Search Results
Abstract
Asexual embryos of Theobroma cacao L. (cacao), initiated from zygotic embryos and grown in nutrient medium with increasing sucrose concentrations, synthesized lipids with fatty acid and triglyceride composition similar to those of zygotic embryos maturing in vitro. Oleo-palmitostearin, the major triglyceride in cocoa butter, was identified in developing asexual embryos cultured in vitro. In vitro culture of asexual embryos of cacao may be a feasible system for the production of cocoa butter.
Abstract
Shoot tips proliferated in vitro were used as explants to determine the effects of various nutrient medium components and environmental conditions on shoot multiplication of Hosta decorata L. H. Bailey ‘Thomas Hogg’. The rate of axillary shoot multiplication was stimulated by the addition of either 0.01 or 0.10 mg×liter α-naphthaleneacetic acid (NAA) to medium containing 5 mg×liter 6-benzylamino purine (BA). Indoleacetic acid (IAA) and indolebutyric acid (IBA) did not promote axillary shoot formation. All 3 auxins were effective in promoting adventitious shoot initiation. In medium with 0.1 mg/liter NAA, BA at 5 mg/liter stimulated a higher number of shoots of axillary origin than did N6-isopentenylaminopurine (2iP) or N6-furfurylaminopurine (kinetin). However, equivalent or greater proliferation of adventitious shoots was achieved with 2iP or kinetin. Sucrose was essential for shoot multiplication and 30 g×liter was optimum. Inorganic phosphate (NaH2PO4 · H2O) and adenine sulfate stimulated growth and shoot multiplication while i-inositol, although not essential, enhanced shoot formation at 30 mg×liter. Axillary and adventitious shoot multiplication was optimum under photosynthetkally active radiation (PAR) of 70 or 130µE m-2s-1 at 21°C and under PAR of 70 µE m-2s-1 at 26°C. Rooting of shoots in vitro was obtained on basal medium without growth regulators or on medium containing 0.01 mg/liter NAA, and the plants were successfully established in soil. Plants obtained from culture which had lost leaf margin variegation regained it after receiving a cold room treatment of 3-6°C for 20 weeks.
Abstract
In propagating Asparagus officinalis L. through the method of shoot apex culture, apices of terminal buds of spears produced in vitro were found to be equally satisfactory as explants as those of lateral buds of spears obtained from the field. A maximum number of plants was obtained when the cultures were illuminated 4-20 hr daily with white fluorescent or Gro-Lux lamps at an intensity of 1000 lux. A constant 27°C temp was also optimum for plant formation in vitro. Histological examination revealed that roots arose adventitiously from callus which formed at the base of the explant, whereas spears originated from axillary buds.
Successful transfer of plants from laboratory to soil required a prior reculture in a medium lacking NAA and with the light intensity increased to 3000 or 10,000 lux. Examination of the chromosome numbers of plants propagated through shoot apex culture showed that the original diploid status had been retained in every plant.
Abstract
Callus was initiated from cultured immature inflorescences of Hosta plantaginea Asch. ‘Grandiflora’ in darkness on a basal medium containing Murashige and Skoog salts, vitamins, glycine, i-inositol, sucrose, agar, and 10 mg/liter naphthaleneacetic acid (NAA) and 0.1 mg/liter 6-benzylamino purine (BA). Reculture of the callus onto a medium containing 0.01 mg/liter NAA and 5 mg/liter BA, resulted in the formation of numerous adventitious shoots. Adventitious shoots were initiated also from leaves and segments of leaves from shoots formed in vitro when cultured on a medium supplemented with 0.01-1 mg/liter NAA and 5 mg/liter BA. Root formation was achieved when individual shoots were excised and transferred to a medium containing the basal constituents without growth regulator supplements. Rooted plants were successfully transferred to soil.
