| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1987: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Research Abstract |
In the majority of angiosperms, the primary root has an exogenous origin. Its development does not effect any tissue disintegration, because the root cap in formed by periclinal divisions of the primary dermatogen, the outermost cell-layer of the embryo. An exceptional case is the first embryonal root of Gramineae. It dissolves the surrounding tissue and makes a cavity which separates the root cap and the outermost envelop, the coleorrhiza. In the embryo of Coix, four root primordia develop successively within a common cavity and a common coleorrhiza. All of them are endogenous and no strctural difference was observed among them.
During the embryogenesis of Commlina, the root cap of the primary root is initiated exogenously from the dermatogen. However, it grows later in a peculiar way. Shortly after germination, some cells within the lateral region of the root cap begin to dissolve by autolysis, forming a cavity. By the enlarging cavity the root cap is separated into an inner and an outer part. The inner part adheres to the root body, but the outer part is pierced by the growing root body, finally spreads off and forms an umbraculiform appendage at the hypocotyl base. It seems possible to consider this mode of development to be intermediate between exogenous and endogenous root formation.
Embryos of Habenaria and Platanthera (Orchidaceae) were cultivated in sterilized nutritious medium. Protocorms, adventitious roots and tuberous roots were investigated morphologically and anatomically. Shoot apex of the main axis is enclosed by proximal part of the tuberous root primordium. Then the tuberous root grows, together with the shoot apex, out of the plant body through a broken hole of the stem.
The author endeavored to draw anatomical figures of these reports by computer graphics. But the sortware programming is not yet completed. He has a plan to make additional reports in the following years.
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