Nodal segments of Hibiscus
moscheutos (hardy hibiscus) were excised from proliferating axillary shoot cultures and encapsulated in high density sodium alginate hardened by 50mM CaCl2. Nodal segments 4mm long grew as well as and were easier to encapsulate than 8mm long nodal segments. Although nodal segments grew regardless of the concentration of sodium alginate, 2.75% was determined to produce the highest quality encapsulated nodal segments beads (sufficient alginate coating and ease of use) because of the viscosity produced by the 2.75% sodium alginate solution. When encapsulated segments were stored at 5°C they did not grow in light or darkness. During the first month on fresh proliferation medium under normal incubation conditions following 5°C storage in the dark for up to 24weeks, root number and root and shoot elongation were inhibited linearly as storage time increased. All encapsulated nodal segments survived 24weeks of 5°C storage in two separate experiments. In fact, 80% of encapsulated hardy hibiscus nodal segments survived refrigerated storage for 1½years (78weeks) and after 3months on proliferation medium, the nodal segments produced nearly the same length axillary shoots with the same number of axillary nodes per shoot as compared to encapsulated segments either not stored at 5°C or stored for 24weeks at 5°C. Growth from encapsulated and cold-stored ‘Lord Baltimore’ nodal segments was more vigorous than from ‘Southern Belle’ nodal segments.
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"Synthetic seed technology is an advancement in micropropagation (Naik and Chand 2006). Encapsulation of germplasm along with micropropagation can be used for in vitro conservation of endangered species (West et al. 2006). Synthetic seed consists of encapsulation matrix such as sodium alginate and vegetative part of plant like shoot tips, axillary buds and somatic embryos. "
[Show abstract][Hide abstract] ABSTRACT: Germplasm can be effectively stored in the form of synthetic seeds. Shoot tips obtained from in vitro shoot cultures of Stevia rebaudiana Bertoni were encapsulated in 4 % calcium alginate. The present work discussed the role of components of culture medium on morphogenic response of Stevia rebaudiana Bertoni encapsulated buds to various MS strengths and sugar alcohol (Mannitol or sorbitol) in different concentrations for long term storage. Germination ability of the synthetic seeds was investigated. Shoots were regenerated from nodal explants of Stevia through axillary shoot proliferation. The induction of multiple shoots from nodal segments was the highest in MS medium supplemented with 1.0 mg l−1 BA. Maximum shoot formation was obtained with fructose at 20 and 40 g l−1 fructose, while with fructose at 20 g l−1 gave the highest leaves number/explants). The longest shoot length obtained with sucrose and fructose than other sugar. Different media type (NN and WPM) were suitable for best shoot number of Stevia, leaf number and shoot length than other media. Growth of shoot was increased and observed in capsules stored for 5 weeks on MS than other MS strengths. The growth of capsules dependent on mineral concentration and storage time. The most suitable conversions of capsules was using 0.05 M mannitol after 6 weeks from storage of synthetic seeds of Stevia. For rooting, when Stevia shoots cultured on MS medium supplemented with IAA, at 0.2 mg l−1 resulted in the maximum number of roots/explant while, IBA at 1.0 and 2.0 mg l−1 resulted in longest root/plant and gave the same length of root.
"For example, it can be used in conjunction with micropropagation for in vitro conservation , germplasm storage, and reduction of the need for transferring and subculturing during off-season periods . Cold storage of encapsulated or synthetic seeds has the potential to reduce the cost of maintaining germplasm cultures as well as to reduce the possibility of genetic instability that could result from frequent subculturing  . The technology is particularly useful for the propagation of rare hybrids, elite genotypes, and genetically engineered plants whose seeds are either too expensive or not readily available . "
[Show abstract][Hide abstract] ABSTRACT: Synthetic seeds were formed from shoot tips of two in vitro grown Begonia cultivars using 3% sodium alginate in Murashige and Skoog medium (MS) salt solution as the gel matrix and 100 mM calcium chloride for complexation. Synthetic seed formation was achieved by releasing the sodium alginate/explant combination into 100 mM calcium chloride (CaCl2 ·H2O) solution for 30 or 45 min. Both control and encapsulated shoots were transferred into sterile Petri dishes and stored at 4°C or 22°C for 0, 2, 4, 6, or 8 weeks. Conversion of synthetic seeds into plantlets for both storage environments was assessed in MS medium or peat-based substrate. No significant difference was found between the 30 and 45 min CaCl2 ·H2O treatments or the two cultivars. Encapsulation of explants improved survival rate over time irrespective of the medium type or storage environment. Survival rates of 88, 53, 28, and 11% for encapsulated microshoots versus 73, 13, 0, and 0% for control explants were achieved in microshoots stored for 2, 4, 6, and 8 weeks, respectively. The best results were obtained when synthetic seeds were stored at 4°C and germinated on MS medium. Regenerated plantlets were successfully established in potting soil.
Full-text · Article · Dec 2013 · The Scientific World Journal
"Furthermore, they can be used for cryopreservation via encapsulation dehydration and encapsulation vitrification (Pennycooke and Towil 2001; Wang et al. 2002). During storage, encapsulated nodal segments requires no transfer to fresh medium, thus reduces the cost of maintaining germplasm cultures (West et al. 2006). Ruta graveolens (Rutaceae), commonly known as rue, is a strong scented medicinal and aromatic plant of Europe, mostly grown in the Mediterranean region (Anonymous 2003). "
[Show abstract][Hide abstract] ABSTRACT: Synthetic seeds technology is a potential tool
for an efficient and cost-effective clonal propagation system.
In the present study, synthetic seeds were produced by
encapsulating nodal segments (synthetic or synseeds) of
Ruta graveolens in calcium alginate gel. The best gel
complex was achieved using 3 % sodium alginate and
100 mM CaCl2.2H2O. Maximum conversion response of
synthetic seeds into plantlets was obtained on MS medium
supplemented with 10 lM 6-benzyladenine (BA) and
2.5 lM a-naphthalene acetic acid (NAA). Encapsulated
nodal segments could be stored at low temperature (4 �C)
up to 4 weeks with a survival frequency of 86.7 %. The
regenerated shoots rooted on MS medium containing
0.5 lM indole-3-butyric acid (IBA). Well-developed
plantlets with proper root and shoot system from encapsulated
nodal segments were hardened off successfully
with 90 % survival rate. The high frequency of plant
re-growth (conversion) from alginate-coated nodal segments
coupled with high viability percentage after 4 weeks
of storage is highly encouraging for the exchange of
R. graveolens genetic resources.
Full-text · Article · Oct 2012 · Acta Physiologiae Plantarum