Somatic Embryogenesis in Cymbidium through In Vitro Culture of Inner Tissue of Protocorm-Like Bodies

Abstract

SummaryEmbryogenic callus (EC) was initiated from inner tissue (IT) of protocorm-like bodies (PLB) of Cymbidium orchid cultured on Murashige and Skoog (MS) media supplemented with 1-naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D). EC was obtained within 15 days on a MS medium containing 2 mg• liter -1 NAA or 0.5 mg • liter -1 2,4-D which was the most effective among the concentrations tested. When EC were transferred to a hormone-free MS medium, they produced protocorms within one month and complete plants in another 3 months. In contrast, the EC, in the presence of BA or NAA, produced light green, hairless, string-like structures in one month. These string-like structures grew 2 to 3 cm in length and died within three months. IT produced no callus in hormone-free MS medium or in a medium to which BA and NAA were added. After 5 days of culture, with NAA or 2,4-D, a small mass of EC differentiated from the parenchyma cells of the vascular bundle on the basal cut end of IT sections. These ECs produced proembryoid-like structures after 10 days of culture; they became globular embryos 5 days later. The globular embryos differentiated into protocorms and plantlets after being transplanted to the hormone-free MS medium. These findings demonstrate that Cymbidium plantlets can be obtained from IT of PLB through somatic embryogenesis by manipulating the culture conditions.

Osmotic sucrose enhancement of single-cell embryogenesis and transformation efficiency in Oncidium

“…In most orchids, the process of somatic embryogenesis is part of the early steps of PLB formation (Begum et al, 1994). This is also true for explants of Oncidium Sharry Baby 'OM8'.…”

“…Instead, protocorm-like bodies (PLBs) are usually used as the target material for producing transgenic plants because of their easy maintenance and plant regeneration. Embryogenesis in Orchidaceae can be initiated from single or multiple cells (Begum et al, 1994;Chang and Chang, 1998;Ishii et al, 1998;Chen et al, 1999). Somatic embryos are usually from multiple cells, which results in a chimeric pattern in transformants (Park and Facchini, 2001).…”

Priming biotic factors for optimal protocorm-like body and callus induction in hybrid Cymbidium (Orchidaceae), and assessment of cytogenetic stability in regenerated plantlets

“…Since then protocols for the tissue culture of Cymbidium by using flower stalks (Wang, 1988), pseudobulbs (Shimasaki and Uemoto, 1990), flower buds (Shimasaki and Uemoto, 1991), shoot tips (Morel, 1960(Morel, , 1964Wimber, 1963;Sagawa et al, 1966;Ueda and Torikata, 1968;Kim and Kako, 1984) and PLBs (Begum et al, 1994b;Tanaka, 2004a, 2004b;Huan et al, 2004) have been described. Studies on callus induction are scarcer, attributed to their slow growth and necrotic tendency (Begum et al, 1994a). Although callus was shown to be inducible from pseudobulb sections, rhizomes and roots of seedlings of Cymbidium ensifolium, a terrestrial orchid species, growth was slow, difficult, timeconsuming (12-18 months) and required high levels of PGRs.…”

Embryogenic Callus Induction from Leaf Tip Explants and Protocorm-Like Body Formation and Shoot Proliferation of Dimorphorchis lowii: Borneon Endemic Orchid

“…Begum, Tamaki, Tahara, & Kako (1994) reported that callus formation from orchids used explants that contained meristematic cells or epidermal cells, suggesting that callus cells arise from these types of cells. Figure 3B shows the cross-section through the leaf tip explants which showed densely lower epidermis and mesophyll cells underwent dedifferentiation.…”