G. S. Virk

CALLUS INDUCTION AND PLANTLET REGENERATION IN WITHANIA SOMNIFERA (L.) DUNAL

SummaryCallus induction was observed from hypocotyl, root, and cotyledonary leaf segments, grown on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KN). Maximum callusing (100%) was obtained from root and cotyledonary leaf segments grown on MS medium supplemented with a combination of 2 mg l−1 (9.1 μM) 2,4-D and 0.2 mg l−1 (0.9 μM) KN. The calluses, when subcultured in the same medium, showed profuse callusing. However, these calluses remained recalcitrant to regenerate regardless of the quality and combinations of plant growth regulators in the nutrient pool. When hypocotyl segments were used as explants, callus induction was noticed in 91% of cultures which showed shoot regeneration on MS medium supplemented with 2 mg l−1 2,4-D and 0.2 mg l−1 KN. These shoots were transferred to fresh medium containing various concentrations and combinations of 6-benzyladenine (BA) and N6-(2-isopentenyl)adenosine (2-iP). Maximum shoot multiplication was observed after 60 d of the second subculture on MS medium containing 2 mg l−1 (8.9 μM) BA. These shoots were rooted best (87%) on MS medium containing 2 mg l−1 (9.9 μM) indole-3-butyric acid (IBA). The plantlets were transferred to the field after acclimatization and showed 60% survival.

Micropropagation of coleus blumei from nodal segments and shoot tips

A rapid and highly-effective method for micropropagation from nodal segment and shoot tip explants was established for Coleus blumei Benth. Nodal segments and shoot tips were inoculated on MS medium containing 0.7 % agar, 3 % commercial sugar, and different combinations of 6-benzyladenine (BA) with indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or α-naphthaleneacetic acid (NAA). Hundred percent shoot induction from both explants was achieved on the medium containing BA (2 mg dm−3) and NAA (1 mg dm−3). Shoot tips were proved to be the better explant in comparison to nodal segments in having high rate of shoot induction and more number of shoots. The same media conditions were found suitable for shoot multiplication. Multiplied shoots rooted best on MS medium supplemented with IBA (2 mg dm−3). Micropropagated plants were successfully established in soil after hardening, with 100 % survival rate.

Indexing Tools for Indian Citrus Ringspot Virus (ICRSV)

Indian citrus ringspot virus (ICRSV) is known to cause serious disease problem in Kinnow (Citrus nobilis LourC. deliciosa Tenora). This paper reports the various methods viz. Bioassay, ELISA and RT-PCR for indexing of ICRSV. Bioassay was performed on Chenopodium amaranticolor, Cucumis sativus, Nicotiana glutinosa, N. tabacum, Pe- tunia hybrida and Phaseolus vulgaris. However necrotic local lesions were observed only in case of Chenopodium ama- ranticolor and Phaseolus vulgaris. Infected trees were also found positive by indirect ELISA. RT-PCR of the infected plants showed an amplification of 539 bp fragment corresponding to coat protein gene and gene for nucleic acid binding protein.