The Influence of Thidiazuron on Direct Somatic Embryo Formation from Various Types of Explant in Phalaenopsis amabilis (L.) Blume Orchid

Advances in Somatic Embryogenesis in Vanilla (Vanilla planifolia Jacks.)

Somatic embryogenesis is an in vitro plant morphogenetic process due to cell totipotentiality to induce shoot regeneration. To induce this proliferation pathway, we used auxins such as 2,4-dichlorophenoxyacetic acid in combination with cytokinins. There are numerous somatic embryogenesis protocols for a great diversity of plants, including orchids, but none has been yet reported in Vanilla planifolia. Vanilla (V. planifolia) is propagated mainly asexually through cuttings. Under in vitro conditions, it is propagated asexually through direct and indirect organogenesis involving the use of various plant growth regulators in different concentrations. The cell response depends on explant type, culture medium used, and incubation conditions. Direct organogenesis involves de novo formation from differentiated cells; the indirect pathway develops from cell dedifferentiation that produces an explant called "callus." In most cases, this type of cell regeneration uses Benzyladenine. The explants most used in this pathway are shoots, roots, and protocorms, although some studies report the use of other types of explants, including leaves and seeds. Somatic embryogenesis in vanilla has been poorly studied partly because of the recalcitrance of this species. This work mentioned the advances in the in vitro morphogenesis of V. planifolia, mentioning the advantages and disadvantages of each morphogenetic pathway and its characteristics.

An Overview of Orchid Protocorm-Like Bodies: Mass Propagation, Biotechnology, Molecular Aspects, and Breeding

The process through induction, proliferation and regeneration of protocorm-like bodies (PLBs) is one of the most advantageous methods for mass propagation of orchids which applied to the world floricultural market. In addition, this method has been used as a tool to identify genes of interest associated with the production of PLBs, and also in breeding techniques that use biotechnology to produce new cultivars, such as to obtain transgenic plants. Most of the molecular studies developed have used model plants as species of Phalaenopsis, and interestingly, despite similarities to somatic embryogenesis, some molecular differences do not yet allow to characterize that PLB induction is in fact a type of somatic embryogenesis. Despite the importance of species for conservation and collection purposes, the flower market is supported by hybrid cultivars, usually polyploid, which makes more detailed molecular evaluations difficult. Studies on the effect of plant growth regulators on induction, proliferation, and regeneration of PLBs are the most numerous. However, studies of other factors and new technologies affecting PLB production such as the use of temporary immersion bioreactors and the use of lighting-emitting diodes have emerged as new tools for advancing the technique with increasing PLB production efficiency. In addition, recent studies on Phalaenopsis equestris genome sequencing have enabled more detailed molecular studies and the molecular characterization of plantlets obtained from this technique currently allow the technique to be evaluated in a more comprehensive way regarding its real applications and main limitations aiming at mass propagation, such as somaclonal variation.

High frequency in vitro regeneration of adventitious shoots in daylilies (Hemerocallis sp) stem tissue using thidiazuron

BACKGROUND

Daylilies are a lucrative crop used for its floral beauty, medicinal proprieties, landscaping, fire prevention, nutritional value, and research. Despite the importance, daylilies remain extremely challenging for multiplying in vitro. The response difficulty is exacerbated because a few good protocols for daylilies micropropagation are generally difficult to reproduce across genotypes. An efficient strategy, currently applied at Langston University, is to systematically explore individual tissues or organs for their potential to micropropagation. This article is a partial report of the investigation carried out under room environmental conditions and focuses on developing an efficient daylilies in vitro propagation protocol that uses the stem tissue as the principal explant.

RESULTS

In less than three months, using thidiazuron, the use of the stem tissue as the in vitro experimental explant was successful in inducing multiple shoots several folds greater than current daylilies shoot organogenesis protocols. The study showed that tissue culture can be conducted successfully under unrestricted room environmental conditions as well as under the controlled environment of a growth chamber. It also showed that splitting lengthwise stem explants formed multiple shoots several folds greater than cross-sectioned and inverted explants. Shoot conversion rate was mostly independent of the number of shoots formed per explants. The overall response was explant and genotype-dependent. Efficient responses were observed in all thidiazuron treatments.

CONCLUSION

An efficient protocol, which can be applied for mass multiple shoots formation using the daylilies stem tissue as the main explant, was successfully developed. This could lead to a broad and rapid propagation of the crop under an array of environmental conditions to meet the market demand and hasten exogenous gene transfer and breeding selection processes.

In vitro culture and characterization of the HSP70 gene on Vanda tricolor Lindley var. Suavis ‘Queen Maxima’

Vanda tricolor Lindey var. Suavis is an endemic orchid from Mt.Merapi, Yogyakarta Special Region, Indonesia. This orchid has beautiful flowers with unique patterns of white and purple spots, fragrant and can live in the slopes of Mt.Merapi which is a very active volcano. UGM in collaboration with the Netherlands carried out ex situ conservation of the V. tricolor Merapi through the self-pollination of orchids by the Queen of the Netherlands, Queen Maxima on March 11, 2020 at the UGM campus, Yogyakarta. In honor, the new generation of crosses is named Vanda tricolor var Suavis ‘Queen Maxima’. This study aims to produce mass quantities of the orchid and characterize the HSP70 gene in it. Methods: Standard in vitro culture for Vanda on MS, NP and VW medium, isolation of plant gDNA, PCR with V. tricolor HSP70primers and sequencing of amplicon DNA. The results showed that > 90 % of V. tricolor ‘Queen Maxima’ seeds germinated well in all media and the best on VW medium. V. tricolor has the HSP70 protein with PTZ00009 super family amino acid motif that 87 % similar to the HSP70 protein from the Phalaenopsis equestris orchid, which is probably the reason V. tricolor become superior to high temperature environments.