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

Abstract

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.

Progress and Challenges in the Improvement of Ornamental Plants by Genome Editing

“…In addition, some results from orchid studies using CRISPR-Cas systems for genome editing have been recently released. Although plants belonging to the Orchidaceae, the second largest family of flowering plants, currently occupy an important position in global commercial floriculture crop production based on economic value [59], limited genomic sequence information on orchid species is available: genome information is available for Dendrobium catenatum [5], Dendrobium officinale [6], Gastrodia elata [60], Phalaenopsis aphrodite [61], and Phalaenopsis equestris [12]. Moreover, only a couple of studies involving genome editing by CRISPR-Cas systems have been reported in orchids.…”

Response of Phalaenopsis Orchid to Selenium and Bio-Nano-Selenium: In Vitro Rooting and Acclimatization

“…Orchid plants belong to family Orchidaceae which represents one of the two largest plant families (6-11% of flowering plant species), which include 736 -899 genera, 27,800 species and more than 100,000 hybrids worldwide (Cardoso et al 2020). Orchids also have several benefits besides its unquestionable importance from the botanical and ecological aspects, the most important cutflowers in the world commercial floriculture and for medicinal purposes (e.g., some species of the genera Dendrobium, Gastrodia and Bletilla) (Cardoso et al 2020). It is reported that orchids have a significant share of the annual sales of the global flower trade more than 4 billion US $ (Zhang et al 2018).…”

“…The seeds of orchid species do not have nutritional reserves and the endosperm is absent from the mature orchid seeds (Yeung et al 2018). Both the seedlings and seed embryos are mainly depending on the symbiosis food relationship with the mycorrhizae, which have the ability to nutritionally supply these plant species at early germination and for a long time till the complete establishment of the seedling under the natural environments (Cardoso et al 2020).The micro-propagation and traditional breeding have been used in several orchids to get the cut flowers and/or potted plants in horticultural markets (Wang et al 2019). Due to the growth nature of orchid roots, their rooting difficulty is one of the main problems facing propagation and production of orchids (Zhang et al 2018).…”

“…Concerning production of Phalaenopsis, the high difficulty of in vitro rooting is considered one of the most barriers facing the micropropagation of this plant. This obstacle may increase the production cost of micro-propagated plantlets of Phalaenopsis, which might lead to fall its profits in the international market (Cardoso et al 2020). It is worth mention that the germination rates of orchids in vitro are reported to be higher than 70%, whereas this rate in germinated seeds may hardly exceed 5% under the natural conditions and in ex vitro conditions (Cardoso et al 2020).…”

Effect of Benzyl Adenin on the Growth of Black Orchid ( Coelogyne pandurata lindl.) Planlets in in vitro Culture

“…Therefore, effective and efficient technologies for mass orchid propagation must be developed to meet commercial demands for successful orchid conservation [4]. Therefore, it is necessary to make efforts to conserve rare orchids and increase the production of black orchid seeds with plant propagation, both generative and vegetative propagation by in vitro culture [5] Currently available cultivation techniques for in vitro production of orchid seedlings or plantlets include asymbiotic germination and micropropagation techniques, which can be employed for the large-scale production of clonal plantlets [6]. Efforts to rescue and propagate black orchids have employed in vitro culture techniques, which enable rapid propagation of explants, preservation of germplasm and multiplication of plants that are difficult to reproduce conventionally [7].…”