高級(jí)植物生理學(xué)課件第七章植物的生殖生理-資料下載頁
2025-01-16 01:26本頁面
【正文】 encarpel sepalpetalpetalsepal Q u ickT ime ? a n d aT IF F (L Z W ) d e co mp re sso ra re n e e d e d to se e t h is p i ct u re .58 The “ABC” model for flower development ? The ABC genes function in the distinct fields. ? The A and C genes are mutually exclusive in their expression. A B C AP1, AP2 AP3, PI AG 59 The A genes: ap1 or ap2 mutants should (and do) make carpelstamenstamencarpel ap1 or ap2 WT 60 The B genes: ap3 or pi mutants should (and do) make sepalsepalcarpelcarpel WT ap3 or pi 61 The C genes: ag mutants should (and do) make sepalpetalpetalsepal WT ag MADSbox proteins (MCM1, AG, DEF, SRF) Plant MADSbox proteins belong to two large families: ? the type I class, which group with the human SRF protein, ? and the type II class that groups with yeast MEF2 ABCE model (A)BC model 66 Gametogenesis and Fertilization Flower an function: 67 generative cell Diploid pollen mother cells undergo meiosis to produce a tetrad of haploid microspores. Each microspore develops into a pollen grain containing two haploid cells (mitosis I): ? the generative cell (small) ? The vegetative cell (large) Male gametogenesis 68 ? the vegetative cell grows to produce the pollen tube ? the generative cell produce 2 sperm cells (mitosis II) 69 an ovule primordium emerges as a bump on the inner wall (placenta) of the ovary the megasporocyte undergoes meiosis to produce 4 haploid cells, only one of which (the megaspore) survives. Female gametogenesis 70 placental wall Female gametogenesis the megaspore undergoes 3 mitotic divisions to produce 8 cells: ? 3 antipodal cells ? 2 synergid cells ? 2 central cell nuclei ? 1 egg cell (EC) 71 Female gametogenesis placental wall 72 Double fertilization Pollens land on the stigma, hydrate, and begin to germinate the pollen tube 73 Pollen tubes grow, by tip growth, down through the stigma and style and into the ovary, toward the ovules. The pollen tube navigates to the micropyle and discharges the two sperm cells. 74 ? One sperm fertilizes the egg cell to develop into the embryo. ? the other sperm fertilizes the diploid central cell nucleus to develop into the endosperm. Micropyle Egg Synergids Antipodal cells Central cell nuclei Sperms Pollen tube Ovule Double fertilization 75 Plant reproduction Ovule (1 to many) Ovary Silique（長(zhǎng)角果） 76 Fruit development ? The ovary and other tissue together produce a fruit. ? Fruit is important for seed dispersal in many species ? Many foods are also called “vegetables”: tomatoes, pea , squash ? Fruit size, texture, and sugar content are determined by genes. ? Ethylene stimulates fruit ripening. 77 Life cycle of a flowering plant 2n 2n 2n 2n 1n 2n
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