K. Nataraja

Efficient Regeneration of Vanda Coerulea, an Endangered Orchid Using Thidiazuron

Efficient shoot regeneration of Vanda coerulea was achieved using thin shoot tip sections and thidiazuron. Protocorm-like bodies or proliferating shoot buds was observed when thin shoot tip sections were cultured on Vacin and Wents (VW) (1949) basal medium supplemented with 11.35 µM thidiazuron. The highest percentage of protocorm-like bodies (95%) survived and ultimately produced healthy shoots with 2 – 3 leaves when subjected to a 4 week thidiazuron treatment. A culture period longer than 8 weeks with thidiazuron resulted in the formation of fasciated or distorted shoots. Shoots produced roots when cultured on half strength VW basal medium supplemented with 11.42 µM IAA. The well rooted shoots were transferred to pots containing charcoal chips, coconut husk and broken tiles (2:2:1) and a 98% survival rate was achieved.

CRYOPRESERVATION AND PLANT REGENERATION VIA SOMATIC EMBRYOGENESIS USING SHOOT APICAL DOMES OF MATURE PINUS ROXBURGHII SARG. TREES

SummaryThe present investigation reports optimized parameters for somatic embryogenesis and cryopreservation of embryogenic cultures using shoot apical domes from mature trees of Pinus roxburghii Sarg. Embryogenic tissue of P. roxburghii Sarg. was cryopreserved for 24 h, 10 d, and 8 wk using sorbitol and dimethylsulfoxide (DMSO) as cryoprotectants. Results indicate that 0.2M sorbitol and 5% DMSO had the best cryoprotecting effect. The recovered tissue showed luxuriant growth on maintenance medium (II). Partial desiccation of thawed embryogenic tissue for 24 h prior to transfer to maturation medium enhanced the maturation of somatic embryos. Maturation frequency increased from 1.3 to 18.3% after 12 h desiccation treatment, and from 18.3 to 61.8% after 24 h of desiccation. However, non-desiccated embryogenic tissue produced the least number of somatic embryos (1.3%) on the maturation medium with the same abscisic acid and Gellan gum concentration. All the three embryogenic lines produced plantlets and had the same appearance and normal growth as compared to unfrozen controls.

Plant regeneration via somatic embryogenesis in Pinus kesiya (Rolye ex. Gord.) influenced by triacontanol

Embryogenic cultures were initiated and established for the first time in 3 different genotypes of Pinus kesiya using mature zygotic embryos and triacontanol. Mature zygotic embryos produced white-mucilaginous embryogenic callus when cultured on half strength MSG (Becwar et al. 1990) basal medium supplemented with 90 mM maltose, 2.0 g l−1 Gellan gum, 9.0 M 2, 4-D and 10 g l−1triacontanol. On subculture of such embryogenic callus on the maintenance medium (II) containing 2.0 M 2,4-D and 2.0 g l−1 triacontanol induced cleavage polyembryogenesis with proembryos. The percentage of somatic embryogenesis was not similar in all the three genotypes. The highest percentage of somatic embryogenesis (88.5 %) was recorded in PK04 genotype. Somatic embryos were successfully germinated on half strength MSG basal medium without growth regulators. Somatic seedlings showed fast growth and a survival rate of 95%. This work for the first time reveals that triacontanol can be used as an effective growth regulator for inducing somatic embryogenesis in conifers.

EFFECT OF TRIACONTANOL ON THE MICROPROPAGATION OF COSTUS SPECIOSUS (KOEN.) SM. USING RHIZOME THIN SECTIONS

SummaryThe highest percentage of shoot regeneration of Costus speciosus was achieved using thin rhizome sections and triacontanol (TRIA). Factors affecting the rate of shoot multiplication and rooting with TRIA have been investigated. Initiation of shoot buds was observed when rhizome thin sections were cultured on B5 basal medium supplemented with 5μgl−1 TRIA. Shoots with two to three leaves produced roots when cultured on B5 basad medium supplemented with 2 μgl−1 TRIA. The well-rooted shoots were hardened and transferred to soil where they showed normal growth and a 100% survival rate was achieved. Results of this study showed that TRIA can be used as an effective growth regulator in the micropropagation and conservation of C. speciosus.

Large Scale Production and Storability of Encapsulated Somatic Embryos of Mothbean ( Vigna aconitifolia Jacq)

Storability and germination of sodium alginate encapsulated somatic embryos of Vigna aconitifolia (Jacq.) cv. BMB-43 were tested on half strength Murashige and Skoog (MS) basal medium fortified with coconut water (10% v/v). The frequency of regeneration from encapsulatd embryos was affected significantly by concentration of sodium alginate and the duration of exposure to calcium chloride. Embryos encapsulated with 2.5 % sodium alginate dissolved in MS basal salts solution recorded significantly higher germination than other treatments. A relatively short (5 min) incubation with calcium chloride solution provided uniform encapsulation of embryos that gave the highest percentage (65%) of germination. Synthetic seeds could be stored at 4üC for 50 days without reduction in viability as opposed to non - encapsulated somatic embryos which showed 6% viability after 20 days at 4°C. Germinated synthetic seeds produced normal plantlets.