA of cytokinins in root-pressure exudates of Urtica dioica plants grown under different nitrogen levels

Abstract: Summary ELISAs for [9R]iP, [9R]Z and (diH) [9R]Z have been worked out which, in combination with HPLC., allow the quantitative determination of cytokinins of the isopentenyladenin-, zeatin- and dihydrozeatin-type in samples of plant material. The three ELISAs are optimally applicable in the range from 0.5 to 20 pmoles of cytokinins per assay but reliable measurements can still be performed down to 0.05 pmoles. The assay has been applied to root pressure exudates obtained from Urtica dioica plants grown under controlled conditions and at different nitrogen (nitrate) levels. The predominant cytokinins of the xylem exudate were Z, Z-nucleotide, iP, [9R]iP and iP-nucleotide, while (diH)Z was present to a minor extent. The concentrations of these compounds were found to range between 0.2 and 3 pmoles per ml exudate. Interestingly, no effect of the different nitrogen nutrition on the pattern and concentration of cytokinins in the xylem exudate could be established.

Cytokinin Concentrations in Roots and Root Xylem Exudate of Cucumber and Figleaf Gourd as Affected by Root Temperature

Abstract: Effects of root temperature on cytokinin concentrations in roots and root xylem exudate were compared between cucumber (Cucumis sativus L. cvs. ‘Suyo’ and ‘Kurume-ochiai H’) and figleaf gourd (Cucurbita ficifolia Bouche). The rootchilling tolerance of the latter plants is known to be considerably higher than that of the former plants.Cytokinin concentrations in root xylem exudate of cucumber cultivars decreased sharply at lower root temperatures, with ‘Suyo’ more greatly affected. In contrast, in figleaf gourd the concentrations were relatively unchanged at 14-23°C, and increased to a strikingly high level at 11°C. Cytokinin concentrations in roots were highest at 23°C in ‘Suyo’ and at 17°C in ‘Kurume-ochiai H’, and decreased at lower root temperatures in both cultivars. In figleaf gourd, on the contrary, the concentrations were significantly higher at 14°C than at higher temperatures, and increased to a still higher level at 12°C. Major cytokinins in the roots of figleaf gourd and probably of cucumber cultivars were zeatin and zeatin riboside, and the composition apparently changed little with root temperature.These results strongly suggest that figleaf gourd roots respond to low root temperature by stimulating cytokinin synthesis within the roots. However, cytokinin synthesis in cucumber roots may be greatly inhibited by low root temperature. The implications for the difference in root-chilling tolerance between cucumber and figleaf gourd are discussed.

Morphogenetic potential of long-term callus cultures of Actinidia deliciosa

Abstract: SummaryPlant regeneration of Actinidia deliciosa Liang and Ferguson (kiwifruit) has been established from long-term cultured petiole callus. Transfer of callus to MS medium supplemented with 1.0 mg 1−1 6-BAP and 2.0 mg l−1 IAA gave roots whilst shoot regeneration was induced, from callus and the newly formed roots, when both tissues were cultured on MS medium supplemented with 1.0 mg 1−1 zeatin alone.

Wheat Development Enhanced by Hormone Syndrome

Abstract: The morphological-physiological alterations that are correlated with increased grain yields in wheat appear to characterize a beneficial hormone syndrome, i.e., increased dwarfing, tillering, seed set, and greenness. Those changes in the growth habit appear to be linked and symbolize cytokinin responses. Similar changes occur in wheat plants treated in several different ways: (1) plants carrying the Rht dwarfing genes, (2) treated with chloro-cholinechloride (CCC), and (3) infected with wheat bunt fungal pathogens. The wheat bunt fungi, Tilletia caries and T. controversa, were analyzed for cytokinins in culture and in bunt-infected ovaries. Zeatin riboside (ZR) and isopentenyl adenosine (IPA) were present in hyphal cultures of the bunt fungi as determined by high-performance liquid chromotography and enzyme-linked immunosorbent assay. The identity of these two cytokinins was established by gas chromatography-mass spectroscopy. Zeatin was detected only in hyphal culture filtrates. Five other cytokinin-like...

