Establishment of a Standard Micropropagation Protocol for the Production of Uniform Planting Material in Musa Laterita (Section: Rhodochlamys).

Musa laterita is one of the dwarf statured, ornamental Musa species, which belongs to the section Rhodochlamys. It is immune to Sigatoka leaf spot and Fusarium wilt diseases and also exhibits tolerance to moisture deficit stress. Among the fungal diseases, fusarium wilt especially race TR4 is highly threatening the banana industry worldwide and hence the TR4 resistant gene should be identified on priority for use in banana improvement programmes. Though, it is a wild seeded type which can be easily propagated through seeds, the off springs are not genetically uniform making it unfit for any molecular analysis. In vitro micro propagation of ornamental banana including Musa laterita is limited due to poor multiplication rates compared to commercial cultivars. Therefore, the present study was undertaken to establish an in vitro protocol for plant regeneration from shoot tip explants. Efforts were made to enhance the multiplication efficiency using MS media fortified with BAP, TDZ, NAA, IAA and IBA in different combinations so as to obtain maximum numbers of plantlets in minimum duration. The plantlets produced would be used to study the molecular mechanism behind Fusarium wilt resistance (TR4), through transcriptome analysis.

Micropropagation of Hibiscus moscheutos L. ‘Luna White’: effect of growth regulators and explants on nuclear DNA content and ploidy stability of regenerants

Hibiscus moscheutos L., also known as hardy hibiscus, is valued for its medicinal and ornamental attributes. It is usually propagated via seeds or cuttings. The purpose of this investigation was to develop a dependable micropropagation for H. moscheutos ‘Luna White’. To that end, the effect of four explant types (leaf, root, node, shoot tip) and two growth regulators 6-benzylaminopurine (BA) and meta-Topolin (mT) (6-(3-hydroxybenzylamino) purine) on in vitro growth of H. moscheutos was investigated. Genetic stability of the in vitro grown plants was assessed using flow cytometry, and chromosome count was investigated. No shoots were obtained from leaf or root explants. An efficient protocol for micropropagation of H. moscheutos using two explant types, 2-node and shoot tip explants, and two cytokinins (BA and mT) capable of producing true-to-type regenerants was established. Both BA and mT can be used at 2 μM or 4 μM using either 2-node or shoot tip explants. No significant difference was found between the nuclear DNA contents of seed-derived and in vitro grown plants (P < 0.05). The mean 2C DNA and monoploid 1Cx-values of seed-derived plants were 3.25 ± 0.08 pg and 1.62 ± 0.04 pg, respectively, compared with 3.26 ± 0.06 pg and 1.63 ± 0.02 pg, respectively, for in vitro grown plants. The chromosome number of both seed-derived plants and regenerants was determined to be 2n = 2x = 38. The mature regenerants obtained were fertile and phenotypically similar to seed-derived plants.

Clonal propagation of Chrysanthemum morifolium ramat using various explants obtained from field grown plants

A reliable and rapid large scale micropropagation method has been established from the node, shoots tip and leaf explant of Chrysanthemum morifolium growing in field condition. Experiments were conducted to standardize the culture media with plant hormone for multiple shoot proliferation and rooting for obtaining plantlets with uniform characteristics like mother plant in terms of growth and habits. Different concentrations and combinations of auxins (IAA) and cytokinins (BAP, Kin) were used in MS for the above purpose. Maximum shoot regeneration was found in MS treated with 2.0 mg/l BAP both in node and shoot tip explants. In the above combination, nodal explants produced 16 initial shoots. Shoot tip explants produced 12 shoots and leaf segment produced 07 shoots. For in vitro rooting, different concentrations of IBA and NAA were used. Higher rooting percentage was recorded on MS fortified with 1.5 mg/l IBA. The rooted plantlets were hardened and successfully established in the soil. About 90% of the regenerated plantlets survived in the natural environment.

In vitro propagation of Nanorrhinum ramosissimum (Wall.) Betsche: A traditionally important medicinal plant

An efficient micropropagation protocol facilitates successful conservation and improvement of Nanorrhinum ramosissimum (Wall.) Betsche by biotechnological means. Shoot tip explants exhibited optimal organogenic response when inoculated on half-strength(1/2) Murashige and Skoog (MS) medium supplemented with kinetin (KN) and indole-3-acetic acid (IAA) (0.5 mg/L each). Shoot organogenesis was further enhanced when the multiplication medium was fortified with dextrose (1%) (2.6 shoots/explant; 7.9 cm shoot length). The regenerated shoots formed roots; however, the best rooting frequency (87%) was achieved on half-strength MS medium containing only IAA (0.5 mg/L). Four-week-old in vitro plantlets were acclimatized with 95% survival under greenhouse conditions. The regeneration protocol developed in this study can be utilized for germplasm conservation of this elite traditional medicinal plant.

