Gamete attachment process revealed in flowering plant fertilization |
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Authors: | Toshiyuki Mori Tomoko Igawa |
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Institution: | 1.Waseda Institute for Advanced Study; Waseda University; Tokyo, Japan;2.Graduate School of Horticulture; Chiba University; Chiba, Japan;#Present address: Department of Biological Sciences; Graduate School of Science; The University of Tokyo; Tokyo, Japan |
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Abstract: | Sex-possessing organisms perform sexual reproduction, in which gametes from different sexes fuse to produce offspring. In most eukaryotes, one or both sex gametes are motile, and gametes actively approach each other to fuse. However, in flowering plants, the gametes of both sexes lack motility. Two sperm cells (male gametes) that are contained in a pollen grain are recessively delivered via pollen tube elongation. After the pollen tube bursts, sperm cells are released toward the egg and central cells (female gametes) within an ovule (). The precise mechanism of sperm cell movement after the pollen tube bursts remains unknown. Ultimately, one sperm cell fuses with the egg cell and the other one fuses with the central cell, producing an embryo and an endosperm, respectively. Fertilization in which 2 sets of gamete fusion events occur, called double fertilization, has been known for over 100 y. The fact that each morphologically identical sperm cell precisely recognizes its fusion partner strongly suggests that an accurate gamete interaction system(s) exists in flowering plants.Open in a separate windowIllustration of the fertilization process in flowering plants. First, each pollen tube accesses an ovule containing egg and central cells. Next, the 2 sperm cells face the female gametes in the ovule after the pollen tube bursts. Finally, each sperm cell simultaneously fuses with either egg or central cell. |
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Keywords: | fertilization gamete attachment gamete fusion GEX2 male gamete sexual reproduction sperm cell |
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