Tiêu đề 02. SEXUAL REPRODUCTION IN FLOWERING.pdf ✅

PRE FERTILISATION FERTILISATION PRE FERTILISATION MICROSPOROGENEIS DOUBLE - FERTILISATION POST- FERTILISATION Microspore Mother Cell or Pollen Mother Cell (2n) Mesiosis I Microspore Dyad Meiosis II Micropore Tetrad (n) Mitosis 2 – celled stage of Pollen grain Tube cell Generative cell Mitosis of Generative Cell 3 – Celled stage of Pollen grain sperm cell Mature Dehisced Anther mature Pollen grains Filament Anther Stigma Style Ovary Exine Intine Hard outer layer Inner layer Vegetative cell Generative cell POLLINATION Autogany (self – Pollination) Eg:- Sunflower Geitonogamy (Cross – Pollination) Eg:- Corn Xenogamy (Cross – Pollination) Eg:- Onion AGENT OF POLLINATION Abiotic Biotic Wind (Anemophily) Eg. Corn Cob Water (Hydrophily) Eg. Vallisneria Insects (Entomophily) Eg. Amorphophallus Birds (Ornithophily) eg. Hibiscus flower present treats to the animals in order to keep them coming back The usual floral rewards are nectar and Pollen grain. Many insects eat pollen or nectar without pollinating flowers, and are called pollen/ nectar robbers. OUTBREEDING ARTIFICIAL HYBRIDIZATION Avoiding synchronization Arranging the anther and stigma in opposite places Self – incompatibility Unisexual Flower production Floral Reward Pollen/Nectar Robbers Emasculation Removal of anthers before dehisce using forceps Preventing pollen Contamination by Covering flower using butter paper. Bagging Pollen – Pistil Interaction Pollen tube Release 2 Male gametes (cytoplasm of synergid) Nucleus of egg cell (syngamy) 1 gamete fuse with Produce Produce Develop into 1 gamete fuse with Two polar Nuclei at Central Cell Triploid Primary Endosperm Nucleus (PEN) Primary Endosperm Cell Becomes Endosperm Zygote Embryo develops into POST FERTILISATION EVENTS Endosperm Development Embryo Development Ovule (s) into Seed Ovary into fruits Dicotyledonous embryo (2 Cotyledon) • • • • • • Monocotyledonous embryo (1 Cotyledon) (Ovules inside the fruit called seeds) Mature Seeds Non – Albuminous Seeds eg, Bean Seeds Albumi- nous Seeds Eg. Corn seeds True fruits Eg Watermelon False fruits Eg Apple • The production of seeds without fertilization is known apomixis Eg. Asterace. Polyembryony is the presence of many embryos in a single seed. Eg. Citrus: Orange Endosperm cells are filled with nutritional reserves PEN undergoes successive division resulting in free nuclei, called free nuclear endosperm. Megaspore Mother cell (2n) Meiosis Megaspores (n) ONE Megaspore suruiues others, degenerate Mitosis 8 Nucleated embryo sac Antipodals Polar nuclei (2n) Eggcell(n) synergids Pollen Grain Wall POLLEN GRAIN Mature Pollen Grain APOMIXIS POLYEMBRYONY Ovule Pollen grain Transverse section pistil multicart- ellary pistil, Anatropous ovule SEXUAL REPRODUCTION IN FLOWERING PLANTS MEGASPOROGENESIS