MECHANISM OF INTERCELLULAR MOVEMENT OF PROTOPLASM IN WHEAT NUCELLUS

Abstract

The outermost layer of the nucellus, immediately after it is carefully taken off from an immature wheat grain (reaching 1/2—2/3 its full size), can exhibit intercellular movement of protoplasm in vivo as has been recorded previously by us in cinemicrographs. The present investigation on its underlying mechanism with electron microscope and by physiological treatment substantiate the visual observation that the intercellular movement is carried out through the enlarged and open channels of the modified plasmodesmata by alternate vigorous contraction and expansion of the protoplasm. Acid phosphatase, presumably released from the lysosome nearby, can be detected in the vicinity of the channel and might be involved in the dissolution of its internal structure and enlargement of its aperture (200—300 mm or even larger). Low temperature (5—6℃), KCN (0.05M) and cytochalasin B (20μg/ml) can withhold the movement reversibly. The energy required for such movement is directly derived from ATP, as is evidenced by the high ATPase activity of the moving units, and the moving apparatus is closely connected with microfilament.