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Reproduction in flowering plants chapter 2
- 1. Chapter 2 Sexual Reproduction in flowering plants Pushpinderjeet Kaur 1
- 2. Summary- • Male reproductive unit • Female reproductive unit • Pollination • Out breeding devices • Pollen pistil Interaction • Artificial Hybridisation • Double fertilisation • Endosperm • Embryo development • Seed & its types • Fruit formation • Apomixis • Polyembryony Pushpinderjeet Kaur 2
- 3. *A flower is a shoot modified for reproduction. *It contain reproductive organs that forms gametes. ANDROCEIUM – male gamete—pollen grain GYNOCEIUM– Female gamete– ova/egg cell Pushpinderjeet Kaur 3
- 4. Parts of Flower • Calyx (sepal) • Corolla(petal) • Androceium • Gynoceium • Receptacle • Peduncle Pushpinderjeet Kaur 4
- 5. Male Reproductive Organ Structure of anther- i)Bilobed ii)Dithecous iii)4 microsporangia (pollen sacs) iv) Tetragonal (4 sided) •Connective tissue •Dehiscence of anthers Pushpinderjeet Kaur 5
- 6. Structure of Microsporangia • Microsporangium is surrounded by four walls- 1. Epidermis 2. Endothecium protection 3. Middle layers 4. Tapetum- nourishment Pushpinderjeet Kaur 6
- 8. Pushpinderjeet Kaur 8 POLLEN GRAIN DEVELOPMENT – MICROSPOROGENESIS
- 9. Male Gametophyte Pollen grain can withstand- • High temperature • Strong acids and alkali • Enzymes Pollen grains are -decay and chemical resistant Pushpinderjeet Kaur 9
- 10. Structure of pollen grains Pollen grain has two layers • Exine- sporopollenin • Intine- cellulose &pectin Pollen grain mature and contain two cells- • Vegetative cell- food reserve • Generative cell-forms two male gametes Pushpinderjeet Kaur 10 2 celled stage
- 11. Pollen grain • Can cause severe allergies (eg. Parthenium) • Bronchial afflictions • Can lead to asthma & bronchitis Pushpinderjeet Kaur 11
- 12. POLLEN PRODUCTS • Rich in nutrients. • Increase the performance of athletes (claim). • Taken in form of tablets & syrups. Pushpinderjeet Kaur 12
- 13. VIABILITY • Viability of pollen grains depends on temperature & humidity • Pollen grains can be stored in liquid nitrogen at -196 ˚C in POLLEN BANKS as part of PLANT BREEDING PROGRAM. Pushpinderjeet Kaur 13 SPECIES VIABILITY Rice & Wheat 30 min Rosaceae, Leguminoseae & Solanaceae Months (Cryopreservation)
- 14. Pushpinderjeet Kaur 14 FEMALE REPRODUCTIVE UNIT - CARPEL
- 15. Gynoecium • Female reproductive unit- Stigma , style and ovary. • Monocarpellary – Gynoecium with single pistil. • Multicarpellary – Gynoecium with more than one pistil. • Syncarpous - Fused pistils • Apocarpous – Free pistils Pushpinderjeet Kaur 15 Apocarpous ovary
- 16. Female Reproductive Unit Pushpinderjeet Kaur 16 @Sargunpreet Singh
- 17. MEGASPORANGIUM • Ovule attach to placenta by a stalk – Funicle • Ovlue fuses with funicle at a region – Hilum • Protective envelopes-Integuments • A small opening at tip – Micropyle • The basal part of ouvle, opposite to micropyle- chalaza • Mass of cells with abundant food reserve – Nucellus Pushpinderjeet Kaur 17
- 18. MEGASPOROGENESIS • The process of formation of megaspore from megaspore mother cell is known as megasporogenesis. • Megaspore (ovule) – Is the female gametophyte. Pushpinderjeet Kaur 18
- 19. Pushpinderjeet Kaur 19 Monosporic development Free Nuclear Division
- 20. Pushpinderjeet Kaur 20 Diagram of a mature embryo sac (8 nucelate 7 celled)
- 21. Pushpinderjeet Kaur 21 Pollination Self pollination Autogamy Geitnogamy Cross pollination Xenogamy *Xenogamy – ensures genetic recombination *Cleistogamous flowers are invariably autogamous.
- 23. • Cleistogamous flowers- bisexual which never open (commelina,oxalis, viola) • Assured set of seeds. Pushpinderjeet Kaur 23
- 24. Water pollination • Water pollination is seen in 30 genera of mocotyledons. • Pollens are long , ribbon like • Female flower stalk is coiled to reach the water surface to receive the pollen grains carried by water currents • Nectar and odour is absent • Pollen grains are light and unwettable due to presence of mucilage layer • Example – vallisneria, Hydrilla, Zostera Pushpinderjeet Kaur 24
- 25. Insect pollination • Colourful petals • Nectar • Fragrant • Sticky pollen • Some flower secrete foul odour to attract flies and beetles. Pushpinderjeet Kaur 25
- 26. Wind Pollination • Pollen grains are _______ (sticky/non sticky) • (heavy/light) • (dry/wet) • Stamens are _______ ( exposed/covered) • Stigma is ____ ( feathery / non – feathery) Pushpinderjeet Kaur 26
- 28. Yucca plant and Moth • Moth lays eggs in the locule of the ovary and flower and inturn get pollinated. • The larvae of the moth comes out of the ggs as the seeds starts developing. Pushpinderjeet Kaur 28