Tephrosia vogelli Hook. f. の雌ずい形成, 受粉および花粉管伸長に関する研究

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Gynoecial development of Tephrosia vogelii Hook. f. was studied to understand events before pollination and pollen tube growth. For anatomical observation, various developmental stages of gynoecium were fixed in Craf II, dehydrated in TBA series, infiltrated and embedded in paraffin. Serial sections of materials were made by rotary microtome at six to ten μm in thickness and stained with Safranin-Fast green. Stigmatic exudate and pollen tube growth were examined with histochemical methods. The gynoecium consisted of one conduplicated carpel. the style developed after the ovary reached a height of five mm. The distal part of gynoecium was curled backward at first, then developed into a long style ending in the stigma. The style formed a 90° angle with the long axis of the ovary. The cavity in the style was formed through disintegration of cells in the central part. The stigma differentiated into a secretory tissue covered by papillate epidermis and thin cuticle. In the ovary 14-18 campylotropous ovules were found. In the ovule, the slit of the outer integument was situated a distance away from the inner integument slit. The monosporous embryosac was of Polygonum type. As megagametogenesis occured, a large portion of nucellus disintegrated. Six days before anthesis the secretory tissue of the stigma produced an exudate, while the anther dehisced and released their pollen one day before anthesis. The stigma showed receptivity four days before anthesis. The histochemical tests showed that in the exudate carbohydrate, protein, and lipid were found. The pollen tube developed and penetrated the stigmatic and the transmitting tissues of the style. It then grew along the epidemal surface of the style and ovarial cavity, and from the outer integumental slit towards the inner integumental slit before it reached the vicinity of the egg. Fertilization occured two days after pollination. Direction of pollen tube growth in gynoecia seemed controlled by substance produced by ovule (Bhojwani and Bhatnagar, 1979). Some workers suggested that chemotropic response led pollen tube growth to the embryo sac (Swamy and Khrisnamurthy, 1980). Tilton et al. (1984) revealed that an obturator in soybean might control the direction of pollen tube growth by secreting a chemotactic exudate.
1993-06-01

Tephrosia vogelli Hook. f. の雌ずい形成, 受粉および花粉管伸長に関する研究

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