被子植物生殖与生物技术幻灯片.pptVIP

(5) Chapter 38 Angiosperm Reproduction and Biotechnology 被子植物生殖與生物技術 To Be or Not to Be (??????) Overview: To Seed or Not to Seed The parasitic plant Rafflesia arnoldii Produces enormous flowers that can produce up to 4 million seeds Key Concepts Concept 38.1: Pollination enables gametes to come together within a flower (受粉作用使得花中的配子聚在一起) Concept 38.2: After fertilization, ovules develop into seeds and ovaries into fruits Concept 38.3: Many flowering plants clone (複製) themselves by asexual reproduction Concept 38.4: Plant biotechnology is transforming agriculture Concept 38.1: Pollination enables gametes to come together within a flower (受粉作用使得花中的配子聚在一起) In angiosperms, the dominant sporophyte (孢子體) Produces spores that develop within flowers into male gametophytes (pollen grains) (雄配子體、花粉粒) Produces female gametophytes (embryo sacs) (雌配子體、胚囊) Flower Structure Flowers Are the reproductive shoots of the angiosperm sporophyte (被子植物配子體) Are composed of four floral organs: Sepals (萼片) Petals (花瓣) Stamens (雄蕊) Carpels (雌蕊) 被子植物花的多樣性 Many variations in floral structure have evolved during the 140 million years of angiosperm history Gametophyte Development and Pollination In angiosperms (被子植物) Pollination (受粉作用) is the transfer of pollen from an anther (花藥) to a stigma (柱頭) If pollination is successful, a pollen grain (花粉粒) produces a structure called a pollen tube (花粉管), which grows down into the ovary (卵房) and discharges sperm near the embryo sac (胚囊) An overview of angiosperm reproduction Pollen (花粉)---Develops from microspores (雄孢子) within the sporangia (孢子囊) of anthers Embryo sacs---Develop from megaspores within ovules Mechanisms That Prevent Self-Fertilization (自我受精) Many angiosperms (被子植物) Have mechanisms that make it difficult or impossible for a flower to fertilize itself (自我受精) The most common anti-selfing mechanism in flowering plants Is known as self-incompatibility (自我排斥、自我不相容), the ability of a plant to reject its own pollen Researchers are unraveling t