Elimination of BBTV via a systemic in vitro electrotherapy approach.

Banana bunchy top virus (BBTV) is the most destructive etiological agent limiting banana cultivation areas globally. This study attempted BBTV elimination by traditional shoot-tip culture (control) and alternative shoot-tip + electrotherapy (treated) techniques. Shoot-tip culture from Musa acuminata cv. 'Grand Naine' infected sources were exposed to 100 mA electric current for different time intervals (20-60 min). Virus indexing (via PCR) and genetic fidelity (by ISSR assay) from the cultures were tested, alongside the physio-biochemical parameters. Exposure of electric current for less than 50 min was ineffective for BBTV elimination. Still, a rise in the duration from 50 min or more led to eradicating the virus from some explants. Elimination of BBTV was complete from 100 % of explants exposed to 100 mA for 60 min, as confirmed by lack of BBTV detection even at six months after acclimatization. In the control treatment, the maximum efficiency of BBTV elimination was 28 % after eight subcultures. On the other hand, improved survival % was observed in the treated culture. Moreover, homogenous ISSR patterns were there between the treated and the mother plant and similar physio-biochemical activities were seen in electro-exposed cultures and healthy ones. Thus, the study reports complete BBTV-elimination from banana with international compliances, for the first time, via electrotherapy while maintaining genomic template and biochemical stability.

Lead Tolerance and its Accumulation by a Tree Legume: Dalbergia sissoo DC.

Dalbergia sissoo DC, a leguminous tropical timber tree has been investigated against the Pb toxicity; under the Pb-stress, plant's morphology, biochemical parameters and genomic template stability (GTS) screened in vitro. At the optimum Pb tolerance level (150 mg L-1), plant's defense mechanism-superoxide dismutase, catalase, ascorbate peroxidases and proline could trigger to achieve optimum vegetative growth with minimum fluctuations of the GTS. Further, D. sissoo roots could accumulate 2399.8 ± 16 mg kg-1 Pb. Scanning electron microscopy and energy dispersive X-ray spectrometer analysis also revealed the deposition of Pb in root tissues. In a 1 year pot experiment with Pb-contaminated soil, the plants exhibited normal growth, and Pb accumulation significantly enhanced by the amalgamation of citric acid in the soil. Thus, the tree may prove as a potential candidate for Pb phytostabilization.

In Vitro Mid-Term Conservation of Acorus calamus L. via Cold Storage of Encapsulated Microrhizome

ABSTRACT In vitro rhizome production, encapsulation and cold storage of Acorus calamus were attempted for its propagation and ‘true-to-type’ conservation. Shoot cultures were initiated using underground rhizome buds, on 6-benzyladenine (BA) containing Murashige and Skoog (MS) medium. Maximum microrhizome production was observed in presence of 33.3 µM BA, on modified MS medium containing 6% sucrose, 100 mg/L citric acid and 1 g/L polyvinyl pyrrolidone-40. Synthetic seeds were produced from regenerated microtubers by encapsulation in calcium alginate beads. These synthetic seeds were stored in complete darkness at 100C temperature for different durations for mid-term conservation. After cold storage, synthetic seeds were re-cultured in vitro, 100% survival was recorded after the storage of 1, 3 or 6 months; and 80% survival was observed after the storage of 12 months. The microrhizomes were produced roots in 4.9 µM indole-3-butyric acid containing half strength MS medium. All the regenerated plantlets were successfully transferred to field after acclimatization. It is the first report on successful one year in vitro cold storage of A. calamus.