Formation of calli and adventitious roots from mesophyll-and embryogenic callus-derived protoplasts of sweetpotato, Ipomoea batatas (L.) Lam
1993
Yoshinaga, M. (Kyushu National Agricultural Experiment Station, Chikugo, Fukuoka (Japan)) | Komaki, K.
To apply the technique of cell fusion and gene transfer including electroporation to sweet potato, Ipomoea batatas (L.) Lam., it is needed to establish a reliable method for protoplast culture and plant regeneration. Some experiments were performed on the isolation and culture of protoplasts from mesophyll cells as well as from embryogenic callus. Colony formation from mesophyll protoplasts was observed after 50 days of culture in Murashige and Skoog (MS) medium supplemented with 0.1 mg/l and 0.5 mg/l of zeatin. Zeatin proved to be superior to kinetin because it induced continuous cell division and colony formation. The colonies grew into micro-calli of 2-3 mm in diameter within two months after planting. Adventitious roots were formed on the micro-calli in all combinations of growth regulators. However, no shoot morphogenesis occurred on the micro-calli. The concentrations of 2.4-D influenced the occurrence of embryogenic calli from shoot apices of 70 genotypes. The effects of 2,4-D varied among the genotypes. Sufficient numbers of protoplasts could be obtained from embryogenic callus of I. batatas var. White Star. Successive cell division of these protoplasts resulted in the formation of small calli. Low 2,4-D and high kinetin concentration favored small calli formation. However, they failed to grow and produce regenerated plants under these conditions
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