Abstract:

Pathway of pollen tube growth and the duration of different phases of fertilization process were studied by paraffin sections and fluorescence microscope technique in 3 varieties of wheat. The results are as follows: Pollen grains germinate soon after pollination. 2 sperms enter pollen tube, leaving vegetative nucleus，which degenerates in pollen soon. Pollen tubes go into intercellular space of branched structure of penniform stigma, then go through the intercellular space of transmitting tissue from the base of style to the top of ovary, after that penetrate ovary wall and grow towards micropyle through the gap between ovary wall and primine. It is about 1h from germination to the arrival at micropyle. The pollen tubes show strong green fluorescence from germination to the arrival at the branched structure of penniform stigma, little fluorescence displays in the pollen tubes，which are in transmitting tissue and the gap between ovary wall and primine. 1 hour after pollination, pollen tube goes through the intercellular space of nucellar epidermis and enters one of the synergids, releases 2 sperms. 2–6 h after pollination, egg-sperm fusion occurs. 16 h after pollination zygocyte begins to mitosis. The fusion of sperm and two polar nuclei occurs. 2–3 h after pollination, and primary endosperm nucleus begins to divide 4h after pollination. Thus, 2–16 h after pollination, which is the duration from egg-sperm fusion to the beginning of zygocyte mitosis, should be the time for exogenous DNA transformation by the method of pollen-tube pathway. The operation is to cut style transversely and drop exogenous DNA on the transection.

Key words: Triticum aestivum L., Pathway of pollen tube growth, Fertilization, Pollen tube pathway