A Scanning Electron Microscope Study on Japonica Type Rice Callus Cultures, with Emphasis on Plantlet Initiation

[摘要] Morphological details of rice callus cultures were examined at the initial stage of plantlet development, together with the growth of callus established from mature seeds, with the aid of scanning elcctron microscopy. The observations revealed an occurrence of small knobs on the scutellum region of intact embryos inoculated on a callus induction medium. When transferred to a shoot-forming medium, the callus cultures gradually exhibited sequential changes in the surface structure and finally developed shoots and roots. A mucilaginous membrane layer interestingly covered the surface of globular structure developed on callus cultures. Fibrillar materials interconnected among the cells exposed where this layer was torn. As the callus growth progressed into more advanced stage, the surface structure transformed into a stabilized appearance from fragile nature and enlargement of nodules occurred showing slightly undulated, smooth faced structure. After then, leafy structures emerged on epidermis-like callus surface. They were laminated or cylindrical shapes attending with trichomes and wart-like structures. After these diverse structures appeared, a shoot-like structure finally ensued. And also, apart from the sites of a leafy structure and a young shoot, adventitious roots emerged from the inside of callus masses, and root hairs and root cap-like structures clearly developed.

[学科分类] 农业科学（综合）

[关键词] Callus;イネ;Japonica type rice;塊状構造;Membranous layer;カルス;Nodular structure;茎葉形成;Oryza sativa;走査型電子顕微鏡;Scanning electron microscopy;日本型イネ;Shoot-bud formation;薄膜層;Surface stabilization;表層の安定化