Asymbiotic Germination and Low-temperature in Vitro Conservation of Cymbidium Dayanum

[Objective] The aim of the research was to establish asymbiotic germination and low-temperature in vitro conservation technique system of Cymbidium dayanum by using plant tissue culture technique to realize its rapid propagation and long-term conservation in vitro. [Method] With mature seeds of C. dayanum as explants, different media were selected to establish asymbiotic germination technique system. With protocorms as materials, conservation, resumptive proliferation and plant regeneration conditions were selected to establish low-temperature in vitro conservation technique system preliminarily. [Result] Mature seeds of C. dayanum could germinate after cultured 90 days on MS media as well as ＂Hyponex 1＂ media. The germination rate reached more than 98%. Protocorms inoculated in ＂Hyponex 1＂ media could be conserved continuously at 5 ℃ in dark for more than 18 months and the survival rate could reach 90%. Conserved protocorms could realize resumptive preliferation culture both on 1/2 MS and ＂Hyponex 1＂ media. The seed- ling-strengthening and rooting media were 1/2 MS media. [Conclusion] This research provided practical basis for in vitro conservation and rapid propagation of C. dayanum germplasm resource.

Importance of Plant Biodiversity and Long-Term Conservation of Plant Genetic Resources via Biotechnological Strategies

Although climate changes are predicted to be an increasingly dominant threat to plant biodiversity, the degradation of ecosystems witnessed to date has been largely driven by factors such as human-induced habitat loss and fragmentation, overexploitation, pollution and the introduction of invasive species. Given the evidence that climate changes and anthropogenic pressures have greatly increased the extinction of natural populations of species, we can recognize that human-induced land use and climate changes are perhaps the greatest threats to terrestrial biodiversity. In this context, effective prioritization of conservation efforts is critical for the sustainability of biodiversity, as current environmental changes are likely to continue in the future. Countries with limited financial resources for conservation projects may be at greater risk from habitat loss, direct harvesting and invasive species, and may also lead to unsustainable exploitation of resources, further accelerating species loss through direct harvesting and causing rapid loss of biodiversity. In this context, the protection of biodiversity is an important issue that concerns the entire world population. Causes such as anthropogenic pressures, great fires, introduction of new species from different regions, invasion of cultivars and dominant species cause a dramatic impact on plant biodiversity as well as an increase in the number of threatened species. Plant biodiversity constitutes the natural source of products used in the food and pharmaceutical industries and also provides basic different raw materials. On the other hand, plant biodiversity is important in the development of species and more productive species that are more resistant to biological and environmental stresses, and in providing new genetic information for feeding programs. Advances in plant biotechnology, particularly in vitro cultures and molecular biology, have been a powerful tool in the control and conservation of plant biodiversity. Today, biotechnological methods include the most suitable methods for the pathogen-free short-, medium- and long-term preservation of ornamental plants, medicinal and aromatic plants and woody species that are in danger of extinction. In vitro conservation strategies are especially important in the protection of plant species that are vegetatively propagated and have seeds that are intolerant to desiccation. In addition, in vitro techniques provide a reliable platform for the international exchange of plant material, enable the creation of large collections using minimal space, enable the acquisition of valuable materials for wild species recovery, and facilitate molecular research and ecological studies.

Regeneration of Cytologically Stable Plants Through Dedifferentiation, Redifferentiation, and Artificial Seeds in Spathoglottis plicata Blume.(Orchidaceae)

Spathoglottis plicata Blume. is a horticulturally important vulnerable ground orchid with beautiful flowers blooming round the year. Highfrequency protocorm-like body(PLB) formation was established via callus culture from vegetative tissues of in vitro germinated seedlings of S.plicata. Media containing MS salts and Gamborg's B5 vitamins supplemented with 1.0 mg·L^(-1) 2,4-dichlorophenoxyacetic acid(2,4-D), 3.0 mg·L^(-1) α-naphthaleneacetic acid(NAA), 1.0 mg·L^(-1) kinetin(KIN), and 10%(v/v) ‘Aloe vera gel'(Av G) were effective in fragile calli induction. A maximum of(22.3 ± 0.52) PLBs were induced from about 250 mg callus within 45–55 days in the presence of 2.0 mg·L^(-1) NAA and 3.0 mg·L^(-1) 6-benzylaminopurine(BAP). Briefly, 3.0% sodium alginate was found to be most suitable for the formation of an appropriate shape and good germination rates(86.7%)of artificial seeds. Out of three different temperatures(4, 15, and 24 °C), the best result was achieved at 4 °C with 66.7% germinability even after90 days of storage. Plantlets were acclimatized with 86.6% survival rate and 76.3% of these plants produced flowers within 12–15 months of field transfer. Chromosomal studies revealed cytological stability of all regenerants containing 2 n = 40 chromosomes as in the parental plants.The present protocol can be applied reliably for the purposes of large-scale commercial propagation and short-term conservation of this orchid.