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- Author or Editor: Paul M. Hasegawa x
- Journal of the American Society for Horticultural Science x
Abstract
In vitro-derived shoot tips of ‘Improved Blaze’ rose (Rosa hybrida L.) proliferated on a medium containing MS salts, thiamine·HCl (0.5 mg/liter), pyridoxine·HCl (0.5 mg/liter), nicotinic acid (0.5 mg/liter), glycine (2.0 mg/liter), i-inositol (100 mg/liter), sucrose (30 g/liter), Bacto agar (8 g/liter), indoleacetic acid (IAA) (0.3 mg/liter) and 6-benzylamino purine (BA) (1.0, 3.0, or 10.0 mg/liter). A 6-fold multiplication could be obtained after 4 weeks; no further increase in multiplication was obtained by extending the length of the culture period. In vitro-proliferated shoots cultured for 10 to 14 days on the basal medium without growth regulators initiated roots and could be successfully transplanted into soil; however, both root formation and transplantability were enhanced by α-naphthaleneacetic acid (NAA) (0.03 or 0.10 mg/liter) or IAA (1.0 mg/liter) and by lowering the MS salt concentration to ¼ or ½ strength. Although the degree of root initiation and successful establishment in soil was variable, 90 to 100% successful transfer to soil could be obtained.
Abstract
Cultured immature sexual embryos of Theobroma cacao proliferated asexual embryos, but embryogenesis was not observed from leaf, pericarp, or ovule tissues. Cotyledons from immature, unpigmented embryos (2.5 to 10 mm long) were highly embryognie, while larger more mature, pigmented cotyledons initiated roots as their only form of organized development. Embryogenesis occurred in light and darkness when a basal medium was supplemented with coconut water and 1.5 mg/liter NAA. Proliferated embryos recultured in a liquid medium continued development.
Abstract
The effects of the components of Lam's 1977 potato nutrient medium on adventitious shoot formation were systematically evaluated. A low concentration (0.03 mg/liter) of naphthaleneacetic acid (NAA) stimulated shoot initiation and increased survival of tuber discs of potato (Solanum tuberosum L.). Indoleacetic acid (IAA), however, did not affect shoot initiation in the concentration range from 0 to 10 mg/liter. Both 6-benzyl-amino purine (BA) at 0.3, 1.0, and 3.0 mg/liter and N6-(4-hydroxy-3-methyl-but-2-enylamino)-purine (zeatin) at 0.3 and 1.0 mg/liter stimulated adventitious shoot formation while N6-furfurylaminopurine (kinetin) had no effect. Sucrose was essential for shoot formation with a concentration of 30 g/liter being optimal. Although not essential, i-inositol enhanced the initiation of adventitious shoots at concentrations of 60 and 100 mg/liter. Casein hydrolysate and additional inorganic phosphate had no promotive effect on shoot formation and adenine sulfate was inhibitory at all concentrations examined.
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
Cotyledonary development of asexual embryos of cacao (Theobroma cacao L.) in liquid medium on a rotary drum apparatus was similar to that of zygotic embryos in vivo. Immature zygotic and asexual embryos synthesized anthocyanins, characteristic of the developing zygotic embryo in vivo, when cultured in vitro in liquid or on semisolid media containing high concentrations of sucrose.
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.