J Integr Plant Biol. ›› 1981, Vol. 23 ›› Issue (3): -.

• Research Articles •    

Intercellular Transport of Macro-Molecular Substances as a Means of Redistribution of Cellular Contents in Detatched Garlic Scape

Zhang Wei-chen, Yan Wen-mei, Chen Zi-qing and Lou Chen-hou   

Abstract: A detached garlic scape in long storage will eventually give rise to a whorl of freshy aerial cloves at its apex (Text fig. 2). This can only be brought about at the expense of the stalk proper, where withering starts from the lower end and extends gradually upward until the whole stalk is completely exhausted. The material transfer involved must be mainly concerned with the redistribution and reultilization of cellular contents from the senescing stalk to the growing cloves. The present systematic investigation on the whole process is primarily based upon serial microscopic and electronmicroscopic examination on conducting channels and withering parenchyma. Our previous investigations on garlic have shown that the exhaustive withdrawl of cellular contents from the senescing tissue is finally accomIished by intercellular movement of the partially disassembled protoplasm itself. The present result are essentially in agreement with such a general scheme. Light and electron-micrographs that show nuclear material and other macro-molecular substances tranversing through the plasmodesmata are rather common. The high resolving electronmicrographs have enabled us to detect the finer details in intercellular transport as given below: 1. Filamentous and fluffy material, somewhat similar in structure to P-protein in sieve tube, can be found in abundance in senescing parenchyma cells in which the demar- kations between protoplasmic components gradually become indistinct. The filamentous material is in transit through plasmodesmata between parenchyma cells and also between parenchyma and sieve tube (Plate Ⅱ, 16, 18). 2. Withdrawl of cellular contents from the deteriorating parenchyma may assume the form of vesicular transport through plasmodesmata (Plate Ⅰ 9, 10, 11). Some of the vesicles are simply filled with vacuolar sap; some fully packed with prefabricated material of maeromolecolar structure; and some actually loaded with disassembled protoplasmic fragments. 3. Fully packed vesicles as well as disassembled protoplasmie components (including disintegrated nucleus, degenerated mitoehondrion, etc.) may extrude into the intercellular spaces and may invade the vessel eavity (Plate Ⅱ, 12, 13, 20; Plate Ⅲ, 21, 22, 23, 24). The fine structure of the moving protoplasm in the vessel is quite distinct from that of the residual deposits which may cause plugging in the same cavity (Plate Ⅲ, 25, 26).

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