Sexual Reproduction in Flowering Plants

Special modesapomixis, parthenocarpy, polyembryony

  1. Apomixis occurs through vegetative propagation and Agamospermy in which vegetative reproduction produces new plant from buds, leaves and stem and there is no requirement of seed.
  2. Agamospermy is of three types
    (i) Recurrent agamospermy
    (ii) Adventive embryony
    (iii) Non-recurrent agamospermy
  3. A diploid embryo-sac is formed having diploid egg cell which grows into a diploid embryo, Termed as re-current agamospermy. Eg: Apple, Allium.
  4. In adventive embryony, one or few extra embryos are formed from diploid cells of nucleus (or) integument but never from egg. Eg. Opuntia, citrus.
  5. Embryo develops parthenogenetically from haploid egg, synergid, antipodal cells is termed as Non-recurrent agamospermy.
  6. Diplospory and Apospory are the sub-types of recurrent agamospermy.
  7. In diplospory, a diploid embryo sac is formed from diploid megaspore mother cell without regular mitotic division.
  8. Apospory develops embryo from diploid nuclear mother cell.
  9. The phenomenon of having more than one embryo is called Polyembryony (Eg. group of ground nut, onion etc.) Which is of 2 types (i) simple and (ii) Adventive.
  10. Polyembryony due to fertilization of more than one egg is termed as simple.
  11. Formation of extra embryos through sporophytic budding is called as adventive polyembryony.
  12. The other two types of polyembryony are false and true wherein false type, more than one embryo arise in different embryo sacs in the ovule.
  13. If more than one embryo is formed in the same embryo sac in the ovule it is termed as true polyembryony.
  14. Development of fruits without fertilization is parthenocarpy, coined by Noll who also suggested that the parthenocarpic fruits are seedless
    Eg. Banana, guava, apple, pineapple.
  15. Parthenocarpy can be induced artificially by following methods: auxins, gibberellins, delaying pollination, use of powdered pollen grains and extracts.
  16. Parthenocarpic fruits don’t contain irritant seeds and are used for quicker food processing.

Part-1: Watch this video for the topic from 56:17 to 

Part-2: Watch this video for the topic from 0:11 to 11:27

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