No abstract

SummaryCambial tissues from the twigs of a mature Japanese persimmon, Diospyros kaki Thunb, cv. `Tsurunoko', were used as the starting material in this experiment. Callli were induced on various callus induction media.Root formation in the calli was observed on Murashige and Skoog's medium containing 1 ppm NAA. KIN in combination with NAA did not inhibit to the root formation at 1 ppm.Root formation in the callus depended largely on the type of medium en which the callus was isolated and subcultured and the number of successive subcultures on a given medium. When the callus was isolated on Murashige and Skoog's medium containing NAA and KIN, roots were formed in the first passage, whereas when the callus was isolated on Murashige and Skoog's medium containing 0.1% yeast extract or 0.1% phytone, NAA, and KIN, the first root formation was not observed until the callus was subcultured on the medium several times.Roots were never formed in calli which were isolated and subcultured on Murashige and Skoog's medium containing 2, 4-D or IBA instead of NAA, nor were either Wolter and Skoog's medium or a modified Wolter and Skoog's medium containing NAA and KIN suitable for root formation.Bud initials were formed in callus which was subcultured several times on Mura shige and Skoog's medium containing NAA and KIN. KIN was effective in promot ing bud initiation in combination with NAA.These initials turned green under continuous light conditions, but they did not succeed in developing themselves into plantlets on various media.Abnormal structures were initiated in callus cultured on Murashige and Skoog's medium containing NAA and KIN, but these structures were not identifiable as either root or bud initials.

No abstract

Callus with multiple buds (CMB) consisting of callus and many buds in which the multiplication of buds was associated with callus growth was induced from the sections of twigs on an agar medium in an ornamental conifer, Chamaecyparis pisifera, var. finifera Beissn. A devised medium containing half strength of Murashige and Skoog's minerals, vitamins, inositol, amino acids, sucrose, 1mg/l BA and 0. 3 mg/l IAA (SF-medium) was favored to induce CMB. CMB is able to be subcultured on SF-medium without a decrease in capacity to form buds for more than 5 years. Buds in various developmental stages were observed in CMB depending on the length of culture period. Buds with scale-like leaves in CMB were observed in the regular subculture cycle. Needle leaves appeared in the buds of CMB with prolonged culture more than about 2 months on SF-medium without regular subculture.Buds developed into shoots when buds were isolated from CMB and cultured on SF-medium with low concentration of NAA or IBA, 0. 03-0. 1 mg/l.Organ formation in in vitro culture of gymnosperms was observed in various isolated organs such as cotyledons,1,2) embryos3-7, hypocotyls, 8) needles9,10) and vegetative buds11) in several species. Those experiment were observed in primary culture, whereas organ formation in the callus culture was marely observed in Sequoia sempervirens. 12) Tissue cultures which consisted of callus like mass containing embryoids were recently induced from isolated embryos in Picea, 13, 14) which were subcultured and regenerated organs such as embryos.In this experiment, we induced bud forming tissue from twigs of an ornamental conifer tree, Chamaecyparis pisifera, var, filifera Beissn. in which callus growth was associated with the multiplication of buds (CMB), and CMB was subcultured for many passages without a decrease in the growth rate and bud multiplication. Materials and MethodsTwigs used in this experiment as starting materials were collected in early August from a tree of Chamaecyparis pisi f era Sieb. et. Zucc. var. filifera Beissn. et Hochst, which tree was established by planting a cutting about 30 years ago and grew up in a garden in Saitama prefecture, Japan. Collected twigs were surface-sterilized with 3% sodium hypochlorite for 15 min and rinsed with sterilized distilled water for several times, and then cut into sections (5 mm long). Twig segments were placed horizontally on agar medium and cultured under continuous light (3,000 lux) at 27+10C.Basal medium was made up of half strength of Murashige and Skoog's minerals,15) 1mg/l thiamine HCI, 1 mg/l pyridoxine HCI, 4 mg/l nicotinic acid, 0.

No abstract