Zeitschrift für Pflanzenphysiologie最新文献

Vegetative multiplication of a Catasetum hybrid was obtained by culturing in vitro root tips measuring about 1.5 mm in length. The cultures showed various growth patterns in accordance with the substances that were added to the media. Most of the protocorm-like bodies were regenerated from the explanted root tips, while some regeneration was obtained with callus cultures.

Callus of Theobroma cacao L. (cacao) possessing embryogenic competence occurred spontaneously with two clones of asexual embryos proliferated in vitro in a hormone-free basal medium by hypocotylary budding. Asexual embryogenesis via callus occurred at low frequency in the hormone-free basal medium. High concentrations of 2,4-D plus coconut water stimulated callus production and suppressed embryo production. Maximum frequency and intensity of embryogenesis occurred at 10⁻³ to 10⁻² mg·l 2,4-D. Embryos originated from meristematic tissue at the periphery of callus clumps. During development asexual embryos either remained embedded in the callus or were connected through suspensor-like structures.

Microspore culture of Saccharum spontaneum L. was investigated as a means to produce haploid plants. Isolated and cultured microspores initiated sporophytic development which in 4 to 6 weeks resulted in procalli and calli.

The percentage of microspores producing multicellular procalli was increased by removing the nonviable microspores before initiating the culture, establishing an optimum population density, and using nutrient media relatively low in sucrose and NH₄NO₃.

The procalli produced from microspore culture ceased development at about the same stage as did procalli within anthers in culture. Thus, a factor or factors other than the anther wall must be responsible for the low yield of haploids from S. spontaneum.

The effect of temperature and of sucrose and 2,4-D in the media changed during the development of calli from unicellular microspores. The apparently different requirements for specific stages of development indicates that successful production of haploid plants from microspore culture will require a series of environmental and cultural manipulations.

Tobacco callus grown under shoot-forming and non-shoot-forming conditions was incubated in ¹⁴C-glucose, ¹⁴C-acetate or ¹⁴C-bicarbonate on different days in culture. ¹⁴CO₂ production, and ¹⁴C incorporation into ethanol-soluble and ethanol-insoluble fractions was greater in shoot-forming than non-shoot-forming tissues. Greatest radioactivity from all substrates was in the ethanol-soluble portion, which was further fractionated into lipids, amino acids, sugars and organic acids. Greater conversion of ¹⁴C-glucose and ¹⁴C-acetate into these various fractions took place in shoot-forming than in the growing tissues, while the reverse was observed with ¹⁴C-bicarbonate. The differences in the metabolic patterns between shoot-forming and non-shoot-forming tobacco callus were in concert with the developmental behavior of the tissues.

Gibberellic acid at 0.05 to 10 mg·l⁻¹ stimulated asexual embryogenesis from embryogeniccompetent callus of clone BC 5 but not BC 36 of Theobroma cacao. AMO 1618 stimulated embryogenesis at 0.05 to 0.1 mg·l⁻¹ but depressed embryogenesis above 0.1 mg·l⁻¹ for clone BC 5. A similar but smaller effect was observed for BC 36. Daminozide and CCC depressed embryogenesis with both clones.

Callus of Euphorbia tirucalli L. was initiated with stem segments cultured on MS medium containing 2,4-D (1 ppm) and NAA (2 ppm) (1-MS-N medium), and was maintained on the same medium plus kinetin (0.5 ppm) (1-MS-NK medium). A fine suspension culture was obtained by subculturing the fast growing callus in liquid medium made up of three volumes of 1-MS-NK medium and one volume of modified B5 medium (medium 8p) as described by Kao and Michayluk (1975). Cells then were subcultured in 1-B5 liquid medium. Protoplasts were isolated by digesting the walls of cells cultured as suspension by Driselase (1%) and Pectolyase (0.1%). When transferred to medium 8p the protoplasts divided and formed large cell clusters.

A new procedure for obtaining more than one seedling per seed in Mung bean (Vigna radiata) is developed. This involves excision and isolation of both cotyledons from imbibed seeds and culturing them individually on a basal medium. Cotyledons directly developed into complete plants with roots. The percentage of the cotyledonary plants that developed was inversely proportional to the imbibition period of the seed. Cotyledon derived plants were transplanted to soil and raised to maturity. Normal pod development with seeds was observed in the transplanted plants. Seeds obtained from such plants were grown again in the field and the progenies obtained were normal. The cotyledon derived plants were comparable to seed raised plants.

Shoot apex expiants were obtained from 5 year-old grafted Taiwan sassafras. A modified Linsmaier and Skoog medium was used. When grown on a medium with 60 mg·l⁻¹ KN, explants formed multiple-bud-masses (MBMs). Shoots of 1 cm or longer from the MBMs were harvested and conditioned for root induction. Sporadic rooting, less than 20%, has been obtained thus far. A 95% survival rate resulted after the rooted plantlets were transplanted into flats. Effective hormonal additives for the primary cultures, MBM proliferation, shoot conditioning and root induction were 60 mg·l⁻¹ KN, 5 mg·l⁻¹ KN + 0.05 mg·l⁻¹ NAA, 5 mg·l⁻¹ BA + 0.05 mg·l⁻¹ NAA and 5 to 10 mg·l⁻¹ IBA, respectively. The rate of leaf chlorosis, abscission and stem necrosis were lower when shoots from MBMs were incubated in medium with 2× FeEDTA at 18–20°C than in 1x FeEDTA at 25°C. The addition of glutamine and arginine in medium stimulated leaf expansion.

A method for rapid multiplication of Rosmarinus officinalis L. var. genuina forma erectus was developed affording production of about 5,000 plants from one nodal segment in one year. Plants could be established in culture only with nodal stem segments taken from fieldgrown plants. Ca. 14 shoot buds differentiated per shoot apex, excised from aseptically established plants, in medium with 0.2 mg·l⁻¹ BAP within 30 days. Isolated shoots rooted 80% in the presence of 0.25 mg·l⁻¹ IPA in 7 days. The in vitro-raised plants grew normally in soil under glasshouse conditions.

In Mahsuri rice callus cultures grown in light, the total amount of callus and the percentage of callus volume composed of embryogenic cells could be increased if 0.1–0.5 mg·l⁻¹ K was added to medium containing 0.5 or 1.0 mg·l⁻¹ 2,4-D. Embryogenic regions could be proliferated and maintained on the same media. E callus on initiation medium gradually produced embryoid-like structures and finally plantlets. This process could be hastened by removing E callus to a regeneration medium containing low concentrations of IAA and BAP or K. If the E callus produced by one seed were proliferated for five four-week passages on 0.5 mg·l⁻¹ 2,4-D and 0.5 mg·l^-1 K and transferred to regeneration medium, 7,318 plants could be produced from 184 g of E callus.