Table 4.
Various explants used for cycad tissue culture and their regeneration
| Explant type | Species | Types of regeneration (variable with species) |
|---|---|---|
| Megagametophyte | Ceratozamia hildae, Ceratozamia mexicana, Cycas circinalis, Cycas revoluta, Dioon edule, Encephalartos altensteinii, Encepalartos umbeluziensis, Zamia fischeri, Zamia furfuracea, Zamia pumila (syn. Z. integrifolia) | Callus formed; or coralloid roots developed after callus formation or from spherical outgrowths; or embryoids formed; or seedlings grew. |
| Zygotic embryos (usually cut transversally or longitudinally or into blocks) | Cycas revoluta, Encephalartos cycadifolius, Encephalartos dyerianus, Encephalartos natalensis, Dioon edule, Zamia pumila (syn Z, latifoliata), Zamia latifolia, | Callus formation triggered with phytohormones; potentially leading to root or shoot or plantlet formation, preferentially from compact callus and somatic embryos (may require ABA for maturation). |
| Cotyledonary leaf sections or epicotyl sections from zygotic embryos | Cycas revoluta | Adventitious root and shoot formation medium- and phytohormone-dependent. |
| Cut, young leaf flushes of mature trees | Ceratozamia euryphyllidia | Somatic embryo production and plantlet conversion. |
| Seed cotyledon, plant scales and in vitro seedling shoot tips | Cycas revoluta | Shoot bud formation; or shoot tip growth. |
| Seedling epicotyl and hypocotyl (1 cm long) | Cycas revoluta | Callus proliferation only. |
| Root of seedlings | Stangeria eriopus | Production of compact white callus leading to leaf emergence. |
| Root or stem | Cycas guizhouensis | Callus formation. |
| Bulbil inner bulb-scales | Cycas revoluta | Shoot buds differentiated. |
aModified from Teixeira da Silva et al. (2014) where a full list of references is provided