Vegetative propagation of Syringa vulgaris L. in vitro

Abstract: Excised shoot tips from adult Syringa vulgaris L. plants were rejuvenated by repeated subculturing in vitro. The number of subcultures required to rejuvenate the shoots was strongly dependent on the age and genotype of the plant material. Three rootstocks (K8, A2 and A3) and 5 cultivars (Mademoiselle Marie Legray, Madame Florent Stepman, Marechal Foch, Hugo Koster and Herman Eilers) were studied in vitro. The basic culture medium for isolation, subculture and shoot elongation contained: Murashige and Skoog (MS) macro-salts 1.5 strength, MS micro-salts (except Fe), NaFeEDTA 50 mg/1, saccharose 3.5°2iP 0.8 mg/1, Difco Bacto-agar 0.8°pH 6.0 and distilled water. The cultures were incubated in a growth room at 21°C and a day/night schedule of 16 h fluorescent light/8 h darkness. After rejuvenation, cloning was realized by repeated single-node culture. The application of a cytokinin and low irradiance (4–5 W m-2) induced stem elongation from pre-formed buds in the axils of the leaves. Zeatin(riboside) was most effective for stem elongation, followed by 2iP. The cytokinins, BA and kinetin, were not very effective in inducing stem elongation. Stem elongation was dependent on the genotype used. High cytokinin levels (2–5 mg/1) induced axillary branching but hardly any stem elongation and the leaves were strongly curled. Single-node culture and stem elongation in a medium containing 1.0 mg/1 2iP was definitely the best method of propagating lilac in vitro. Shoots were easy to root on a cytokinin-free medium with auxin or on an artificial substrate (rock wool) after an auxin dip. Acclimatization of in vitro rooted shoots to greenhouse conditions was successful when at low irradiance and high relative humidity for the first 2 weeks after transfer.

Cytokinin activity in Citrus jambhiri Lush. seedlings colonized by vesicular-arbuscular mycorrhizal fungi

Abstract: The influence of vesicular-arbuscular mycorrhizal symbiosis on cytokinin activity in Citrus jambhiri Lush, seedlings was investigated. C. jambhiri inoculated with cultures of Glomus caledonium (Nicol. and Gerd.), G. epigaeum (Dan. and Trappe), G. etunicatum (Becker and Gerd.), G. fasciculatum Thaxt. (Gerd, and Trappe) or G. mosseae (Nicol and Gerd.) was grown from seed for 105 days in a glasshouse. Cytokinin activity in roots and leaves of seedlings was analyzed using high-performance liquid chromatography, mass spectrometry and a bioassay. Seedling leaf tissue had greater cytokinin activity than root tissue. Zeatin, zeatin riboside, and their dihydro- and glucoside derivatives were isolated from leaves of 105-day-old seedlings inoculated with G. fasciculatum and G. mosseae. Cytokinin activity in roots and leaves was associated with differences in seedling total dry weight and vesicular-arbuscular mycorrhizal colonization. The ribose moiety and the saturated side chain apparently influence cytokinin transport and physiological activity in Citrus seedlings.

Plant regeneration from oca (Oxalis tuberosa M.): the effect of explant type and culture media

Abstract: Shoot regeneration has been obtained from internode and petiole sections of oca on a number of culture media supplemented with 3 mgl-1 naphthaleneacetic acid and 3 mgl-1 of either benzylaminopurine or zeatin, the latter being more effective. A greater percentage of sections from the 4th, 5th and 6th internodes (numbered from the apex) produced shoots than sections from older or younger internodes. Of five locally available genotypes based on tuber colour, a weak-growing type ‘white’ showed the greatest morphogenetic potential. Out of eight nutrient media tested, a modified B5 medium containing casein hydrolysate and L-glutamate supported the most consistent shoot regeneration. Shoot regeneration was preceded by the formation of a dark red smooth-surfaced callus. This was usually followed by the formation of a short tapering root. Swellings arose at the base of the root and developed into single or multiple shoots. These shoots were excised, rooted in basal Murashige & Skoog medium and transferred to the field.

Somatic Embryogenesis from the Leaf Tissues of Continuously Subcultured Shoots in Japanese Persimmon (Diospyros kaki THUNB.)

Abstract: Indirect somatic embryogenesis occurred in Japanese persimmon 'Fuyu' Ieaf segments which were cut from shoots one year plus four or five weeks after the beginning of subculturing on Murashige and Skoog's medium which contained half strength nitrogen (1/2 NMS) supplemented with 10-5M zeatin. Embryo formation was increased by the addition of 10-6M BAP and 10-5 M NAA to the same 1/2NMS medium in which the shoots had been cultured. Leaf segments planted with their obverse sides in contact with the medium showed a higher percentage of embryo formation than those planted with their reverse sides in contact.