Study On Cytoskeleton In Pollen And Pollen Tubes Of Ginkgo Biloba L.

Microtubules (MTs) and microfllaments (MFs) exist extensively in all eukaryotic cells as major components of cytoskeleton. They are involved in many essential cellular functions in plant cells. Pollen germination and pollen tube growth in which the MFs and MTs are important are crutial to complete sexual reproduction for seed plants. Now it is still absent from the report about MFs and MTs in relatively primitive gymnosperm. We investigated the MFs and MTs in germinated pollen and pollen tube of Ginkgo biioba L. known as 憀iving fossil? By the chemical fixation and fluorescent labeling, the study on MFs showed that there exist dense MFs network in germinated pollen and pollen tube of GingAv biloba L. and different distribution in different stage. We can also see there are circular MFs in germinated pollen and pollen tube. Compared to the F-actin distribution in germinated pollen and pollen tube of angiosperm, that of Gin.~sko biloba L. is mainly distinguished as following, (a). We found obvious spot in membrane where MFs concentrated in germinated pollen of Gingko biloba L.. (b). MFs network is rich in the apical dome of pollen tube, especially in the swollen pollen tube late during the pollen tube growth. In addition, a lot of fine MFs arrays are present in the cortical of the whole pollen tube and there scatter MFs in scarcely branched tube. (c). Investigation indicated radial dense F-actin arrays around the nucleus in germinated pollen and pollen tube and we supposed that the nLIcleLIsmaybe serve as a MFs organizing center. (d). When the tube nucleus changed its movement direction during pollen germination, the F-actin in pollen changed their distribution direction. Double labeling between MFs and myosin manifested co- localization occurred and also appeared around the tube nucleus. Those implied that MFs system was important during the change in the direction of tube nucleus. Using indirect immunofluorescence labeling, we found that MTs filled in germinated pollen and pollen tube of Ginkgo biloba L.. Most MTs were localized in the cortical of the pollen and pollen tube. In the pollen tube apex there was also thick MTs array network.