Abstract
A nutrient medium which enabled rapid formation of new spears and roots in shoot apices excised from buds as well as lateral branches of Asparagus officinalis L. spears was developed. This medium was composed of the following, in mg/1 : Murashige and Skoog’s inorganic salts; NAA, 0.3; kinetin, 0.1; thiamin·HC1, 1.0; pyridoxin·HCl, 5.0; nicotinic acid, 5.0; myo-inositol, 100; adenine sulfate·dihydrate, 40; sucrose, 25,000; Difco Bacto malt extract, 500; NaH2PO4·H2O, 170; and Difco Bacto agar, 6000. The shoot apices were cultured under 1000 lux Gro Lux or Plant Gro light and at constant 27°C. The explants were 0.15 mm in height and composed of the apical meristem plus a few visible subjacent primordial leaves. Within 6 weeks an avg of 80-90% of the cultures developed into miniature plants with several spears and roots. These plants, however, could not be transferred to soil with much success. The transfer necessitated further culture under another set of conditions, details of which are currently under investigation. The nutrient medium was inapplicable to shoot apex cultures of A. densiflora (Kunth) Jessop cv. Meyers, A. densiflora (Kunth) Jessop cv. Sprengeri, and, A. sarmentosus (Hort.).
Abstract
Numerous bulblets were obtained directly from flower bud tissue of Hyacinthus orientalis L. cvs. Anna Marie and Delft Blue on medium containing Murashige and Skoog salts, vitamins, glycine, i-inositol, sucrose, and agar plus 3 mg/liter 6-benzylamino purine (BA) and 0.3 mg/liter naphthaleneacetic acid (NAA), both in darkness and in light. Root formation occurred when individual bulblets were separated and transferred to a medium containing 0.1 mg/liter NAA. Over 90% of bulblets of both cultivars grown on this medium were successfully transferred to a soil mixture.
Abstract
The node position from which axillary buds were isolated from shoots of rose (Rosa hybrida L.) markedly affected their growth and development in culture. Those buds nearest to and furthest from the apex either failed to develop or took the longest time to develop in culture compared to those buds in the middle portion of the stem. Benzylamino purine (BA) at low concentrations (0.03 to 0.3 mg/liter) stimulated the development of the axillary buds of ‘Gold Glow’ but not of ‘Improved Blaze’. A photon flux density (400-700 nm) of 17μE m−2 s−1 for 12 to 24 hours daily was optimum for the stimulation of shoot multiplication, while 66 μE mm−2s−1 for 12 to 24 hr was optimum for root initiation and for subsequent successful transplantation to soil of tissue culture-derived plants. A constant temperature of 21°C resulted in the highest rate of shoot multiplication and root initiation. Plants which initiated roots at 16, 21, or 26° had the highest level of transplant survival. An alteration in the temperature of the 8-hr dark period from 21° did not increase shoot multiplication, although root initiation was enhanced by lowering the night temperature to 11 or 16°. Histological analysis indicated that shoot multiplication of rose shoots occurs through the growth and development of axillary buds. The development of axillary buds is apparently under the repressive influence of the shoot apex, because physical excision of the apex or application to the shoot apex of 2,3,5-triiodobenzoic acid (TIBA) facilitated axillary bud development. Root initiation was affected markedly by the length of time that cultures had been maintained on shoot multiplication medium prior to transfer to rooting medium. This effect may be attributable to the BA in the shoot multiplication medium which may have accumulated in the tissue. If the endogenous cytokinin level is too high, root initiation may be inhibited and if it is too low the shoot undergoes senescence before it becomes cytokinin-autonomous, which occurs after root initiation.
Gibberellins (GAs) are phytohormones that regulate plant height and flowering time in plants. Plants with reduced GA or disrupted in GA signaling exhibit a dwarf phenotype. DELLA proteins are transcriptional repressors that attenuate GA-mediated promotion of plant growth. Alleles in which the eponymous DELLA motif in these proteins is disrupted result in constitutive repression of GA signaling and a dominantly inherited dwarf phenotype. We found that the dwarf Helianthus annuus (sunflower) cultivar Sunspot is hyposensitive to GA3 as compared with the tall cultivar Mammoth Grey. Sequencing of the HaDella1 gene indicates that ‘Sunspot’ has a single nucleotide polymorphism resulting in a missense mutation in the DELLA motif as compared with ‘Mammoth Grey’ and the reference sequence. Helianthus annuus has five genes encoding DELLA proteins, including HaDella1. We propose that the DELLA motif alteration in the HaDella1 gene results in a dominant mutation in ‘Sunspot’ and is the cause of its dwarf phenotype.