Micropropagation of Citrus indica Tanaka using Shoot tips from Mature Trees

A study was conducted to standardize a protocol for in-vitro direct regeneration and mass multiplication of Citrus indica Tanaka using shoot tip explants excised from mature trees. Shoot tips were inoculated in MS medium supplemented with varying concentrations and combinations of cytokinins and auxins. MS media when fortified with BAP 0.5 mg/l and 0.5 mg/l BAP + 1.0 mg/l Kn were found to be the best treatments for shoot initiation while MS supplemented with 1 mg/l IBA; 0.5 mg/l NAA + 0.5 mg/l IBA and 0.5 mg/l NAA + 0.5 mg/l IAA were the best treatments for root induction. Among the different media used for hardening, 100 % survivability was obtained when plantlets were hardened using vermicompost as the potting medium. Subsequently, these plantlets were transferred to larger pots and acclimatization was achieved gradually in outdoor conditions. Plant Tissue Cult. & Biotech. 31(1): 13-23, 2021 (June)

In vitro Propagation of Two Tannia (Xanthosoma sagittifolium (L.) Schott) Cultivars from Shoot Tip Explants

This study was carried out to develop an in vitro propagation protocol for two tannia (Xanthosoma sagittifolium (L.) Schott) cultivars (green and purple), using shoot tip explants. Shoots were best initiated on the MS supplemented with 2.0 mg/l BAP. The highest number of shoot per explant (green tannia: 4.56 ± 0.35 purple tannia: 4.83 ± 0.26) was recorded on the MS supplemented with 2.5 mg/l BAP and 0.5 mg/l NAA. The longest shoot (green tannia: 3.92 ± 0.40 cm and purple tannia: 4.36 ± 0.46 cm) was recorded on the MS supplemented with 5.0 mg/l BAP, 1.0 mg/l Kn and 0.5 mg/l NAA. The highest number of roots per shoot (green tannia: 6.00 ± 0.74 and purple tannia: 5.83 ± 0.49) was obtained on the medium containing 2.0 mg/l IBA. The results of this study showed that tannia could efficiently be propagated in vitro by incorporating appropriate concentration of PGRs. Plant Tissue Cult. & Biotech. 31(1): 25-34, 2021 (June)

The Effect of MS Media Strength and Cytokinin in the Induction of Shoots from Shoot Tip Explants of Australian Finger Lime (Citrus australasica cv. Tasty Green)

The Australian Finger Lime (Citrus australasica) is a type of citrus from the Rutaceae family, endemic to the east coast of Australia. The finger lime, loaded with numerous vitamins and renders a unique taste, has also been backed by science to contain essential amounts of antioxidants that are beneficial for cell protection, immune response, cancer prevention, ageing, arthritis and prevention of kidney stones. Current propagation attempts still rely on conventional methods that are less efficient and resulted in the slow establishment of farms for finger lime especially for commercialization purposes. This study focuses on the induction of shoots from shoot tip explants using 6-Benzylaminopurine (BAP) and Kinetin. Aseptic explants were inoculated into Murashige and Skoog (MS) medium of full-strength and half-strength followed by full-strength MS media supplemented with different concentrations of BAP and Kinetin. Results obtained in this study showed no significant differences in terms of the number of axillary shoots produced between explants cultured in full and half-strength MS media. However, the highest number of shoots and increment in shoot length were obtained from MS media supplemented with 2.0 mg/L BAP with the values 1.80 ± 0.27 and 2.56 ± 0.36 cm, respectively. In conclusion, MS media supplemented with 2.0 mg/L BAP was found optimal in the induction of shoots and shoot elongation of C. australasica cv. Tasty Green.

In vitro propagation and cytological analysis of Sophora mollis Royle: an endangered medicinal shrub

Background Sophora mollis Royle (family Fabaceae, subfamily-Papilionaceae) is a multipurpose legume distributed in plains and foothills of the North-West Himalaya to Nepal and is facing high risk of extinction due to habitat loss and exploitation by the local people for its fuel and fodder values. Therefore, the present study was conducted to standardize a micropropagation protocol for Sophora mollis by using shoot tip explants and to study the meiotic chromosome count in the species. Results Multiple shoots were induced in shoot tip explants of Sophora mollis in Murashige and Skoog medium supplemented with different concentrations of cytokinins alone (BAP, TDZ, and Kinetin) and in combination with varying concentrations of NAA. MS medium supplemented with BAP (8.9 μM) was observed to be the optimal medium for multiple shoot induction and maximum 25.32 shoots per explant was obtained with average length of 4.5 ± 0.8 cm. In vitro developed shoots were transferred onto rooting media supplemented with different concentrations of auxin (IAA, IBA, and NAA). Maximum 86% rooting was observed in half-strength MS medium supplemented with 21.20 μM NAA with an average of 21.26 roots per culture. In vitro raised plantlets were adapted to greenhouse for better acclimatization and 60% plants were successfully transferred to the open environment. Based on the chromosome counts available from the literature and the current study, the species tend to show a basic chromosome number of x = 9. Conclusion The micropropagation protocol standardized can be helpful for the ex situ mass multiplication and germplasm conservation of the endangered species. Moreover, the ex situ conservation approach will be helpful in actively bridging the gap between ex situ and in situ approaches through the reintroduction of species in the wild. The cytological studies revealed the basic chromosome number x = 9 of the species.