Enhanced somatic embryogenesis in sorghum bicolor from shoot tip culture
Tóm tắt
Shoot tip cultures from 2- to 3-d-old seedlings ofSorghum bicolor (L.) Moench cv. IS3620C develop highly embryogenic callus from which plants can be regenerated when transferred to plant growth regulator-free medium. Isolated shoot tips were cultured on Murashige and Skoog medium supplemented with 2.5 mg/liter 2,4-dichloro-phenoxyacetic acid and 0.05 mg/liter kinetin. Purple pigmentation characteristic of sorghum cultures on growth regulator-free medium is virtually eliminated with the shoot tip culture. Embryogenic callus is white and hard with an undulating appearance but can be separated into multiple bipolar structures by application of gentle pressure. The well-developed embryos have a cup-shaped scutellum. These germinate like zygotic embryos and develop root-shoot axis. Lack of vascular connections to the parent tissue and the synchronous development of the plumule and radicle suggest that these embryos may be of unicellular origin. In contrast, when the entire seedling serves as the explant, all meristematic centers in the shoot, including the coleoptile sheath close to the apical meristem respond to plant growth regulators in the medium by callus formation. Upon subsequent reculture onto growth regulator-free medium several modes of development occur. The differential response of these tissues to identical culture conditions indicate the presence of different population of cells that respond differently to exogenous plant growth regulators.
Tài liệu tham khảo
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