Rapid in vitro propagation of the threatened endemic orchid, Ipsea malabarica (Reichb.f.) J D Hook through protocorm-like bodies.

Rapid propagation of I. malabarica (Reichb. f.) J D Hook, an endemic and endangered orchid of the Western Ghats of Kerala, India through conversion of axillary buds to protocorm-like bodies (PLBs), and subsequent plant regeneration was achieved. Growth regulators and sugar displayed significant influence in the induction of PLBs. In vitro derived shoots from field grown rhizomes of Ipsea cultured on Murashige and Skoog (MS) medium with 13.3 microM N6-benzyladenine (BA) containing 2% commercial grade sugar turned the axillary buds to PLBs within 25 days, and developed a mean of 33.1 PLBs within 50 days. Kinetin (KIN) did not induce PLBs, but facilitated axillary bud proliferation. Transfer of PLBs on medium having same concentration of BA and sugar facilitated rapid multiplication, and developed a mean of 47.5 PLBs. No decline of PLB proliferation was observed up to 10th subculture. Half strength MS medium with 6.97 microM KIN facilitated conversion of 98% PLBs to plantlets. On this media, a mean of 5.8 roots were also developed per shoot. Shoots developed bulbs during culture were grown to rhizomes. Increase of sugar to 6 or 8% hastened the development of bulbs/rhizomes. Reintroduction of PLB-derived plantlets in the natural habitat i.e. at Vellarimala (at 1300 m height) of the Western Ghats of Kerala was attempted as a means to assist in situ conservation. This is the first report of conversion of axillary buds to PLBs. The protocol enables to surmount the threat of extinction of this endemic and endangered orchid.

In vitro propagation of Dendrobium hybrids using flower stalk node explants.

Large-scale in vitro propagation protocol for Dendrobium hybrids Sonia 17 and 28, two highly prized commercial cut flower cultivars through shoot multiplication using flower stalk node explants and protocorm-like bodies (PLBs) formation was accomplished. Both hybrids did not exhibit significant differences in initiation, multiplication, rooting, and field establishment. Flower stalk nodes cultured on half strength Murashige and Skoog (MS) medium supplemented with 6.97 microM kinetin (Kn), or 15% coconut water (CW) or 13.3 microM of N6-benzyladenine (BA) evoked bud break. Kn showed better growth of the initiated bud. Excision and culture of the initiated shoots on medium having same amount of Kn developed more than 5 shoots per shoot directly from the base. Subsequent culture enhanced the rate of shoot induction. Transfer of isolated shoots onto 44.4 microM of BA enriched medium displayed induction of more than 6 PLBs from the base within 60 days. PLBs underwent rapid multiplication upon transferral to medium having the same concentration of BA (44.4 microM). Subsequent culture increased the proliferation of PLBs. No decline was observed in the proliferation of shoots as well as PLBs up to 15th subculture. PLBs transferred onto half strength MS medium with 6.97 microM of Kn underwent conversion of more than 90% PLBs to shoots. The shoots were rooted at the best on half strength MS medium with 2 g l(-1) activated charcoal. Survival rate of the plantlets of the two hybrid cultivars after acclimatization was more than 80%.

In vitro propagation of three commercial cut flower cultivars of Anthurium andraeanum Hort.

In vitro propagation of Anthurium andraeanum Hort. cut flower cultivars viz. Lima White, Tropical White and Tropical Red through organogenesis using mature plant derived leaf explants was established on Murashige and Skoog (MS) medium fortified with different growth regulators. Cultivar, stage and different regions of the source leaf, and type of growth regulators significantly influenced callus induction. Explants from folded brown leaves were superior in induction of callus. Half strength MS medium fortified with 0.88 microM of benzyiadenine (BA), 0.9 microM of 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.46 microM of kinetin (Kn) at pH 5.5 was most effective for callus induction. Transfer of callus to medium with 0.54 microM of NAA in place of 2,4-D induced higher number of shoots. Subsequent cultures displayed enhanced rate of shoot initiation and multiplication. Transfer of shoots onto half strength MS medium supplemented with 0.54 microM of NAA favoured rooting of shoots. Cultivar Tropical White was superior in callus, shoot and root induction compared to Lima White and Tropical Red. Plantlets after acclimation in greenhouse were transferred to net-house, that exhibited ninety seven per cent survival. Plants flowered normally between 12 and 15 months and were morphologically similar to that of the mother plants.