Encapsulation technology for short-term preservation and germplasm distribution of the African mahogany Khaya senegalensis

Abstract

A protocol was developed for short-term preservation and distribution of the medicinal and timber plantation tree, Khaya senegalensis, using alginate-encapsulated shoot tips. The study assessed the effects of culture medium, storage temperature, auxin concentration and planting substrate on shoot regrowth or conversion into plantlets of four different clones. Optimal shoot growth was obtained, with high frequencies (92-100%) of shoot emergence, on Murashige and Skoog (MS) culture media containing 4.4 lM benzyladenine (BA). Encapsulated shoot tips survived longer at 25°C than at 4°C, with viability of 73-88% after 8 weeks. Conversion into plantlets was achieved on half-strength MS medium by pre-culture treatment of shoot tips with 49-490 lM indole-3-butyric acid (IBA) before encapsulation. Treatment with 245 lM IBA provided 52-98% conversion, and 90-95% of plantlets survived acclimatisation under nursery conditions. To eliminate the in vitro culture step after encapsulation, synthetic seeds were allowed to pre-convert before sowing directly onto a range of ex vitro non-sterile substrates. Highest frequencies of plantlet formation from pre-converted synthetic seeds (42-86%) were obtained by transferring synthetic seeds to organic compost, and these plantlets exhibited almost 100% survival in the nursery without mist irrigation. Pre-conversion is a novel and convenient method for producing synthetic seeds that are suitable for distribution to commercial nurseries.

Alginate Encapsulation of Begonia Microshoots for Short‐Term Storage and Distribution

“…Furthermore, the improved germination percentage of encapsulated microshoots over control explants, even after a considerable amount of storage time, can be attributed to the inclusion of MS salts in encapsulation matrix, which serves as an artificial endosperm to the encapsulated microshoots for conversion to plantlets [ 35 , 36 ]. Hung and Trueman [ 37 ] reported that direct transfer of synthetic seeds of African mahogany ( Khaya senegalensis ) to nonsterile substrates was ineffective unless the seeds were allowed to preconvert (i.e., to form roots in vitro with the aid of growth regulators) prior to transfer as most of the seeds were contaminated with fungi within a week. However, in the current study, such an extra step was not required as synthetic Begonia seeds readily germinated, formed roots, and were easily acclimated when transferred to nonsterile peat-based media ( Figure 1(g) ).…”

Encapsulation of Shoot Tips and Nodal Segments for in Vitro Storage of “Kober 5BB” Grapevine Rootstock

“…In cryopreservation, this technique has been used for different species [32][33][34]. Moreover, various studies have described encapsulation for short and medium conservation (from 1 month to 1 year) without losing explant viability [35][36][37][38] and for increasing the interval between subcultures by reducing growth.…”

Aplicación de semillas artificiales como método de conservación in vitro de orquídeas

“…Entre estos limitantes se encuentra el pequeño tamaño y la delicada estructura de las semillas de orquídea, la ausencia de tejido nutricional y la necesidad de germinaciones simbióticas para su correcto desarrollo. Por su parte, las semillas artificiales están conformadas por una cubierta que tiene la función de garantizar la protección de los explantes (Hung & Trueman, 2011); dicha cubierta o matriz debe incluir nutrientes y otros factores de crecimiento, formando así un endospermo artificial; igualmente, debe proteger la semilla artificial durante el almacenamiento y manipulación sin afectar su estado natural (Jain et al, 2018), permitir la germinación del embrión o protocormo, no ser tóxica y preferiblemente ser biodegradable (Sankari et al, 2020). Para el caso de las orquídeas, la formación de un endospermo artificial es fundamental para el mejoramiento de su viabilidad y germinación.…”