Cost-effective tissue culture protocols have been established for the commercial multiplication of three banana varieties, ‘Rasthali’ (AAB – Silk), ‘Grand Naine’ (AAA – Cavendish), and ‘Udhayam’ (ABB – Pisang Awak). Reverse osmosis water and 3% (w/v) table sugar were used as the low-cost water and carbon source, respectively. Six different gelling agent treatments were tested: sago alone (T1), Isabgol alone (T2), sago + agar (T3), Isabgol + agar (T4), sago + Isabgol (T5), and agar alone as a control (T6). Full-strength Murashige and Skoog (MS) medium supplemented with 3 mg l^–1 6-benzylaminopurine (BAP) and 1 mg l^–1 indole-3-acetic acid (IAA) were used for culture initiation and subculturing. Rooting was accomplished on low-cost MS medium containing 1.0 mg l^–1 α-napthaleneacetic acid (NAA), 1.0 mg l^–1 indole-3-butyric acid (IBA), and 250 mg l^–1 activated charcoal. Statistical analysis indicated that sago + Isabgol (T5) produced the maximum number of shoots (10 per explant) in ‘Udhayam’ and ‘Rasthali’, while sago alone (T1) produced the maximum number of shoots (6 per explant) in ‘Grand Naine’. The genetic stability of tissue-cultured banana plantlets produced using these low-cost substitutes was assessed using inter-simple sequence repeat (ISSR) markers. The results indicated that the ISSR profiles of the five treatments and the control (T6) were similar, indicating genetic stability using these cost-effective tissue culture protocols. Reductions in cost over the control (l^–1 of MS medium) ranged from 65% to 86%, while the per plant production cost was reduced by 12.5%–20.0%. Adoption of these treatments (T1–T5) as low-cost tissue culture protocols for in vitro propagation would reduce production costs significantly, leading to an expansion of the area planted with tissue-cultured banana, thereby increasing productivity.

Musa balbisiana is one of the progenitors of present-day bananas. The B genome from M. balbisiana has been a rich source of genes conferring resistance to various biotic and abiotic stresses, yet studies on this species are very limited. The present study analysed 29 pure M. balbisiana types (BB), collected from the Indian mainland and from the Andaman and Nicobar Islands, using RAPD markers. The total number of amplified fragments was 48, of which 39 showed polymorphism. A tree matrix based on these DNA markers was constructed using NTSYS software. The results clearly distinguished two clusters, one containing accessions from the Indian sub-continent, and the other, accessions from the Andaman and Nicobar Islands. The dissimilarity between these two clusters was more than 65%. From the results, we propose that M. balbisiana originated from one location, North Eastern India, but now has three distinguishable areas of diversity including the Andaman and Nicobar Islands.

Summary Natural transgression between Musa acuminata and Musa balbisiana, the well accepted progenitors of Musa spp., has led to the evolution of modern bananas and plantains with various ploidy levels and genomic constitutions. Silk is an important group of triploid, dessert bananas of bispecific origin (AAB). Though it has wide geographic distribution across the globe, the variability seems to be very limited. This study was undertaken with 25 Silk group representatives of both indigenous and exotic origins. The genetic variation and phylogenetic relationships were analysed using Random Amplified Polymorphic DNA (RAPD) markers. Out of the 80 primers screened, 34 primers produced reproducible bands and only four primers were selected for the polymorphic study. A total of 35 DNA fragments across all materials were amplified with four random primers, averaging 8.75 per primer. Within the amplified fragments, 18 showed polymorphism with an average of 4.5 per primer. The average polymorphism among the amplified products was 51.2% indicating the existence of considerable variation at the DNA level among the test accessions. Most of the commercial Silk clones formed only two clusters and the extent of variability ranged only between 0–30%. The results indicate, irrespective of wider distribution of Silk group members across the globe, the spectrum of variability is very narrow.