J Integr Plant Biol. ›› 1997, Vol. 39 ›› Issue (12): -.

• Research Articles •    

Changes of Freeze-Fracture Ultrastructure and 27 kD Polypeptide of Photosynthetic Membranes During the Germination of Lotus Seeds Under Light

Zuo Bao-yu, Li Guo-qing, Tang Chong-qin, Zhang Quan, Jiang Gui-zhen and Kuang Ting-yun   

Abstract: Investigation of freeze-fracture electron microscopy and analysis of polypeptide components of photosynthetic membranes from lotus (Nelumbo nucifera Gaertn. ) showed that the ultrastructural development of chloroplast photosynthetic membranes in the plumule were in concert with the changes of 27 kD polypeptide (LHC Ⅱ ) during the germination of lotus seeds under light. 1 ) Two days after germination, the thylakoid membranes of giant grana became destacked. Only endoplasmic fracture face of destacked thylakoid region (EF) and protoplasmic fracture face of destacked thylokoids (PF) could be observed with freeze-fracture electron microscopy. The majority was 30 kD polypeptide, but 27 kD was scarce. 2) Four days after germination, photosynthetic membranes changed from destacked type to small grana. At the same time, the particle density of the endoplasmic fracture face in the stacked thylakoid region (EFs) and protoplasmic fracture face in the stacked thylakoid region (PFs) began to develop and 27 kD increased while 30 kD decreased. 3) 6 to 8 days after germination, the unstacked membrane region was developed, the particle density of the endoplasmic fracture face in the unstacked region (EFu) and protoplasmic fracture face in the unstacked region (PFu) could be seen. The particles on EFs and PFs gradually appeared. In the meantime, 27 kD kept on increasing while 30 kD decreasing. 4) 10 to 12 days after gennination, fully developed stacked and unstacked photosynthetic membranes arranged orderly in the chloroplast. The density, size and distribution of particles on EFs, PFs, EFu and PFu developed nonnally. There were more and more 27 kD polypeptide, as 30 kD almost disappeared. It was significant that the ongoing changes of supramolecular architecture concured with the changes of the uhrastructure and the quantitative variations of 27 kD polypeptide. Thus not only proved that LHC II is the main internal factor which induce the membrane stacking, but also gave the evidence which indicated that sacred lotus possess an unique position in phylogeny of Angiespermae.

Key words: Lotus, Germination of lotus seeds under light, Chloroplast, Ultrastructure of photosynthetic membranes, 27 kD polypeptide

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