| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1991: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1990: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1989: ¥5,500,000 (Direct Cost: ¥5,500,000)
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| Research Abstract |
The present study was undertaken to describe the cytopathic processes occurring in viroid-infected cells and to demonstrate the mechanism of pathogenesis specific to viroid infection. By using citrus exocortis viroid (CEVd), hop stunt viroid (HSVD) and apple scar skin viroid (ASSVd), following results are obtained.
1. Cytopathic changes in CEVd-infected tomato leaf cells.
Leaflets on terminal leaves bearing severe rugosity showed the undulated cell wall, disorganization of chloroplasts, mitochondrial disintegration etc. In the leaflets on 5th leaf bearing mild curling symptom, however, no specific symptoms were observed.
2. Cytopathic changes in HSVd-infected resin glands of hops.
In hop plants, there have been formed two kinds of resin glands, i. e., disk-shaped gland and cup-shaped gland. Typical cell wall distortion and disorganization of subcellular organella were predominatly observed in the infected secretory cells of both the glands. Moreover, it was evident in the infected cells that resinous substance (alpha acid) could not fully liberated into subcuticular space, thus the cup could not filled with lattice-like structure, suggesting the decrease in extracellular secretion of alpha acid.
3. Cytopathic changes in ASSVd-infected fruit skin of apple.
The cell shapes of fruit skin (epidermis and hypodermal layers) of the infected apple fruit (cv. Indo) were severely distorted and their cell walls were undulated with irregular thickness. In the hypodermal layers, it was noticeable that pectic substances could not accumulated into the intercellular space. thus resulting in the flattened hypodermal cells.
4. To be summarized.
The results mentioned above indicated to suggest that cell wall distortion in the leaf cells, secretory cells and fruit skin cells consistently leads to the sequential processes of the structural deformation of cell skeltones which are disturbed as a consequence of viroid infection.
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