Histological Observation on Callus Tissue Derived from Root-tuber of Sweet Potato.

[摘要] Histological aspects of the formation and growth of callus tissue derived from root-tuber of sweet potato have been reported in this paper. When the tissue disk which was obtained from root-tuber was placed on a White's medium containing 0.5% yeast extract and 2, 4-D (1 mg/1) or NAA (20 mg/1), it was recognized that the cell division which occurred in some starchy cells in the surface region of tissue disk induced the formation of meristematic tissue. Then, the meristematic tissue on the lateral side of tissue disk grew vigorously to form callus tissue which had layers of meristematic cells in the surface region. The obvious difference between 2, 4-D and NAA medium was observed in the structure of callus. Many "vascular bundle-like tissues" which were consisted of tracheid-like tissue and cambium-like tissue were observed in the callus on NAA medium. On the other hand, even tracheid-like element was scarcely observed on 2, 4-D medium. It was recognized that vascular system of the root differentiated in callus tissue did not connect with the above mentioned "vascular bundle-like tissue" of the callus, but was observed as closely connected with the secondary vascular bundle of root-tuber included in the original disk.

[学科分类] 农业科学（综合）