No abstract

An in vitro process for rapid clonal propagation of Clerodendrum serratum (Linn.) Moon, a rare and threatened medicinal shrub, has been developed. Nodal stem segments having axillary bud, taken from field-grown plant, showed bud-break within 15 days of culture on modified Murashige and Skoog (MS) (Physiol Plant 15:473-497, 1962) medium supplemented with 0.25 mg/l each of 6-benzylaminopurine and indole-3-acetic acid along with 15 mg/l adenine sulphate (AdS). Regenerated shoots could be further multiplied on the same agarified morphogenetic medium in presence of 0.5 mg/l 2-chloroethyltrimethyl ammonium chloride with increased concentration of AdS, i.e., 30 mg/l. A group of five shoots used as inoculum produced on an average 4.98 new shoots per original shoot after 4 weeks of subculture. Shoots excised from cultures of proliferating shoots were rooted in half-strength MS medium having 1 mg/l indole-3-propionic acid. In vitro rooted shoots-plantlets-grew luxuriantly under field conditions and came to flowering after 10 months of transplantation. The genetic fidelity of in vitro-raised field-grown plants and their mother plant was ascertained by random amplified polymorphic DNA markers. The protocol developed holds good for in vitro cloning of C. serratum.

An efficient in vitro process for rapid production of cloned plants of Uraria picta has been developed employing nodal stem segments taken from field-grown plants. Explants showed bud-break followed by regeneration of shoots with restricted growth within 12 days on modified Murashige and Skoog's medium supplemented with 0.25 mg l(-1) each of 6-benzylaminopurine and indole-3-acetic acid and 25 mg l(-1) adenine sulfate. Normal growth of shoots with good proliferation rate was achieved by reducing the concentrations of 6-benzylaminopurine and indole-3-acetic acid to 0.1 mg l(-1) each and incorporating 0.5 mg l(-1) gibberellic acid in the medium in which, on an average, 19.6 shoots per explant were produced. Further, during successive subcultures, increased concentrations of adenine sulfate (50 mg l(-l)) and gibberellic acid (2 mg l(-l)) along with the addition of 20 mg l(-l)  DL: -tryptophan were found conducive to control the problem of necrosis of shoots. In this treatment, several "crops" of shoots were obtained from single culture by repeated subculturing of basal portion of stalk in long-term. Isolated shoots rooted 100% in 0.25 mg l(-1) indole-3-butyric acid. In vitro-raised plants after hardening in inorganic salt solution grew normally in soil and came to flowering. Genetic fidelity of in vitro-raised plants was ascertained by rapid amplified polymorphic DNA (RAPD) markers. Also, quantitative estimation of two isoflavonones in their root extracts further confirmed true-to-type nature of plantlets.

Bean yellow mosaic virus (BYMV) is a prevalent virus and major threat to gladiolus cultivation the world over. In the gladiolus repository at CSIR-NBRI, Lucknow, several plants (82-88%) of three economically important cultivars were found infected by BYMV showing severe mosaic and stripe symptoms. Affected plants exhibit diminished quality and quantity of florets and corms, thus reducing their value. Attempts were made to eliminate BYMV from the infected gladiolus cormel explants in vitro through thermotherapy (37 °C for 30 days), chemotherapy (30 mg/L ribavirin for 30 days), and electrotherapy (30 mA for 20 min), either alone and in different combinations. The in vitro regenerated plants were free from BYMV infection when checked by RT-PCR using BYMV-specific primers. The combination of electro-and chemotherapies has given the best response as compared to other treatments. Among the individual therapies, electrotherapy (30 mA/20 min) was found to be the best for and production of BYMV-free gladiolus plants (44-46%) with moderate regeneration efficiency (54-58%) followed by chemotherapy and thermotherapy. However, the cormels obtained from a combination of electro-and chemotherapy treatment (30 mA/20 min + 30 mg/L) has given highest virus free (46-52%) and highest therapy efficiency indices (56%) as compared to other treatments. Further, these cormels showed better developed root systems and produced more cormels which were larger in size as compared to the other treatments and control when grown in tissue culture media.

Canna (Canna indica L.) is an ornamental landscape plant used specially for the garden borders and beds. It grows in tropical and subtropical countries including India. Canna is a less explored crop, mainly because it is a slow growing monocot with extremely hard seed coat and difficult to establish in vitro, as bacterial contamination is carried through the soil-grown rhizome. Many cultivars (ca. 150) of canna are being maintained in the garden germplasm of National Botanical Research Institute. To obtain 100% in vitro seed germination, chipping off of seeds with a sterilized nail clipper and soaking for 24-48 h or until radical emergence was a prerequisite. To obtain a foolproof tissue culture protocol of canna, in the present study, shoot multiplication was obtained through rhizome axillary buds. Among semisolid, liquid submerged and liquid media with glass beads, the highest multiplication of shoots (10) was obtained in liquid media with glass beads in 'Canna Flaccida' cv. within 6 weeks of culture incubation. During a comparative analysis of shoot regeneration among ten most attractive selected cultivars of canna, two did not respond, whereas a significant difference was obtained among eight cultivars. The regenerated shoots were rooted, acclimatized, and transferred to the pots, where they grew normally.