Sumitra Sen

Plant regeneration from alginate encapsulated somatic embryos of Asparagus cooperi baker.

Somatic embryos of Asparagus cooperi were encapsulated as single embryos approximately 4–6 mm in diameter to produce individual synthetic seeds. The frequency of conversion of artificial seeds to plants was 34%. This frequency was affected by the concentration of calcium chloride, the commercial sources of sodium alginate, and the nutrient medium. The conversion frequency of artificial seeds to seedling plants was 8.3% after storage for 90 days at 2°C.

A revised scheme for mass propagation of Easter Lily

Lilium longiflorum Thunb., commonly known as Easter Lily is widely propagated by vegetative means for its high ornamental value as a pot plant. Following in vitro technique, mass propagation has been achieved through direct production of bulblets from the explant as well as regeneration from callus. The chromosome analysis of the progeny derived from callus even from long term culture, did not reveal any marked variability in chromosome morphology. The stable nature of callus maintained in modified MS medium in long term culture has been confirmed. Along with rapid growth, the regenerating capacity of calli has been maintained for 3 years of culture in the above medium. Following shake culture, large number of bulblets could be obtained from such differentiated calli within 3–4 weeks. The shake culture technique of calli is ideally suited for securing stable regenerants on a mass scale in this species.

In vitro regeneration from bulb explants of Indian squill, Urginea indica Kunth

Callus cultures were established from bulb explants of diploid Urginea indica Kunth (Indian squill) on a modified basal medium of Murashige and Skoog (1962) supplemented with either 2 mg/l-1 2,4-D+15% (v/v) CM or 4 mg/l-1 2,4-D+2 mg/l-1 NAA+2 mg/l-1 KN+1 g/l-1 YE. Shoot primordia developed after 2–3 subcultures in that medium. Increased growth of shoot primordia was obtained in media containing less auxins and vitamins. Rooted bulbous plantlets obtained were maintained in MS medium with 0.5% sucrose.Adventitious shoots were induced from adaxial epidermal cells of outer scales of regenerated bulbs used as secondary expiants in presence of 1 mg/l-1 of 2,4-D with slightly higher concentration of the three vitamins of MS medium. From each scale leaf, approximately 400 bulblets were produced in 18 weeks in liquid culture. 90% of the plants transferred to potted soil have survived.

Enhancement of Regeneration Potential and Variability by γ-Irradiation in Cultured Cells of Scilla Indica

Induced mutagenesis in callus tissues was studied in the medicinal plant Scilla indica irradiated with different doses of γ-radiation ranging from 2.5 to 20 Gy. Low doses accelerated the cell division and growth rate of the tissues whereas high doses repressed growth rate and resulted in lethality of tissues. Various cytological and chromosomal abnormalities were observed in the irradiated calli, the degree of which depended upon the dosage. Low doses of irradiation also promoted the regenerating capacity of the calli tissues and plants regenerating from them exhibited better growth and vigour compared to normal plants. High doses led to loss of regenerating capacity and promoted formation of malformed and stunted plants. Cytological study of regenerants revealed both diploid and mixoploid plants but no tetraploids were obtained.

Plant regeneration through somatic embryogenesis from spear callus culture of Asparagus cooperi Baker

Somatic embryogenesis and plantlet formation were obtained from callus derived from the subapical region of spears of Asparagus cooperi Baker. Callus was obtained in Murashige and Skoogs medium supplemented with 1-naphthaleneacetic acid and kinetin. Increase in the concentration of potassium nitrate in subsequent subcultures resulted in the formation of embryos. Rapid multiplication of embryos was secured on transfer to a medium containing a different source of nitrogen and a low level (0.01 mg/1) of gibberellic acid. Media containing zeatin or gibberellic acid led to the formation of complete plantlets from embryos. Regenerated plants were cytologically and phenotypically stable.

Two-step bud culture technique for a high frequency regeneration of Gladiolus corms

Abstract High frequency in vitro bud multiplication has been achieved in four cultivais of Gladiolus by a simple two-step process. This involves an initial short-term exposure of the buds to a hormone-supplemented medium followed by withdrawal of hormones and subsequent culture of shoots and cormlets in liquid nutrient. This method ensures production of true-to-type stable plants, eliminating the chances of chromosome instability within a short period.

Propagation of Asparagus racemosus through tissue culture

Murashige and Skoogs medium with 2, 4-D and kinetin induced callus in the shoot segments of Asparagus racemosus. Regeneration of shoot buds and clonal multiplication of excised shoots through proliferation of nodal buds could be achieved by the use of IAA and BAP in the medium. Rooting was achieved with half strength MS basal medium plus IBA. Complete plants with cladode, crown and root systems were developed in hormone free medium. The plants were successfully transferred to soil.

Rapid and stable propagation ofOrnithogalum umbellatum L. in long term culture

Callus cultures were raised from bulb scale segments ofOrinthogalum umbellatum L. (Liliaceae), on a Murashige and Skoog (1962) medium (MS) with 8 mg/l naphthaleneacetic acid (NAA). Bulbous shoots developed from calli after 2 months using MS medium with 2 mg/l NAA and 0.5 mg/l N6 - benzyladenine (BA). Shoots were also induced directly from scales of regenerated bulb used as secondary explants on MS medium supplemented with 0.5 mg/l BA. Shoots developed roots in 1/2 - strength MS medium. Regenerants multiplied rapidly in 1/2-MS liquid medium. Chromosome instability was reduced in callus grown on 2 mg/l NAA compared to callus grown on 8 mg/l NAA. Callus retained regeneration potential for 5 years in this modified MS medium. The chromosome analysis of regenerants dervied from callus, even from long term culture of 5 years, revealed only diploid cells with normal karyotype comprising 2n=46 chromosomes. Stable nature of callus and regenerants were further confirmed by cytophotometry. This procedure can be applied for securing stable regenerants on a mass scale inO. umbellatum.

Bufadienolides in different chromosomal races of Indian squill

Abstract Scilliphaeoside and anhydroscilliphaeosidin have been isolated from tetraploid Indian squill. The absence of scilliphaeoside in all populations of diploids and hexaploids and anhydrophaeosidin in diploids, triploids and hexaploids might be one of the reasons why they were not detected in previous studies.

Regeneration and rapid multiplication of Bowiea volubilis Harv. in tissue culture.

Callus cultures were raised from segments of inflorescence axis of Bowies volubilis Harv. (Liliaceae) on a modified basal medium of Murashige and Skoog (1962) (MS) supplemented with 1 mg 1−1 2,4-dichlorophenoxy acetic acid (2,4-D) + 15% v/v coconut milk. Shoot primordia developed after 2–3 subcultures when auxin concentration was lowered. Rooted bulbous plants were obtained in MS medium without any hormone.Shoots were induced directly on scales of regenerated bulbs used as secondary explants on modified MS medium supplemented with 2 mg 1−1 6-benzylaminopurine (BAP) + 0.05 mg 1−1 2,4-D. These shoots grew and multiplied rapidly in shake culture using liquid MS medium. From each scale, 400–600 bulblets could be produced in 16–20 weeks period. Eighty percent of plants have survived on transferring to potted soil.